module Syck

YAML

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).

About This Library

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).

Example

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

YAML::BaseNode class

Constants used throughout the library

Handle Unicode-to-Internal conversion

Error messages and exception class

YAML::Loader class .. type handling ..

$Id$

yaml/tag.rb: methods for associating a taguri to a class.

Author

why the lucky stiff

Classes required by the full core typeset

Constants

DEFAULTS

Default settings

DNS_COMP_RE
DNS_NAME_RE
ERROR_ANCHOR_ALIAS
ERROR_BAD_ALIAS
ERROR_BAD_ANCHOR
ERROR_BAD_EXPLICIT
ERROR_MANY_ALIAS
ERROR_MANY_ANCHOR
ERROR_MANY_EXPLICIT
ERROR_MANY_IMPLICIT
ERROR_NEED_HEADER
ERROR_NO_ANCHOR
ERROR_NO_HEADER_NODE

Error messages

ERROR_UNSUPPORTED_ENCODING
ERROR_UNSUPPORTED_VERSION
ERROR_ZERO_INDENT
ESCAPES
ESCAPE_CHAR
INDICATOR_CHAR
NOT_PLAIN_CHAR
PRINTABLE_CHAR
RESTRICTED_INDICATORS
SPACE_INDICATORS
SUPPORTED_YAML_VERSIONS
UNESCAPES
VERSION

Constants

WORD_CHAR

Parser tokens

Public Class Methods

add_builtin_type( type_tag, &transfer_proc ) click to toggle source

Add a transfer method for a builtin type

# File lib/syck.rb, line 317
def self.add_builtin_type( type_tag, &transfer_proc )
    resolver.add_type( "tag:yaml.org,2002:#{ type_tag }", transfer_proc )
end
add_domain_type( domain, type_tag, &transfer_proc ) click to toggle source

Add a global handler for a YAML domain type.

# File lib/syck.rb, line 310
def self.add_domain_type( domain, type_tag, &transfer_proc )
    resolver.add_type( "tag:#{ domain }:#{ type_tag }", transfer_proc )
end
add_private_type( type_re, &transfer_proc ) click to toggle source

Add a private document type

# File lib/syck.rb, line 332
def self.add_private_type( type_re, &transfer_proc )
    warn "#{caller[0]}: YAML.add_private_type is deprecated, use add_domain_type" if $VERBOSE && !caller[0].start_with?(File.dirname(__FILE__))
    resolver.add_type( "x-private:" + type_re, transfer_proc )
end
add_ruby_type( type_tag, &transfer_proc ) click to toggle source

Add a transfer method for a builtin type

# File lib/syck.rb, line 324
def self.add_ruby_type( type_tag, &transfer_proc )
    warn "#{caller[0]}: YAML.add_ruby_type is deprecated, use add_domain_type" if $VERBOSE && !caller[0].start_with?(File.dirname(__FILE__))
    resolver.add_type( "tag:ruby.yaml.org,2002:#{ type_tag }", transfer_proc )
end
detect_implicit( val ) click to toggle source

Detect typing of a string

# File lib/syck.rb, line 340
def self.detect_implicit( val )
    warn "#{caller[0]}: YAML.detect_implicit is deprecated" if $VERBOSE && !caller[0].start_with?(File.dirname(__FILE__))
    resolver.detect_implicit( val )
end
dump( obj, io = nil ) click to toggle source

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/syck.rb, line 124
def self.dump( obj, io = nil )
    obj.to_yaml( io || io2 = StringIO.new )
    io || ( io2.rewind; io2.read )
end
dump_stream( *objs ) click to toggle source

Returns a YAML stream containing each of the items in objs, each having their own document.

YAML.dump_stream( 0, [], {} )
  #=> --- 0
      --- []
      --- {}
# File lib/syck.rb, line 299
def self.dump_stream( *objs )
    d = Stream.new
    objs.each do |doc|
        d.add( doc )
    end
    d.emit
end
each_document( io, &block ) click to toggle source

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/syck.rb, line 224
def self.each_document( io, &block )
    warn "#{caller[0]}: YAML.each_document is deprecated" if $VERBOSE && !caller[0].start_with?(File.dirname(__FILE__))
    parser.load_documents( io, &block )
end
each_node( io, &doc_proc ) click to toggle source

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/syck.rb, line 255
def self.each_node( io, &doc_proc )
    warn "#{caller[0]}: YAML.each_node is deprecated" if $VERBOSE && !caller[0].start_with?(File.dirname(__FILE__))
    generic_parser.load_documents( io, &doc_proc )
end
emitter() click to toggle source

