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| -rw-r--r-- | doc/manual.html | 3575 |
3 files changed, 17 insertions, 3776 deletions
diff --git a/doc/contents.html b/doc/contents.html index 9ecf8ab..e549044 100644 --- a/doc/contents.html +++ b/doc/contents.html @@ -1,7 +1,7 @@ <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <HTML> <HEAD> -<TITLE>Lua 5.1 Reference Manual - contents</TITLE> +<TITLE>Teliva Reference Manual - contents</TITLE> <LINK REL="stylesheet" TYPE="text/css" HREF="lua.css"> <META HTTP-EQUIV="content-type" CONTENT="text/html; charset=utf-8"> <STYLE TYPE="text/css"> @@ -15,17 +15,15 @@ ul { <HR> <H1> -<A HREF="http://www.lua.org/"><IMG SRC="logo.gif" ALT="" BORDER=0></A> -Lua 5.1 Reference Manual +Teliva Reference Manual </H1> <P> -The reference manual is the official definition of the Lua language. -For a complete introduction to Lua programming, see the book -<A HREF="http://www.lua.org/docs.html#pil">Programming in Lua</A>. +This reference manual for Teliva is based on the official definition of the +Lua language. <P> -This manual is also available as a book: +Please support Lua by <A HREF="http://www.lua.org/donations.html">donating</A> or purchasing: <BLOCKQUOTE> <A HREF="http://www.amazon.com/exec/obidos/ASIN/8590379833/lua-indexmanual-20"> <IMG SRC="cover.png" ALT="" TITLE="buy from Amazon" BORDER=1 ALIGN="left" HSPACE=12> @@ -38,12 +36,6 @@ This manual is also available as a book: </BLOCKQUOTE> <P> -<A HREF="http://www.amazon.com/exec/obidos/ASIN/8590379833/lua-indexmanual-20">Buy a copy</A> -of this book and -<A HREF="http://www.lua.org/donations.html">help to support</A> -the Lua project. - -<P> <A HREF="manual.html">start</A> · <A HREF="#contents">contents</A> @@ -104,23 +96,6 @@ Freely available under the terms of the <LI><A HREF="manual.html#2.11">2.11 – Coroutines</A> </UL> <P> -<LI><A HREF="manual.html#3">3 – The Application Program Interface</A> -<UL> -<LI><A HREF="manual.html#3.1">3.1 – The Stack</A> -<LI><A HREF="manual.html#3.2">3.2 – Stack Size</A> -<LI><A HREF="manual.html#3.3">3.3 – Pseudo-Indices</A> -<LI><A HREF="manual.html#3.4">3.4 – C Closures</A> -<LI><A HREF="manual.html#3.5">3.5 – Registry</A> -<LI><A HREF="manual.html#3.6">3.6 – Error Handling in C</A> -<LI><A HREF="manual.html#3.7">3.7 – Functions and Types</A> -<LI><A HREF="manual.html#3.8">3.8 – The Debug Interface</A> -</UL> -<P> -<LI><A HREF="manual.html#4">4 – The Auxiliary Library</A> -<UL> -<LI><A HREF="manual.html#4.1">4.1 – Functions and Types</A> -</UL> -<P> <LI><A HREF="manual.html#5">5 – Standard Libraries</A> <UL> <LI><A HREF="manual.html#5.1">5.1 – Basic Functions</A> @@ -137,15 +112,6 @@ Freely available under the terms of the <LI><A HREF="manual.html#5.9">5.9 – The Debug Library</A> </UL> <P> -<LI><A HREF="manual.html#6">6 – Lua Stand-alone</A> -<P> -<LI><A HREF="manual.html#7">7 – Incompatibilities with the Previous Version</A> -<UL> -<LI><A HREF="manual.html#7.1">7.1 – Changes in the Language</A> -<LI><A HREF="manual.html#7.2">7.2 – Changes in the Libraries</A> -<LI><A HREF="manual.html#7.3">7.3 – Changes in the API</A> -</UL> -<P> <LI><A HREF="manual.html#8">8 – The Complete Syntax of Lua</A> </UL> @@ -286,183 +252,9 @@ Freely available under the terms of the <A HREF="manual.html#pdf-table.sort">table.sort</A><BR> </TD> -<TD> -<H3>C API</H3> -<A HREF="manual.html#lua_Alloc">lua_Alloc</A><BR> -<A HREF="manual.html#lua_CFunction">lua_CFunction</A><BR> -<A HREF="manual.html#lua_Debug">lua_Debug</A><BR> -<A HREF="manual.html#lua_Hook">lua_Hook</A><BR> -<A HREF="manual.html#lua_Integer">lua_Integer</A><BR> -<A HREF="manual.html#lua_Number">lua_Number</A><BR> -<A HREF="manual.html#lua_Reader">lua_Reader</A><BR> -<A HREF="manual.html#lua_State">lua_State</A><BR> -<A HREF="manual.html#lua_Writer">lua_Writer</A><BR> -<P> - -<A HREF="manual.html#lua_atpanic">lua_atpanic</A><BR> -<A HREF="manual.html#lua_call">lua_call</A><BR> -<A HREF="manual.html#lua_checkstack">lua_checkstack</A><BR> -<A HREF="manual.html#lua_close">lua_close</A><BR> -<A HREF="manual.html#lua_concat">lua_concat</A><BR> -<A HREF="manual.html#lua_cpcall">lua_cpcall</A><BR> -<A HREF="manual.html#lua_createtable">lua_createtable</A><BR> -<A HREF="manual.html#lua_dump">lua_dump</A><BR> -<A HREF="manual.html#lua_equal">lua_equal</A><BR> -<A HREF="manual.html#lua_error">lua_error</A><BR> -<A HREF="manual.html#lua_gc">lua_gc</A><BR> -<A HREF="manual.html#lua_getallocf">lua_getallocf</A><BR> -<A HREF="manual.html#lua_getfenv">lua_getfenv</A><BR> -<A HREF="manual.html#lua_getfield">lua_getfield</A><BR> -<A HREF="manual.html#lua_getglobal">lua_getglobal</A><BR> -<A HREF="manual.html#lua_gethook">lua_gethook</A><BR> -<A HREF="manual.html#lua_gethookcount">lua_gethookcount</A><BR> -<A HREF="manual.html#lua_gethookmask">lua_gethookmask</A><BR> -<A HREF="manual.html#lua_getinfo">lua_getinfo</A><BR> -<A HREF="manual.html#lua_getlocal">lua_getlocal</A><BR> -<A HREF="manual.html#lua_getmetatable">lua_getmetatable</A><BR> -<A HREF="manual.html#lua_getstack">lua_getstack</A><BR> -<A HREF="manual.html#lua_gettable">lua_gettable</A><BR> -<A HREF="manual.html#lua_gettop">lua_gettop</A><BR> -<A HREF="manual.html#lua_getupvalue">lua_getupvalue</A><BR> -<A HREF="manual.html#lua_insert">lua_insert</A><BR> -<A HREF="manual.html#lua_isboolean">lua_isboolean</A><BR> -<A HREF="manual.html#lua_iscfunction">lua_iscfunction</A><BR> -<A HREF="manual.html#lua_isfunction">lua_isfunction</A><BR> -<A HREF="manual.html#lua_islightuserdata">lua_islightuserdata</A><BR> -<A HREF="manual.html#lua_isnil">lua_isnil</A><BR> -<A HREF="manual.html#lua_isnone">lua_isnone</A><BR> -<A HREF="manual.html#lua_isnoneornil">lua_isnoneornil</A><BR> -<A HREF="manual.html#lua_isnumber">lua_isnumber</A><BR> -<A HREF="manual.html#lua_isstring">lua_isstring</A><BR> -<A HREF="manual.html#lua_istable">lua_istable</A><BR> -<A HREF="manual.html#lua_isthread">lua_isthread</A><BR> -<A HREF="manual.html#lua_isuserdata">lua_isuserdata</A><BR> -<A HREF="manual.html#lua_lessthan">lua_lessthan</A><BR> -<A HREF="manual.html#lua_load">lua_load</A><BR> -<A HREF="manual.html#lua_newstate">lua_newstate</A><BR> -<A HREF="manual.html#lua_newtable">lua_newtable</A><BR> -<A HREF="manual.html#lua_newthread">lua_newthread</A><BR> -<A HREF="manual.html#lua_newuserdata">lua_newuserdata</A><BR> -<A HREF="manual.html#lua_next">lua_next</A><BR> -<A HREF="manual.html#lua_objlen">lua_objlen</A><BR> -<A HREF="manual.html#lua_pcall">lua_pcall</A><BR> -<A HREF="manual.html#lua_pop">lua_pop</A><BR> -<A HREF="manual.html#lua_pushboolean">lua_pushboolean</A><BR> -<A HREF="manual.html#lua_pushcclosure">lua_pushcclosure</A><BR> -<A HREF="manual.html#lua_pushcfunction">lua_pushcfunction</A><BR> -<A HREF="manual.html#lua_pushfstring">lua_pushfstring</A><BR> -<A HREF="manual.html#lua_pushinteger">lua_pushinteger</A><BR> -<A HREF="manual.html#lua_pushlightuserdata">lua_pushlightuserdata</A><BR> -<A HREF="manual.html#lua_pushliteral">lua_pushliteral</A><BR> -<A HREF="manual.html#lua_pushlstring">lua_pushlstring</A><BR> -<A HREF="manual.html#lua_pushnil">lua_pushnil</A><BR> -<A HREF="manual.html#lua_pushnumber">lua_pushnumber</A><BR> -<A HREF="manual.html#lua_pushstring">lua_pushstring</A><BR> -<A HREF="manual.html#lua_pushthread">lua_pushthread</A><BR> -<A HREF="manual.html#lua_pushvalue">lua_pushvalue</A><BR> -<A HREF="manual.html#lua_pushvfstring">lua_pushvfstring</A><BR> -<A HREF="manual.html#lua_rawequal">lua_rawequal</A><BR> -<A HREF="manual.html#lua_rawget">lua_rawget</A><BR> -<A HREF="manual.html#lua_rawgeti">lua_rawgeti</A><BR> -<A HREF="manual.html#lua_rawset">lua_rawset</A><BR> -<A HREF="manual.html#lua_rawseti">lua_rawseti</A><BR> -<A HREF="manual.html#lua_register">lua_register</A><BR> -<A HREF="manual.html#lua_remove">lua_remove</A><BR> -<A HREF="manual.html#lua_replace">lua_replace</A><BR> -<A HREF="manual.html#lua_resume">lua_resume</A><BR> -<A HREF="manual.html#lua_setallocf">lua_setallocf</A><BR> -<A HREF="manual.html#lua_setfenv">lua_setfenv</A><BR> -<A HREF="manual.html#lua_setfield">lua_setfield</A><BR> -<A HREF="manual.html#lua_setglobal">lua_setglobal</A><BR> -<A HREF="manual.html#lua_sethook">lua_sethook</A><BR> -<A HREF="manual.html#lua_setlocal">lua_setlocal</A><BR> -<A HREF="manual.html#lua_setmetatable">lua_setmetatable</A><BR> -<A HREF="manual.html#lua_settable">lua_settable</A><BR> -<A HREF="manual.html#lua_settop">lua_settop</A><BR> -<A HREF="manual.html#lua_setupvalue">lua_setupvalue</A><BR> -<A HREF="manual.html#lua_status">lua_status</A><BR> -<A HREF="manual.html#lua_toboolean">lua_toboolean</A><BR> -<A HREF="manual.html#lua_tocfunction">lua_tocfunction</A><BR> -<A HREF="manual.html#lua_tointeger">lua_tointeger</A><BR> -<A HREF="manual.html#lua_tolstring">lua_tolstring</A><BR> -<A HREF="manual.html#lua_tonumber">lua_tonumber</A><BR> -<A HREF="manual.html#lua_topointer">lua_topointer</A><BR> -<A HREF="manual.html#lua_tostring">lua_tostring</A><BR> -<A HREF="manual.html#lua_tothread">lua_tothread</A><BR> -<A HREF="manual.html#lua_touserdata">lua_touserdata</A><BR> -<A HREF="manual.html#lua_type">lua_type</A><BR> -<A HREF="manual.html#lua_typename">lua_typename</A><BR> -<A HREF="manual.html#lua_upvalueindex">lua_upvalueindex</A><BR> -<A HREF="manual.html#lua_xmove">lua_xmove</A><BR> -<A HREF="manual.html#lua_yield">lua_yield</A><BR> - -</TD> -<TD> -<H3>auxiliary library</H3> -<A HREF="manual.html#luaL_Buffer">luaL_Buffer</A><BR> -<A HREF="manual.html#luaL_Reg">luaL_Reg</A><BR> -<P> - -<A HREF="manual.html#luaL_addchar">luaL_addchar</A><BR> -<A HREF="manual.html#luaL_addlstring">luaL_addlstring</A><BR> -<A HREF="manual.html#luaL_addsize">luaL_addsize</A><BR> -<A HREF="manual.html#luaL_addstring">luaL_addstring</A><BR> -<A HREF="manual.html#luaL_addvalue">luaL_addvalue</A><BR> -<A HREF="manual.html#luaL_argcheck">luaL_argcheck</A><BR> -<A HREF="manual.html#luaL_argerror">luaL_argerror</A><BR> -<A HREF="manual.html#luaL_buffinit">luaL_buffinit</A><BR> -<A HREF="manual.html#luaL_callmeta">luaL_callmeta</A><BR> -<A HREF="manual.html#luaL_checkany">luaL_checkany</A><BR> -<A HREF="manual.html#luaL_checkint">luaL_checkint</A><BR> -<A HREF="manual.html#luaL_checkinteger">luaL_checkinteger</A><BR> -<A HREF="manual.html#luaL_checklong">luaL_checklong</A><BR> -<A HREF="manual.html#luaL_checklstring">luaL_checklstring</A><BR> -<A HREF="manual.html#luaL_checknumber">luaL_checknumber</A><BR> -<A HREF="manual.html#luaL_checkoption">luaL_checkoption</A><BR> -<A HREF="manual.html#luaL_checkstack">luaL_checkstack</A><BR> -<A HREF="manual.html#luaL_checkstring">luaL_checkstring</A><BR> -<A HREF="manual.html#luaL_checktype">luaL_checktype</A><BR> -<A HREF="manual.html#luaL_checkudata">luaL_checkudata</A><BR> -<A HREF="manual.html#luaL_dofile">luaL_dofile</A><BR> -<A HREF="manual.html#luaL_dostring">luaL_dostring</A><BR> -<A HREF="manual.html#luaL_error">luaL_error</A><BR> -<A HREF="manual.html#luaL_getmetafield">luaL_getmetafield</A><BR> -<A HREF="manual.html#luaL_getmetatable">luaL_getmetatable</A><BR> -<A HREF="manual.html#luaL_gsub">luaL_gsub</A><BR> -<A HREF="manual.html#luaL_loadbuffer">luaL_loadbuffer</A><BR> -<A HREF="manual.html#luaL_loadfile">luaL_loadfile</A><BR> -<A HREF="manual.html#luaL_loadstring">luaL_loadstring</A><BR> -<A HREF="manual.html#luaL_newmetatable">luaL_newmetatable</A><BR> -<A HREF="manual.html#luaL_newstate">luaL_newstate</A><BR> -<A HREF="manual.html#luaL_openlibs">luaL_openlibs</A><BR> -<A HREF="manual.html#luaL_optint">luaL_optint</A><BR> -<A HREF="manual.html#luaL_optinteger">luaL_optinteger</A><BR> -<A HREF="manual.html#luaL_optlong">luaL_optlong</A><BR> -<A HREF="manual.html#luaL_optlstring">luaL_optlstring</A><BR> -<A HREF="manual.html#luaL_optnumber">luaL_optnumber</A><BR> -<A HREF="manual.html#luaL_optstring">luaL_optstring</A><BR> -<A HREF="manual.html#luaL_prepbuffer">luaL_prepbuffer</A><BR> -<A HREF="manual.html#luaL_pushresult">luaL_pushresult</A><BR> -<A HREF="manual.html#luaL_ref">luaL_ref</A><BR> -<A HREF="manual.html#luaL_register">luaL_register</A><BR> -<A HREF="manual.html#luaL_typename">luaL_typename</A><BR> -<A HREF="manual.html#luaL_typerror">luaL_typerror</A><BR> -<A HREF="manual.html#luaL_unref">luaL_unref</A><BR> -<A HREF="manual.html#luaL_where">luaL_where</A><BR> - -</TD> </TR> </TABLE> <P> -<HR> -<SMALL CLASS="footer"> -Last update: -Mon Feb 13 18:53:32 BRST 2012 -</SMALL> -<!-- -Last change: revised for Lua 5.1.5 ---> - </BODY> </HTML> diff --git a/doc/logo.gif b/doc/logo.gif deleted file mode 100644 index 2f5e4ac..0000000 --- a/doc/logo.gif +++ /dev/null Binary files differdiff --git a/doc/manual.html b/doc/manual.html index 7110848..e0c9d1a 100644 --- a/doc/manual.html +++ b/doc/manual.html @@ -2,7 +2,7 @@ <html> <head> -<title>Lua 5.1 Reference Manual</title> +<title>Teliva Reference Manual</title> <link rel="stylesheet" type="text/css" href="lua.css"> <link rel="stylesheet" type="text/css" href="manual.css"> <META HTTP-EQUIV="content-type" CONTENT="text/html; charset=iso-8859-1"> @@ -12,11 +12,11 @@ <hr> <h1> -<a href="http://www.lua.org/"><img src="logo.gif" alt="" border="0"></a> -Lua 5.1 Reference Manual +Teliva Reference Manual </h1> -by Roberto Ierusalimschy, Luiz Henrique de Figueiredo, Waldemar Celes +Based on <a href="http://www.lua.org/">Lua 5.1</a> by Roberto Ierusalimschy, +Luiz Henrique de Figueiredo, Waldemar Celes <p> <small> Copyright © 2006–2012 Lua.org, PUC-Rio. @@ -42,43 +42,16 @@ Freely available under the terms of the <h1>1 - <a name="1">Introduction</a></h1> -<p> -Lua is an extension programming language designed to support -general procedural programming with data description -facilities. -It also offers good support for object-oriented programming, -functional programming, and data-driven programming. -Lua is intended to be used as a powerful, light-weight -scripting language for any program that needs one. -Lua is implemented as a library, written in <em>clean</em> C -(that is, in the common subset of ANSI C and C++). - +Teliva is a platform based on Lua for sandboxed software packaged with an +environment for making changes to it. For a more detailed introduction, see +<a href='../README.md'>the Readme</a>. <p> -Being an extension language, Lua has no notion of a "main" program: -it only works <em>embedded</em> in a host client, -called the <em>embedding program</em> or simply the <em>host</em>. -This host program can invoke functions to execute a piece of Lua code, -can write and read Lua variables, -and can register C functions to be called by Lua code. -Through the use of C functions, Lua can be augmented to cope with -a wide range of different domains, -thus creating customized programming languages sharing a syntactical framework. -The Lua distribution includes a sample host program called <code>lua</code>, -which uses the Lua library to offer a complete, stand-alone Lua interpreter. +Teliva is free software, and is provided as usual with no guarantees, as +stated in its license. <p> -Lua is free software, -and is provided as usual with no guarantees, -as stated in its license. -The implementation described in this manual is