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Questions tagged [pegjs]

PEG.js is a simple parser generator for JavaScript that produces fast parsers with excellent error reporting. Forked to a now-maintained version called Peggy.

PEG.js is a simple parser generator for JavaScript that produces fast parsers with excellent error reporting.

See https://pegjs.org/

The project was forked to create Peggy, which is now maintained at:

https://peggyjs.org/

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Converting pegjs to C++

I have used pegjs to create a parser, quite similar actually to the example shown here for a custom string-formatting function. I would like to port this to C++. What might be the best way to do this? Are there are existing parsers in C/C++ that are…
David542
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Parse expression with JavaScript using PEG

I have written the code to parse the following expression !=10 AND <=99 To { operator: 'AND', values: [ { op: '!=', value: '10', }, { op: '<=', value: '99', }, …
Benk I
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How can i make a backslash for change line with peg.js?

Currently, I use '\n' to split each line (paragraph), but now, I want to make a backslash like python for change line. This is my current rule: Start = _ head:Line tail:('\n'+ l:Line { return l })* _ { return [head].concat(tail) …
MoeCasts
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Parsing and validating conditional IF in PEG parser

Trying to parse a single line conditional where code tries to test the left hand is equal to the right hand. { user = {id: 'abc123'} function_name() {...} } if (user.id === 'abc123...') { function_name() } I've so far looked at these posts…
Chris
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PEGjs grammar star (*) not matching as expected

I have this lexeme: a().length() And this PEGjs grammar: start = func_call func_call = header "(" ")" header = "a" suffix* suffix = "(" ")" ("." "length") In the grammar, I'm parsing a function call. This currently parses, as you can try online…
Andy Ray
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pegjs: How to handle character class preceded by more general class

I have identifiers that may contain dots but not as the last character. For example, I would like to parse "date.ymd" as identifier but "execute." as (identifier + punctuation character). A regexp would be…
Frans Houweling
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Terminating list of expressions in PEG.js

I have another question related to How to extend default PEG.js arithmetic example to allow multiple expressions not single one? I have this grammar: start = code:statements { return { "type": "Program", "body": code }; …
jcubic
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How to extend default PEG.js arithmetic example to allow multiple expressions not single one?

As part of my parser I want to add arithmetic and boolean expressions. I wanted to take default PEG.js example at https://pegjs.org/online but the problem is that that parser is recursive and you can't write two or more lines: For instance this is…
jcubic
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Peg.JS: Simple if..then..else implementation

I am trying to implement a grammar for a simple if..then..else statement along with simple statements. It should be able to parse a statement like: if things are going fine then things are supposed to be this way just go with it else …
funkycoder
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PEG js : How to match string within a single quote in peg js grammer rule expression?

I am writing a peg js grammar to parse logical query literals into a json format but facing an issue with selecting a multi value word in a condition value. Like (city = 'a' OR city = 'b') works properly but (city = 'a b' OR city = 'b') is not…
Harshad Sindhav
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Is it possible to create a simple parser and create a javascript file and then call that file with that parser?

I am trying to create a parser, a file. I am trying to use this file created to be parsed by the parser. The steps are: Add pegjs with Create an parser with var parserFile Create file with var makeFile Add contentFile, nameFile with var…
user12169855
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Use PEG.js generated parser to beautify code

I want to create a formatter/linter for a custom program language and was reading about it but seems that im missing something. Was looking/playing with PEG.js and seems that it will do the work. Ive wrote a small parser and when ran - it correctly…
Stefan Stoichev
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parser unable to match the consequent rule due to error evaluating a former rule

Example: start = name / invocation; name = [a-zA-Z]+ { return text() }; invocation = a:name "()" { return {type: 'inv', value: a } }; If input is abc() I am getting error: Expected [a-zA-Z] or end of input but "(" found However, if start was…
deostroll
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PegJS Maths Parsing

Currently, my grammar supports basic variable assignments, which I'll be using for this example, but I am experiencing some issues with the maths parsing. It returns correctly when tried with: test = 10^2 for example, but it returns: Line 1, column…
Llama Boy
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Deep labeling of parameters inside pegjs regex group

Consider the following grammar: list = head:item (',' tail:item)* { return [head].concat(tail); } item = $ ([0-9]*) It should describe lists of positive integers. The problem is that tail is undefined as it is inside parens. So I'm forced to do…
Pierre Arlaud
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