Returns a new default emitter

# File lib/syck.rb, line 106
def self.emitter
    warn "#{caller[0]}: YAML.emitter is deprecated" if $VERBOSE && !caller[0].start_with?(File.dirname(__FILE__))
    Emitter.new.set_resolver( self.resolver )
end
escape( value, skip = "" ) click to toggle source

Escape the string, condensing common escapes

# File lib/syck/encoding.rb, line 10
def self.escape( value, skip = "" )
      warn "#{caller[0]}: YAML.escape is deprecated" if $VERBOSE
        value.gsub( /\\/, "\\\\\\" ).
      gsub( /"/, "\\\"" ).
      gsub( /([\x00-\x1f])/ ) do
         skip[$&] || ESCAPES[ $&.unpack("C")[0] ]
     end
end
generic_parser() click to toggle source

Returns a new generic parser

# File lib/syck.rb, line 94
def self.generic_parser
    warn "#{caller[0]}: YAML.generic_parser is deprecated, switch to psych" if $VERBOSE && !caller[0].start_with?(File.dirname(__FILE__))
    Parser.new.set_resolver( GenericResolver )
end
load( io ) click to toggle source

Load a document from the current io stream.

File.open( 'animals.yaml' ) { |yf| YAML::load( yf ) }
   #=> ['badger', 'elephant', 'tiger']

Can also load from a string.

YAML.load( "--- :locked" )
   #=> :locked
# File lib/syck.rb, line 140
def self.load( io )
    parser.load( io )
end
load_documents( io, &doc_proc ) click to toggle source

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/syck.rb, line 240
def self.load_documents( io, &doc_proc )
    parser.load_documents( io, &doc_proc )
end
load_file( filepath ) click to toggle source

Load a document from the file located at filepath.

YAML.load_file( 'animals.yaml' )
   #=> ['badger', 'elephant', 'tiger']
# File lib/syck.rb, line 150
def self.load_file( filepath )
    File.open( filepath ) do |f|
        load( f )
    end
end
load_stream( io ) click to toggle source

Loads all documents from the current io stream, returning a YAML::Stream object containing all loaded documents.

# File lib/syck.rb, line 281
def self.load_stream( io )
    d = nil
    parser.load_documents( io ) do |doc|
        d = Stream.new if not d
        d.add( doc )
    end
    return d
end
make_stream( io ) click to toggle source

Class method for creating streams

# File lib/syck/stringio.rb, line 57
def Syck.make_stream( io )
if String === io
    io = StringIO.new( io )
elsif not IO === io
    raise Syck::Error, "YAML stream must be an IO or String object."
end
if Syck::unicode
    def io.readline
        Syck.utf_to_internal( readline( @ln_sep ), @utf_encoding )
    end
    def io.check_unicode
        @utf_encoding = Syck.sniff_encoding( read( 4 ) )
        @ln_sep = Syck.enc_separator( @utf_encoding )
        seek( -4, IO::SEEK_CUR )
    end
            def io.utf_encoding
              @utf_encoding
            end
    io.check_unicode
else
    def io.utf_encoding
        :None
    end
end
io
end
object_maker( obj_class, val ) click to toggle source

Allocate blank object

# File lib/syck.rb, line 383
def self.object_maker( obj_class, val )
    warn "#{caller[0]}: YAML.object_maker is deprecated" if $VERBOSE && !caller[0].start_with?(File.dirname(__FILE__))
    if Hash === val
        o = obj_class.allocate
        val.each_pair { |k,v|
            o.instance_variable_set("@#{k}", v)
        }
        o
    else
        raise Error, "Invalid object explicitly tagged !ruby/Object: " + val.inspect
    end
end
parse( io ) click to toggle source

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/syck.rb, line 183
def self.parse( io )
    generic_parser.load( io )
end
parse_documents( io, &doc_proc ) click to toggle source

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/syck.rb, line 271
def self.parse_documents( io, &doc_proc )
    warn "#{caller[0]}: YAML.parse_documents is deprecated, use load_stream" if $VERBOSE && !caller[0].start_with?(File.dirname(__FILE__))
    self.each_node( io, &doc_proc )
end
parse_file( filepath ) click to toggle source

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/syck.rb, line 207
def self.parse_file( filepath )
    File.open( filepath ) do |f|
        parse( f )
    end
end
parser() click to toggle source

