2005-07-17 Perry

 PATCH: [ 1239275 ] Fixes for sd_ComputeByteDiff
  Src: stringdiffs.cpp

diff --git a/Src/readme.txt b/Src/readme.txt
index 48456f8..9d133b1 100644 (file)
--- a/Src/readme.txt
+++ b/Src/readme.txt
@@ -1,3 +1,7 @@
+2005-07-17 Perry
+ PATCH: [ 1239275 ] Fixes for sd_ComputeByteDiff
+  Src: stringdiffs.cpp
+
 2005-07-15 Jochen
  PATCH: [ 1229867 ] RFE [ 1205516 ], RFE [ 887948 ], and other issues (w/o command line tool integration)
   Src: 7zCommon.cpp 7zCommon.h DiffContext.cpp DiffItem.cpp DiffItem.h DiffThread.cpp DiffWrapper.cpp DirActions.cpp DirDoc.cpp

diff --git a/Src/stringdiffs.cpp b/Src/stringdiffs.cpp
index 02423b7..c32d2dd 100644 (file)
--- a/Src/stringdiffs.cpp
+++ b/Src/stringdiffs.cpp
@@ -571,6 +571,8 @@ sd_ComputeByteDiff(CString & str1, CString & str2,
        // Advance py1 & py2 from beginning until find difference or end
        while (1)
        {
+               // Potential difference extends from py1 to pen1 and py2 to pen2
+
                // Check if either side finished
                if (py1 > pen1 && py2 > pen2)
                {
@@ -590,9 +592,9 @@ sd_ComputeByteDiff(CString & str1, CString & str2,
                        if (xwhite==1 && !isSafeWhitespace(*py2))
                                break; // done with forward search
                        // gobble up all whitespace in current area
-                       while (py1 < pen1 && isSafeWhitespace(*py1))
+                       while (isSafeWhitespace(*py1))
                                ++py1; // DBCS safe because of isSafeWhitespace above
-                       while (py2 < pen2 && isSafeWhitespace(*py2))
+                       while (isSafeWhitespace(*py2))
                                ++py2; // DBCS safe because of isSafeWhitespace above
                        continue;
 
@@ -626,16 +628,21 @@ sd_ComputeByteDiff(CString & str1, CString & str2,
                        ++py1; // DBCS safe b/c we checked above
                        ++py2; // DBCS safe b/c we checked above
                }
-
        }
 
+       // Potential difference extends from py1 to pen1 and py2 to pen2
 
        // Store results of advance into return variables (begin1 & begin2)
        // -1 in a begin variable means no visible diff area
        begin1 = (py1 > pen1) ? -1 : (py1 - pbeg1);
        begin2 = (py2 > pen2) ? -1 : (py2 - pbeg2);
 
-       if (!alldone)
+       if (alldone)
+       {
+               end1 = pen1 - pbeg1;
+               end2 = pen2 - pbeg2;
+       }
+       else
        {
                LPCTSTR pz1 = pen1;
                LPCTSTR pz2 = pen2;
@@ -644,6 +651,8 @@ sd_ComputeByteDiff(CString & str1, CString & str2,
                // Retreat pz1 & pz2 from end until find difference or beginning
                while (1)
                {
+                       // Potential difference extends from py1 to pz1 and from py2 to pz2
+
                        // Check if either side finished
                        if (pz1 < py1 && pz2 < py2)
                        {
@@ -685,8 +694,6 @@ sd_ComputeByteDiff(CString & str1, CString & str2,
                                // DBCS (we assume if a lead byte, then character is 2-byte)
                                if (!(pz1[0] == pz2[0] && pz1[1] == pz2[1]))
                                        break; // done with forward search
-                               pz1 = CharPrev(py1, pz1);
-                               pz2 = CharPrev(py2, pz2);
                        }
                        else
                        {
@@ -694,10 +701,16 @@ sd_ComputeByteDiff(CString & str1, CString & str2,
                                        break; // done with forward search
                                if (!matchchar(pz1[0], pz2[0], casitive))
                                        break; // done with forward search
+                       }
+                       // decrement pz1 and pz2
+                       if (pz1 == pbeg1)
+                               pz1 = pbeg1 - 1; // earlier than pbeg1 signifies no difference
+                       else
                                pz1 = CharPrev(pbeg1, pz1);
+                       if (pz2 == pbeg2)
+                               pz2 = pbeg2 - 1; // earlier than pbeg1 signifies no difference
+                       else
                                pz2 = CharPrev(pbeg2, pz2);
-                       }
-
                }
 
                // Store results of advance into return variables (end1 & end2)
@@ -711,8 +724,4 @@ sd_ComputeByteDiff(CString & str1, CString & str2,
                        end2 = pz2 - pbeg2;
                
        }
-
-       // Check if difference region was empty
-       if (begin1 >= end1 && begin2 >= end2)
-               begin1 = -1; // no diff
 }