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Class: Psych::Parser

Relationships & Source Files
Namespace Children
Classes:
Mark
Inherits: Object
Defined in: ext/psych/lib/psych/parser.rb,
ext/psych/psych_parser.c

Overview

YAML event parser class. This class parses a YAML document and calls events on the handler that is passed to the constructor. The events can be used for things such as constructing a YAML AST or deserializing YAML documents. It can even be fed back to Emitter to emit the same document that was parsed.

See Handler for documentation on the events that Parser emits.

Here is an example that prints out ever scalar found in a YAML document:

# Handler for detecting scalar values
class ScalarHandler < Psych::Handler
  def scalar value, anchor, tag, plain, quoted, style
    puts value
  end
end

parser = Psych::Parser.new(ScalarHandler.new)
parser.parse(yaml_document)

Here is an example that feeds the parser back in to Emitter. The YAML document is read from STDIN and written back out to STDERR:

parser = Psych::Parser.new(Psych::Emitter.new($stderr))
parser.parse($stdin)

::Psych uses Parser in combination with TreeBuilder to construct an AST of the parsed YAML document.

Constant Summary

Class Method Summary

Instance Attribute Summary

Instance Method Summary

Constructor Details

.new(handler = Handler.new) ⇒ Parser

Creates a new Parser instance with #handler. YAML events will be called on #handler. See Parser for more details.

[ GitHub ] 

  


# File 'ext/psych/lib/psych/parser.rb', line 47



def initialize handler = Handler.new
  @handler = handler
  @external_encoding = ANY
end


  







Instance Attribute Details



  

    #external_encoding=(value)   (writeonly)
  



  

    

Set the encoding for this parser to encoding


  



  [ GitHub ]


  

  


# File 'ext/psych/lib/psych/parser.rb', line 41



attr_writer :external_encoding


  








  

    #handler   (rw)
  



  

    

The handler on which events will be called


  



  [ GitHub ]


  

  


# File 'ext/psych/lib/psych/parser.rb', line 38



attr_accessor :handler


  







Instance Method Details



  

    #mark(#)  ⇒ Parser   



  

    

Returns a Parser::Mark object that contains line, column, and index information.


  









  

    #parse(yaml)    



  

    

Parse the YAML document contained in yaml.  Events will be called on the handler set on the parser instance.



See Parser and #handler