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Class: Psych::Handler

Relationships & Source Files
Namespace Children
Classes:
DumperOptions
Extension / Inclusion / Inheritance Descendants
Subclasses:
Emitter, TreeBuilder, Psych::Handlers::DocumentStream, Psych::Handlers::Recorder, JSON::TreeBuilder, Stream::Emitter, JSON::Stream::Emitter
Inherits: Object
Defined in: ext/psych/lib/psych/handler.rb,
ext/psych/psych_emitter.c

Overview

Handler is an abstract base class that defines the events used when dealing with Parser. Clients who want to use Parser should implement a class that inherits from Handler and define events that they can handle.

Handler defines all events that Parser can possibly send to event handlers.

See Parser for more details

Constant Summary

Instance Attribute Summary

Instance Method Summary

Instance Attribute Details

#streaming? ⇒ Boolean (readonly)

Is this handler a streaming handler?

[ GitHub ] 

  


# File 'ext/psych/lib/psych/handler.rb', line 251



def streaming?
  false
end


  







Instance Method Details



  

    #alias(anchor)  
  



  

    

Called when an alias is found to anchor.  anchor will be the name of the anchor found.



Example



Here we have an example of an array that references itself in YAML:



--- &ponies
- first element
- *ponies



&ponies is the anchor, *ponies is the alias.  In this case, alias is called with “ponies”.


  



  [ GitHub ]


  

  


# File 'ext/psych/lib/psych/handler.rb', line 110



def alias anchor
end


  








  

    #empty  
  



  

    

Called when an empty event happens. (Which, as far as I can tell, is never).


  



  [ GitHub ]


  

  


# File 'ext/psych/lib/psych/handler.rb', line 236



def empty
end


  








  

    #end_document(implicit)  
  



  

    

Called with the document ends.  implicit is a boolean value indicating whether or not the document has an implicit ending.



Example



Given the following YAML:



---
  hello world



implicit will be true.  Given this YAML:



---
  hello world
#...



implicit will be false.


  



  [ GitHub ]


  

  


# File 'ext/psych/lib/psych/handler.rb', line 93



def end_document implicit
end


  








  

    #end_mapping  
  



  

    

Called when a map ends


  



  [ GitHub ]


  

  


# File 'ext/psych/lib/psych/handler.rb', line 230



def end_mapping
end


  








  

    #end_sequence  
  



  

    

Called when a sequence ends.


  



  [ GitHub ]


  

  


# File 'ext/psych/lib/psych/handler.rb', line 191



def end_sequence
end


  








  

    #end_stream  
  



  

    

Called when the YAML stream ends


  



  [ GitHub ]


  

  


# File 'ext/psych/lib/psych/handler.rb', line 241



def end_stream
end


  








  

    #event_location(start_line, start_column, end_line, end_column)  
  



  

    

Called before each event with line/column information.


  



  [ GitHub ]


  

  


# File 'ext/psych/lib/psych/handler.rb', line 246



def event_location(start_line, start_column, end_line, end_column)
end


  








  

    #scalar(value, anchor, tag, plain, quoted, style)  
  



  

    

Called when a scalar value is found.  The scalar may have an anchor, a tag, be implicitly plain or implicitly quoted



value is the string value of the scalar anchor is an associated anchor or nil tag is an associated tag or nil plain is a boolean value quoted is a boolean value style is an integer idicating the string style



See the constants in Nodes::Scalar for the possible values of style



Example



Here is a YAML document that exercises most of the possible ways this method can be called:



---
- !str "foo"
- &anchor fun
- many
  lines
- |
  many
  newlines



The above YAML document contains a list with four strings.  Here are the parameters sent to this method in the same order:



# value               anchor    tag     plain   quoted  style
["foo",               nil,      "!str", false,  false,  3    ]
["fun",               "anchor", nil,    true,   false,  1    ]
["many lines",        nil,      nil,    true,   false,  1    ]
["many\nnewlines\n",  nil,      nil,    false,  true,   4    ]


  



  [ GitHub ]


  

  


# File 'ext/psych/lib/psych/handler.rb', line 150



def scalar value, anchor, tag, plain, quoted, style
end


  








  

    #start_document(version, tag_directives, implicit)  
  



  

    

Called when the document starts with the declared version, tag_directives, if the document is implicit.



version will be an array of integers indicating the YAML version being dealt with, tag_directives is a list of tuples indicating the prefix and suffix of each tag, and implicit is a boolean indicating whether the document is started implicitly.



Example



Given the following YAML:



%YAML 1.1
%TAG ! tag:tenderlovemaking.com,2009:
--- !squee



The parameters for start_document must be this:



version         # => [1, 1]
tag_directives  # => [["!", "tag:tenderlovemaking.com,2009:"]]
implicit        # => false


  



  [ GitHub ]


  

  


# File 'ext/psych/lib/psych/handler.rb', line 72



def start_document version, tag_directives, implicit
end


  








  

    #start_mapping(anchor, tag, implicit, style)  
  



  

    

Called when a map starts.



anchor is the anchor associated with the map or nil. tag is the tag associated with the map or nil. implicit is a boolean indicating whether or not the map was implicitly started. style is an integer indicating the mapping style.



See the constants in Nodes::Mapping for the possible values of style.



Example



Here is a YAML document that exercises most of the possible ways this method can be called:



---
k: !!map { hello: world }
v: &pewpew
  hello: world



The above YAML document consists of three maps, an outer map that contains two inner maps.  Below is a matrix of the parameters sent in order to represent these three maps:



# anchor    tag                       implicit  style
[nil,       nil,                      true,     1     ]
[nil,       "tag:yaml.org,2002:map",  false,    2     ]
["pewpew",  nil,                      true,     1     ]


  



  [ GitHub ]


  

  


# File 'ext/psych/lib/psych/handler.rb', line 225



def start_mapping anchor, tag, implicit, style
end


  








  

    #start_sequence(anchor, tag, implicit, style)  
  



  

    

Called when a sequence is started.



anchor is the anchor associated with the sequence or nil. tag is the tag associated with the sequence or nil. implicit a boolean indicating whether or not the sequence was implicitly started. style is an integer indicating the list style.



See the constants in Nodes::Sequence for the possible values of style.



Example



Here is a YAML document that exercises most of the possible ways this method can be called:



---
- !!seq [
  a
]
- &pewpew
  - b



The above YAML document consists of three lists, an outer list that contains two inner lists.  Here is a matrix of the parameters sent to represent these lists:



# anchor    tag                       implicit  style
[nil,       nil,                      true,     1     ]
[nil,       "tag:yaml.org,2002:seq",  false,    2     ]
["pewpew",  nil,                      true,     1     ]


  



  [ GitHub ]


  

  


# File 'ext/psych/lib/psych/handler.rb', line 186



def start_sequence anchor, tag, implicit, style
end


  








  

    #start_stream(encoding)  
  



  

    

Called with encoding when the YAML stream starts.  This method is called once per stream.  A stream may contain multiple documents.



See the constants in Parser for the possible values of encoding.


  



  [ GitHub ]


  

  


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



def start_stream encoding
end