available -at Lua's official web site, <code>www.lua.org</code>. - - -<p> -Like any other reference manual, -this document is dry in places. For a discussion of the decisions behind the design of Lua, see the technical papers available at Lua's web site. For a detailed introduction to programming in Lua, @@ -2233,3396 +2206,10 @@ When you run it, it produces the following output: -<h1>3 - <a name="3">The Application Program Interface</a></h1> - -<p> - -This section describes the C API for Lua, that is, -the set of C functions available to the host program to communicate -with Lua. -All API functions and related types and constants -are declared in the header file <a name="pdf-lua.h"><code>lua.h</code></a>. - - -<p> -Even when we use the term "function", -any facility in the API may be provided as a macro instead. -All such macros use each of their arguments exactly once -(except for the first argument, which is always a Lua state), -and so do not generate any hidden side-effects. - - -<p> -As in most C libraries, -the Lua API functions do not check their arguments for validity or consistency. -However, you can change this behavior by compiling Lua -with a proper definition for the macro <a name="pdf-luai_apicheck"><code>luai_apicheck</code></a>, -in file <code>luaconf.h</code>. - - - -<h2>3.1 - <a name="3.1">The Stack</a></h2> - -<p> -Lua uses a <em>virtual stack</em> to pass values to and from C. -Each element in this stack represents a Lua value -(<b>nil</b>, number, string, etc.). - - -<p> -Whenever Lua calls C, the called function gets a new stack, -which is independent of previous stacks and of stacks of -C functions that are still active. -This stack initially contains any arguments to the C function -and it is where the C function pushes its results -to be returned to the caller (see <a href="#lua_CFunction"><code>lua_CFunction</code></a>). - - -<p> -For convenience, -most query operations in the API do not follow a strict stack discipline. -Instead, they can refer to any element in the stack -by using an <em>index</em>: -A positive index represents an <em>absolute</em> stack position -(starting at 1); -a negative index represents an <em>offset</em> relative to the top of the stack. -More specifically, if the stack has <em>n</em> elements, -then index 1 represents the first element -(that is, the element that was pushed onto the stack first) -and -index <em>n</em> represents the last element; -index -1 also represents the last element -(that is, the element at the top) -and index <em>-n</em> represents the first element. -We say that an index is <em>valid</em> -if it lies between 1 and the stack top -(that is, if <code>1 ≤ abs(index) ≤ top</code>). - - - - - - -<h2>3.2 - <a name="3.2">Stack Size</a></h2> - -<p> -When you interact with Lua API, -you are responsible for ensuring consistency. -In particular, -<em>you are responsible for controlling stack overflow</em>. -You can use the function <a href="#lua_checkstack"><code>lua_checkstack</code></a> -to grow the stack size. - - -<p> -Whenever Lua calls C, -it ensures that at least <a name="pdf-LUA_MINSTACK"><code>LUA_MINSTACK</code></a> stack positions are available. -<code>LUA_MINSTACK</code> is defined as 20, -so that usually you do not have to worry about stack space -unless your code has loops pushing elements onto the stack. - - -<p> -Most query functions accept as indices any value inside the -available stack space, that is, indices up to the maximum stack size -you have set through <a href="#lua_checkstack"><code>lua_checkstack</code></a>. -Such indices are called <em>acceptable indices</em>. -More formally, we define an <em>acceptable index</em> -as follows: - -<pre> - (index < 0 && abs(index) <= top) || - (index > 0 && index <= stackspace) -</pre><p> -Note that 0 is never an acceptable index. - - - - - -<h2>3.3 - <a name="3.3">Pseudo-Indices</a></h2> - -<p> -Unless otherwise noted, -any function that accepts valid indices can also be called with -<em>pseudo-indices</em>, -which represent some Lua values that are accessible to C code -but which are not in the stack. -Pseudo-indices are used to access the thread environment, -the function environment, -the registry, -and the upvalues of a C function (see <a href="#3.4">§3.4</a>). - - -<p> -The thread environment (where global variables live) is -always at pseudo-index <a name="pdf-LUA_GLOBALSINDEX"><code>LUA_GLOBALSINDEX</code></a>. -The environment of the running C function is always -at pseudo-index <a name="pdf-LUA_ENVIRONINDEX"><code>LUA_ENVIRONINDEX</code></a>. - - -<p> -To access and change the value of global variables, -you can use regular table operations over an environment table. -For instance, to access the value of a global variable, do - -<pre> - lua_getfield(L, LUA_GLOBALSINDEX, varname); -</pre> - - - - -<h2>3.4 - <a name="3.4">C Closures</a></h2> - -<p> -When a C function is created, -it is possible to associate some values with it, -thus creating a <em>C closure</em>; -these values are called <em>upvalues</em> and are -accessible to the function whenever it is called -(see <a href="#lua_pushcclosure"><code>lua_pushcclosure</code></a>). - - -<p> -Whenever a C function is called, -its upvalues are located at specific pseudo-indices. -These pseudo-indices are produced by the macro -<a name="lua_upvalueindex"><code>lua_upvalueindex</code></a>. -The first value associated with a function is at position -<code>lua_upvalueindex(1)</code>, and so on. -Any access to <code>lua_upvalueindex(<em>n</em>)</code>, -where <em>n</em> is greater than the number of upvalues of the -current function (but not greater than 256), -produces an acceptable (but invalid) index. - - - - - -<h2>3.5 - <a name="3.5">Registry</a></h2> - -<p> -Lua provides a <em>registry</em>, -a pre-defined table that can be used by any C code to -store whatever Lua value it needs to store. -This table is always located at pseudo-index -<a name="pdf-LUA_REGISTRYINDEX"><code>LUA_REGISTRYINDEX</code></a>. -Any C library can store data into this table, -but it should take care to choose keys different from those used -by other libraries, to avoid collisions. -Typically, you should use as key a string containing your library name -or a light userdata with the address of a C object in your code. - - -<p> -The integer keys in the registry are used by the reference mechanism, -implemented by the auxiliary library, -and therefore should not be used for other purposes. - - - - - -<h2>3.6 - <a name="3.6">Error Handling in C</a></h2> - -<p> -Internally, Lua uses the C <code>longjmp</code> facility to handle errors. -(You can also choose to use exceptions if you use C++; -see file <code>luaconf.h</code>.) -When Lua faces any error -(such as memory allocation errors, type errors, syntax errors, -and runtime errors) -it <em>raises</em> an error; -that is, it does a long jump. -A <em>protected environment</em> uses <code>setjmp</code> -to set a recover point; -any error jumps to the most recent active recover point. - - -<p> -Most functions in the API can throw an error, -for instance due to a memory allocation error. -The documentation for each function indicates whether -it can throw errors. - - -<p> -Inside a C function you can throw an error by calling <a href="#lua_error"><code>lua_error</code></a>. - - - - - -<h2>3.7 - <a name="3.7">Functions and Types</a></h2> - -<p> -Here we list all functions and types from the C API in -alphabetical order. -Each function has an indicator like this: -<span class="apii">[-o, +p, <em>x</em>]</span> - - -<p> -The first field, <code>o</code>, -is how many elements the function pops from the stack. -The second field, <code>p</code>, -is how many elements the function pushes onto the stack. -(Any function always pushes its results after popping its arguments.) -A field in the form <code>x|y</code> means the function can push (or pop) -<code>x</code> or <code>y</code> elements, -depending on the situation; -an interrogation mark '<code>?</code>' means that -we cannot know how many elements the function pops/pushes -by looking only at its arguments -(e.g., they may depend on what is on the stack). -The third field, <code>x</code>, -tells whether the function may throw errors: -'<code>-</code>' means the function never throws any error; -'<code>m</code>' means the function may throw an error -only due to not enough memory; -'<code>e</code>' means the function may throw other kinds of errors; -'<code>v</code>' means the function may throw an error on purpose. - - - -<hr><h3><a name="lua_Alloc"><code>lua_Alloc</code></a></h3> -<pre>typedef void * (*lua_Alloc) (void *ud, - void *ptr, - size_t osize, - size_t nsize);</pre> - -<p> -The type of the memory-allocation function used by Lua states. -The allocator function must provide a -functionality similar to <code>realloc</code>, -but not exactly the same. -Its arguments are -<code>ud</code>, an opaque pointer passed to <a href="#lua_newstate"><code>lua_newstate</code></a>; -<code>ptr</code>, a pointer to the block being allocated/reallocated/freed; -<code>osize</code>, the original size of the block; -<code>nsize</code>, the new size of the block. -<code>ptr</code> is <code>NULL</code> if and only if <code>osize</code> is zero. -When <code>nsize</code> is zero, the allocator must return <code>NULL</code>; -if <code>osize</code> is not zero, -it should free the block pointed to by <code>ptr</code>. -When <code>nsize</code> is not zero, the allocator returns <code>NULL</code> -if and only if it cannot fill the request. -When <code>nsize</code> is not zero and <code>osize</code> is zero, -the allocator should behave like <code>malloc</code>. -When <code>nsize</code> and <code>osize</code> are not zero, -the allocator behaves like <code>realloc</code>. -Lua assumes that the allocator never fails when -<code>osize >= nsize</code>. - - -<p> -Here is a simple implementation for the allocator function. -It is used in the auxiliary library by <a href="#luaL_newstate"><code>luaL_newstate</code></a>. - -<pre> - static void *l_alloc (void *ud, void *ptr, size_t osize, - size_t nsize) { - (void)ud; (void)osize; /* not used */ - if (nsize == 0) { - free(ptr); - return NULL; - } - else - return realloc(ptr, nsize); - } -</pre><p> -This code assumes -that <code>free(NULL)</code> has no effect and that -<code>realloc(NULL, size)</code> is equivalent to <code>malloc(size)</code>. -ANSI C ensures both behaviors. - - - - - -<hr><h3><a name="lua_atpanic"><code>lua_atpanic</code></a></h3><p> -<span class="apii">[-0, +0, <em>-</em>]</span> -<pre>lua_CFunction lua_atpanic (lua_State *L, lua_CFunction panicf);</pre> - -<p> -Sets a new panic function and returns the old one. - - -<p> -If an error happens outside any protected environment, -Lua calls a <em>panic function</em> -and then calls <code>exit(EXIT_FAILURE)</code>, -thus exiting the host application. -Your panic function can avoid this exit by -never returning (e.g., doing a long jump). - - -<p> -The panic function can access the error message at the top of the stack. - - - - - -<hr><h3><a name="lua_call"><code>lua_call</code></a></h3><p> -<span class="apii">[-(nargs + 1), +nresults, <em>e</em>]</span> -<pre>void lua_call (lua_State *L, int nargs, int nresults);</pre> - -<p> -Calls a function. - - -<p> -To call a function you must use the following protocol: -first, the function to be called is pushed onto the stack; -then, the arguments to the function are pushed -in direct order; -that is, the first argument is pushed first. -Finally you call <a href="#lua_call"><code>lua_call</code></a>; -<code>nargs</code> is the number of arguments that you pushed onto the stack. -All arguments and the function value are popped from the stack -when the function is called. -The function results are pushed onto the stack when the function returns. -The number of results is adjusted to <code>nresults</code>, -unless <code>nresults</code> is <a name="pdf-LUA_MULTRET"><code>LUA_MULTRET</code></a>. -In this case, <em>all</em> results from the function are pushed. -Lua takes care that the returned values fit into the stack space. -The function results are pushed onto the stack in direct order -(the first result is pushed first), -so that after the call the last result is on the top of the stack. - - -<p> -Any error inside the called function is propagated upwards -(with a <code>longjmp</code>). - - -<p> -The following example shows how the host program can do the -equivalent to this Lua code: - -<pre> - a = f("how", t.x, 14) -</pre><p> -Here it is in C: - -<pre> - lua_getfield(L, LUA_GLOBALSINDEX, "f"); /* function to be called */ - lua_pushstring(L, "how"); /* 1st argument */ - lua_getfield(L, LUA_GLOBALSINDEX, "t"); /* table to be indexed */ - lua_getfield(L, -1, "x"); /* push result of t.x (2nd arg) */ - lua_remove(L, -2); /* remove 't' from the stack */ - lua_pushinteger(L, 14); /* 3rd argument */ - lua_call(L, 3, 1); /* call 'f' with 3 arguments and 1 result */ - lua_setfield(L, LUA_GLOBALSINDEX, "a"); /* set global 'a' */ -</pre><p> -Note that the code above is "balanced": -at its end, the stack is back to its original configuration. -This is considered good programming practice. - - - - - -<hr><h3><a name="lua_CFunction"><code>lua_CFunction</code></a></h3> -<pre>typedef int (*lua_CFunction) (lua_State *L);</pre> - -<p> -Type for C functions. - - -<p> -In order to communicate properly with Lua, -a C function must use the following protocol, -which defines the way parameters and results are passed: -a C function receives its arguments from Lua in its stack -in direct order (the first argument is pushed first). -So, when the function starts, -<code>lua_gettop(L)</code> returns the number of arguments received by the function. -The first argument (if any) is at index 1 -and its last argument is at index <code>lua_gettop(L)</code>. -To return values to Lua, a C function just pushes them onto the stack, -in direct order (the first result is pushed first), -and returns the number of results. -Any other value in the stack below the results will be properly -discarded by Lua. -Like a Lua function, a C function called by Lua can also return -many results. - - -<p> -As an example, the following function receives a variable number -of numerical arguments and returns their average and sum: - -<pre> - static int foo (lua_State *L) { - int n = lua_gettop(L); /* number of arguments */ - lua_Number sum = 0; - int i; - for (i = 1; i <= n; i++) { - if (!lua_isnumber(L, i)) { - lua_pushstring(L, "incorrect argument"); - lua_error(L); - } - sum += lua_tonumber(L, i); - } - lua_pushnumber(L, sum/n); /* first result */ - lua_pushnumber(L, sum); /* second result */ - return 2; /* number of results */ - } -</pre> - - - - -<hr><h3><a name="lua_checkstack"><code>lua_checkstack</code></a></h3><p> -<span class="apii">[-0, +0, <em>m</em>]</span> -<pre>int lua_checkstack (lua_State *L, int extra);</pre> - -<p> -Ensures that there are at least <code>extra</code> free stack slots in the stack. -It returns false if it cannot grow the stack to that size. -This function never