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 (file)
--- 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 (file)
--- 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