class StringPool
Overview
A string pool is a collection of strings. It allows a runtime to save memory by preserving strings in a pool, allowing to reuse an instance of a common string instead of creating a new one.
NOTE To use StringPool, you must explicitly import it with require "string_pool"
require "string_pool"
pool = StringPool.new
a = "foo" + "bar"
b = "foo" + "bar"
a.object_id # => 136294360
b.object_id # => 136294336
a = pool.get(a)
b = pool.get(b)
a.object_id # => 136294312
b.object_id # => 136294312Defined in:
string_pool.crConstructors
-
.new(initial_capacity = 8)
Creates a new empty string pool.
Instance Method Summary
-
#empty? : Bool
Returns
trueif theStringPoolhas no element otherwise returnsfalse. -
#get(str : Pointer(UInt8), len) : String
Returns a
Stringwith the contents given by the pointer str of size len. -
#get(slice : Bytes) : String
Returns a
Stringwith the contents of the given slice. -
#get(str : IO::Memory) : String
Returns a
Stringwith the contents of the givenIO::Memory. -
#get(str : String) : String
Returns a
Stringwith the contents of the given string. -
#get?(str : Pointer(UInt8), len) : String | Nil
Returns a
Stringwith the contents given by the pointer str of size len, ornilif no such string exists in the pool. -
#get?(slice : Bytes) : String | Nil
Returns a
Stringwith the contents of the given slice, ornilif no such string exists in the pool. -
#get?(str : IO::Memory) : String | Nil
Returns a
Stringwith the contents of the givenIO::Memory, ornilif no such string exists in the pool. -
#get?(str : String) : String | Nil
Returns a
Stringwith the contents of the given string, ornilif no such string exists in the pool. -
#rehash : Nil
Rebuilds the hash based on the current hash values for each key, if values of key objects have changed since they were inserted.
-
#size : Int32
Returns the size
Instance methods inherited from class Reference
==(other : self)==(other : JSON::Any)
==(other : YAML::Any)
==(other) ==, dup dup, hash(hasher) hash, initialize initialize, inspect(io : IO) : Nil inspect, object_id : UInt64 object_id, pretty_print(pp) : Nil pretty_print, same?(other : Reference) : Bool
same?(other : Nil) same?, to_s(io : IO) : Nil to_s
Constructor methods inherited from class Reference
new
new,
unsafe_construct(address : Pointer, *args, **opts) : self
unsafe_construct
Class methods inherited from class Reference
pre_initialize(address : Pointer)
pre_initialize
Instance methods inherited from class Object
! : Bool
!,
!=(other)
!=,
!~(other)
!~,
==(other)
==,
===(other : JSON::Any)===(other : YAML::Any)
===(other) ===, =~(other) =~, as(type : Class) as, as?(type : Class) as?, class class, dup dup, hash(hasher)
hash hash, in?(collection : Object) : Bool
in?(*values : Object) : Bool in?, inspect(io : IO) : Nil
inspect : String inspect, is_a?(type : Class) : Bool is_a?, itself itself, nil? : Bool nil?, not_nil!(message)
not_nil! not_nil!, pretty_inspect(width = 79, newline = "\n", indent = 0) : String pretty_inspect, pretty_print(pp : PrettyPrint) : Nil pretty_print, responds_to?(name : Symbol) : Bool responds_to?, tap(&) tap, to_json(io : IO) : Nil
to_json : String to_json, to_pretty_json(indent : String = " ") : String
to_pretty_json(io : IO, indent : String = " ") : Nil to_pretty_json, to_s(io : IO) : Nil
to_s : String to_s, to_yaml(io : IO) : Nil
to_yaml : String to_yaml, try(&) try, unsafe_as(type : T.class) forall T unsafe_as
Class methods inherited from class Object
from_json(string_or_io, root : String)from_json(string_or_io) from_json, from_yaml(string_or_io : String | IO) from_yaml
Macros inherited from class Object
class_getter(*names, &block)
class_getter,
class_getter!(*names)
class_getter!,
class_getter?(*names, &block)
class_getter?,
class_property(*names, &block)
class_property,
class_property!(*names)
class_property!,
class_property?(*names, &block)
class_property?,
class_setter(*names)
class_setter,
def_clone
def_clone,
def_equals(*fields)
def_equals,
def_equals_and_hash(*fields)
def_equals_and_hash,
def_hash(*fields)
def_hash,
delegate(*methods, to object)
delegate,
forward_missing_to(delegate)
forward_missing_to,
getter(*names, &block)
getter,
getter!(*names)
getter!,
getter?(*names, &block)
getter?,
property(*names, &block)
property,
property!(*names)
property!,
property?(*names, &block)
property?,
setter(*names)
setter
Constructor Detail
Creates a new empty string pool.
