Module | YAML |
In: |
lib/yaml.rb
|
YAML(tm) (rhymes with ‘camel’) is a straightforward machine parsable data serialization format designed for human readability and interaction with scripting languages such as Perl and Python. YAML is optimized for data serialization, formatted dumping, configuration files, log files, Internet messaging and filtering. This specification describes the YAML information model and serialization format. Together with the Unicode standard for characters, it provides all the information necessary to understand YAML Version 1.0 and construct computer programs to process it.
See yaml.org/ for more information. For a quick tutorial, please visit YAML In Five Minutes (yaml.kwiki.org/?YamlInFiveMinutes).
The YAML 1.0 specification outlines four stages of YAML loading and dumping. This library honors all four of those stages, although data is really only available to you in three stages.
The four stages are: native, representation, serialization, and presentation.
The native stage refers to data which has been loaded completely into Ruby‘s own types. (See +YAML::load+.)
The representation stage means data which has been composed into +YAML::BaseNode+ objects. In this stage, the document is available as a tree of node objects. You can perform YPath queries and transformations at this level. (See +YAML::parse+.)
The serialization stage happens inside the parser. The YAML parser used in Ruby is called Syck. Serialized nodes are available in the extension as SyckNode structs.
The presentation stage is the YAML document itself. This is accessible to you as a string. (See +YAML::dump+.)
For more information about the various information models, see Chapter 3 of the YAML 1.0 Specification (yaml.org/spec/#id2491269).
The YAML module provides quick access to the most common loading (YAML::load) and dumping (YAML::dump) tasks. This module also provides an API for registering global types (YAML::add_domain_type).
A simple round-trip (load and dump) of an object.
require "yaml" test_obj = ["dogs", "cats", "badgers"] yaml_obj = YAML::dump( test_obj ) # -> --- - dogs - cats - badgers ruby_obj = YAML::load( yaml_obj ) # => ["dogs", "cats", "badgers"] ruby_obj == test_obj # => true
To register your custom types with the global resolver, use add_domain_type.
YAML::add_domain_type( "your-site.com,2004", "widget" ) do |type, val| Widget.new( val ) end
Resolver | = | YAML::Syck::Resolver |
DefaultResolver | = | YAML::Syck::DefaultResolver |
GenericResolver | = | YAML::Syck::GenericResolver |
Parser | = | YAML::Syck::Parser |
Emitter | = | YAML::Syck::Emitter |
Add a private document type
# File lib/yaml.rb, line 320 def YAML.add_private_type( type_re, &transfer_proc ) resolver.add_type( "x-private:" + type_re, transfer_proc ) end
Detect typing of a string
# File lib/yaml.rb, line 327 def YAML.detect_implicit( val ) resolver.detect_implicit( val ) end
Converts obj to YAML and writes the YAML result to io.
File.open( 'animals.yaml', 'w' ) do |out| YAML.dump( ['badger', 'elephant', 'tiger'], out ) end
If no io is provided, a string containing the dumped YAML is returned.
YAML.dump( :locked ) #=> "--- :locked"
# File lib/yaml.rb, line 116 def YAML.dump( obj, io = nil ) obj.to_yaml( io || io2 = StringIO.new ) io || ( io2.rewind; io2.read ) end
Calls block with each consecutive document in the YAML stream contained in io.
File.open( 'many-docs.yaml' ) do |yf| YAML.each_document( yf ) do |ydoc| ## ydoc contains the single object ## from the YAML document end end
# File lib/yaml.rb, line 216 def YAML.each_document( io, &block ) yp = parser.load_documents( io, &block ) end
Calls block with a tree of +YAML::BaseNodes+, one tree for each consecutive document in the YAML stream contained in io.
File.open( 'many-docs.yaml' ) do |yf| YAML.each_node( yf ) do |ydoc| ## ydoc contains a tree of nodes ## from the YAML document end end
# File lib/yaml.rb, line 246 def YAML.each_node( io, &doc_proc ) yp = generic_parser.load_documents( io, &doc_proc ) end
Calls block with each consecutive document in the YAML stream contained in io.
