In Files

  • psych/emitter.c
  • psych/lib/psych/handler.rb
  • psych/lib/psych/visitors/emitter.rb

Psych::Handler

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

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

See Psych::Parser for more details

Constants

OPTIONS

Default dumping options

Public Instance Methods

alias(anchor) click to toggle source

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

 
               # File psych/lib/psych/handler.rb, line 96
def alias anchor
end
            
empty() click to toggle source

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

 
               # File psych/lib/psych/handler.rb, line 222
def empty
end
            
end_document(implicit) click to toggle source

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.

 
               # File psych/lib/psych/handler.rb, line 79
def end_document implicit
end
            
end_mapping() click to toggle source

Called when a map ends

 
               # File psych/lib/psych/handler.rb, line 216
def end_mapping
end
            
end_sequence() click to toggle source

Called when a sequence ends.

 
               # File psych/lib/psych/handler.rb, line 177
def end_sequence
end
            
end_stream() click to toggle source

Called when the YAML stream ends

 
               # File psych/lib/psych/handler.rb, line 227
def end_stream
end
            
scalar(value, anchor, tag, plain, quoted, style) click to toggle source

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 Psych::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    ]
 
               # File psych/lib/psych/handler.rb, line 136
def scalar value, anchor, tag, plain, quoted, style
end
            
start_document(version, tag_directives, implicit) click to toggle source

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
 
               # File psych/lib/psych/handler.rb, line 58
def start_document version, tag_directives, implicit
end
            
start_mapping(anchor, tag, implicit, style) click to toggle source

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 Psych::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     ]
 
               # File psych/lib/psych/handler.rb, line 211
def start_mapping anchor, tag, implicit, style
end
            
start_sequence(anchor, tag, implicit, style) click to toggle source

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 Psych::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     ]
 
               # File psych/lib/psych/handler.rb, line 172
def start_sequence anchor, tag, implicit, style
end
            
start_stream(encoding) click to toggle source

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 Psych::Parser for the possible values of encoding.

 
               # File psych/lib/psych/handler.rb, line 33
def start_stream encoding
end
            
streaming?() click to toggle source

Is this handler a streaming handler?

 
               # File psych/lib/psych/handler.rb, line 232
def streaming?
  false
end
            

Commenting is here to help enhance the documentation. For example, code samples, or clarification of the documentation.

If you have questions about Ruby or the documentation, please post to one of the Ruby mailing lists. You will get better, faster, help that way.

If you wish to post a correction of the docs, please do so, but also file bug report so that it can be corrected for the next release. Thank you.

If you want to help improve the Ruby documentation, please visit Documenting-ruby.org.

blog comments powered by Disqus