1 files changed, 77 insertions, 35 deletions

diff --git a/Objects/stringlib/fastsearch.h b/Objects/stringlib/fastsearch.h
index 23bccfb..7b9dd47 100644
--- a/Objects/stringlib/fastsearch.h
+++ b/Objects/stringlib/fastsearch.h
@@ -5,7 +5,7 @@
 
 /* fast search/count implementation, based on a mix between boyer-
    moore and horspool, with a few more bells and whistles on the top.
-   for some more background, see: http://effbot.org/stringlib.htm */
+   for some more background, see: http://effbot.org/zone/stringlib.htm */
 
 /* note: fastsearch may access s[n], which isn't a problem when using
    Python's ordinary string types, but may cause problems if you're
@@ -16,6 +16,7 @@
 
 #define FAST_COUNT 0
 #define FAST_SEARCH 1
+#define FAST_RSEARCH 2
 
 Py_LOCAL_INLINE(Py_ssize_t)
 fastsearch(const STRINGLIB_CHAR* s, Py_ssize_t n,
@@ -41,51 +42,92 @@ fastsearch(const STRINGLIB_CHAR* s, Py_ssize_t n,
                 if (s[i] == p[0])
                     count++;
             return count;
-        } else {
+        } else if (mode == FAST_SEARCH) {
             for (i = 0; i < n; i++)
                 if (s[i] == p[0])
                     return i;
+        } else {    /* FAST_RSEARCH */
+            for (i = n - 1; i > -1; i--)
+                if (s[i] == p[0])
+                    return i;
         }
         return -1;
     }
 
     mlast = m - 1;
-
-    /* create compressed boyer-moore delta 1 table */
     skip = mlast - 1;
-    /* process pattern[:-1] */
-    for (mask = i = 0; i < mlast; i++) {
-        mask |= (1 << (p[i] & 0x1F));
-        if (p[i] == p[mlast])
-            skip = mlast - i - 1;
-    }
-    /* process pattern[-1] outside the loop */
-    mask |= (1 << (p[mlast] & 0x1F));
-
-    for (i = 0; i <= w; i++) {
-        /* note: using mlast in the skip path slows things down on x86 */
-        if (s[i+m-1] == p[m-1]) {
-            /* candidate match */
-            for (j = 0; j < mlast; j++)
-                if (s[i+j] != p[j])
-                    break;
-            if (j == mlast) {
-                /* got a match! */
-                if (mode != FAST_COUNT)
+
+    if (mode != FAST_RSEARCH) {
+
+        /* create compressed boyer-moore delta 1 table */
+
+        /* process pattern[:-1] */
+        for (mask = i = 0; i < mlast; i++) {
+            mask |= (1 << (p[i] & 0x1F));
+            if (p[i] == p[mlast])
+                skip = mlast - i - 1;
+        }
+        /* process pattern[-1] outside the loop */
+        mask |= (1 << (p[mlast] & 0x1F));
+
+        for (i = 0; i <= w; i++) {
+            /* note: using mlast in the skip path slows things down on x86 */
+            if (s[i+m-1] == p[m-1]) {
+                /* candidate match */
+                for (j = 0; j < mlast; j++)
+                    if (s[i+j] != p[j])
+                        break;
+                if (j == mlast) {
+                    /* got a match! */
+                    if (mode != FAST_COUNT)
+                        return i;
+                    count++;
+                    i = i + mlast;
+                    continue;
+                }
+                /* miss: check if next character is part of pattern */
+                if (!(mask & (1 << (s[i+m] & 0x1F))))
+                    i = i + m;
+                else
+                    i = i + skip;
+            } else {
+                /* skip: check if next character is part of pattern */
+                if (!(mask & (1 << (s[i+m] & 0x1F))))
+                    i = i + m;
+            }
+        }
+    } else {    /* FAST_RSEARCH */
+
+        /* create compressed boyer-moore delta 1 table */
+
+        /* process pattern[0] outside the loop */
+        mask = (1 << (p[0] & 0x1F));
+        /* process pattern[:0:-1] */
+        for (i = mlast; i > 0; i--) {
+            mask |= (1 << (p[i] & 0x1F));
+            if (p[i] == p[0])
+                skip = i - 1;
+        }
+
+        for (i = w; i >= 0; i--) {
+            if (s[i] == p[0]) {
+                /* candidate match */
+                for (j = mlast; j > 0; j--)
+                    if (s[i+j] != p[j])
+                        break;
+                if (j == 0)
+                    /* got a match! */
                     return i;
-                count++;
-                i = i + mlast;
-                continue;
+                /* miss: check if previous character is part of pattern */
+                if (!(mask & (1 << (s[i-1] & 0x1F))))
+                    i = i - m;
+                else
+                    i = i - skip;
+            } else {
+                /* skip: check if previous character is part of pattern */
+                if (!(mask & (1 << (s[i-1] & 0x1F))))
+                    i = i - m;
             }
-            /* miss: check if next character is part of pattern */
-            if (!(mask & (1 << (s[i+m] & 0x1F))))
-                i = i + m;
-            else
-                i = i + skip;
-        } else {
-            /* skip: check if next character is part of pattern */
-            if (!(mask & (1 << (s[i+m] & 0x1F))))
-                i = i + m;
         }
     }