File.open( 'many-docs.yaml' ) do |yf| YAML.load_documents( yf ) do |ydoc| ## ydoc contains the single object ## from the YAML document end end
# File lib/yaml.rb, line 231 def YAML.load_documents( io, &doc_proc ) YAML.each_document( io, &doc_proc ) end
Load a document from the file located at filepath.
YAML.load_file( 'animals.yaml' ) #=> ['badger', 'elephant', 'tiger']
# File lib/yaml.rb, line 142 def YAML.load_file( filepath ) File.open( filepath ) do |f| load( f ) end end
Loads all documents from the current io stream, returning a +YAML::Stream+ object containing all loaded documents.
# File lib/yaml.rb, line 270 def YAML.load_stream( io ) d = nil parser.load_documents( io ) do |doc| d = YAML::Stream.new if not d d.add( doc ) end return d end
Allocate blank object
# File lib/yaml.rb, line 365 def YAML.object_maker( obj_class, val ) if Hash === val o = obj_class.allocate val.each_pair { |k,v| o.instance_variable_set("@#{k}", v) } o else raise YAML::Error, "Invalid object explicitly tagged !ruby/Object: " + val.inspect end end
Parse the first document from the current io stream
File.open( 'animals.yaml' ) { |yf| YAML::load( yf ) } #=> #<YAML::Syck::Node:0x82ccce0 @kind=:seq, @value= [#<YAML::Syck::Node:0x82ccd94 @kind=:scalar, @type_id="str", @value="badger">, #<YAML::Syck::Node:0x82ccd58 @kind=:scalar, @type_id="str", @value="elephant">, #<YAML::Syck::Node:0x82ccd1c @kind=:scalar, @type_id="str", @value="tiger">]>
Can also load from a string.
YAML.parse( "--- :locked" ) #=> #<YAML::Syck::Node:0x82edddc @type_id="tag:ruby.yaml.org,2002:sym", @value=":locked", @kind=:scalar>
# File lib/yaml.rb, line 175 def YAML.parse( io ) yp = generic_parser.load( io ) end
Calls block with a tree of +YAML::BaseNodes+, one tree for each consecutive document in the YAML stream contained in io.
File.open( 'many-docs.yaml' ) do |yf| YAML.parse_documents( yf ) do |ydoc| ## ydoc contains a tree of nodes ## from the YAML document end end
# File lib/yaml.rb, line 261 def YAML.parse_documents( io, &doc_proc ) YAML.each_node( io, &doc_proc ) end
Parse a document from the file located at filepath.
YAML.parse_file( 'animals.yaml' ) #=> #<YAML::Syck::Node:0x82ccce0 @kind=:seq, @value= [#<YAML::Syck::Node:0x82ccd94 @kind=:scalar, @type_id="str", @value="badger">, #<YAML::Syck::Node:0x82ccd58 @kind=:scalar, @type_id="str", @value="elephant">, #<YAML::Syck::Node:0x82ccd1c @kind=:scalar, @type_id="str", @value="tiger">]>
# File lib/yaml.rb, line 199 def YAML.parse_file( filepath ) File.open( filepath ) do |f| parse( f ) end end
Allocate an Emitter if needed
# File lib/yaml.rb, line 380 def YAML.quick_emit( oid, opts = {}, &e ) out = if opts.is_a? YAML::Emitter opts else emitter.reset( opts ) end oid = case oid when Fixnum, NilClass; oid else oid = "#{oid.object_id}-#{oid.hash}" end out.emit( oid, &e ) end
Method to extract colon-seperated type and class, returning the type and the constant of the class
# File lib/yaml.rb, line 356 def YAML.read_type_class( type, obj_class ) scheme, domain, type, tclass = type.split( ':', 4 ) tclass.split( "::" ).each { |c| obj_class = obj_class.const_get( c ) } if tclass return [ type, obj_class ] end
Convert a type_id to a taguri
# File lib/yaml.rb, line 334 def YAML.tagurize( val ) resolver.tagurize( val ) end