[Help-smalltalk] [PATCH 1/2] optimize FileStream>>#upTo: and FileStream>>#nextLine

[Paolo Bonzini]

2013-05-04  Paolo Bonzini  <address@hidden>

        * kernel/FileStream.st: Avoid a useless copy from the
        buffer when #upTo: and #nextLine are using a stream.
---
 kernel/FileStream.st | 45 ++++++++++++++++++++++++++++++---------------
 1 files changed, 30 insertions(+), 15 deletions(-)

diff --git a/kernel/FileStream.st b/kernel/FileStream.st
index 1aa5635..0c66169 100644
--- a/kernel/FileStream.st
+++ b/kernel/FileStream.st
@@ -394,7 +394,7 @@ file object, such as /dev/rmt0 on UNIX or MTA0: on VMS).'>
         the stream's contents if no such character is found."
 
        <category: 'overriding inherited methods'>
-       | n resultStream result ch |
+       | start resultStream result ch |
        writePtr notNil ifTrue: [self flush].
        ptr > endPtr 
            ifTrue: 
@@ -408,16 +408,22 @@ file object, such as /dev/rmt0 on UNIX or MTA0: on VMS).'>
                [:i | 
                (ch := collection at: i) == aCharacter
                    ifTrue: 
-                       [result := collection copyFrom: ptr to: i - 1.
+                       [start := ptr.
                        ptr := i + 1.
 
-                       "If we went through the loop only once, we're done."
-                       resultStream isNil ifTrue: [^result].
+                       "If we went through the loop only once, copy from
+                        the buffer."
+                       resultStream isNil ifTrue: [
+                           result := collection copyFrom: start to: i - 1.
+                           ^result].
 
                        "Else finish the stream and return its contents."
-                       ^resultStream
-                           nextPutAll: result;
-                           contents]].
+                       resultStream
+                           next: i - start
+                           putAll: collection
+                           startingAt: start.
+
+                       ^resultStream contents]].
        resultStream isNil 
            ifTrue: 
                [resultStream := WriteStream on: (self species new: endPtr - 
ptr + 20)].
@@ -438,7 +444,7 @@ file object, such as /dev/rmt0 on UNIX or MTA0: on VMS).'>
         stream's contents if no new-line character is found."
 
        <category: 'overriding inherited methods'>
-       | n resultStream result ch |
+       | start resultStream result ch |
        writePtr notNil ifTrue: [self flush].
        ptr > endPtr 
            ifTrue: 
@@ -452,17 +458,26 @@ file object, such as /dev/rmt0 on UNIX or MTA0: on VMS).'>
                [:i | 
                ((ch := collection at: i) == ##(Character cr) or: [ch == 
##(Character nl)]) 
                    ifTrue: 
-                       [result := collection copyFrom: ptr to: i - 1.
+                       [start := ptr.
                        ptr := i + 1.
-                       ch == ##(Character cr) ifTrue: [self peekFor: 
##(Character nl)].
 
-                       "If we went through the loop only once, we're done."
-                       resultStream isNil ifTrue: [^result].
+                       "If we went through the loop only once, copy from
+                        the buffer.  We cannot check for CR/LF yet, #peekFor:
+                        could refill collection."
+                       resultStream isNil ifTrue: [
+                           result := collection copyFrom: start to: i - 1.
+                           ch == ##(Character cr) ifTrue: [self peekFor: 
##(Character nl)].
+                           ^result].
 
                        "Else finish the stream and return its contents."
-                       ^resultStream
-                           nextPutAll: result;
-                           contents]].
+                       resultStream
+                           next: i - start
+                           putAll: collection
+                           startingAt: start.
+
+                       ch == ##(Character cr) ifTrue: [self peekFor: 
##(Character nl)].
+                       ^resultStream contents]].
+
        resultStream isNil 
            ifTrue: 
                [resultStream := WriteStream on: (self species new: endPtr - 
ptr + 20)].
-- 
1.8.2