shrinks the stack; -if the stack is already larger than the new size, -it is left unchanged. - - - - - -<hr><h3><a name="lua_close"><code>lua_close</code></a></h3><p> -<span class="apii">[-0, +0, <em>-</em>]</span> -<pre>void lua_close (lua_State *L);</pre> - -<p> -Destroys all objects in the given Lua state -(calling the corresponding garbage-collection metamethods, if any) -and frees all dynamic memory used by this state. -On several platforms, you may not need to call this function, -because all resources are naturally released when the host program ends. -On the other hand, long-running programs, -such as a daemon or a web server, -might need to release states as soon as they are not needed, -to avoid growing too large. - - - - - -<hr><h3><a name="lua_concat"><code>lua_concat</code></a></h3><p> -<span class="apii">[-n, +1, <em>e</em>]</span> -<pre>void lua_concat (lua_State *L, int n);</pre> - -<p> -Concatenates the <code>n</code> values at the top of the stack, -pops them, and leaves the result at the top. -If <code>n</code> is 1, the result is the single value on the stack -(that is, the function does nothing); -if <code>n</code> is 0, the result is the empty string. -Concatenation is performed following the usual semantics of Lua -(see <a href="#2.5.4">§2.5.4</a>). - - - - - -<hr><h3><a name="lua_cpcall"><code>lua_cpcall</code></a></h3><p> -<span class="apii">[-0, +(0|1), <em>-</em>]</span> -<pre>int lua_cpcall (lua_State *L, lua_CFunction func, void *ud);</pre> - -<p> -Calls the C function <code>func</code> in protected mode. -<code>func</code> starts with only one element in its stack, -a light userdata containing <code>ud</code>. -In case of errors, -<a href="#lua_cpcall"><code>lua_cpcall</code></a> returns the same error codes as <a href="#lua_pcall"><code>lua_pcall</code></a>, -plus the error object on the top of the stack; -otherwise, it returns zero, and does not change the stack. -All values returned by <code>func</code> are discarded. - - - - - -<hr><h3><a name="lua_createtable"><code>lua_createtable</code></a></h3><p> -<span class="apii">[-0, +1, <em>m</em>]</span> -<pre>void lua_createtable (lua_State *L, int narr, int nrec);</pre> - -<p> -Creates a new empty table and pushes it onto the stack. -The new table has space pre-allocated -for <code>narr</code> array elements and <code>nrec</code> non-array elements. -This pre-allocation is useful when you know exactly how many elements -the table will have. -Otherwise you can use the function <a href="#lua_newtable"><code>lua_newtable</code></a>. - - - - - -<hr><h3><a name="lua_dump"><code>lua_dump</code></a></h3><p> -<span class="apii">[-0, +0, <em>m</em>]</span> -<pre>int lua_dump (lua_State *L, lua_Writer writer, void *data);</pre> - -<p> -Dumps a function as a binary chunk. -Receives a Lua function on the top of the stack -and produces a binary chunk that, -if loaded again, -results in a function equivalent to the one dumped. -As it produces parts of the chunk, -<a href="#lua_dump"><code>lua_dump</code></a> calls function <code>writer</code> (see <a href="#lua_Writer"><code>lua_Writer</code></a>) -with the given <code>data</code> -to write them. - - -<p> -The value returned is the error code returned by the last -call to the writer; -0 means no errors. - - -<p> -This function does not pop the Lua function from the stack. - - - - - -<hr><h3><a name="lua_equal"><code>lua_equal</code></a></h3><p> -<span class="apii">[-0, +0, <em>e</em>]</span> -<pre>int lua_equal (lua_State *L, int index1, int index2);</pre> - -<p> -Returns 1 if the two values in acceptable indices <code>index1</code> and -<code>index2</code> are equal, -following the semantics of the Lua <code>==</code> operator -(that is, may call metamethods). -Otherwise returns 0. -Also returns 0 if any of the indices is non valid. - - - - - -<hr><h3><a name="lua_error"><code>lua_error</code></a></h3><p> -<span class="apii">[-1, +0, <em>v</em>]</span> -<pre>int lua_error (lua_State *L);</pre> - -<p> -Generates a Lua error. -The error message (which can actually be a Lua value of any type) -must be on the stack top. -This function does a long jump, -and therefore never returns. -(see <a href="#luaL_error"><code>luaL_error</code></a>). - - - - - -<hr><h3><a name="lua_gc"><code>lua_gc</code></a></h3><p> -<span class="apii">[-0, +0, <em>e</em>]</span> -<pre>int lua_gc (lua_State *L, int what, int data);</pre> - -<p> -Controls the garbage collector. - - -<p> -This function performs several tasks, -according to the value of the parameter <code>what</code>: - -<ul> - -<li><b><code>LUA_GCSTOP</code>:</b> -stops the garbage collector. -</li> - -<li><b><code>LUA_GCRESTART</code>:</b> -restarts the garbage collector. -</li> - -<li><b><code>LUA_GCCOLLECT</code>:</b> -performs a full garbage-collection cycle. -</li> - -<li><b><code>LUA_GCCOUNT</code>:</b> -returns the current amount of memory (in Kbytes) in use by Lua. -</li> - -<li><b><code>LUA_GCCOUNTB</code>:</b> -returns the remainder of dividing the current amount of bytes of -memory in use by Lua by 1024. -</li> - -<li><b><code>LUA_GCSTEP</code>:</b> -performs an incremental step of garbage collection. -The step "size" is controlled by <code>data</code> -(larger values mean more steps) in a non-specified way. -If you want to control the step size -you must experimentally tune the value of <code>data</code>. -The function returns 1 if the step finished a -garbage-collection cycle. -</li> - -<li><b><code>LUA_GCSETPAUSE</code>:</b> -sets <code>data</code> as the new value -for the <em>pause</em> of the collector (see <a href="#2.10">§2.10</a>). -The function returns the previous value of the pause. -</li> - -<li><b><code>LUA_GCSETSTEPMUL</code>:</b> -sets <code>data</code> as the new value for the <em>step multiplier</em> of -the collector (see <a href="#2.10">§2.10</a>). -The function returns the previous value of the step multiplier. -</li> - -</ul> - - - - -<hr><h3><a name="lua_getallocf"><code>lua_getallocf</code></a></h3><p> -<span class="apii">[-0, +0, <em>-</em>]</span> -<pre>lua_Alloc lua_getallocf (lua_State *L, void **ud);</pre> - -<p> -Returns the memory-allocation function of a given state. -If <code>ud</code> is not <code>NULL</code>, Lua stores in <code>*ud</code> the -opaque pointer passed to <a href="#lua_newstate"><code>lua_newstate</code></a>. - - - - - -<hr><h3><a name="lua_getfenv"><code>lua_getfenv</code></a></h3><p> -<span class="apii">[-0, +1, <em>-</em>]</span> -<pre>void lua_getfenv (lua_State *L, int index);</pre> - -<p> -Pushes onto the stack the environment table of -the value at the given index. - - - - - -<hr><h3><a name="lua_getfield"><code>lua_getfield</code></a></h3><p> -<span class="apii">[-0, +1, <em>e</em>]</span> -<pre>void lua_getfield (lua_State *L, int index, const char *k);</pre> - -<p> -Pushes onto the stack the value <code>t[k]</code>, -where <code>t</code> is the value at the given valid index. -As in Lua, this function may trigger a metamethod -for the "index" event (see <a href="#2.8">§2.8</a>). - - - - - -<hr><h3><a name="lua_getglobal"><code>lua_getglobal</code></a></h3><p> -<span class="apii">[-0, +1, <em>e</em>]</span> -<pre>void lua_getglobal (lua_State *L, const char *name);</pre> - -<p> -Pushes onto the stack the value of the global <code>name</code>. -It is defined as a macro: - -<pre> - #define lua_getglobal(L,s) lua_getfield(L, LUA_GLOBALSINDEX, s) -</pre> - - - - -<hr><h3><a name="lua_getmetatable"><code>lua_getmetatable</code></a></h3><p> -<span class="apii">[-0, +(0|1), <em>-</em>]</span> -<pre>int lua_getmetatable (lua_State *L, int index);</pre> - -<p> -Pushes onto the stack the metatable of the value at the given -acceptable index. -If the index is not valid, -or if the value does not have a metatable, -the function returns 0 and pushes nothing on the stack. - - - - - -<hr><h3><a name="lua_gettable"><code>lua_gettable</code></a></h3><p> -<span class="apii">[-1, +1, <em>e</em>]</span> -<pre>void lua_gettable (lua_State *L, int index);</pre> - -<p> -Pushes onto the stack the value <code>t[k]</code>, -where <code>t</code> is the value at the given valid index -and <code>k</code> is the value at the top of the stack. - - -<p> -This function pops the key from the stack -(putting the resulting value in its place). -As in Lua, this function may trigger a metamethod -for the "index" event (see <a href="#2.8">§2.8</a>). - - - - - -<hr><h3><a name="lua_gettop"><code>lua_gettop</code></a></h3><p> -<span class="apii">[-0, +0, <em>-</em>]</span> -<pre>int lua_gettop (lua_State *L);</pre> - -<p> -Returns the index of the top element in the stack. -Because indices start at 1, -this result is equal to the number of elements in the stack -(and so 0 means an empty stack). - - - - - -<hr><h3><a name="lua_insert"><code>lua_insert</code></a></h3><p> -<span class="apii">[-1, +1, <em>-</em>]</span> -<pre>void lua_insert (lua_State *L, int index);</pre> - -<p> -Moves the top element into the given valid index, -shifting up the elements above this index to open space. -Cannot be called with a pseudo-index, -because a pseudo-index is not an actual stack position. - - - - - -<hr><h3><a name="lua_Integer"><code>lua_Integer</code></a></h3> -<pre>typedef ptrdiff_t lua_Integer;</pre> - -<p> -The type used by the Lua API to represent integral values. - - -<p> -By default it is a <code>ptrdiff_t</code>, -which is usually the largest signed integral type the machine handles -"comfortably". - - - - - -<hr><h3><a name="lua_isboolean"><code>lua_isboolean</code></a></h3><p> -<span class="apii">[-0, +0, <em>-</em>]</span> -<pre>int lua_isboolean (lua_State *L, int index);</pre> - -<p> -Returns 1 if the value at the given acceptable index has type boolean, -and 0 otherwise. - - - - - -<hr><h3><a name="lua_iscfunction"><code>lua_iscfunction</code></a></h3><p> -<span class="apii">[-0, +0, <em>-</em>]</span> -<pre>int lua_iscfunction (lua_State *L, int index);</pre> - -<p> -Returns 1 if the value at the given acceptable index is a C function, -and 0 otherwise. - - - - - -<hr><h3><a name="lua_isfunction"><code>lua_isfunction</code></a></h3><p> -<span class="apii">[-0, +0, <em>-</em>]</span> -<pre>int lua_isfunction (lua_State *L, int index);</pre> - -<p> -Returns 1 if the value at the given acceptable index is a function -(either C or Lua), and 0 otherwise. - - - - - -<hr><h3><a name="lua_islightuserdata"><code>lua_islightuserdata</code></a></h3><p> -<span class="apii">[-0, +0, <em>-</em>]</span> -<pre>int lua_islightuserdata (lua_State *L, int index);</pre> - -<p> -Returns 1 if the value at the given acceptable index is a light userdata, -and 0 otherwise. - - - - - -<hr><h3><a name="lua_isnil"><code>lua_isnil</code></a></h3><p> -<span class="apii">[-0, +0, <em>-</em>]</span> -<pre>int lua_isnil (lua_State *L, int index);</pre> - -<p> -Returns 1 if the value at the given acceptable index is <b>nil</b>, -and 0 otherwise. - - - - - -<hr><h3><a name="lua_isnone"><code>lua_isnone</code></a></h3><p> -<span class="apii">[-0, +0, <em>-</em>]</span> -<pre>int lua_isnone (lua_State *L, int index);</pre> - -<p> -Returns 1 if the given acceptable index is not valid -(that is, it refers to an element outside the current stack), -and 0 otherwise. - - - - - -<hr><h3><a name="lua_isnoneornil"><code>lua_isnoneornil</code></a></h3><p> -<span class="apii">[-0, +0, <em>-</em>]</span> -<pre>int lua_isnoneornil (lua_State *L, int index);</pre> - -<p> -Returns 1 if the given acceptable index is not valid -(that is, it refers to an element outside the current stack) -or if the value at this index is <b>nil</b>, -and 0 otherwise. - - - - - -<hr><h3><a name="lua_isnumber"><code>lua_isnumber</code></a></h3><p> -<span class="apii">[-0, +0, <em>-</em>]</span> -<pre>int lua_isnumber (lua_State *L, int index);</pre> - -<p> -Returns 1 if the value at the given acceptable index is a number -or a string convertible to a number, -and 0 otherwise. - - - - - -<hr><h3><a name="lua_isstring"><code>lua_isstring</code></a></h3><p> -<span class="apii">[-0, +0, <em>-</em>]</span> -<pre>int lua_isstring (lua_State *L, int index);</pre> - -<p> -Returns 1 if the value at the given acceptable index is a string -or a number (which is always convertible to a string), -and 0 otherwise. - - - - - -<hr><h3><a name="lua_istable"><code>lua_istable</code></a></h3><p> -<span class="apii">[-0, +0, <em>-</em>]</span> -<pre>int lua_istable (lua_State *L, int index);</pre> - -<p> -Returns 1 if the value at the given acceptable index is a table, -and 0 otherwise. - - - - - -<hr><h3><a name="lua_isthread"><code>lua_isthread</code></a></h3><p> -<span class="apii">[-0, +0, <em>-</em>]</span> -<pre>int lua_isthread (lua_State *L, int index);</pre> - -<p> -Returns 1 if the value at the given acceptable index is a thread, -and 0 otherwise. - - - - - -<hr><h3><a name="lua_isuserdata"><code>lua_isuserdata</code></a></h3><p> -<span class="apii">[-0, +0, <em>-</em>]</span> -<pre>int lua_isuserdata (lua_State *L, int index);</pre> - -<p> -Returns 1 if the value at the given acceptable index is a userdata -(either full or light), and 0 otherwise. - - - - - -<hr><h3><a name="lua_lessthan"><code>lua_lessthan</code></a></h3><p> -<span class="apii">[-0, +0, <em>e</em>]</span> -<pre>int lua_lessthan (lua_State *L, int index1, int index2);</pre> - -<p> -Returns 1 if the value at acceptable index <code>index1</code> is smaller -than the value at acceptable index <code>index2</code>, -following the semantics of the Lua <code><</code> operator -(that is, may call metamethods). -Otherwise returns 0. -Also returns 0 if any of the indices is non valid. - - - - - -<hr><h3><a name="lua_load"><code>lua_load</code></a></h3><p> -<span class="apii">[-0, +1, <em>-</em>]</span> -<pre>int lua_load (lua_State *L, - lua_Reader reader, - void *data, - const char *chunkname);</pre> - -<p> -Loads a Lua chunk. -If there are no errors, -<a href="#lua_load"><code>lua_load</code></a> pushes the compiled chunk as a Lua -function on top of the stack. -Otherwise, it pushes an error message. -The return values of <a href="#lua_load"><code>lua_load</code></a> are: - -<ul> - -<li><b>0:</b> no errors;</li> - -<li><b><a name="pdf-LUA_ERRSYNTAX"><code>LUA_ERRSYNTAX</code></a>:</b> -syntax error during pre-compilation;</li> - -<li><b><a href="#pdf-LUA_ERRMEM"><code>LUA_ERRMEM</code></a>:</b> -memory allocation error.