diff options
| author | Kartik K. Agaram <vc@akkartik.com> | 2022-03-10 23:33:03 -0800 |
|---|---|---|
| committer | Kartik K. Agaram <vc@akkartik.com> | 2022-03-10 23:36:22 -0800 |
| commit | cebe9abffe88ef10d974eadeda468aaa032524ee (patch) | |
| tree | f762c8eceb1da90de6b8d55e829c8d5cd63c0e5d /doc/manual.html | |
| parent | cee42880e581c6a7d7a419ee05bb282edf57b549 (diff) | |
| download | teliva-cebe9abffe88ef10d974eadeda468aaa032524ee.tar.gz | |
more extensive deletions from the Lua manual
I'm trying to represent where Teliva borrows from Lua, but without making it seem identical. Please support the Lua project!
Diffstat (limited to 'doc/manual.html')
| -rw-r--r-- | doc/manual.html | 3575 |
1 files changed, 12 insertions, 3563 deletions
diff --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> |