class 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
- EVENTS
Events that a Handler should respond to.
- OPTIONS
Default dumping options
Public Instance Methods
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 ext/psych/lib/psych/handler.rb, line 109 def alias anchor end
Called when an empty event happens. (Which, as far as I can tell, is never).
# File ext/psych/lib/psych/handler.rb, line 235 def empty end
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 ext/psych/lib/psych/handler.rb, line 92 def end_document implicit end
Called when a map ends
# File ext/psych/lib/psych/handler.rb, line 229 def end_mapping end
Called when a sequence ends.
# File ext/psych/lib/psych/handler.rb, line 190 def end_sequence end
Called when the YAML stream ends
# File ext/psych/lib/psych/handler.rb, line 240 def end_stream end
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 ext/psych/lib/psych/handler.rb, line 149 def scalar value, anchor, tag, plain, quoted, style end
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 ext/psych/lib/psych/handler.rb, line 71 def start_document version, tag_directives, implicit end
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 ext/psych/lib/psych/handler.rb, line 224 def start_mapping anchor, tag, implicit, style end
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 ext/psych/lib/psych/handler.rb, line 185 def start_sequence anchor, tag, implicit, style end
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 ext/psych/lib/psych/handler.rb, line 46 def start_stream encoding end
Is this handler a streaming handler?
# File ext/psych/lib/psych/handler.rb, line 245 def streaming? false end