</li> - -</ul> - -<p> -This function only loads a chunk; -it does not run it. - - -<p> -<a href="#lua_load"><code>lua_load</code></a> automatically detects whether the chunk is text or binary, -and loads it accordingly (see program <code>luac</code>). - - -<p> -The <a href="#lua_load"><code>lua_load</code></a> function uses a user-supplied <code>reader</code> function -to read the chunk (see <a href="#lua_Reader"><code>lua_Reader</code></a>). -The <code>data</code> argument is an opaque value passed to the reader function. - - -<p> -The <code>chunkname</code> argument gives a name to the chunk, -which is used for error messages and in debug information (see <a href="#3.8">§3.8</a>). - - - - - -<hr><h3><a name="lua_newstate"><code>lua_newstate</code></a></h3><p> -<span class="apii">[-0, +0, <em>-</em>]</span> -<pre>lua_State *lua_newstate (lua_Alloc f, void *ud);</pre> - -<p> -Creates a new, independent state. -Returns <code>NULL</code> if cannot create the state -(due to lack of memory). -The argument <code>f</code> is the allocator function; -Lua does all memory allocation for this state through this function. -The second argument, <code>ud</code>, is an opaque pointer that Lua -simply passes to the allocator in every call. - - - - - -<hr><h3><a name="lua_newtable"><code>lua_newtable</code></a></h3><p> -<span class="apii">[-0, +1, <em>m</em>]</span> -<pre>void lua_newtable (lua_State *L);</pre> - -<p> -Creates a new empty table and pushes it onto the stack. -It is equivalent to <code>lua_createtable(L, 0, 0)</code>. - - - - - -<hr><h3><a name="lua_newthread"><code>lua_newthread</code></a></h3><p> -<span class="apii">[-0, +1, <em>m</em>]</span> -<pre>lua_State *lua_newthread (lua_State *L);</pre> - -<p> -Creates a new thread, pushes it on the stack, -and returns a pointer to a <a href="#lua_State"><code>lua_State</code></a> that represents this new thread. -The new state returned by this function shares with the original state -all global objects (such as tables), -but has an independent execution stack. - - -<p> -There is no explicit function to close or to destroy a thread. -Threads are subject to garbage collection, -like any Lua object. - - - - - -<hr><h3><a name="lua_newuserdata"><code>lua_newuserdata</code></a></h3><p> -<span class="apii">[-0, +1, <em>m</em>]</span> -<pre>void *lua_newuserdata (lua_State *L, size_t size);</pre> - -<p> -This function allocates a new block of memory with the given size, -pushes onto the stack a new full userdata with the block address, -and returns this address. - - -<p> -Userdata represent C values in Lua. -A <em>full userdata</em> represents a block of memory. -It is an object (like a table): -you must create it, it can have its own metatable, -and you can detect when it is being collected. -A full userdata is only equal to itself (under raw equality). - - -<p> -When Lua collects a full userdata with a <code>gc</code> metamethod, -Lua calls the metamethod and marks the userdata as finalized. -When this userdata is collected again then -Lua frees its corresponding memory. - - - - - -<hr><h3><a name="lua_next"><code>lua_next</code></a></h3><p> -<span class="apii">[-1, +(2|0), <em>e</em>]</span> -<pre>int lua_next (lua_State *L, int index);</pre> - -<p> -Pops a key from the stack, -and pushes a key-value pair from the table at the given index -(the "next" pair after the given key). -If there are no more elements in the table, -then <a href="#lua_next"><code>lua_next</code></a> returns 0 (and pushes nothing). - - -<p> -A typical traversal looks like this: - -<pre> - /* table is in the stack at index 't' */ - lua_pushnil(L); /* first key */ - while (lua_next(L, t) != 0) { - /* uses 'key' (at index -2) and 'value' (at index -1) */ - printf("%s - %s\n", - lua_typename(L, lua_type(L, -2)), - lua_typename(L, lua_type(L, -1))); - /* removes 'value'; keeps 'key' for next iteration */ - lua_pop(L, 1); - } -</pre> - -<p> -While traversing a table, -do not call <a href="#lua_tolstring"><code>lua_tolstring</code></a> directly on a key, -unless you know that the key is actually a string. -Recall that <a href="#lua_tolstring"><code>lua_tolstring</code></a> <em>changes</em> -the value at the given index; -this confuses the next call to <a href="#lua_next"><code>lua_next</code></a>. - - - - - -<hr><h3><a name="lua_Number"><code>lua_Number</code></a></h3> -<pre>typedef double lua_Number;</pre> - -<p> -The type of numbers in Lua. -By default, it is double, but that can be changed in <code>luaconf.h</code>. - - -<p> -Through the configuration file you can change -Lua to operate with another type for numbers (e.g., float or long). - - - - - -<hr><h3><a name="lua_objlen"><code>lua_objlen</code></a></h3><p> -<span class="apii">[-0, +0, <em>-</em>]</span> -<pre>size_t lua_objlen (lua_State *L, int index);</pre> - -<p> -Returns the "length" of the value at the given acceptable index: -for strings, this is the string length; -for tables, this is the result of the length operator ('<code>#</code>'); -for userdata, this is the size of the block of memory allocated -for the userdata; -for other values, it is 0. - - - - - -<hr><h3><a name="lua_pcall"><code>lua_pcall</code></a></h3><p> -<span class="apii">[-(nargs + 1), +(nresults|1), <em>-</em>]</span> -<pre>int lua_pcall (lua_State *L, int nargs, int nresults, int errfunc);</pre> - -<p> -Calls a function in protected mode. - - -<p> -Both <code>nargs</code> and <code>nresults</code> have the same meaning as -in <a href="#lua_call"><code>lua_call</code></a>. -If there are no errors during the call, -<a href="#lua_pcall"><code>lua_pcall</code></a> behaves exactly like <a href="#lua_call"><code>lua_call</code></a>. -However, if there is any error, -<a href="#lua_pcall"><code>lua_pcall</code></a> catches it, -pushes a single value on the stack (the error message), -and returns an error code. -Like <a href="#lua_call"><code>lua_call</code></a>, -<a href="#lua_pcall"><code>lua_pcall</code></a> always removes the function -and its arguments from the stack. - - -<p> -If <code>errfunc</code> is 0, -then the error message returned on the stack -is exactly the original error message. -Otherwise, <code>errfunc</code> is the stack index of an -<em>error handler function</em>. -(In the current implementation, this index cannot be a pseudo-index.) -In case of runtime errors, -this function will be called with the error message -and its return value will be the message returned on the stack by <a href="#lua_pcall"><code>lua_pcall</code></a>. - - -<p> -Typically, the error handler function is used to add more debug -information to the error message, such as a stack traceback. -Such information cannot be gathered after the return of <a href="#lua_pcall"><code>lua_pcall</code></a>, -since by then the stack has unwound. - - -<p> -The <a href="#lua_pcall"><code>lua_pcall</code></a> function returns 0 in case of success -or one of the following error codes -(defined in <code>lua.h</code>): - -<ul> - -<li><b><a name="pdf-LUA_ERRRUN"><code>LUA_ERRRUN</code></a>:</b> -a runtime error. -</li> - -<li><b><a name="pdf-LUA_ERRMEM"><code>LUA_ERRMEM</code></a>:</b> -memory allocation error. -For such errors, Lua does not call the error handler function. -</li> - -<li><b><a name="pdf-LUA_ERRERR"><code>LUA_ERRERR</code></a>:</b> -error while running the error handler function. -</li> - -</ul> - - - - -<hr><h3><a name="lua_pop"><code>lua_pop</code></a></h3><p> -<span class="apii">[-n, +0, <em>-</em>]</span> -<pre>void lua_pop (lua_State *L, int n);</pre> - -<p> -Pops <code>n</code> elements from the stack. - - - - - -<hr><h3><a name="lua_pushboolean"><code>lua_pushboolean</code></a></h3><p> -<span class="apii">[-0, +1, <em>-</em>]</span> -<pre>void lua_pushboolean (lua_State *L, int b);</pre> - -<p> -Pushes a boolean value with value <code>b</code> onto the stack. - - - - - -<hr><h3><a name="lua_pushcclosure"><code>lua_pushcclosure</code></a></h3><p> -<span class="apii">[-n, +1, <em>m</em>]</span> -<pre>void lua_pushcclosure (lua_State *L, lua_CFunction fn, int n);</pre> - -<p> -Pushes a new C closure onto the stack. - - -<p> -When a C function is created, -it is possible to associate some values with it, -thus creating a C closure (see <a href="#3.4">§3.4</a>); -these values are then accessible to the function whenever it is called. -To associate values with a C function, -first these values should be pushed onto the stack -(when there are multiple values, the first value is pushed first). -Then <a href="#lua_pushcclosure"><code>lua_pushcclosure</code></a> -is called to create and push the C function onto the stack, -with the argument <code>n</code> telling how many values should be -associated with the function. -<a href="#lua_pushcclosure"><code>lua_pushcclosure</code></a> also pops these values from the stack. - - -<p> -The maximum value for <code>n</code> is 255. - - - - - -<hr><h3><a name="lua_pushcfunction"><code>lua_pushcfunction</code></a></h3><p> -<span class="apii">[-0, +1, <em>m</em>]</span> -<pre>void lua_pushcfunction (lua_State *L, lua_CFunction f);</pre> - -<p> -Pushes a C function onto the stack. -This function receives a pointer to a C function -and pushes onto the stack a Lua value of type <code>function</code> that, -when called, invokes the corresponding C function. - - -<p> -Any function to be registered in Lua must -follow the correct protocol to receive its parameters -and return its results (see <a href="#lua_CFunction"><code>lua_CFunction</code></a>). - - -<p> -<code>lua_pushcfunction</code> is defined as a macro: - -<pre> - #define lua_pushcfunction(L,f) lua_pushcclosure(L,f,0) -</pre> - - - - -<hr><h3><a name="lua_pushfstring"><code>lua_pushfstring</code></a></h3><p> -<span class="apii">[-0, +1, <em>m</em>]</span> -<pre>const char *lua_pushfstring (lua_State *L, const char *fmt, ...);</pre> - -<p> -Pushes onto the stack a formatted string -and returns a pointer to this string. -It is similar to the C function <code>sprintf</code>, -but has some important differences: - -<ul> - -<li> -You do not have to allocate space for the result: -the result is a Lua string and Lua takes care of memory allocation -(and deallocation, through garbage collection). -</li> - -<li> -The conversion specifiers are quite restricted. -There are no flags, widths, or precisions. -The conversion specifiers can only be -'<code>%%</code>' (inserts a '<code>%</code>' in the string), -'<code>%s</code>' (inserts a zero-terminated string, with no size restrictions), -'<code>%f</code>' (inserts a <a href="#lua_Number"><code>lua_Number</code></a>), -'<code>%p</code>' (inserts a pointer as a hexadecimal numeral), -'<code>%d</code>' (inserts an <code>int</code>), and -'<code>%c</code>' (inserts an <code>int</code> as a character). -</li> - -</ul> - - - - -<hr><h3><a name="lua_pushinteger"><code>lua_pushinteger</code></a></h3><p> -<span class="apii">[-0, +1, <em>-</em>]</span> -<pre>void lua_pushinteger (lua_State *L, lua_Integer n);</pre> - -<p> -Pushes a number with value <code>n</code> onto the stack. - - - - - -<hr><h3><a name="lua_pushlightuserdata"><code>lua_pushlightuserdata</code></a></h3><p> -<span class="apii">[-0, +1, <em>-</em>]</span> -<pre>void lua_pushlightuserdata (lua_State *L, void *p);</pre> - -<p> -Pushes a light userdata onto the stack. - - -<p> -Userdata represent C values in Lua. -A <em>light userdata</em> represents a pointer. -It is a value (like a number): -you do not create it, it has no individual metatable, -and it is not collected (as it was never created). -A light userdata is equal to "any" -light userdata with the same C address. - - - - - -<hr><h3><a name="lua_pushliteral"><code>lua_pushliteral</code></a></h3><p> -<span class="apii">[-0, +1, <em>m</em>]</span> -<pre>void lua_pushliteral (lua_State *L, const char *s);</pre> - -<p> -This macro is equivalent to <a href="#lua_pushlstring"><code>lua_pushlstring</code></a>, -but can be used only when <code>s</code> is a literal string. -In these cases, it automatically provides the string length. - - - - - -<hr><h3><a name="lua_pushlstring"><code>lua_pushlstring</code></a></h3><p> -<span class="apii">[-0, +1, <em>m</em>]</span> -<pre>void lua_pushlstring (lua_State *L, const char *s, size_t len);</pre> - -<p> -Pushes the string pointed to by <code>s</code> with size <code>len</code> -onto the stack. -Lua makes (or reuses) an internal copy of the given string, -so the memory at <code>s</code> can be freed or reused immediately after -the function returns. -The string can contain embedded zeros. - - - - - -<hr><h3><a name="lua_pushnil"><code>lua_pushnil</code></a></h3><p> -<span class="apii">[-0, +1, <em>-</em>]</span> -<pre>void lua_pushnil (lua_State *L);</pre> - -<p> -Pushes a nil value onto the stack. - - - - - -<hr><h3><a name="lua_pushnumber"><code>lua_pushnumber</code></a></h3><p> -<span class="apii">[-0, +1, <em>-</em>]</span> -<pre>void lua_pushnumber (lua_State *L, lua_Number n);</pre> - -<p> -Pushes a number with value <code>n</code> onto the stack. - - - - - -<hr><h3><a name="lua_pushstring"><code>lua_pushstring</code></a></h3><p> -<span class="apii">[-0, +1, <em>m</em>]</span> -<pre>void lua_pushstring (lua_State *L, const char *s);</pre> - -<p> -Pushes the zero-terminated string pointed to by <code>s</code> -onto the stack. -Lua makes (or reuses) an internal copy of the given string, -so the memory at <code>s</code> can be freed or reused immediately after -the function returns. -The string cannot contain embedded zeros; -it is assumed to end at the first zero. - - - - - -<hr><h3><a name="lua_pushthread"><code>lua_pushthread</code></a></h3><p> -<span class="apii">[-0, +1, <em>-</em>]</span> -<pre>int lua_pushthread (lua_State *L);</pre> - -<p> -Pushes the thread represented by <code>L</code> onto the stack. -Returns 1 if this thread is the main thread of its state. - - - - - -<hr><h3><a name="lua_pushvalue"><code>lua_pushvalue</code></a></h3><p> -<span class="apii">[-0, +1, <em>-</em>]</span> -<pre>void lua_pushvalue (lua_State *L, int index);</pre> - -<p> -Pushes a copy of the element at the given valid index -onto the stack. - - - - - -<hr><h3><a name="lua_pushvfstring"><code>lua_pushvfstring</code></a></h3><p> -<span class="apii">[-0, +1, <em>m</em>]</span> -<pre>const char *lua_pushvfstring (lua_State *L, - const char *fmt, - va_list argp);</pre> - -<p> -Equivalent to <a href="#lua_pushfstring"><code>lua_pushfstring</code></a>, except that it receives a <code>va_list</code> -instead of a variable number of arguments. - - - - - -<hr><h3><a name="lua_rawequal"><code>lua_rawequal</code></a></h3><p> -<span class="apii">[-0, +0, <em>-</em>]</span> -<pre>int lua_rawequal (lua_State *L, int index1, int index2);</pre> - -<p> -Returns 1 if the two values in acceptable indices <code>index1</code> and -<code>index2</code> are primitively equal -(that is, without calling metamethods). -Otherwise returns 0. -Also returns 0 if any of the indices are non valid. - - - - - -<hr><h3><a name="lua_rawget"><code>lua_rawget</code></a></h3><p> -<span class="apii">[-1, +1, <em>-</em>]</span> -<pre>void lua_rawget (lua_State *L, int index);</pre> - -<p> -Similar to <a href="#lua_gettable"><code>lua_gettable</code></a>, but does a raw access -(i.e., without metamethods). - - - - - -<hr><h3><a name="lua_rawgeti"><code>lua_rawgeti</code></a></h3><p> -<span class="apii">[-0, +1, <em>-</em>]</span> -<pre>void lua_rawgeti (lua_State *L, int index, int n);</pre> - -<p> -Pushes onto the stack the value <code>t[n]</code>, -where <code>t</code> is the value at the given valid index. -The access is raw; -that is, it does not invoke metamethods. - - - - - -<hr><h3><a name="lua_rawset"><code>lua_rawset</code></a></h3><p> -<span class="apii">[-2, +0, <em>m</em>]</span> -<pre>void lua_rawset (lua_State *L, int index);</pre> - -<p> -Similar to <a