xdiff-interface: export comparing and hashing strings

This will turn out to be useful in a later patch.

xdl_recmatch is exported in xdiff/xutils.h, to be used by various
xdiff/*.c files, but not outside of xdiff/. This one makes it available
to the outside, too.

While at it, add documentation.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

2 files changed, 28 insertions, 0 deletions

diff --git a/xdiff-interface.c b/xdiff-interface.c
index 018e03308..770e1f7f8 100644
--- a/xdiff-interface.c
+++ b/xdiff-interface.c
@@ -5,6 +5,7 @@
 #include "xdiff/xdiffi.h"
 #include "xdiff/xemit.h"
 #include "xdiff/xmacros.h"
+#include "xdiff/xutils.h"
 
 struct xdiff_emit_state {
 	xdiff_emit_consume_fn consume;
@@ -296,6 +297,17 @@ void xdiff_clear_find_func(xdemitconf_t *xecfg)
 	}
 }
 
+unsigned long xdiff_hash_string(const char *s, size_t len, long flags)
+{
+	return xdl_hash_record(&s, s + len, flags);
+}
+
+int xdiff_compare_lines(const char *l1, long s1,
+			const char *l2, long s2, long flags)
+{
+	return xdl_recmatch(l1, s1, l2, s2, flags);
+}
+
 int git_xmerge_style = -1;
 
 int git_xmerge_config(const char *var, const char *value, void *cb)
diff --git a/xdiff-interface.h b/xdiff-interface.h
index 6f6ba9095..135fc05d7 100644
--- a/xdiff-interface.h
+++ b/xdiff-interface.h
@@ -29,4 +29,20 @@ extern void xdiff_clear_find_func(xdemitconf_t *xecfg);
 extern int git_xmerge_config(const char *var, const char *value, void *cb);
 extern int git_xmerge_style;
 
+/*
+ * Compare the strings l1 with l2 which are of size s1 and s2 respectively.
+ * Returns 1 if the strings are deemed equal, 0 otherwise.
+ * The `flags` given as XDF_WHITESPACE_FLAGS determine how white spaces
+ * are treated for the comparision.
+ */
+extern int xdiff_compare_lines(const char *l1, long s1,
+			       const char *l2, long s2, long flags);
+
+/*
+ * Returns a hash of the string s of length len.
+ * The `flags` given as XDF_WHITESPACE_FLAGS determine how white spaces
+ * are treated for the hash.
+ */
+extern unsigned long xdiff_hash_string(const char *s, size_t len, long flags);
+
 #endif