From: Scott Wheeler <wheeler@kde.org>
Date: Fri, 16 Jun 2006 22:38:20 +0000 (+0000)
Subject: A couple more optimizations for splitting vectors.  One of them makes search
X-Git-Tag: v1.5~232
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=e83f93b2c0c65e1cd26ab5f608c7ccb1ba72df5a;p=taglib

A couple more optimizations for splitting vectors.  One of them makes search
faster in the simple case (no need for Boyer-Moore for a one-character search)
and append a null vector rather than instantiating a new one when we find empty
fields.

This gets the reading time down to 6 seconds here for the reported bug, which
still isn't great, but it's starting to get close to acceptable.  I'll see if I
can get it a little tighter...

BUG:122183


git-svn-id: svn://anonsvn.kde.org/home/kde/trunk/kdesupport/taglib@552196 283d02a7-25f6-0310-bc7c-ecb5cbfe19da
---

diff --git a/toolkit/tbytevector.cpp b/toolkit/tbytevector.cpp
index 241a08c5..46e015d5 100644
--- a/toolkit/tbytevector.cpp
+++ b/toolkit/tbytevector.cpp
@@ -92,6 +92,18 @@ namespace TagLib {
     if(pattern.size() > v.size() || offset >= v.size() - 1)
       return -1;
 
+    // Let's go ahead and special case a pattern of size one since that's common
+    // and easy to make fast.
+
+    if(pattern.size() == 1) {
+      char p = pattern[0];
+      for(uint i = offset; i < v.size(); i++) {
+	if(v[i] == p && i % byteAlign == 0)
+	  return i;
+      }
+      return 0;
+    }
+
     uchar lastOccurrence[256];
 
     for(uint i = 0; i < 256; ++i)
diff --git a/toolkit/tbytevectorlist.cpp b/toolkit/tbytevectorlist.cpp
index f2b2c128..76613369 100644
--- a/toolkit/tbytevectorlist.cpp
+++ b/toolkit/tbytevectorlist.cpp
@@ -48,7 +48,11 @@ ByteVectorList ByteVectorList::split(const ByteVector &v, const ByteVector &patt
       offset != -1 && (max == 0 || max > int(l.size()) + 1);
       offset = v.find(pattern, offset + pattern.size(), byteAlign))
   {
-    l.append(v.mid(previousOffset, offset - previousOffset));
+    if(offset - previousOffset > 1)
+      l.append(v.mid(previousOffset, offset - previousOffset));
+    else
+      l.append(ByteVector::null);
+
     previousOffset = offset + pattern.size();
   }