class YAML::DBM

YAML + DBM = YDBM

YAML::DBM provides the same interface as ::DBM.

However, while DBM only allows strings for both keys and values, this library allows one to use most Ruby objects for values by first converting them to YAML. Keys must be strings.

Conversion to and from YAML is performed automatically.

See the documentation for ::DBM and ::YAML for more information.

Public Instance Methods

ydbm[key] → value click to toggle source

Return value associated with key from database.

Returns nil if there is no such key.

See fetch for more information.

# File lib/yaml/dbm.rb, line 28
def []( key )
    fetch( key )
end

ydbm[key] = value click to toggle source

Set key to value in database.

value will be converted to YAML before storage.

See store for more information.

# File lib/yaml/dbm.rb, line 40
def []=( key, val )
    store( key, val )
end

delete(key) click to toggle source

Deletes value from database associated with key.

Returns value or nil.

Calls superclass method #delete

# File lib/yaml/dbm.rb, line 101
def delete( key )
    v = super( key )
    if String === v
        v = YAML.load( v )
    end
    v
end

delete_if { |key, value| ... } click to toggle source

Calls the given block once for each key, value pair in the database. Deletes all entries for which the block returns true.

Returns self.

# File lib/yaml/dbm.rb, line 116
def delete_if # :yields: [key, value]
    del_keys = keys.dup
    del_keys.delete_if { |k| yield( k, fetch( k ) ) == false }
    del_keys.each { |k| delete( k ) }
    self
end

each()

Alias for: each_pair

each_pair { |key, value| ... } click to toggle source

Calls the given block once for each key, value pair in the database.

Returns self.

# File lib/yaml/dbm.rb, line 139
def each_pair # :yields: [key, value]
    keys.each { |k| yield k, fetch( k ) }
    self
end

Also aliased as: each

each_value { |value| ... } click to toggle source

Calls the given block for each value in database.

Returns self.

Calls superclass method #each_value

# File lib/yaml/dbm.rb, line 150
def each_value # :yields: value
    super { |v| yield YAML.load( v ) }
    self
end

fetch( key, ifnone = nil ) click to toggle source

fetch( key ) { |key| ... }

Return value associated with key.

If there is no value for key and no block is given, returns ifnone.

Otherwise, calls block passing in the given key.

See DBM#fetch for more information.

Calls superclass method #fetch

# File lib/yaml/dbm.rb, line 55
def fetch( keystr, ifnone = nil )
    begin
        val = super( keystr )
        return YAML.load( val ) if String === val
    rescue IndexError
    end
    if block_given?
        yield keystr
    else
        ifnone
    end
end

has_value?(value) click to toggle source

Returns true if specified value is found in the database.

# File lib/yaml/dbm.rb, line 167
def has_value?( val )
    each_value { |v| return true if v == val }
    return false
end

index( keystr ) click to toggle source

Deprecated, used #key instead.

Note: #index makes warning from internal of ::DBM#index. It says 'DBM#index is deprecated; use #key', but #key behaves not same as #index.

Calls superclass method

# File lib/yaml/dbm.rb, line 75
def index( keystr )
    super( keystr.to_yaml )
end

invert → hash click to toggle source

Returns a Hash (not a DBM database) created by using each value in the database as a key, with the corresponding key as its value.

Note that all values in the hash will be Strings, but the keys will be actual objects.

# File lib/yaml/dbm.rb, line 180
def invert
    h = {}
    keys.each { |k| h[ self.fetch( k ) ] = k }
    h
end

key(value) → string click to toggle source

Returns the key for the specified value.

# File lib/yaml/dbm.rb, line 83
def key( keystr )
    invert[keystr]
end

reject { |key, value| ... } click to toggle source

Converts the contents of the database to an in-memory Hash, then calls Hash#reject with the specified code block, returning a new Hash.

# File lib/yaml/dbm.rb, line 128
def reject
    hsh = self.to_hash
    hsh.reject { |k,v| yield k, v }
end

replace(hash) → ydbm click to toggle source

Replaces the contents of the database with the contents of the specified object. Takes any object which implements the #each_pair method, including Hash and DBM objects.

# File lib/yaml/dbm.rb, line 192
def replace( hsh )
    clear
    update( hsh )
end

select { |key, value| ... } click to toggle source

select(*keys)

If a block is provided, returns a new array containing [key, value] pairs for which the block returns true.

Otherwise, same as values_at

# File lib/yaml/dbm.rb, line 218
def select( *keys )
    if block_given?
        self.keys.collect { |k| v = self[k]; [k, v] if yield k, v }.compact
    else
        values_at( *keys )
    end
end

shift → [key, value] click to toggle source

Removes a [key, value] pair from the database, and returns it. If the database is empty, returns nil.

The order in which values are removed/returned is not guaranteed.

Calls superclass method #shift

# File lib/yaml/dbm.rb, line 204
def shift
    a = super
    a[1] = YAML.load( a[1] ) if a
    a
end

store(key, value) → value click to toggle source

Stores value in database with key as the index. value is converted to YAML before being stored.

Returns value

Calls superclass method #store

# File lib/yaml/dbm.rb, line 233
def store( key, val )
    super( key, val.to_yaml )
    val
end

to_a → array click to toggle source

Converts the contents of the database to an array of [key, value] arrays, and returns it.

# File lib/yaml/dbm.rb, line 258
def to_a
    a = []
    keys.each { |k| a.push [ k, self.fetch( k ) ] }
    a
end

to_hash → hash click to toggle source

Converts the contents of the database to an in-memory Hash object, and returns it.

# File lib/yaml/dbm.rb, line 270
def to_hash
    h = {}
    keys.each { |k| h[ k ] = self.fetch( k ) }
    h
end

update(hash) → ydbm click to toggle source

Updates the database with multiple values from the specified object. Takes any object which implements the #each_pair method, including Hash and DBM objects.

Returns self.

# File lib/yaml/dbm.rb, line 246
def update( hsh )
    hsh.each_pair do |k,v|
        self.store( k, v )
    end
    self
end

values click to toggle source

Returns an array of values from the database.

Calls superclass method #values

# File lib/yaml/dbm.rb, line 159
def values
    super.collect { |v| YAML.load( v ) }
end

values_at(*keys) click to toggle source

Returns an array containing the values associated with the given keys.

# File lib/yaml/dbm.rb, line 91
def values_at( *keys )
    keys.collect { |k| fetch( k ) }
end