pkorzh/parslets

js parslets library

#parslets

##Parslets

partlets.lValue

Consumes identifier or literal.

partlets.rValue

Consumes identifier.

partlets.formalArgs

Consumes formal arguments list.

parslets.actualArgs

Consumes actual arguments list.

parslets.arith

Options:

• postfixOps
• unaryOps

parslets.sequence

Returns a function that can be consumed. Usefull to parse list items to a list

parslets.search

Scans input stream for sucessfull consume. Ignorign the rest. Usefull when you need to extract only specific nodes

Consumes arith expression.

#Token wrapper

consume(form)

Consumes a token from input stream if it is satisfied by form criteria

If string, passed as a parameter, starts with :, method will consume a token with specified tag, otherwise — with specified lexeme.

It is possible to pass a list of functions. They will be executed in a row, if neither will return a successfull consume an error wil be thrown.

consumeIf(form)

same as consume(form), but will not throw an error

is(form)

checks if current token match the criteria

##Example

###Parsing arith expressions

var util     = require('util');
var parslets = require('parslets');
var toker    = require('toker');
var lex      = new toker.LexicalAnalyzer('2 + 2 * -2');


var tokens = lex.getTokens();
var tw     = new parslets.TokenWrapper(tokens);
var parsed = tw.consume(parslets.arith());

console.log(util.inspect(parsed, {showHidden: false, depth: null}));

Will output:

{ type: 'binary',
  left: 
   { source: undefined,
     loc: { start: { line: 1, column: 0 }, end: { line: 1, column: 1 } },
     lexeme: 2,
     tag: 'decimalLiteral' },
  op: 
   { source: undefined,
     loc: { start: { line: 1, column: 2 }, end: { line: 1, column: 3 } },
     lexeme: '+',
     tag: 'operator' },
  right: 
   { type: 'binary',
     left: 
      { source: undefined,
        loc: { start: { line: 1, column: 4 }, end: { line: 1, column: 5 } },
        lexeme: 2,
        tag: 'decimalLiteral' },
     op: 
      { source: undefined,
        loc: { start: { line: 1, column: 6 }, end: { line: 1, column: 7 } },
        lexeme: '*',
        tag: 'operator' },
     right: 
      { type: 'unary',
        op: 
         { source: undefined,
           loc: { start: { line: 1, column: 8 }, end: { line: 1, column: 9 } },
           lexeme: '-',
           tag: 'operator' },
        expr: 
         { source: undefined,
           loc: { start: { line: 1, column: 9 }, end: { line: 1, column: 10 } },
           lexeme: 2,
           tag: 'decimalLiteral' } } } }