class Psych::Handler - Documentation for Ruby 2.3.0 (original) (raw)

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

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

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

empty() click to toggle source

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

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.

def end_document implicit end

end_mapping() click to toggle source

end_sequence() click to toggle source

Called when a sequence ends.

end_stream() click to toggle source

Called when the YAML stream ends

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:

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

["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 ]

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
tag_directives
implicit

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:

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

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:

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:

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

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.

def start_stream encoding end

streaming?() click to toggle source

Is this handler a streaming handler?