StringPool
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 # => 136294312Constructors
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 methods
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.