href="#lua_settable"><code>lua_settable</code></a>, but does a raw assignment -(i.e., without metamethods). - - - - - -<hr><h3><a name="lua_rawseti"><code>lua_rawseti</code></a></h3><p> -<span class="apii">[-1, +0, <em>m</em>]</span> -<pre>void lua_rawseti (lua_State *L, int index, int n);</pre> - -<p> -Does the equivalent of <code>t[n] = v</code>, -where <code>t</code> is the value at the given valid index -and <code>v</code> is the value at the top of the stack. - - -<p> -This function pops the value from the stack. -The assignment is raw; -that is, it does not invoke metamethods. - - - - - -<hr><h3><a name="lua_Reader"><code>lua_Reader</code></a></h3> -<pre>typedef const char * (*lua_Reader) (lua_State *L, - void *data, - size_t *size);</pre> - -<p> -The reader function used by <a href="#lua_load"><code>lua_load</code></a>. -Every time it needs another piece of the chunk, -<a href="#lua_load"><code>lua_load</code></a> calls the reader, -passing along its <code>data</code> parameter. -The reader must return a pointer to a block of memory -with a new piece of the chunk -and set <code>size</code> to the block size. -The block must exist until the reader function is called again. -To signal the end of the chunk, -the reader must return <code>NULL</code> or set <code>size</code> to zero. -The reader function may return pieces of any size greater than zero. - - - - - -<hr><h3><a name="lua_register"><code>lua_register</code></a></h3><p> -<span class="apii">[-0, +0, <em>e</em>]</span> -<pre>void lua_register (lua_State *L, - const char *name, - lua_CFunction f);</pre> - -<p> -Sets the C function <code>f</code> as the new value of global <code>name</code>. -It is defined as a macro: - -<pre> - #define lua_register(L,n,f) \ - (lua_pushcfunction(L, f), lua_setglobal(L, n)) -</pre> - - - - -<hr><h3><a name="lua_remove"><code>lua_remove</code></a></h3><p> -<span class="apii">[-1, +0, <em>-</em>]</span> -<pre>void lua_remove (lua_State *L, int index);</pre> - -<p> -Removes the element at the given valid index, -shifting down the elements above this index to fill the gap. -Cannot be called with a pseudo-index, -because a pseudo-index is not an actual stack position. - - - - - -<hr><h3><a name="lua_replace"><code>lua_replace</code></a></h3><p> -<span class="apii">[-1, +0, <em>-</em>]</span> -<pre>void lua_replace (lua_State *L, int index);</pre> - -<p> -Moves the top element into the given position (and pops it), -without shifting any element -(therefore replacing the value at the given position). - - - - - -<hr><h3><a name="lua_resume"><code>lua_resume</code></a></h3><p> -<span class="apii">[-?, +?, <em>-</em>]</span> -<pre>int lua_resume (lua_State *L, int narg);</pre> - -<p> -Starts and resumes a coroutine in a given thread. - - -<p> -To start a coroutine, you first create a new thread -(see <a href="#lua_newthread"><code>lua_newthread</code></a>); -then you push onto its stack the main function plus any arguments; -then you call <a href="#lua_resume"><code>lua_resume</code></a>, -with <code>narg</code> being the number of arguments. -This call returns when the coroutine suspends or finishes its execution. -When it returns, the stack contains all values passed to <a href="#lua_yield"><code>lua_yield</code></a>, -or all values returned by the body function. -<a href="#lua_resume"><code>lua_resume</code></a> returns -<a href="#pdf-LUA_YIELD"><code>LUA_YIELD</code></a> if the coroutine yields, -0 if the coroutine finishes its execution -without errors, -or an error code in case of errors (see <a href="#lua_pcall"><code>lua_pcall</code></a>). -In case of errors, -the stack is not unwound, -so you can use the debug API over it. -The error message is on the top of the stack. -To restart a coroutine, you put on its stack only the values to -be passed as results from <code>yield</code>, -and then call <a href="#lua_resume"><code>lua_resume</code></a>. - - - - - -<hr><h3><a name="lua_setallocf"><code>lua_setallocf</code></a></h3><p> -<span class="apii">[-0, +0, <em>-</em>]</span> -<pre>void lua_setallocf (lua_State *L, lua_Alloc f, void *ud);</pre> - -<p> -Changes the allocator function of a given state to <code>f</code> -with user data <code>ud</code>. - - - - - -<hr><h3><a name="lua_setfenv"><code>lua_setfenv</code></a></h3><p> -<span class="apii">[-1, +0, <em>-</em>]</span> -<pre>int lua_setfenv (lua_State *L, int index);</pre> - -<p> -Pops a table from the stack and sets it as -the new environment for the value at the given index. -If the value at the given index is -neither a function nor a thread nor a userdata, -<a href="#lua_setfenv"><code>lua_setfenv</code></a> returns 0. -Otherwise it returns 1. - - - - - -<hr><h3><a name="lua_setfield"><code>lua_setfield</code></a></h3><p> -<span class="apii">[-1, +0, <em>e</em>]</span> -<pre>void lua_setfield (lua_State *L, int index, const char *k);</pre> - -<p> -Does the equivalent to <code>t[k] = v</code>, -where <code>t</code> is the value at the given valid index -and <code>v</code> is the value at the top of the stack. - - -<p> -This function pops the value from the stack. -As in Lua, this function may trigger a metamethod -for the "newindex" event (see <a href="#2.8">§2.8</a>). - - - - - -<hr><h3><a name="lua_setglobal"><code>lua_setglobal</code></a></h3><p> -<span class="apii">[-1, +0, <em>e</em>]</span> -<pre>void lua_setglobal (lua_State *L, const char *name);</pre> - -<p> -Pops a value from the stack and -sets it as the new value of global <code>name</code>. -It is defined as a macro: - -<pre> - #define lua_setglobal(L,s) lua_setfield(L, LUA_GLOBALSINDEX, s) -</pre> - - - - -<hr><h3><a name="lua_setmetatable"><code>lua_setmetatable</code></a></h3><p> -<span class="apii">[-1, +0, <em>-</em>]</span> -<pre>int lua_setmetatable (lua_State *L, int index);</pre> - -<p> -Pops a table from the stack and -sets it as the new metatable for the value at the given -acceptable index. - - - - - -<hr><h3><a name="lua_settable"><code>lua_settable</code></a></h3><p> -<span class="apii">[-2, +0, <em>e</em>]</span> -<pre>void lua_settable (lua_State *L, int index);</pre> - -<p> -Does the equivalent to <code>t[k] = v</code>, -where <code>t</code> is the value at the given valid index, -<code>v</code> is the value at the top of the stack, -and <code>k</code> is the value just below the top. - - -<p> -This function pops both the key and the value from the stack. -As in Lua, this function may trigger a metamethod -for the "newindex" event (see <a href="#2.8">§2.8</a>). - - - - - -<hr><h3><a name="lua_settop"><code>lua_settop</code></a></h3><p> -<span class="apii">[-?, +?, <em>-</em>]</span> -<pre>void lua_settop (lua_State *L, int index);</pre> - -<p> -Accepts any acceptable index, or 0, -and sets the stack top to this index. -If the new top is larger than the old one, -then the new elements are filled with <b>nil</b>. -If <code>index</code> is 0, then all stack elements are removed. - - - - - -<hr><h3><a name="lua_State"><code>lua_State</code></a></h3> -<pre>typedef struct lua_State lua_State;</pre> - -<p> -Opaque structure that keeps the whole state of a Lua interpreter. -The Lua library is fully reentrant: -it has no global variables. -All information about a state is kept in this structure. - - -<p> -A pointer to this state must be passed as the first argument to -every function in the library, except to <a href="#lua_newstate"><code>lua_newstate</code></a>, -which creates a Lua state from scratch. - - - - - -<hr><h3><a name="lua_status"><code>lua_status</code></a></h3><p> -<span class="apii">[-0, +0, <em>-</em>]</span> -<pre>int lua_status (lua_State *L);</pre> - -<p> -Returns the status of the thread <code>L</code>. - - -<p> -The status can be 0 for a normal thread, -an error code if the thread finished its execution with an error, -or <a name="pdf-LUA_YIELD"><code>LUA_YIELD</code></a> if the thread is suspended. - - - - - -<hr><h3><a name="lua_toboolean"><code>lua_toboolean</code></a></h3><p> -<span class="apii">[-0, +0, <em>-</em>]</span> -<pre>int lua_toboolean (lua_State *L, int index);</pre> - -<p> -Converts the Lua value at the given acceptable index to a C boolean -value (0 or 1). -Like all tests in Lua, -<a href="#lua_toboolean"><code>lua_toboolean</code></a> returns 1 for any Lua value -different from <b>false</b> and <b>nil</b>; -otherwise it returns 0. -It also returns 0 when called with a non-valid index. -(If you want to accept only actual boolean values, -use <a href="#lua_isboolean"><code>lua_isboolean</code></a> to test the value's type.) - - - - - -<hr><h3><a name="lua_tocfunction"><code>lua_tocfunction</code></a></h3><p> -<span class="apii">[-0, +0, <em>-</em>]</span> -<pre>lua_CFunction lua_tocfunction (lua_State *L, int index);</pre> - -<p> -Converts a value at the given acceptable index to a C function. -That value must be a C function; -otherwise, returns <code>NULL</code>. - - - - - -<hr><h3><a name="lua_tointeger"><code>lua_tointeger</code></a></h3><p> -<span class="apii">[-0, +0, <em>-</em>]</span> -<pre>lua_Integer lua_tointeger (lua_State *L, int index);</pre> - -<p> -Converts the Lua value at the given acceptable index -to the signed integral type <a href="#lua_Integer"><code>lua_Integer</code></a>. -The Lua value must be a number or a string convertible to a number -(see <a href="#2.2.1">§2.2.1</a>); -otherwise, <a href="#lua_tointeger"><code>lua_tointeger</code></a> returns 0. - - -<p> -If the number is not an integer, -it is truncated in some non-specified way. - - - - - -<hr><h3><a name="lua_tolstring"><code>lua_tolstring</code></a></h3><p> -<span class="apii">[-0, +0, <em>m</em>]</span> -<pre>const char *lua_tolstring (lua_State *L, int index, size_t *len);</pre> - -<p> -Converts the Lua value at the given acceptable index to a C string. -If <code>len</code> is not <code>NULL</code>, -it also sets <code>*len</code> with the string length. -The Lua value must be a string or a number; -otherwise, the function returns <code>NULL</code>. -If the value is a number, -then <a href="#lua_tolstring"><code>lua_tolstring</code></a> also -<em>changes the actual value in the stack to a string</em>. -(This change confuses <a href="#lua_next"><code>lua_next</code></a> -when <a href="#lua_tolstring"><code>lua_tolstring</code></a> is applied to keys during a table traversal.) - - -<p> -<a href="#lua_tolstring"><code>lua_tolstring</code></a> returns a fully aligned pointer -to a string inside the Lua state. -This string always has a zero ('<code>\0</code>') -after its last character (as in C), -but can contain other zeros in its body. -Because Lua has garbage collection, -there is no guarantee that the pointer returned by <a href="#lua_tolstring"><code>lua_tolstring</code></a> -will be valid after the corresponding value is removed from the stack. - - - - - -<hr><h3><a name="lua_tonumber"><code>lua_tonumber</code></a></h3><p> -<span class="apii">[-0, +0, <em>-</em>]</span> -<pre>lua_Number lua_tonumber (lua_State *L, int index);</pre> - -<p> -Converts the Lua value at the given acceptable index -to the C type <a href="#lua_Number"><code>lua_Number</code></a> (see <a href="#lua_Number"><code>lua_Number</code></a>). -The Lua value must be a number or a string convertible to a number -(see <a href="#2.2.1">§2.2.1</a>); -otherwise, <a href="#lua_tonumber"><code>lua_tonumber</code></a> returns 0. - - - - - -<hr><h3><a name="lua_topointer"><code>lua_topointer</code></a></h3><p> -<span class="apii">[-0, +0, <em>-</em>]</span> -<pre>const void *lua_topointer (lua_State *L, int index);</pre> - -<p> -Converts the value at the given acceptable index to a generic -C pointer (<code>void*</code>). -The value can be a userdata, a table, a thread, or a function; -otherwise, <a href="#lua_topointer"><code>lua_topointer</code></a> returns <code>NULL</code>. -Different objects will give different pointers. -There is no way to convert the pointer back to its original value. - - -<p> -Typically this function is used only for debug information. - - - - - -<hr><h3><a name="lua_tostring"><code>lua_tostring</code></a></h3><p> -<span class="apii">[-0, +0, <em>m</em>]</span> -<pre>const char *lua_tostring (lua_State *L, int index);</pre> - -<p> -Equivalent to <a href="#lua_tolstring"><code>lua_tolstring</code></a> with <code>len</code> equal to <code>NULL</code>. - - - - - -<hr><h3><a name="lua_tothread"><code>lua_tothread</code></a></h3><p> -<span class="apii">[-0, +0, <em>-</em>]</span> -<pre>lua_State *lua_tothread (lua_State *L, int index);</pre> - -<p> -Converts the value at the given acceptable index to a Lua thread -(represented as <code>lua_State*</code>). -This value must be a thread; -otherwise, the function returns <code>NULL</code>. - - - - - -<hr><h3><a name="lua_touserdata"><code>lua_touserdata</code></a></h3><p> -<span class="apii">[-0, +0, <em>-</em>]</span> -<pre>void *lua_touserdata (lua_State *L, int index);</pre> - -<p> -If the value at the given acceptable index is a full userdata, -returns its block address. -If the value is a light userdata, -returns its pointer. -Otherwise, returns <code>NULL</code>. - - - - - -<hr><h3><a name="lua_type"><code>lua_type</code></a></h3><p> -<span class="apii">[-0, +0, <em>-</em>]</span> -<pre>int lua_type (lua_State *L, int index);</pre> - -<p> -Returns the type of the value in the given acceptable index, -or <code>LUA_TNONE</code> for a non-valid index -(that is, an index to an "empty" stack position). -The types returned by <a href="#lua_type"><code>lua_type</code></a> are coded by the following constants -defined in <code>lua.h</code>: -<code>LUA_TNIL</code>, -<code>LUA_TNUMBER</code>, -<code>LUA_TBOOLEAN</code>, -<code>LUA_TSTRING</code>, -<code>LUA_TTABLE</code>, -<code>LUA_TFUNCTION</code>, -<code>LUA_TUSERDATA</code>, -<code>LUA_TTHREAD</code>, -and -<code>LUA_TLIGHTUSERDATA</code>. - - - - - -<hr><h3><a name="lua_typename"><code>lua_typename</code></a></h3><p> -<span class="apii">[-0, +0, <em>-</em>]</span> -<pre>const char *lua_typename (lua_State *L, int tp);</pre> - -<p> -Returns the name of the type encoded by the value <code>tp</code>, -which must be one the values returned by <a href="#lua_type"><code>lua_type</code></a>. - - - - - -<hr><h3><a name="lua_Writer"><code>lua_Writer</code></a></h3> -<pre>typedef int (*lua_Writer) (lua_State *L, - const void* p, - size_t sz, - void* ud);</pre> - -<p> -The type of the writer function used by <a href="#lua_dump"><code>lua_dump</code></a>. -Every time it produces another piece of chunk, -<a href="#lua_dump"><code>lua_dump</code></a> calls the writer, -passing along the buffer to be written (<code>p</code>), -its size (<code>sz</code>), -and the <code>data</code> parameter supplied to <a href="#lua_dump"><code>lua_dump</code></a>. - - -<p> -The writer returns an error code: -0 means no errors; -any other value means an error and stops <a href="#lua_dump"><code>lua_dump</code></a> from -calling the writer again. - - - - - -<hr><h3><a name="lua_xmove"><code>lua_xmove</code></a></h3><p> -<span class="apii">[-?, +?, <em>-</em>]</span> -<pre>void lua_xmove (lua_State *from, lua_State *to, int n);</pre> - -<p> -Exchange values