Class | Parslet::Parser |
In: |
lib/parslet/export.rb
lib/parslet/parser.rb lib/parslet/atoms/visitor.rb |
Parent: | Object |
The base class for all your parsers. Use as follows:
require 'parslet' class MyParser < Parslet::Parser rule(:a) { str('a').repeat } root(:a) end pp MyParser.new.parse('aaaa') # => 'aaaa' pp MyParser.new.parse('bbbb') # => Parslet::Atoms::ParseFailed: # Don't know what to do with bbbb at line 1 char 1.
Parslet::Parser is also a grammar atom. This means that you can mix full fledged parsers freely with small parts of a different parser.
Example:
class ParserA < Parslet::Parser root :aaa rule(:aaa) { str('a').repeat(3,3) } end class ParserB < Parslet::Parser root :expression rule(:expression) { str('b') >> ParserA.new >> str('b') } end
In the above example, ParserB would parse something like ‘baaab’.
Define the parsers root function. This is the place where you start parsing; if you have a rule for ‘file’ that describes what should be in a file, this would be your root declaration:
class Parser root :file rule(:file) { ... } end
root declares a ‘parse’ function that works just like the parse function that you can call on a simple parslet, taking a string as input and producing parse output.
In a way, root is a shorthand for:
def parse(str) your_parser_root.parse(str) end
Exports the current parser instance as a string in the Citrus dialect.
Example:
require 'parslet/export' class MyParser < Parslet::Parser root(:expression) rule(:expression) { str('foo') } end MyParser.new.to_citrus # => a citrus grammar as a string