Returns a new default parser

# File lib/syck.rb, line 91
def self.parser; Parser.new.set_resolver( self.resolver ); end
quick_emit( oid, opts = {}, &e ) click to toggle source

Allocate an Emitter if needed

# File lib/syck.rb, line 399
def self.quick_emit( oid, opts = {}, &e )
    warn "#{caller[0]}: YAML.quick_emit is deprecated" if $VERBOSE && !caller[0].start_with?(File.dirname(__FILE__))
    out =
        if opts.is_a? Emitter
            opts
        else
            emitter.reset( opts )
        end
    out.emit( oid, &e )
end
read_type_class( type, obj_class ) click to toggle source

Method to extract colon-separated type and class, returning the type and the constant of the class

# File lib/syck.rb, line 373
def self.read_type_class( type, obj_class )
    warn "#{caller[0]}: YAML.read_type_class is deprecated" if $VERBOSE && !caller[0].start_with?(File.dirname(__FILE__))
    type, tclass = type.split( ':', 4 ).last(2)
    tclass.split( "::" ).each { |c| obj_class = obj_class.const_get( c ) } if tclass
    return [ type, obj_class ]
end
resolver() click to toggle source

Returns the default resolver

# File lib/syck.rb, line 100
def self.resolver
    warn "#{caller[0]}: YAML.resolver is deprecated" if $VERBOSE && !caller[0].start_with?(File.dirname(__FILE__))
    DefaultResolver
end
tag_class( tag, cls ) click to toggle source

Associates a taguri tag with a Ruby class cls. The taguri is used to give types to classes when loading YAML. Taguris are of the form:

tag:authorityName,date:specific

The authorityName is a domain name or email address. The date is the date the type was issued in YYYY or YYYY-MM or YYYY-MM-DD format. The specific is a name for the type being added.

For example, built-in YAML types have 'yaml.org' as the authorityName and '2002' as the date. The specific is simply the name of the type:

tag:yaml.org,2002:int
tag:yaml.org,2002:float
tag:yaml.org,2002:timestamp

The domain must be owned by you on the date declared. If you don't own any domains on the date you declare the type, you can simply use an e-mail address.

tag:why@ruby-lang.org,2004:notes/personal
# File lib/syck/tag.rb, line 34
def self.tag_class( tag, cls )
    if @@tagged_classes.has_key? tag
        warn "class #{ @@tagged_classes[tag] } held ownership of the #{ tag } tag"
    end
    @@tagged_classes[tag] = cls
end
tagged_classes() click to toggle source

Returns the complete dictionary of taguris, paired with classes. The key for the dictionary is the full taguri. The value for each key is the class constant associated to that taguri.

YAML.tagged_classes["tag:yaml.org,2002:int"] => Integer
# File lib/syck/tag.rb, line 47
def self.tagged_classes
    @@tagged_classes
end
tagurize( val ) click to toggle source

Convert a type_id to a taguri

# File lib/syck.rb, line 348
def self.tagurize( val )
    warn "#{caller[0]}: YAML.tagurize is deprecated" if $VERBOSE && !caller[0].start_with?(File.dirname(__FILE__))
    resolver.tagurize( val )
end
transfer( type_id, obj ) click to toggle source

Apply a transfer method to a Ruby object

# File lib/syck.rb, line 356
def self.transfer( type_id, obj )
    warn "#{caller[0]}: YAML.transfer is deprecated" if $VERBOSE && !caller[0].start_with?(File.dirname(__FILE__))
    resolver.transfer( tagurize( type_id ), obj )
end
try_implicit( obj ) click to toggle source

Apply any implicit a node may qualify for

# File lib/syck.rb, line 364
def self.try_implicit( obj )
    warn "#{caller[0]}: YAML.try_implicit is deprecated" if $VERBOSE && !caller[0].start_with?(File.dirname(__FILE__))
    transfer( detect_implicit( obj ), obj )
end
unescape( value ) click to toggle source

Unescape the condenses escapes

# File lib/syck/encoding.rb, line 22
def self.unescape( value )
      warn "#{caller[0]}: YAML.unescape is deprecated" if $VERBOSE
        value.gsub( /\\(?:([nevfbart\\])|0?x([0-9a-fA-F]{2})|u([0-9a-fA-F]{4}))/ ) {
                if $3
                        ["#$3".hex ].pack('U*')
                elsif $2
                        [$2].pack( "H2" )
                else
                        UNESCAPES[$1]
                end
        }
end