between different threads of the <em>same</em> global state. - - -<p> -This function pops <code>n</code> values from the stack <code>from</code>, -and pushes them onto the stack <code>to</code>. - - - - - -<hr><h3><a name="lua_yield"><code>lua_yield</code></a></h3><p> -<span class="apii">[-?, +?, <em>-</em>]</span> -<pre>int lua_yield (lua_State *L, int nresults);</pre> - -<p> -Yields a coroutine. - - -<p> -This function should only be called as the -return expression of a C function, as follows: - -<pre> - return lua_yield (L, nresults); -</pre><p> -When a C function calls <a href="#lua_yield"><code>lua_yield</code></a> in that way, -the running coroutine suspends its execution, -and the call to <a href="#lua_resume"><code>lua_resume</code></a> that started this coroutine returns. -The parameter <code>nresults</code> is the number of values from the stack -that are passed as results to <a href="#lua_resume"><code>lua_resume</code></a>. - - - - - - - -<h2>3.8 - <a name="3.8">The Debug Interface</a></h2> - -<p> -Lua has no built-in debugging facilities. -Instead, it offers a special interface -by means of functions and <em>hooks</em>. -This interface allows the construction of different -kinds of debuggers, profilers, and other tools -that need "inside information" from the interpreter. - - - -<hr><h3><a name="lua_Debug"><code>lua_Debug</code></a></h3> -<pre>typedef struct lua_Debug { - int event; - const char *name; /* (n) */ - const char *namewhat; /* (n) */ - const char *what; /* (S) */ - const char *source; /* (S) */ - int currentline; /* (l) */ - int nups; /* (u) number of upvalues */ - int linedefined; /* (S) */ - int lastlinedefined; /* (S) */ - char short_src[LUA_IDSIZE]; /* (S) */ - /* private part */ - <em>other fields</em> -} lua_Debug;</pre> - -<p> -A structure used to carry different pieces of -information about an active function. -<a href="#lua_getstack"><code>lua_getstack</code></a> fills only the private part -of this structure, for later use. -To fill the other fields of <a href="#lua_Debug"><code>lua_Debug</code></a> with useful information, -call <a href="#lua_getinfo"><code>lua_getinfo</code></a>. - - -<p> -The fields of <a href="#lua_Debug"><code>lua_Debug</code></a> have the following meaning: - -<ul> - -<li><b><code>source</code>:</b> -If the function was defined in a string, -then <code>source</code> is that string. -If the function was defined in a file, -then <code>source</code> starts with a '<code>@</code>' followed by the file name. -</li> - -<li><b><code>short_src</code>:</b> -a "printable" version of <code>source</code>, to be used in error messages. -</li> - -<li><b><code>linedefined</code>:</b> -the line number where the definition of the function starts. -</li> - -<li><b><code>lastlinedefined</code>:</b> -the line number where the definition of the function ends. -</li> - -<li><b><code>what</code>:</b> -the string <code>"Lua"</code> if the function is a Lua function, -<code>"C"</code> if it is a C function, -<code>"main"</code> if it is the main part of a chunk, -and <code>"tail"</code> if it was a function that did a tail call. -In the latter case, -Lua has no other information about the function. -</li> - -<li><b><code>currentline</code>:</b> -the current line where the given function is executing. -When no line information is available, -<code>currentline</code> is set to -1. -</li> - -<li><b><code>name</code>:</b> -a reasonable name for the given function. -Because functions in Lua are first-class values, -they do not have a fixed name: -some functions can be the value of multiple global variables, -while others can be stored only in a table field. -The <code>lua_getinfo</code> function checks how the function was -called to find a suitable name. -If it cannot find a name, -then <code>name</code> is set to <code>NULL</code>. -</li> - -<li><b><code>namewhat</code>:</b> -explains the <code>name</code> field. -The value of <code>namewhat</code> can be -<code>"global"</code>, <code>"local"</code>, <code>"method"</code>, -<code>"field"</code>, <code>"upvalue"</code>, or <code>""</code> (the empty string), -according to how the function was called. -(Lua uses the empty string when no other option seems to apply.) -</li> - -<li><b><code>nups</code>:</b> -the number of upvalues of the function. -</li> - -</ul> - - - - -<hr><h3><a name="lua_gethook"><code>lua_gethook</code></a></h3><p> -<span class="apii">[-0, +0, <em>-</em>]</span> -<pre>lua_Hook lua_gethook (lua_State *L);</pre> - -<p> -Returns the current hook function. - - - - - -<hr><h3><a name="lua_gethookcount"><code>lua_gethookcount</code></a></h3><p> -<span class="apii">[-0, +0, <em>-</em>]</span> -<pre>int lua_gethookcount (lua_State *L);</pre> - -<p> -Returns the current hook count. - - - - - -<hr><h3><a name="lua_gethookmask"><code>lua_gethookmask</code></a></h3><p> -<span class="apii">[-0, +0, <em>-</em>]</span> -<pre>int lua_gethookmask (lua_State *L);</pre> - -<p> -Returns the current hook mask. - - - - - -<hr><h3><a name="lua_getinfo"><code>lua_getinfo</code></a></h3><p> -<span class="apii">[-(0|1), +(0|1|2), <em>m</em>]</span> -<pre>int lua_getinfo (lua_State *L, const char *what, lua_Debug *ar);</pre> - -<p> -Returns information about a specific function or function invocation. - - -<p> -To get information about a function invocation, -the parameter <code>ar</code> must be a valid activation record that was -filled by a previous call to <a href="#lua_getstack"><code>lua_getstack</code></a> or -given as argument to a hook (see <a href="#lua_Hook"><code>lua_Hook</code></a>). - - -<p> -To get information about a function you push it onto the stack -and start the <code>what</code> string with the character '<code>></code>'. -(In that case, -<code>lua_getinfo</code> pops the function in the top of the stack.) -For instance, to know in which line a function <code>f</code> was defined, -you can write the following code: - -<pre> - lua_Debug ar; - lua_getfield(L, LUA_GLOBALSINDEX, "f"); /* get global 'f' */ - lua_getinfo(L, ">S", &ar); - printf("%d\n", ar.linedefined); -</pre> - -<p> -Each character in the string <code>what</code> -selects some fields of the structure <code>ar</code> to be filled or -a value to be pushed on the stack: - -<ul> - -<li><b>'<code>n</code>':</b> fills in the field <code>name</code> and <code>namewhat</code>; -</li> - -<li><b>'<code>S</code>':</b> -fills in the fields <code>source</code>, <code>short_src</code>, -<code>linedefined</code>, <code>lastlinedefined</code>, and <code>what</code>; -</li> - -<li><b>'<code>l</code>':</b> fills in the field <code>currentline</code>; -</li> - -<li><b>'<code>u</code>':</b> fills in the field <code>nups</code>; -</li> - -<li><b>'<code>f</code>':</b> -pushes onto the stack the function that is -running at the given level; -</li> - -<li><b>'<code>L</code>':</b> -pushes onto the stack a table whose indices are the -numbers of the lines that are valid on the function. -(A <em>valid line</em> is a line with some associated code, -that is, a line where you can put a break point. -Non-valid lines include empty lines and comments.) -</li> - -</ul> - -<p> -This function returns 0 on error -(for instance, an invalid option in <code>what</code>). - - - - - -<hr><h3><a name="lua_getlocal"><code>lua_getlocal</code></a></h3><p> -<span class="apii">[-0, +(0|1), <em>-</em>]</span> -<pre>const char *lua_getlocal (lua_State *L, lua_Debug *ar, int n);</pre> - -<p> -Gets information about a local variable of a given activation record. -The parameter <code>ar</code> must be a valid activation record that was -filled by a previous call to <a href="#lua_getstack"><code>lua_getstack</code></a> or -given as argument to a hook (see <a href="#lua_Hook"><code>lua_Hook</code></a>). -The index <code>n</code> selects which local variable to inspect -(1 is the first parameter or active local variable, and so on, -until the last active local variable). -<a href="#lua_getlocal"><code>lua_getlocal</code></a> pushes the variable's value onto the stack -and returns its name. - - -<p> -Variable names starting with '<code>(</code>' (open parentheses) -represent internal variables -(loop control variables, temporaries, and C function locals). - - -<p> -Returns <code>NULL</code> (and pushes nothing) -when the index is greater than -the number of active local variables. - - - - - -<hr><h3><a name="lua_getstack"><code>lua_getstack</code></a></h3><p> -<span class="apii">[-0, +0, <em>-</em>]</span> -<pre>int lua_getstack (lua_State *L, int level, lua_Debug *ar);</pre> - -<p> -Get information about the interpreter runtime stack. - - -<p> -This function fills parts of a <a href="#lua_Debug"><code>lua_Debug</code></a> structure with -an identification of the <em>activation record</em> -of the function executing at a given level. -Level 0 is the current running function, -whereas level <em>n+1</em> is the function that has called level <em>n</em>. -When there are no errors, <a href="#lua_getstack"><code>lua_getstack</code></a> returns 1; -when called with a level greater than the stack depth, -it returns 0. - - - - - -<hr><h3><a name="lua_getupvalue"><code>lua_getupvalue</code></a></h3><p> -<span class="apii">[-0, +(0|1), <em>-</em>]</span> -<pre>const char *lua_getupvalue (lua_State *L, int funcindex, int n);</pre> - -<p> -Gets information about a closure's upvalue. -(For Lua functions, -upvalues are the external local variables that the function uses, -and that are consequently included in its closure.) -<a href="#lua_getupvalue"><code>lua_getupvalue</code></a> gets the index <code>n</code> of an upvalue, -pushes the upvalue's value onto the stack, -and returns its name. -<code>funcindex</code> points to the closure in the stack. -(Upvalues have no particular order, -as they are active through the whole function. -So, they are numbered in an arbitrary order.) - - -<p> -Returns <code>NULL</code> (and pushes nothing) -when the index is greater than the number of upvalues. -For C functions, this function uses the empty string <code>""</code> -as a name for all upvalues. - - - - - -<hr><h3><a name="lua_Hook"><code>lua_Hook</code></a></h3> -<pre>typedef void (*lua_Hook) (lua_State *L, lua_Debug *ar);</pre> - -<p> -Type for debugging hook functions. - - -<p> -Whenever a hook is called, its <code>ar</code> argument has its field -<code>event</code> set to the specific event that triggered the hook. -Lua identifies these events with the following constants: -<a name="pdf-LUA_HOOKCALL"><code>LUA_HOOKCALL</code></a>, <a name="pdf-LUA_HOOKRET"><code>LUA_HOOKRET</code></a>, -<a name="pdf-LUA_HOOKTAILRET"><code>LUA_HOOKTAILRET</code></a>, <a name="pdf-LUA_HOOKLINE"><code>LUA_HOOKLINE</code></a>, -and <a name="pdf-LUA_HOOKCOUNT"><code>LUA_HOOKCOUNT</code></a>. -Moreover, for line events, the field <code>currentline</code> is also set. -To get the value of any other field in <code>ar</code>, -the hook must call <a href="#lua_getinfo"><code>lua_getinfo</code></a>. -For return events, <code>event</code> can be <code>LUA_HOOKRET</code>, -the normal value, or <code>LUA_HOOKTAILRET</code>. -In the latter case, Lua is simulating a return from -a function that did a tail call; -in this case, it is useless to call <a href="#lua_getinfo"><code>lua_getinfo</code></a>. - - -<p> -While Lua is running a hook, it disables other calls to hooks. -Therefore, if a hook calls back Lua to execute a function or a chunk, -this execution occurs without any calls to hooks. - - - - - -<hr><h3><a name="lua_sethook"><code>lua_sethook</code></a></h3><p> -<span class="apii">[-0, +0, <em>-</em>]</span> -<pre>int lua_sethook (lua_State *L, lua_Hook f, int mask, int count);</pre> - -<p> -Sets the debugging hook function. - - -<p> -Argument <code>f</code> is the hook function. -<code>mask</code> specifies on which events the hook will be called: -it is formed by a bitwise or of the constants -<a name="pdf-LUA_MASKCALL"><code>LUA_MASKCALL</code></a>, -<a name="pdf-LUA_MASKRET"><code>LUA_MASKRET</code></a>, -<a name="pdf-LUA_MASKLINE"><code>LUA_MASKLINE</code></a>, -and <a name="pdf-LUA_MASKCOUNT"><code>LUA_MASKCOUNT</code></a>. -The <code>count</code> argument is only meaningful when the mask -includes <code>LUA_MASKCOUNT</code>. -For each event, the hook is called as explained below: - -<ul> - -<li><b>The call hook:</b> is called when the interpreter calls a function. -The hook is called just after Lua enters the new function, -before the function gets its arguments. -</li> - -<li><b>The return hook:</b> is called when the interpreter returns from a function. -The hook is called just before Lua leaves the function. -You have no access to the values to be returned by the function. -</li> - -<li><b>The line hook:</b> is called when the interpreter is about to -start the execution of a new line of code, -or when it jumps back in the code (even to the same line). -(This event only happens while Lua is executing a Lua function.) -</li> - -<li><b>The count hook:</b> is called after the interpreter executes every -<code>count</code> instructions. -(This event only happens while Lua is executing a Lua function.) -</li> - -</ul> - -<p> -A hook is disabled by setting <code>mask</code> to zero. - - - - - -<hr><h3><a name="lua_setlocal"><code>lua_setlocal</code></a></h3><p> -<span class="apii">[-(0|1), +0, <em>-</em>]</span> -<pre>const char *lua_setlocal (lua_State *L, lua_Debug *ar, int n);</pre> - -<p> -Sets the value of a local variable of a given activation record. -Parameters <code>ar</code> and <code>n</code> are as in <a href="#lua_getlocal"><code>lua_getlocal</code></a> -(see <a href="#lua_getlocal"><code>lua_getlocal</code></a>). -<a href="#lua_setlocal"><code>lua_setlocal</code></a> assigns the value at the top of the stack -to the variable and returns its name. -It also pops the value from the stack. - - -<p> -Returns <code>NULL</code> (and pops nothing) -when the index is greater than -the number of active local variables. - - - - - -<hr><h3><a name="lua_setupvalue"><code>lua_setupvalue</code></a></h3><p> -<span class="apii">[-(0|1), +0, <em>-</em>]</span> -<pre>const char *lua_setupvalue (lua_State *L, int funcindex, int n);</pre> - -<p> -Sets the value of a closure's upvalue. -It assigns the value at the top of the stack -to the upvalue and returns its name. -It also pops the value from the stack. -Parameters <code>funcindex</code> and <code>n</code> are as in the <a href="#lua_getupvalue"><code>lua_getupvalue</code></a> -(see <a href="#lua_getupvalue"><code>lua_getupvalue</code></a>). - - -<p> -Returns <code>NULL</code> (and pops nothing) -when the index is greater than the number of upvalues. - - - - - - - -<h1>4 - <a name="4">The Auxiliary Library</a></h1> - -<p> - -The <em>auxiliary library</em> provides several convenient functions -to interface C with Lua. -While the basic API provides the primitive functions for all -interactions between C and Lua, -the auxiliary library provides higher-level functions for some -common tasks. - - -<p> -All functions from the auxiliary library -are defined in header file <code>lauxlib.h</code> and -have a