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module Psych
###
# 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
class Handler
###
# Configuration options for dumping YAML.
class DumperOptions
attr_accessor :line_width, :indentation, :canonical
def initialize
@line_width = 0
@indentation = 2
@canonical = false
end
end
# Default dumping options
OPTIONS = DumperOptions.new
# Events that a Handler should respond to.
EVENTS = [ :alias,
:empty,
:end_document,
:end_mapping,
:end_sequence,
:end_stream,
:scalar,
:start_document,
:start_mapping,
:start_sequence,
:start_stream ]
###
# 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
###
# 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
def start_document version, tag_directives, implicit
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.
def end_document implicit
end
###
# 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".
def alias anchor
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 ]
#
def scalar value, anchor, tag, plain, quoted, 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 ]
def start_sequence anchor, tag, implicit, style
end
###
# Called when a sequence ends.
def end_sequence
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 ]
def start_mapping anchor, tag, implicit, style
end
###
# Called when a map ends
def end_mapping
end
###
# Called when an empty event happens. (Which, as far as I can tell, is
# never).
def empty
end
###
# Called when the YAML stream ends
def end_stream
end
###
# Is this handler a streaming handler?
def streaming?
false
end
end
end