The initial_capacity is useful to avoid unnecessary reallocations of the internal buffers in case of growth. If you have an estimate of the maximum number of elements the pool will hold it should be initialized with that capacity for improved performance. Inputs lower than 8 are ignored.
pool = StringPool.new(256)
pool.size # => 0Instance Method Detail
Returns true if the StringPool has no element otherwise returns false.
require "string_pool"
pool = StringPool.new
pool.empty? # => true
pool.get("crystal")
pool.empty? # => falseReturns a String with the contents given by the pointer str of size len.
If a string with those contents was already present in the pool, that one is returned. Otherwise a new string is created, put in the pool and returned.
require "string_pool"
pool = StringPool.new
pool.get("hey".to_unsafe, 3)
pool.size # => 1Returns a String with the contents of the given slice.
If a string with those contents was already present in the pool, that one is returned. Otherwise a new string is created, put in the pool and returned.
require "string_pool"
pool = StringPool.new
ptr = Pointer.malloc(9) { |i| ('a'.ord + i).to_u8 }
slice = Slice.new(ptr, 3)
pool.empty? # => true
pool.get(slice)
pool.empty? # => falseReturns a String with the contents of the given IO::Memory.
If a string with those contents was already present in the pool, that one is returned. Otherwise a new string is created, put in the pool and returned.
require "string_pool"
pool = StringPool.new
io = IO::Memory.new "crystal"
pool.empty? # => true
pool.get(io)
pool.empty? # => falseReturns a String with the contents of the given string.
If a string with those contents was already present in the pool, that one is returned. Otherwise a new string is created, put in the pool and returned.
require "string_pool"
pool = StringPool.new
string = "crystal"
pool.empty? # => true
pool.get(string)
pool.empty? # => falseReturns a String with the contents given by the pointer str of size
len, or nil if no such string exists in the pool.
require "string_pool"
pool = StringPool.new
pool.get?("hey".to_unsafe, 3) # => nil
pool.empty? # => true
pool.get("hey".to_unsafe, 3) # => "hey"
pool.empty? # => false
pool.get?("hey".to_unsafe, 3) # => "hey"Returns a String with the contents of the given slice, or nil if no
such string exists in the pool.
require "string_pool"
pool = StringPool.new
bytes = "abc".to_slice
pool.get?(bytes) # => nil
pool.empty? # => true
pool.get(bytes) # => "abc"
pool.empty? # => false
pool.get?(bytes) # => "abc"Returns a String with the contents of the given IO::Memory, or nil if
no such string exists in the pool.
require "string_pool"
pool = StringPool.new
io = IO::Memory.new "crystal"
pool.get?(io) # => nil
pool.empty? # => true
pool.get(io) # => "crystal"
pool.empty? # => false
pool.get?(io) # => "crystal"Returns a String with the contents of the given string, or nil if no
such string exists in the pool.
require "string_pool"
pool = StringPool.new
string = "crystal"
pool.get?(string) # => nil
pool.empty? # => true
pool.get(string) # => "crystal"
pool.empty? # => false
pool.get?(string) # => "crystal"Rebuilds the hash based on the current hash values for each key, if values of key objects have changed since they were inserted.
Call this method if you modified a string submitted to the pool.
Returns the size
require "string_pool"
pool = StringPool.new
pool.size # => 0