prefix <code>luaL_</code>. - - -<p> -All functions in the auxiliary library are built on -top of the basic API, -and so they provide nothing that cannot be done with this API. - - -<p> -Several functions in the auxiliary library are used to -check C function arguments. -Their names are always <code>luaL_check*</code> or <code>luaL_opt*</code>. -All of these functions throw an error if the check is not satisfied. -Because the error message is formatted for arguments -(e.g., "<code>bad argument #1</code>"), -you should not use these functions for other stack values. - - - -<h2>4.1 - <a name="4.1">Functions and Types</a></h2> - -<p> -Here we list all functions and types from the auxiliary library -in alphabetical order. - - - -<hr><h3><a name="luaL_addchar"><code>luaL_addchar</code></a></h3><p> -<span class="apii">[-0, +0, <em>m</em>]</span> -<pre>void luaL_addchar (luaL_Buffer *B, char c);</pre> - -<p> -Adds the character <code>c</code> to the buffer <code>B</code> -(see <a href="#luaL_Buffer"><code>luaL_Buffer</code></a>). - - - - - -<hr><h3><a name="luaL_addlstring"><code>luaL_addlstring</code></a></h3><p> -<span class="apii">[-0, +0, <em>m</em>]</span> -<pre>void luaL_addlstring (luaL_Buffer *B, const char *s, size_t l);</pre> - -<p> -Adds the string pointed to by <code>s</code> with length <code>l</code> to -the buffer <code>B</code> -(see <a href="#luaL_Buffer"><code>luaL_Buffer</code></a>). -The string may contain embedded zeros. - - - - - -<hr><h3><a name="luaL_addsize"><code>luaL_addsize</code></a></h3><p> -<span class="apii">[-0, +0, <em>m</em>]</span> -<pre>void luaL_addsize (luaL_Buffer *B, size_t n);</pre> - -<p> -Adds to the buffer <code>B</code> (see <a href="#luaL_Buffer"><code>luaL_Buffer</code></a>) -a string of length <code>n</code> previously copied to the -buffer area (see <a href="#luaL_prepbuffer"><code>luaL_prepbuffer</code></a>). - - - - - -<hr><h3><a name="luaL_addstring"><code>luaL_addstring</code></a></h3><p> -<span class="apii">[-0, +0, <em>m</em>]</span> -<pre>void luaL_addstring (luaL_Buffer *B, const char *s);</pre> - -<p> -Adds the zero-terminated string pointed to by <code>s</code> -to the buffer <code>B</code> -(see <a href="#luaL_Buffer"><code>luaL_Buffer</code></a>). -The string may not contain embedded zeros. - - - - - -<hr><h3><a name="luaL_addvalue"><code>luaL_addvalue</code></a></h3><p> -<span class="apii">[-1, +0, <em>m</em>]</span> -<pre>void luaL_addvalue (luaL_Buffer *B);</pre> - -<p> -Adds the value at the top of the stack -to the buffer <code>B</code> -(see <a href="#luaL_Buffer"><code>luaL_Buffer</code></a>). -Pops the value. - - -<p> -This is the only function on string buffers that can (and must) -be called with an extra element on the stack, -which is the value to be added to the buffer. - - - - - -<hr><h3><a name="luaL_argcheck"><code>luaL_argcheck</code></a></h3><p> -<span class="apii">[-0, +0, <em>v</em>]</span> -<pre>void luaL_argcheck (lua_State *L, - int cond, - int narg, - const char *extramsg);</pre> - -<p> -Checks whether <code>cond</code> is true. -If not, raises an error with the following message, -where <code>func</code> is retrieved from the call stack: - -<pre> - bad argument #<narg> to <func> (<extramsg>) -</pre> - - - - -<hr><h3><a name="luaL_argerror"><code>luaL_argerror</code></a></h3><p> -<span class="apii">[-0, +0, <em>v</em>]</span> -<pre>int luaL_argerror (lua_State *L, int narg, const char *extramsg);</pre> - -<p> -Raises an error with the following message, -where <code>func</code> is retrieved from the call stack: - -<pre> - bad argument #<narg> to <func> (<extramsg>) -</pre> - -<p> -This function never returns, -but it is an idiom to use it in C functions -as <code>return luaL_argerror(<em>args</em>)</code>. - - - - - -<hr><h3><a name="luaL_Buffer"><code>luaL_Buffer</code></a></h3> -<pre>typedef struct luaL_Buffer luaL_Buffer;</pre> - -<p> -Type for a <em>string buffer</em>. - - -<p> -A string buffer allows C code to build Lua strings piecemeal. -Its pattern of use is as follows: - -<ul> - -<li>First you declare a variable <code>b</code> of type <a href="#luaL_Buffer"><code>luaL_Buffer</code></a>.</li> - -<li>Then you initialize it with a call <code>luaL_buffinit(L, &b)</code>.</li> - -<li> -Then you add string pieces to the buffer calling any of -the <code>luaL_add*</code> functions. -</li> - -<li> -You finish by calling <code>luaL_pushresult(&b)</code>. -This call leaves the final string on the top of the stack. -</li> - -</ul> - -<p> -During its normal operation, -a string buffer uses a variable number of stack slots. -So, while using a buffer, you cannot assume that you know where -the top of the stack is. -You can use the stack between successive calls to buffer operations -as long as that use is balanced; -that is, -when you call a buffer operation, -the stack is at the same level -it was immediately after the previous buffer operation. -(The only exception to this rule is <a href="#luaL_addvalue"><code>luaL_addvalue</code></a>.) -After calling <a href="#luaL_pushresult"><code>luaL_pushresult</code></a> the stack is back to its -level when the buffer was initialized, -plus the final string on its top. - - - - - -<hr><h3><a name="luaL_buffinit"><code>luaL_buffinit</code></a></h3><p> -<span class="apii">[-0, +0, <em>-</em>]</span> -<pre>void luaL_buffinit (lua_State *L, luaL_Buffer *B);</pre> - -<p> -Initializes a buffer <code>B</code>. -This function does not allocate any space; -the buffer must be declared as a variable -(see <a href="#luaL_Buffer"><code>luaL_Buffer</code></a>). - - - - - -<hr><h3><a name="luaL_callmeta"><code>luaL_callmeta</code></a></h3><p> -<span class="apii">[-0, +(0|1), <em>e</em>]</span> -<pre>int luaL_callmeta (lua_State *L, int obj, const char *e);</pre> - -<p> -Calls a metamethod. - - -<p> -If the object at index <code>obj</code> has a metatable and this -metatable has a field <code>e</code>, -this function calls this field and passes the object as its only argument. -In this case this function returns 1 and pushes onto the -stack the value returned by the call. -If there is no metatable or no metamethod, -this function returns 0 (without pushing any value on the stack). - - - - - -<hr><h3><a name="luaL_checkany"><code>luaL_checkany</code></a></h3><p> -<span class="apii">[-0, +0, <em>v</em>]</span> -<pre>void luaL_checkany (lua_State *L, int narg);</pre> - -<p> -Checks whether the function has an argument -of any type (including <b>nil</b>) at position <code>narg</code>. - - - - - -<hr><h3><a name="luaL_checkint"><code>luaL_checkint</code></a></h3><p> -<span class="apii">[-0, +0, <em>v</em>]</span> -<pre>int luaL_checkint (lua_State *L, int narg);</pre> - -<p> -Checks whether the function argument <code>narg</code> is a number -and returns this number cast to an <code>int</code>. - - - - - -<hr><h3><a name="luaL_checkinteger"><code>luaL_checkinteger</code></a></h3><p> -<span class="apii">[-0, +0, <em>v</em>]</span> -<pre>lua_Integer luaL_checkinteger (lua_State *L, int narg);</pre> - -<p> -Checks whether the function argument <code>narg</code> is a number -and returns this number cast to a <a href="#lua_Integer"><code>lua_Integer</code></a>. - - - - - -<hr><h3><a name="luaL_checklong"><code>luaL_checklong</code></a></h3><p> -<span class="apii">[-0, +0, <em>v</em>]</span> -<pre>long luaL_checklong (lua_State *L, int narg);</pre> - -<p> -Checks whether the function argument <code>narg</code> is a number -and returns this number cast to a <code>long</code>. - - - - - -<hr><h3><a name="luaL_checklstring"><code>luaL_checklstring</code></a></h3><p> -<span class="apii">[-0, +0, <em>v</em>]</span> -<pre>const char *luaL_checklstring (lua_State *L, int narg, size_t *l);</pre> - -<p> -Checks whether the function argument <code>narg</code> is a string -and returns this string; -if <code>l</code> is not <code>NULL</code> fills <code>*l</code> -with the string's length. - - -<p> -This function uses <a href="#lua_tolstring"><code>lua_tolstring</code></a> to get its result, -so all conversions and caveats of that function apply here. - - - - - -<hr><h3><a name="luaL_checknumber"><code>luaL_checknumber</code></a></h3><p> -<span class="apii">[-0, +0, <em>v</em>]</span> -<pre>lua_Number luaL_checknumber (lua_State *L, int narg);</pre> - -<p> -Checks whether the function argument <code>narg</code> is a number -and returns this number. - - - - - -<hr><h3><a name="luaL_checkoption"><code>luaL_checkoption</code></a></h3><p> -<span class="apii">[-0, +0, <em>v</em>]</span> -<pre>int luaL_checkoption (lua_State *L, - int narg, - const char *def, - const char *const lst[]);</pre> - -<p> -Checks whether the function argument <code>narg</code> is a string and -searches for this string in the array <code>lst</code> -(which must be NULL-terminated). -Returns the index in the array where the string was found. -Raises an error if the argument is not a string or -if the string cannot be found. - - -<p> -If <code>def</code> is not <code>NULL</code>, -the function uses <code>def</code> as a default value when -there is no argument <code>narg</code> or if this argument is <b>nil</b>. - - -<p> -This is a useful function for mapping strings to C enums. -(The usual convention in Lua libraries is -to use strings instead of numbers to select options.) - - - - - -<hr><h3><a name="luaL_checkstack"><code>luaL_checkstack</code></a></h3><p> -<span class="apii">[-0, +0, <em>v</em>]</span> -<pre>void luaL_checkstack (lua_State *L, int sz, const char *msg);</pre> - -<p> -Grows the stack size to <code>top + sz</code> elements, -raising an error if the stack cannot grow to that size. -<code>msg</code> is an additional text to go into the error message. - - - - - -<hr><h3><a name="luaL_checkstring"><code>luaL_checkstring</code></a></h3><p> -<span class="apii">[-0, +0, <em>v</em>]</span> -<pre>const char *luaL_checkstring (lua_State *L, int narg);</pre> - -<p> -Checks whether the function argument <code>narg</code> is a string -and returns this string. - - -<p> -This function uses <a href="#lua_tolstring"><code>lua_tolstring</code></a> to get its result, -so all conversions and caveats of that function apply here. - - - - - -<hr><h3><a name="luaL_checktype"><code>luaL_checktype</code></a></h3><p> -<span class="apii">[-0, +0, <em>v</em>]</span> -<pre>void luaL_checktype (lua_State *L, int narg, int t);</pre> - -<p> -Checks whether the function argument <code>narg</code> has type <code>t</code>. -See <a href="#lua_type"><code>lua_type</code></a> for the encoding of types for <code>t</code>. - - - - - -<hr><h3><a name="luaL_checkudata"><code>luaL_checkudata</code></a></h3><p> -<span class="apii">[-0, +0, <em>v</em>]</span> -<pre>void *luaL_checkudata (lua_State *L, int narg, const char *tname);</pre> - -<p> -Checks whether the function argument <code>narg</code> is a userdata -of the type <code>tname</code> (see <a href="#luaL_newmetatable"><code>luaL_newmetatable</code></a>). - - - - - -<hr><h3><a name="luaL_dofile"><code>luaL_dofile</code></a></h3><p> -<span class="apii">[-0, +?, <em>m</em>]</span> -<pre>int luaL_dofile (lua_State *L, const char *filename);</pre> - -<p> -Loads and runs the given file. -It is defined as the following macro: - -<pre> - (luaL_loadfile(L, filename) || lua_pcall(L, 0, LUA_MULTRET, 0)) -</pre><p> -It returns 0 if there are no errors -or 1 in case of errors. - - - - - -<hr><h3><a name="luaL_dostring"><code>luaL_dostring</code></a></h3><p> -<span class="apii">[-0, +?, <em>m</em>]</span> -<pre>int luaL_dostring (lua_State *L, const char *str);</pre> - -<p> -Loads and runs the given string. -It is defined as the following macro: - -<pre> - (luaL_loadstring(L, str) || lua_pcall(L, 0, LUA_MULTRET, 0)) -</pre><p> -It returns 0 if there are no errors -or 1 in case of errors. - - - - - -<hr><h3><a name="luaL_error"><code>luaL_error</code></a></h3><p> -<span class="apii">[-0, +0, <em>v</em>]</span> -<pre>int luaL_error (lua_State *L, const char *fmt, ...);</pre> - -<p> -Raises an error. -The error message format is given by <code>fmt</code> -plus any extra arguments, -following the same rules of <a href="#lua_pushfstring"><code>lua_pushfstring</code></a>. -It also adds at the beginning of the message the file name and -the line number where the error occurred, -if this information is available. - - -<p> -This function never returns, -but it is an idiom to use it in C functions -as <code>return luaL_error(<em>args</em>)</code>. - - - - - -<hr><h3><a name="luaL_getmetafield"><code>luaL_getmetafield</code></a></h3><p> -<span class="apii">[-0, +(0|1), <em>m</em>]</span> -<pre>int luaL_getmetafield (lua_State *L, int obj, const char *e);</pre> - -<p> -Pushes onto the stack the field <code>e</code> from the metatable -of the object at index <code>obj</code>. -If the object does not have a metatable, -or if the metatable does not have this field, -returns 0 and pushes nothing. - - - - - -<hr><h3><a name="luaL_getmetatable"><code>luaL_getmetatable</code></a></h3><p> -<span class="apii">[-0, +1, <em>-</em>]</span> -<pre>void luaL_getmetatable (lua_State *L, const char *tname);</pre> - -<p> -Pushes onto the stack the metatable associated with name <code>tname</code> -in the registry (see <a href="#luaL_newmetatable"><code>luaL_newmetatable</code></a>). - - - - - -<hr><h3><a name="luaL_gsub"><code>luaL_gsub</code></a></h3><p> -<span class="apii">[-0, +1, <em>m</em>]</span> -<pre>const char *luaL_gsub (lua_State *L, - const char *s, - const char *p, - const char *r);</pre> - -<p> -Creates a copy of string <code>s</code> by replacing -any occurrence of the string <code>p</code> -with the string <code>r</code>. -Pushes the resulting string on the stack and returns it. - - - - - -<hr><h3><a name="luaL_loadbuffer"><code>luaL_loadbuffer</code></a></h3><p> -<span class="apii">[-0, +1, <em>m</em>]</span> -<pre>int luaL_loadbuffer (lua_State *L, - const char *buff, - size_t sz, - const char *name);</pre> - -<p> -Loads a buffer as a Lua chunk. -This function uses <a href="#lua_load"><code>lua_load</code></a> to load the chunk in the -buffer pointed to by <code>buff</code> with size <code>sz</code>. - - -<p> -This function returns the same results as <a href="#lua_load"><code>lua_load</code></a>. -<code>name</code> is the chunk name, -used for debug information and error messages. - - - - - -<hr><h3><a name="luaL_loadfile"><code>luaL_loadfile</code></a></h3><p> -<span class="apii">[-0, +1, <em>m</em>]</span> -<pre>int luaL_loadfile (lua_State *L, const char *filename);</pre> - -<p> -Loads a file as a Lua chunk. -This function uses <a href="#lua_load"><code>lua_load</code></a> to load the chunk in the file -named <code>filename</code>. -If <code>filename</code> is <code>NULL</code>, -then it loads from the standard input. -The first line in the file is ignored if it starts with a <code>#</code>. - - -<p> -This function returns the same results as <a href="#lua_load"><code>lua_load</code></a>, -but it has an extra error code <a name="pdf-LUA_ERRFILE"><code>LUA_ERRFILE</code></a> -if it cannot open/read the file. - - -<p> -As <a href="#lua_load"><code>lua_load</code></a>, this