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 29
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 41
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 102
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 117
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 140
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 151
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 56
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 168
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 76
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 181
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 84
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 129
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 193
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 219
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 205
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 234
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 259
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 271
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 247
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 160
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 92
def values_at( *keys )
    keys.collect { |k| fetch( k ) }
end