Bug #4693 » 0001-Documentation-for-YAML-DBM.patch
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require 'yaml'
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require 'dbm'
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#
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# YAML + DBM = YDBM
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# - Same interface as DBM class
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#
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module YAML
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# YAML + DBM = YDBM
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#
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# YAML::DBM provides the same interface as ::DBM.
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#
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# However, while DBM only allows strings for both keys and values,
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# this library allows one to use most Ruby objects for values
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# by first converting them to YAML. Keys must be strings.
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#
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# Conversion to and from YAML is performed automatically.
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#
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# See the documentation for ::DBM and ::YAML for more information.
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class DBM < ::DBM
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VERSION = "0.1"
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# Return value associated with +key+ from database.
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#
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# Returns +nil+ if there is no such +key+.
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def []( key )
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fetch( key )
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end
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# :call-seq:
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# []=( key, value )
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#
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# Set +key+ to +value+ in database.
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#
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# +value+ will be converted to YAML before storage.
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def []=( key, val )
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store( key, val )
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end
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# :call-seq:
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# fetch( key, ifnone = nil )
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# fetch( key, &block )
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#
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# Return value associated with +key+.
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#
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# If there is no value for +key+ and no block is given, returns +ifnone+.
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#
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# Otherwise, calls block passing in the given +key+.
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def fetch( keystr, ifnone = nil )
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begin
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val = super( keystr )
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| ... | ... | |
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ifnone
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end
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end
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# Deprecated, used YAML::DBM#key instead.
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def index( keystr )
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super( keystr.to_yaml )
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end
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# Returns an array containing the values associated with the given keys.
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def values_at( *keys )
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keys.collect { |k| fetch( k ) }
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end
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# Deletes value from database assocated with +key+.
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#
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# Returns value or +nil+.
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def delete( key )
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v = super( key )
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if String === v
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| ... | ... | |
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end
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v
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end
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def delete_if
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# Calls the given block once for each +key+, +value+ pair in the database.
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# Deletes all entries for which the block returns true.
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#
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# Returns +self+.
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def delete_if # :yields: [key, value]
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del_keys = keys.dup
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del_keys.delete_if { |k| yield( k, fetch( k ) ) == false }
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del_keys.each { |k| delete( k ) }
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self
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end
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# Converts the contents of the database to an in-memory Hash, then calls
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# Hash#reject with the specified code block, returning a new Hash.
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def reject
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hsh = self.to_hash
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hsh.reject { |k,v| yield k, v }
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end
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def each_pair
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# Calls the given block once for each +key+, +value+ pair in the database.
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#
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# Returns +self+.
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def each_pair # :yields: [key, value]
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keys.each { |k| yield k, fetch( k ) }
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self
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end
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def each_value
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# Calls the given block for each value in database.
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#
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# Returns +self+.
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def each_value # :yields: value
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super { |v| yield YAML.load( v ) }
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self
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end
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# Returns an array of values from the database.
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def values
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super.collect { |v| YAML.load( v ) }
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end
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# Returns true if specified value is found in the database.
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def has_value?( val )
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each_value { |v| return true if v == val }
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return false
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end
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# Returns a Hash (not a DBM database) created by using each value in the
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# database as a key, with the corresponding key as its value.
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#
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# Note that all values in the hash will be Strings, but the keys will be
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# actual objects.
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def invert
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h = {}
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keys.each { |k| h[ self.fetch( k ) ] = k }
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h
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end
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# Replaces the contents of the database with the contents of the specified
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# object. Takes any object which implements the each_pair method, including
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# Hash and DBM objects.
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def replace( hsh )
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clear
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update( hsh )
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end
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# Removes a [key, value] pair from the database, and returns it.
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# If the database is empty, returns +nil+.
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#
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# The order in which values are removed/returned is not guaranteed.
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def shift
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a = super
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a[1] = YAML.load( a[1] ) if a
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a
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end
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# :call-seq:
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# select( &block )
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# select( *keys )
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#
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# If a block is provided, returns a new array containing [key, value] pairs
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# for which the block returns true.
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#
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# Otherwise, same as #values_at
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def select( *keys )
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if block_given?
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self.keys.collect { |k| v = self[k]; [k, v] if yield k, v }.compact
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| ... | ... | |
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values_at( *keys )
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end
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end
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# :call-seq:
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# store( key, value )
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#
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#Stores +value+ in database with +key+ as the index. +value+ is converted
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#to YAML before being stored.
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#
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#Returns +value+
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def store( key, val )
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super( key, val.to_yaml )
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val
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end
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# Updates the database with multiple values from the specified object.
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# Takes any object which implements the each_pair method, including
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# Hash and DBM objects.
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#
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# Returns +self+.
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def update( hsh )
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hsh.keys.each do |k|
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self.store( k, hsh.fetch( k ) )
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end
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self
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end
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# Converts the contents of the database to an array of [key, value] arrays,
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# and returns it.
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def to_a
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a = []
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keys.each { |k| a.push [ k, self.fetch( k ) ] }
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a
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end
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# Converts the contents of the database to an in-memory Hash object, and
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# returns it.
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def to_hash
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h = {}
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keys.each { |k| h[ k ] = self.fetch( k ) }
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h
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end
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alias :each :each_pair
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end
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