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.

Methods
#
D
E
F
H
I
K
R
S
T
U
V
Constants
VERSION = "0.1"
 
Instance Public methods
[]( key )

Return value associated with key from database.

Returns nil if there is no such key.

# File lib/yaml/dbm.rb, line 23
def []( key )
    fetch( key )
end
[]=( key, value )

Set key to value in database.

value will be converted to YAML before storage.

# File lib/yaml/dbm.rb, line 33
def []=( key, val )
    store( key, val )
end
delete( key )

Deletes value from database associated with key.

Returns value or nil.

# File lib/yaml/dbm.rb, line 82
def delete( key )
    v = super( key )
    if String === v
        v = YAML.load( v )
    end
    v
end
delete_if()

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 94
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()

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

Returns self.

Also aliased as: each
# File lib/yaml/dbm.rb, line 111
def each_pair # :yields: [key, value]
    keys.each { |k| yield k, fetch( k ) }
    self
end
each_value()

Calls the given block for each value in database.

Returns self.

# File lib/yaml/dbm.rb, line 119
def each_value # :yields: value
    super { |v| yield YAML.load( v ) }
    self
end
fetch( key, ifnone = nil )
fetch( key, &block )

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.

# File lib/yaml/dbm.rb, line 46
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?( val )

Returns true if specified value is found in the database.

# File lib/yaml/dbm.rb, line 130
def has_value?( val )
    each_value { |v| return true if v == val }
    return false
end
index( keystr )

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.

# File lib/yaml/dbm.rb, line 66
def index( keystr )
    super( keystr.to_yaml )
end
invert()

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 140
def invert
    h = {}
    keys.each { |k| h[ self.fetch( k ) ] = k }
    h
end
key( keystr )
# File lib/yaml/dbm.rb, line 70
def key( keystr )
    invert[keystr]
end
reject()

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 103
def reject
    hsh = self.to_hash
    hsh.reject { |k,v| yield k, v }
end
replace( hsh )

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 149
def replace( hsh )
    clear
    update( hsh )
end
select( &block )
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 172
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()

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.

# File lib/yaml/dbm.rb, line 158
def shift
    a = super
    a[1] = YAML.load( a[1] ) if a
    a
end
store( key, value )

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

Returns value

# File lib/yaml/dbm.rb, line 187
def store( key, val )
    super( key, val.to_yaml )
    val
end
to_a()

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

# File lib/yaml/dbm.rb, line 206
def to_a
    a = []
    keys.each { |k| a.push [ k, self.fetch( k ) ] }
    a
end
to_hash()

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

# File lib/yaml/dbm.rb, line 215
def to_hash
    h = {}
    keys.each { |k| h[ k ] = self.fetch( k ) }
    h
end
update( hsh )

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 197
def update( hsh )
    hsh.each_pair do |k,v|
        self.store( k, v )
    end
    self
end
values()

Returns an array of values from the database.

# File lib/yaml/dbm.rb, line 125
def values
    super.collect { |v| YAML.load( v ) }
end
values_at( *keys )

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

# File lib/yaml/dbm.rb, line 75
def values_at( *keys )
    keys.collect { |k| fetch( k ) }
end