Reduce number of allocations during FcSortWalk().

[fontconfig.git] / src / fccharset.c

diff --git a/src/fccharset.c b/src/fccharset.c
index d42d78f3df06835c8c54302f3a4fb1e3c18b63ae..98ced278703dfd7f1d3a109cc2dc6ef94dca9e7f 100644 (file)
--- a/src/fccharset.c
+++ b/src/fccharset.c
@@ -452,6 +452,68 @@ FcCharSetUnion (const FcCharSet *a, const FcCharSet *b)
     return FcCharSetOperate (a, b, FcCharSetUnionLeaf, FcTrue, FcTrue);
 }
 
+FcCharSet *
+FcCharSetMerge (FcCharSet *a, const FcCharSet *b)
+{
+    FcCharSet      *fcs;
+    FcCharSetIter    ai, bi;
+
+    if (a == NULL) {
+       return FcCharSetCopy ((FcCharSet *) b);
+    } else if (a->ref == FC_REF_CONSTANT) {
+       fcs = FcCharSetCreate ();
+       if (fcs == NULL)
+           return NULL;
+    } else
+       fcs = a;
+
+    FcCharSetIterStart (a, &ai);
+    FcCharSetIterStart (b, &bi);
+    while (ai.leaf || bi.leaf)
+    {
+       if (ai.ucs4 < bi.ucs4)
+       {
+           if (!FcCharSetAddLeaf (fcs, ai.ucs4, ai.leaf))
+               goto bail;
+
+           FcCharSetIterNext (a, &ai);
+       }
+       else if (bi.ucs4 < ai.ucs4)
+       {
+           if (!FcCharSetAddLeaf (fcs, bi.ucs4, bi.leaf))
+               goto bail;
+
+           FcCharSetIterNext (b, &bi);
+       }
+       else
+       {
+           FcCharLeaf  leaf;
+
+           if (FcCharSetUnionLeaf (&leaf, ai.leaf, bi.leaf))
+           {
+               if (!FcCharSetAddLeaf (fcs, ai.ucs4, &leaf))
+                   goto bail;
+           }
+
+           FcCharSetIterNext (a, &ai);
+           FcCharSetIterNext (b, &bi);
+       }
+    }
+
+    if (fcs != a)
+       FcCharSetDestroy (a);
+
+    return fcs;
+
+bail:
+    FcCharSetDestroy (fcs);
+
+    if (fcs != a)
+       FcCharSetDestroy (a);
+
+    return NULL;
+}
+
 static FcBool
 FcCharSetSubtractLeaf (FcCharLeaf *result,
                       const FcCharLeaf *al,