[PATCH 3/5] xdiff: introduce XDF_INEXACT_MATCH

[Junio C Hamano <gitster@pobox.com>]

The XDF_WHITESPACE_FLAGS mask is used to decide if a simple memcmp() is
sufficient to tell if two lines are the same for the purpose of producing
diff. In the current code, only options in the ignore-whitespace family
happen to call for a matching logic that is more complex than memcmp(),
but when we add new options, e.g. ignore-case, it will become apparent
that the mask is misnamed.

Introduce XDF_INEXACT_MATCH mask to express its true meaning: when any of
these bits are set, we may need to inspect the contents of the two lines
that are not exactly the same, as we may still consider them "matching".

The XDF_WHITESPACE_FLAGS will become useful again in a later patch in the
series and its definition is kept.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 diff.c         |    2 +-
 xdiff/xdiff.h  |    6 +++++-
 xdiff/xutils.c |    4 ++--
 3 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/diff.c b/diff.c
index 52cda7a..87b2ec1 100644
--- a/diff.c
+++ b/diff.c
@@ -2142,7 +2142,7 @@ static void builtin_diff(const char *name_a,
 		struct emit_callback ecbdata;
 		const struct userdiff_funcname *pe;
 
-		if (!DIFF_XDL_TST(o, WHITESPACE_FLAGS) || must_show_header) {
+		if (!DIFF_XDL_TST(o, INEXACT_MATCH) || must_show_header) {
 			fprintf(o->file, "%s", header.buf);
 			strbuf_reset(&header);
 		}
diff --git a/xdiff/xdiff.h b/xdiff/xdiff.h
index 09215af..48793f9 100644
--- a/xdiff/xdiff.h
+++ b/xdiff/xdiff.h
@@ -32,7 +32,11 @@ extern "C" {
 #define XDF_IGNORE_WHITESPACE (1 << 2)
 #define XDF_IGNORE_WHITESPACE_CHANGE (1 << 3)
 #define XDF_IGNORE_WHITESPACE_AT_EOL (1 << 4)
-#define XDF_WHITESPACE_FLAGS (XDF_IGNORE_WHITESPACE | XDF_IGNORE_WHITESPACE_CHANGE | XDF_IGNORE_WHITESPACE_AT_EOL)
+#define XDF_WHITESPACE_FLAGS \
+	(XDF_IGNORE_WHITESPACE | \
+	 XDF_IGNORE_WHITESPACE_CHANGE | \
+	 XDF_IGNORE_WHITESPACE_AT_EOL)
+#define XDF_INEXACT_MATCH XDF_WHITESPACE_FLAGS
 
 #define XDF_PATIENCE_DIFF (1 << 5)
 #define XDF_HISTOGRAM_DIFF (1 << 6)
diff --git a/xdiff/xutils.c b/xdiff/xutils.c
index 0de084e..aa6de74 100644
--- a/xdiff/xutils.c
+++ b/xdiff/xutils.c
@@ -176,7 +176,7 @@ int xdl_recmatch(const char *l1, long s1, const char *l2, long s2, long flags)
 
 	if (s1 == s2 && !memcmp(l1, l2, s1))
 		return 1;
-	if (!(flags & XDF_WHITESPACE_FLAGS))
+	if (!(flags & XDF_INEXACT_MATCH))
 		return 0;
 
 	i1 = 0;
@@ -281,7 +281,7 @@ unsigned long xdl_hash_record(char const **data, char const *top, long flags) {
 	unsigned long ha = 5381;
 	char const *ptr = *data;
 
-	if (flags & XDF_WHITESPACE_FLAGS)
+	if (flags & XDF_INEXACT_MATCH)
 		return xdl_hash_record_with_whitespace(data, top, flags);
 
 	for (; ptr < top && *ptr != '\n'; ptr++) {
-- 
1.7.9.1.265.g25f75