Parsers: Difference between revisions

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(Created page with "= Parsers = The '''Parsers''' module provides parsing functionality for the SCM programming language. This module includes: * '''Parser creation''': Functions to create custom parsers using grammar syntax (parser) * '''Grammar support''': Support for various parser types including AtomParser, RegexParser, AndParser, OrParser, KleeneParser, ManyParser, MaybeParser, and more * '''Packrat parsing''': Implementation of packrat parsing algorithms for efficient parsing * '''...")
 
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← Back to [[Full SCM API documentation]]
← Back to [[Full SCM API documentation]]


== parser ==
== parser ==
Line 16: Line 17:
creates a parser
creates a parser


SCM parsers work this way:
<pre>Scm parsers work this way:
<code>(parser syntax scmerresult) -> func</code>
(parser syntax scmerresult) -&gt; func


syntax can be one of:
syntax can be one of:
* <code>(parser syntax scmerresult)</code> will execute scmerresult after parsing syntax
(parser syntax scmerresult) will execute scmerresult after parsing syntax
* <code>(parser syntax scmerresult "skipper")</code> will add a different whitespace skipper regex to the root parser
(parser syntax scmerresult &quot;skipper&quot;) will add a different whitespace skipper regex to the root parser
* <code>(define var syntax)</code> valid inside <code>(parser...)</code>, stores the result of syntax into var for use in scmerresult
(define var syntax) valid inside (parser...), stores the result of syntax into var for use in scmerresult
* <code>"str"</code> AtomParser
&quot;str&quot; AtomParser
* <code>(atom "str" caseinsensitive skipws)</code> AtomParser
(atom &quot;str&quot; caseinsensitive skipws) AtomParser
* <code>(regex "asdf" caseinsensitive skipws)</code> RegexParser
(regex &quot;asdf&quot; caseinsensitive skipws) RegexParser
* <code>'(a b c)</code> AndParser
'(a b c) AndParser
* <code>(or a b c)</code> OrParser
(or a b c) OrParser
* <code>(* sub separator)</code> KleeneParser
(* sub separator noMemo) KleeneParser
* <code>(+ sub separator)</code> ManyParser
(+ sub separator) ManyParser
* <code>(? xyz)</code> MaybeParser (if >1 AndParser)
(? xyz) MaybeParser (if &gt;1 AndParser)
* <code>(not mainparser parser1 parser2 parser3 ...)</code> a parser that matches mainparser but not parser1...
(not mainparser parser1 parser2 parser3 ...) a parser that matches mainparser but not parser1...
* <code>$</code> EndParser
(capture subparser) wraps a parser and returns (matched_text parsed_result)
* <code>empty</code> EmptyParser
$ EndParser
* <code>symbol</code> -> use other parser defined in env
empty EmptyParser
symbol -&gt; use other parser defined in env


For further details on packrat parsers, take a look at https://github.com/launix-de/go-packrat
for further details on packrat parsers, take a look at https://github.com/launix-de/go-packrat</pre>
'''Allowed number of parameters:''' 1–3


'''Allowed number of parameters:''' 1–3
<span id="parameters"></span>
=== Parameters ===


'''Parameters:'''
* '''syntax''' (<code>any</code>): syntax of the grammar (see docs)
* '''syntax''' (<code>any</code>): syntax of the grammar (see docs)
* '''generator''' (<code>any</code>): (optional) expressions to evaluate. All captured variables are available in the scope.
* '''generator''' (<code>any</code>): (optional) expressions to evaluate. All captured variables are available in the scope. ''(optional)''
* '''skipper''' (<code>string</code>): (optional) string that defines the skip mechanism for whitespaces as regexp
* '''skipper''' (<code>string</code>): (optional) string that defines the skip mechanism for whitespaces as regexp ''(optional)''
 
<span id="returns"></span>
=== Returns ===


'''Returns:''' <code>func</code>
<code>func</code>

Revision as of 08:17, 27 August 2026

Parsers

The Parsers module provides parsing functionality for the SCM programming language. This module includes:

  • Parser creation: Functions to create custom parsers using grammar syntax (parser)
  • Grammar support: Support for various parser types including AtomParser, RegexParser, AndParser, OrParser, KleeneParser, ManyParser, MaybeParser, and more
  • Packrat parsing: Implementation of packrat parsing algorithms for efficient parsing
  • Whitespace handling: Configurable whitespace skipping mechanisms

These functions provide essential tools for creating custom parsers and processing structured text data in SCM programs.

← Back to Full SCM API documentation


parser

creates a parser 

Scm parsers work this way:
(parser syntax scmerresult) -> func

syntax can be one of:
(parser syntax scmerresult) will execute scmerresult after parsing syntax
(parser syntax scmerresult "skipper") will add a different whitespace skipper regex to the root parser
(define var syntax) valid inside (parser...), stores the result of syntax into var for use in scmerresult
"str" AtomParser
(atom "str" caseinsensitive skipws) AtomParser
(regex "asdf" caseinsensitive skipws) RegexParser
'(a b c) AndParser
(or a b c) OrParser
(* sub separator noMemo) KleeneParser
(+ sub separator) ManyParser
(? xyz) MaybeParser (if >1 AndParser)
(not mainparser parser1 parser2 parser3 ...) a parser that matches mainparser but not parser1...
(capture subparser) wraps a parser and returns (matched_text parsed_result)
$ EndParser
empty EmptyParser
symbol -> use other parser defined in env

for further details on packrat parsers, take a look at https://github.com/launix-de/go-packrat

Allowed number of parameters: 1–3

Parameters

  • syntax (any): syntax of the grammar (see docs)
  • generator (any): (optional) expressions to evaluate. All captured variables are available in the scope. (optional)
  • skipper (string): (optional) string that defines the skip mechanism for whitespaces as regexp (optional)

Returns

func

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