From: Lucas Bajolet <r4pass@hotmail.com>
Date: Mon, 24 Mar 2014 18:03:43 +0000 (-0400)
Subject: stdlib/strings: Abstracted hash (breaks hash on Buffer temporarily)
X-Git-Tag: v0.6.5~7^2~3^2~3
X-Git-Url: http://nitlanguage.org

stdlib/strings: Abstracted hash (breaks hash on Buffer temporarily)

Signed-off-by: Lucas Bajolet <r4pass@hotmail.com>
---

diff --git a/lib/standard/string.nit b/lib/standard/string.nit
index ecf7cf1..ff18a7d 100644
--- a/lib/standard/string.nit
+++ b/lib/standard/string.nit
@@ -38,6 +38,8 @@ abstract class Text
 	# Type of self (used for factorization of several methods, ex : substring_from, empty...)
 	type SELFTYPE: Text
 
+	var hash_cache: nullable Int = null
+
 	# Gets a view on the chars of the Text object
 	fun chars: SELFVIEW is abstract
 
@@ -462,6 +464,23 @@ abstract class Text
 	# Flat representation of self
 	fun flatten: FlatText is abstract
 
+	redef fun hash
+	do
+		if hash_cache == null then
+			# djb2 hash algorithm
+			var h = 5381
+			var i = length - 1
+
+			for char in self.chars do
+				h = (h * 32) + h + char.ascii
+				i -= 1
+			end
+
+			hash_cache = h
+		end
+		return hash_cache.as(not null)
+	end
+
 end
 
 # All kinds of array-based text representations.
@@ -872,21 +891,25 @@ class FlatString
 
 	redef fun hash
 	do
-		# djb2 hash algorythm
-		var h = 5381
-		var i = length - 1
+		if hash_cache == null then
+			# djb2 hash algorythm
+			var h = 5381
+			var i = length - 1
 
-		var myitems = items
-		var strStart = index_from
+			var myitems = items
+			var strStart = index_from
 
-		i += strStart
+			i += strStart
+
+			while i >= strStart do
+				h = (h * 32) + h + self.items[i].ascii
+				i -= 1
+			end
 
-		while i >= strStart do
-			h = (h * 32) + h + self.items[i].ascii
-			i -= 1
+			hash_cache = h
 		end
 
-		return h
+		return hash_cache.as(not null)
 	end
 end