diff options
Diffstat (limited to 'lib/pure/strscans.nim')
| -rw-r--r-- | lib/pure/strscans.nim | 52 |
1 files changed, 28 insertions, 24 deletions
diff --git a/lib/pure/strscans.nim b/lib/pure/strscans.nim index 73b53e3d6..16ef9e642 100644 --- a/lib/pure/strscans.nim +++ b/lib/pure/strscans.nim @@ -12,7 +12,7 @@ This module contains a `scanf`:idx: macro that can be used for extracting substrings from an input string. This is often easier than regular expressions. Some examples as an appetizer: -.. code-block:: nim + ```nim # check if input string matches a triple of integers: const input = "(1,2,4)" var x, y, z: int @@ -26,6 +26,7 @@ Some examples as an appetizer: var myfloat: float if scanf(input, "$i-$i-$i $w$s$f", year, month, day, identifier, myfloat): echo "yes, we have a match!" + ``` As can be seen from the examples, strings are matched verbatim except for substrings starting with ``$``. These constructions are available: @@ -35,7 +36,7 @@ substrings starting with ``$``. These constructions are available: ``$o`` Matches an octal integer. This uses ``parseutils.parseOct``. ``$i`` Matches a decimal integer. This uses ``parseutils.parseInt``. ``$h`` Matches a hex integer. This uses ``parseutils.parseHex``. -``$f`` Matches a floating pointer number. Uses ``parseFloat``. +``$f`` Matches a floating-point number. Uses ``parseFloat``. ``$w`` Matches an ASCII identifier: ``[A-Za-z_][A-Za-z_0-9]*``. ``$c`` Matches a single ASCII character. ``$s`` Skips optional whitespace. @@ -52,7 +53,7 @@ substrings starting with ``$``. These constructions are available: ================= ======================================================== Even though ``$*`` and ``$+`` look similar to the regular expressions ``.*`` -and ``.+`` they work quite differently, there is no non-deterministic +and ``.+``, they work quite differently. There is no non-deterministic state machine involved and the matches are non-greedy. ``[$*]`` matches ``[xyz]`` via ``parseutils.parseUntil``. @@ -83,8 +84,7 @@ matches optional tokens without any result binding. In this example, we define a helper proc ``someSep`` that skips some separators which we then use in our scanf pattern to help us in the matching process: -.. code-block:: nim - + ```nim proc someSep(input: string; start: int; seps: set[char] = {':','-','.'}): int = # Note: The parameters and return value must match to what ``scanf`` requires result = 0 @@ -92,11 +92,11 @@ which we then use in our scanf pattern to help us in the matching process: if scanf(input, "$w$[someSep]$w", key, value): ... + ``` -It also possible to pass arguments to a user definable matcher: - -.. code-block:: nim +It is also possible to pass arguments to a user definable matcher: + ```nim proc ndigits(input: string; intVal: var int; start: int; n: int): int = # matches exactly ``n`` digits. Matchers need to return 0 if nothing # matched or otherwise the number of processed chars. @@ -115,6 +115,7 @@ It also possible to pass arguments to a user definable matcher: var year, month, day: int if scanf("2013-01-03", "${ndigits(4)}-${ndigits(2)}-${ndigits(2)}$.", year, month, day): ... + ``` The scanp macro @@ -145,8 +146,7 @@ not implemented. Simple example that parses the ``/etc/passwd`` file line by line: -.. code-block:: nim - + ```nim const etc_passwd = """root:x:0:0:root:/root:/bin/bash daemon:x:1:1:daemon:/usr/sbin:/bin/sh @@ -165,16 +165,16 @@ Simple example that parses the ``/etc/passwd`` file line by line: result.add entry else: break + ``` The ``scanp`` maps the grammar code into Nim code that performs the parsing. The parsing is performed with the help of 3 helper templates that that can be implemented for a custom type. These templates need to be named ``atom`` and ``nxt``. ``atom`` should be -overloaded to handle both single characters and sets of character. - -.. code-block:: nim +overloaded to handle both `char` and `set[char]`. + ```nim import std/streams template atom(input: Stream; idx: int; c: char): bool = @@ -190,11 +190,11 @@ overloaded to handle both single characters and sets of character. if scanp(content, idx, +( ~{'\L', '\0'} -> entry.add(peekChar($input))), '\L'): result.add entry + ``` Calling ordinary Nim procs inside the macro is possible: -.. code-block:: nim - + ```nim proc digits(s: string; intVal: var int; start: int): int = var x = 0 while result+start < s.len and s[result+start] in {'0'..'9'} and s[result+start] != ':': @@ -220,12 +220,12 @@ Calling ordinary Nim procs inside the macro is possible: result.add login & " " & homedir else: break + ``` When used for matching, keep in mind that likewise scanf, no backtracking is performed. -.. code-block:: nim - + ```nim proc skipUntil(s: string; until: string; unless = '\0'; start: int): int = # Skips all characters until the string `until` is found. Returns 0 # if the char `unless` is found first or the end is reached. @@ -256,12 +256,12 @@ is performed. for r in collectLinks(body): echo r + ``` In this example both macros are combined seamlessly in order to maximise efficiency and perform different checks. -.. code-block:: nim - + ```nim iterator parseIps*(soup: string): string = ## ipv4 only! const digits = {'0'..'9'} @@ -279,13 +279,17 @@ efficiency and perform different checks. yield buf buf.setLen(0) # need to clear `buf` each time, cause it might contain garbage idx.inc - + ``` ]## -import macros, parseutils +import std/[macros, parseutils] import std/private/since +when defined(nimPreviewSlimSystem): + import std/assertions + + proc conditionsToIfChain(n, idx, res: NimNode; start: int): NimNode = assert n.kind == nnkStmtList if start >= n.len: return newAssignment(res, newLit true) @@ -468,7 +472,7 @@ macro scanf*(input: string; pattern: static[string]; results: varargs[typed]): b macro scanTuple*(input: untyped; pattern: static[string]; matcherTypes: varargs[untyped]): untyped {.since: (1, 5).}= ## Works identically as scanf, but instead of predeclaring variables it returns a tuple. - ## Tuple is started with a bool which indicates if the scan was successful + ## Tuple is started with a bool which indicates if the scan was successful ## followed by the requested data. ## If using a user defined matcher, provide the types in order they appear after pattern: ## `line.scanTuple("${yourMatcher()}", int)` @@ -508,7 +512,7 @@ macro scanTuple*(input: untyped; pattern: static[string]; matcherTypes: varargs[ inc userMatches else: discard inc p - result.add newPar(newCall(ident("scanf"), input, newStrLitNode(pattern))) + result.add nnkTupleConstr.newTree(newCall(ident("scanf"), input, newStrLitNode(pattern))) for arg in arguments: result[^1][0].add arg result[^1].add arg @@ -584,7 +588,7 @@ macro scanp*(input, idx: typed; pattern: varargs[untyped]): bool = action # (x) a # bind action a to (x) - if it[0].kind == nnkPar and it.len == 2: + if it[0].kind in {nnkPar, nnkTupleConstr} and it.len == 2: result = atm(it[0], input, idx, placeholder(it[1], input, idx)) elif it.kind == nnkInfix and it[0].eqIdent"->": # bind matching to some action: |