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.

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 # => 136294312

Defined in:

string_pool.cr

Class Method Summary

Instance Method Summary

Instance methods inherited from class Reference

==(other)
==(other : self) ==, dup dup, hash hash, inspect(io : IO) : Nil inspect, object_id : UInt64 object_id, same?(other : Reference)
same?(other : Nil) same?, to_s(io : IO) : Nil to_s

Instance methods inherited from class Object

!=(other) !=, !~(other) !~, ==(other) ==, ===(other)
===(other : YAML::Any)
===(other : JSON::Any) ===, =~(other) =~, class class, crystal_type_id crystal_type_id, dup dup, hash hash, inspect(io : IO)
inspect inspect, itself itself, not_nil! not_nil!, tap(&block) tap, to_json to_json, to_pretty_json(io : IO)
to_pretty_json to_pretty_json, to_s
to_s(io : IO) to_s, to_yaml
to_yaml(io : IO) to_yaml, try(&block) try

Class methods inherited from class Object

==(other : Class) ==, ===(other) ===, cast(other) : self cast, clone clone, dup dup, from_json(string_or_io, root : String) : self
from_json(string_or_io) : self from_json, from_yaml(string : String) : self from_yaml, hash hash, inspect(io) inspect, name : String name, to_s(io) to_s, |(other : U.class) |

Class Method Detail

def self.new #

Creates a new empty string pool.


[View source]

Instance Method Detail

def empty? #

Returns true if the String Pool has no element otherwise returns false.

pool = StringPool.new
pool.empty? # => true
pool.get("crystal")
pool.empty? # => false

[View source]
def get(str : MemoryIO) #

Returns a string with the contents of the given MemoryIO.

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

pool = StringPool.new
io = MemoryIO.new "crystal"
pool.empty? # => true
pool.get(io)
pool.empty? # => false

[View source]
def get(str : String) #

Returns 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

pool = StringPool.new
string = "crystal"
pool.empty? # => true
pool.get(string)
pool.empty? # => false

[View source]
def get(slice : Slice(UInt8)) #

Returns 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.

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? # => false
 ```

[View source]
def get(str : Pointer(UInt8), len) #

Returns 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.

pool = StringPool.new
pool.get("hey".to_unsafe, 3)
pool.size # => 1

[View source]
def rehash #

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.


[View source]
def size : Int32 #

Returns the size

pool = StringPool.new
pool.size # => 0

[View source]