From: Jean Privat <jean@pryen.org>
Date: Tue, 10 Mar 2015 13:51:03 +0000 (+0700)
Subject: Merge: Faster buffers
X-Git-Tag: v0.7.3~34
X-Git-Url: http://nitlanguage.org?hp=e42ec5ff886b153fd8733f24ffde3513c42da250

Merge: Faster buffers

Make flatbuffers a little faster on substrings

for nitc/nitc/nitc
before: 0m7.168s
after: 0m7.068s (-1.4%)

Pull-Request: #1189
Reviewed-by: Lucas Bajolet <r4pass@hotmail.com>
Reviewed-by: Alexis Laferrière <alexis.laf@xymus.net>
Reviewed-by: Alexandre Terrasa <alexandre@moz-code.org>
---

diff --git a/lib/standard/stream.nit b/lib/standard/stream.nit
index 1e4ba18..7df1bd1 100644
--- a/lib/standard/stream.nit
+++ b/lib/standard/stream.nit
@@ -404,6 +404,7 @@ abstract class BufferedReader
 		if _buffer_pos + i >= _buffer.length then
 			var from = _buffer_pos
 			_buffer_pos = _buffer.length
+			if from == 0 then return _buffer.to_s
 			return _buffer.substring_from(from).to_s
 		end
 		_buffer_pos += i
diff --git a/lib/standard/string.nit b/lib/standard/string.nit
index b99fc99..e78f655 100644
--- a/lib/standard/string.nit
+++ b/lib/standard/string.nit
@@ -1180,10 +1180,14 @@ class FlatString
 	#              String Specific Methods           #
 	##################################################
 
-	private init with_infos(items: NativeString, len: Int, from: Int, to: Int)
+	# Low-level creation of a new string with given data.
+	#
+	# `items` will be used as is, without copy, to retrieve the characters of the string.
+	# Aliasing issues is the responsibility of the caller.
+	private init with_infos(items: NativeString, length: Int, from: Int, to: Int)
 	do
 		self.items = items
-		length = len
+		self.length = length
 		index_from = from
 		index_to = to
 	end
@@ -1627,6 +1631,20 @@ class FlatBuffer
 	# Create a new empty string.
 	init do end
 
+	# Low-level creation a new buffer with given data.
+	#
+	# `items` will be used as is, without copy, to store the characters of the buffer.
+	# Aliasing issues is the responsibility of the caller.
+	#
+	# If `items` is shared, `written` should be set to true after the creation
+	# so that a modification will do a copy-on-write.
+	private init with_infos(items: NativeString, capacity, length: Int)
+	do
+		self.items = items
+		self.length = length
+		self.capacity = capacity
+	end
+
 	# Create a new string copied from `s`.
 	init from(s: Text)
 	do
@@ -1651,7 +1669,6 @@ class FlatBuffer
 	init with_capacity(cap: Int)
 	do
 		assert cap >= 0
-		# _items = new NativeString.calloc(cap)
 		items = new NativeString(cap+1)
 		capacity = cap
 		length = 0
@@ -1695,11 +1712,10 @@ class FlatBuffer
 		if from < 0 then from = 0
 		if count > length then count = length
 		if from < count then
-			var r = new FlatBuffer.with_capacity(count - from)
-			while from < count do
-				r.chars.push(items[from])
-				from += 1
-			end
+			var len = count - from
+			var r_items = new NativeString(len)
+			items.copy_to(r_items, len, from, 0)
+			var r = new FlatBuffer.with_infos(r_items, len, len)
 			return r
 		else
 			return new FlatBuffer