function only loads the chunk; -it does not run it. - - - - - -<hr><h3><a name="luaL_loadstring"><code>luaL_loadstring</code></a></h3><p> -<span class="apii">[-0, +1, <em>m</em>]</span> -<pre>int luaL_loadstring (lua_State *L, const char *s);</pre> - -<p> -Loads a string as a Lua chunk. -This function uses <a href="#lua_load"><code>lua_load</code></a> to load the chunk in -the zero-terminated string <code>s</code>. - - -<p> -This function returns the same results as <a href="#lua_load"><code>lua_load</code></a>. - - -<p> -Also as <a href="#lua_load"><code>lua_load</code></a>, this function only loads the chunk; -it does not run it. - - - - - -<hr><h3><a name="luaL_newmetatable"><code>luaL_newmetatable</code></a></h3><p> -<span class="apii">[-0, +1, <em>m</em>]</span> -<pre>int luaL_newmetatable (lua_State *L, const char *tname);</pre> - -<p> -If the registry already has the key <code>tname</code>, -returns 0. -Otherwise, -creates a new table to be used as a metatable for userdata, -adds it to the registry with key <code>tname</code>, -and returns 1. - - -<p> -In both cases pushes onto the stack the final value associated -with <code>tname</code> in the registry. - - - - - -<hr><h3><a name="luaL_newstate"><code>luaL_newstate</code></a></h3><p> -<span class="apii">[-0, +0, <em>-</em>]</span> -<pre>lua_State *luaL_newstate (void);</pre> - -<p> -Creates a new Lua state. -It calls <a href="#lua_newstate"><code>lua_newstate</code></a> with an -allocator based on the standard C <code>realloc</code> function -and then sets a panic function (see <a href="#lua_atpanic"><code>lua_atpanic</code></a>) that prints -an error message to the standard error output in case of fatal -errors. - - -<p> -Returns the new state, -or <code>NULL</code> if there is a memory allocation error. - - - - - -<hr><h3><a name="luaL_openlibs"><code>luaL_openlibs</code></a></h3><p> -<span class="apii">[-0, +0, <em>m</em>]</span> -<pre>void luaL_openlibs (lua_State *L);</pre> - -<p> -Opens all standard Lua libraries into the given state. - - - - - -<hr><h3><a name="luaL_optint"><code>luaL_optint</code></a></h3><p> -<span class="apii">[-0, +0, <em>v</em>]</span> -<pre>int luaL_optint (lua_State *L, int narg, int d);</pre> - -<p> -If the function argument <code>narg</code> is a number, -returns this number cast to an <code>int</code>. -If this argument is absent or is <b>nil</b>, -returns <code>d</code>. -Otherwise, raises an error. - - - - - -<hr><h3><a name="luaL_optinteger"><code>luaL_optinteger</code></a></h3><p> -<span class="apii">[-0, +0, <em>v</em>]</span> -<pre>lua_Integer luaL_optinteger (lua_State *L, - int narg, - lua_Integer d);</pre> - -<p> -If the function argument <code>narg</code> is a number, -returns this number cast to a <a href="#lua_Integer"><code>lua_Integer</code></a>. -If this argument is absent or is <b>nil</b>, -returns <code>d</code>. -Otherwise, raises an error. - - - - - -<hr><h3><a name="luaL_optlong"><code>luaL_optlong</code></a></h3><p> -<span class="apii">[-0, +0, <em>v</em>]</span> -<pre>long luaL_optlong (lua_State *L, int narg, long d);</pre> - -<p> -If the function argument <code>narg</code> is a number, -returns this number cast to a <code>long</code>. -If this argument is absent or is <b>nil</b>, -returns <code>d</code>. -Otherwise, raises an error. - - - - - -<hr><h3><a name="luaL_optlstring"><code>luaL_optlstring</code></a></h3><p> -<span class="apii">[-0, +0, <em>v</em>]</span> -<pre>const char *luaL_optlstring (lua_State *L, - int narg, - const char *d, - size_t *l);</pre> - -<p> -If the function argument <code>narg</code> is a string, -returns this string. -If this argument is absent or is <b>nil</b>, -returns <code>d</code>. -Otherwise, raises an error. - - -<p> -If <code>l</code> is not <code>NULL</code>, -fills the position <code>*l</code> with the results's length. - - - - - -<hr><h3><a name="luaL_optnumber"><code>luaL_optnumber</code></a></h3><p> -<span class="apii">[-0, +0, <em>v</em>]</span> -<pre>lua_Number luaL_optnumber (lua_State *L, int narg, lua_Number d);</pre> - -<p> -If the function argument <code>narg</code> is a number, -returns this number. -If this argument is absent or is <b>nil</b>, -returns <code>d</code>. -Otherwise, raises an error. - - - - - -<hr><h3><a name="luaL_optstring"><code>luaL_optstring</code></a></h3><p> -<span class="apii">[-0, +0, <em>v</em>]</span> -<pre>const char *luaL_optstring (lua_State *L, - int narg, - const char *d);</pre> - -<p> -If the function argument <code>narg</code> is a string, -returns this string. -If this argument is absent or is <b>nil</b>, -returns <code>d</code>. -Otherwise, raises an error. - - - - - -<hr><h3><a name="luaL_prepbuffer"><code>luaL_prepbuffer</code></a></h3><p> -<span class="apii">[-0, +0, <em>-</em>]</span> -<pre>char *luaL_prepbuffer (luaL_Buffer *B);</pre> - -<p> -Returns an address to a space of size <a name="pdf-LUAL_BUFFERSIZE"><code>LUAL_BUFFERSIZE</code></a> -where you can copy a string to be added to buffer <code>B</code> -(see <a href="#luaL_Buffer"><code>luaL_Buffer</code></a>). -After copying the string into this space you must call -<a href="#luaL_addsize"><code>luaL_addsize</code></a> with the size of the string to actually add -it to the buffer. - - - - - -<hr><h3><a name="luaL_pushresult"><code>luaL_pushresult</code></a></h3><p> -<span class="apii">[-?, +1, <em>m</em>]</span> -<pre>void luaL_pushresult (luaL_Buffer *B);</pre> - -<p> -Finishes the use of buffer <code>B</code> leaving the final string on -the top of the stack. - - - - - -<hr><h3><a name="luaL_ref"><code>luaL_ref</code></a></h3><p> -<span class="apii">[-1, +0, <em>m</em>]</span> -<pre>int luaL_ref (lua_State *L, int t);</pre> - -<p> -Creates and returns a <em>reference</em>, -in the table at index <code>t</code>, -for the object at the top of the stack (and pops the object). - - -<p> -A reference is a unique integer key. -As long as you do not manually add integer keys into table <code>t</code>, -<a href="#luaL_ref"><code>luaL_ref</code></a> ensures the uniqueness of the key it returns. -You can retrieve an object referred by reference <code>r</code> -by calling <code>lua_rawgeti(L, t, r)</code>. -Function <a href="#luaL_unref"><code>luaL_unref</code></a> frees a reference and its associated object. - - -<p> -If the object at the top of the stack is <b>nil</b>, -<a href="#luaL_ref"><code>luaL_ref</code></a> returns the constant <a name="pdf-LUA_REFNIL"><code>LUA_REFNIL</code></a>. -The constant <a name="pdf-LUA_NOREF"><code>LUA_NOREF</code></a> is guaranteed to be different -from any reference returned by <a href="#luaL_ref"><code>luaL_ref</code></a>. - - - - - -<hr><h3><a name="luaL_Reg"><code>luaL_Reg</code></a></h3> -<pre>typedef struct luaL_Reg { - const char *name; - lua_CFunction func; -} luaL_Reg;</pre> - -<p> -Type for arrays of functions to be registered by -<a href="#luaL_register"><code>luaL_register</code></a>. -<code>name</code> is the function name and <code>func</code> is a pointer to -the function. -Any array of <a href="#luaL_Reg"><code>luaL_Reg</code></a> must end with an sentinel entry -in which both <code>name</code> and <code>func</code> are <code>NULL</code>. - - - - - -<hr><h3><a name="luaL_register"><code>luaL_register</code></a></h3><p> -<span class="apii">[-(0|1), +1, <em>m</em>]</span> -<pre>void luaL_register (lua_State *L, - const char *libname, - const luaL_Reg *l);</pre> - -<p> -Opens a library. - - -<p> -When called with <code>libname</code> equal to <code>NULL</code>, -it simply registers all functions in the list <code>l</code> -(see <a href="#luaL_Reg"><code>luaL_Reg</code></a>) into the table on the top of the stack. - - -<p> -When called with a non-null <code>libname</code>, -<code>luaL_register</code> creates a new table <code>t</code>, -sets it as the value of the global variable <code>libname</code>, -and registers on it all functions in the list <code>l</code>. -If there is a table in variable <code>libname</code>, -reuses this table instead of creating a new one. - - -<p> -In any case the function leaves the table -on the top of the stack. - - - - - -<hr><h3><a name="luaL_typename"><code>luaL_typename</code></a></h3><p> -<span class="apii">[-0, +0, <em>-</em>]</span> -<pre>const char *luaL_typename (lua_State *L, int index);</pre> - -<p> -Returns the name of the type of the value at the given index. - - - - - -<hr><h3><a name="luaL_typerror"><code>luaL_typerror</code></a></h3><p> -<span class="apii">[-0, +0, <em>v</em>]</span> -<pre>int luaL_typerror (lua_State *L, int narg, const char *tname);</pre> - -<p> -Generates an error with a message like the following: - -<pre> - <em>location</em>: bad argument <em>narg</em> to '<em>func</em>' (<em>tname</em> expected, got <em>rt</em>) -</pre><p> -where <code><em>location</em></code> is produced by <a href="#luaL_where"><code>luaL_where</code></a>, -<code><em>func</em></code> is the name of the current function, -and <code><em>rt</em></code> is the type name of the actual argument. - - - - - -<hr><h3><a name="luaL_unref"><code>luaL_unref</code></a></h3><p> -<span class="apii">[-0, +0, <em>-</em>]</span> -<pre>void luaL_unref (lua_State *L, int t, int ref);</pre> - -<p> -Releases reference <code>ref</code> from the table at index <code>t</code> -(see <a href="#luaL_ref"><code>luaL_ref</code></a>). -The entry is removed from the table, -so that the referred object can be collected. -The reference <code>ref</code> is also freed to be used again. - - -<p> -If <code>ref</code> is <a href="#pdf-LUA_NOREF"><code>LUA_NOREF</code></a> or <a href="#pdf-LUA_REFNIL"><code>LUA_REFNIL</code></a>, -<a href="#luaL_unref"><code>luaL_unref</code></a> does nothing. - - - - - -<hr><h3><a name="luaL_where"><code>luaL_where</code></a></h3><p> -<span class="apii">[-0, +1, <em>m</em>]</span> -<pre>void luaL_where (lua_State *L, int lvl);</pre> - -<p> -Pushes onto the stack a string identifying the current position -of the control at level <code>lvl</code> in the call stack. -Typically this string has the following format: - -<pre> - <em>chunkname</em>:<em>currentline</em>: -</pre><p> -Level 0 is the running function, -level 1 is the function that called the running function, -etc. - - -<p> -This function is used to build a prefix for error messages. - - - - +<h1>3 - <a name="3">C API</a></h1> +Unlike Lua, Teliva isn't intended to be modified at the C level. However, +forks of Teliva are encouraged. <h1>5 - <a name="5">Standard Libraries</a></h1> @@ -7880,141 +4467,6 @@ to start the traceback -<h1>6 - <a name="6">Lua Stand-alone</a></h1> - -<p> -Although Lua has been designed as an extension language, -to be embedded in a host C program, -it is also frequently used as a stand-alone language. -An interpreter for Lua as a stand-alone language, -called simply <code>lua</code>, -is provided with the standard distribution. -The stand-alone interpreter includes -all standard libraries, including the debug library. -Its usage is: - -<pre> - lua [options] [script [args]] -</pre><p> -The options are: - -<ul> -<li><b><code>-e <em>stat</em></code>:</b> executes string <em>stat</em>;</li> -<li><b><code>-l <em>mod</em></code>:</b> "requires" <em>mod</em>;</li> -<li><b><code>-i</code>:</b> enters interactive mode after running <em>script</em>;</li> -<li><b><code>-v</code>:</b> prints version information;</li> -<li><b><code>--</code>:</b> stops handling options;</li> -<li><b><code>-</code>:</b> executes <code>stdin</code> as a file and stops handling options.</li> -</ul><p> -After handling its options, <code>lua</code> runs the given <em>script</em>, -passing to it the given <em>args</em> as string arguments. -When called without arguments, -<code>lua</code> behaves as <code>lua -v -i</code> -when the standard input (<code>stdin</code>) is a terminal, -and as <code>lua -</code> otherwise. - - -<p> -Before running any argument, -the interpreter checks for an environment variable <a name="pdf-LUA_INIT"><code>LUA_INIT</code></a>. -If its format is <code>@<em>filename</em></code>, -then <code>lua</code> executes the file. -Otherwise, <code>lua</code> executes the string itself. - - -<p> -All options are handled in order, except <code>-i</code>. -For instance, an invocation like - -<pre> - $ lua -e'a=1' -e 'print(a)' script.lua -</pre><p> -will first set <code>a</code> to 1, then print the value of <code>a</code> (which is '<code>1</code>'), -and finally run the file <code>script.lua</code> with no arguments. -(Here <code>$</code> is the shell prompt. Your prompt may be different.) - - -<p> -Before starting to run the script, -<code>lua</code> collects all arguments in the command line -in a global table called <code>arg</code>. -The script name is stored at index 0, -the first argument after the script name goes to index 1, -and so on. -Any arguments before the script name -(that is, the interpreter name plus the options) -go to negative indices. -For instance, in the call - -<pre> - $ lua -la b.lua t1 t2 -</pre><p> -the interpreter first runs the file <code>a.lua</code>, -then creates a table - -<pre> - arg = { [-2] = "lua", [-1] = "-la", - [0] = "b.lua", - [1] = "t1", [2] = "t2" } -</pre><p> -and finally runs the file <code>b.lua</code>. -The script is called with <code>arg[1]</code>, <code>arg[2]</code>, ··· -as arguments; -it can also access these arguments with the vararg expression '<code>...</code>'. - - -<p> -In interactive mode, -if you write an incomplete statement, -the interpreter waits for its completion -by issuing a different prompt. - - -<p> -If the global variable <a name="pdf-_PROMPT"><code>_PROMPT</code></a> contains a string, -then its value is used as the prompt. -Similarly, if the global variable <a name="pdf-_PROMPT2"><code>_PROMPT2</code></a> contains a string, -its value is used as the secondary prompt -(issued during incomplete statements). -Therefore, both prompts can be changed directly on the command line -or in any Lua programs by assigning to <code>_PROMPT</code>. -See the next example: - -<pre> - $ lua -e"_PROMPT='myprompt> '" -i -</pre><p> -(The outer pair of quotes is for the shell, -the inner pair is for Lua.) -Note the use of <code>-i</code> to enter interactive mode; -otherwise, -the program would just end silently -right after the assignment to <code>_PROMPT</code>. - - -<p> -To allow the use of Lua as a -script interpreter in Unix systems, -the stand-alone interpreter skips -the first line of a chunk if it starts with <code>#</code>. -Therefore, Lua scripts can be made into executable programs -by using <code>chmod +x</code> and the <code>#!</code> form, -as in - -<pre> - #!/usr/local/bin/lua -</pre><p> -(Of course, -the location of the Lua interpreter may be different in your machine. -If <code>lua</code> is in your <code>PATH</code>, -then - -<pre> - #!/usr/bin/env lua -</pre><p> -is a more portable solution.) - - - <h1>8 - <a name="8">The Complete Syntax of Lua</a></h1> <p> @@ -8098,9 +4550,6 @@ Here is the complete syntax of Lua in extended BNF. Last update: Mon Feb 13 18:54:19 BRST 2012 </SMALL> -<!-- -Last change: revised for Lua 5.1.5 ---> </body></html> |
