[PATCH v2 1/3] Introduce sorted-array binary-search function.

[Yann Dirson <ydirson@altern.org>]

We use a cpp-based template mechanism to declare the array and its
management data, as well as a search function, derived from locate_rename_dst()
from diffcore-rename.c.  Naming is kept compatible with the original use
of that function.

Signed-off-by: Yann Dirson <ydirson@altern.org>
---
 Makefile          |    1 +
 diffcore-rename.c |   53 +++++++++++++++--------------------------------------
 sorted-array.h    |   36 ++++++++++++++++++++++++++++++++++++
 3 files changed, 52 insertions(+), 38 deletions(-)
 create mode 100644 sorted-array.h

diff --git a/Makefile b/Makefile
index 1f1ce04..fa5b2e6 100644
--- a/Makefile
+++ b/Makefile
@@ -536,6 +536,7 @@ LIB_H += run-command.h
 LIB_H += sha1-lookup.h
 LIB_H += sideband.h
 LIB_H += sigchain.h
+LIB_H += sorted-array.h
 LIB_H += strbuf.h
 LIB_H += string-list.h
 LIB_H += submodule.h
diff --git a/diffcore-rename.c b/diffcore-rename.c
index df41be5..72a9b94 100644
--- a/diffcore-rename.c
+++ b/diffcore-rename.c
@@ -5,52 +5,29 @@
 #include "diff.h"
 #include "diffcore.h"
 #include "hash.h"
+#include "sorted-array.h"
 
 /* Table of rename/copy destinations */
 
-static struct diff_rename_dst {
+struct diff_rename_dst {
 	struct diff_filespec *two;
 	struct diff_filepair *pair;
-} *rename_dst;
-static int rename_dst_nr, rename_dst_alloc;
+};
 
-static struct diff_rename_dst *locate_rename_dst(struct diff_filespec *two,
-						 int insert_ok)
+static int rename_dst_cmp(void* data, struct diff_rename_dst *elem)
 {
-	int first, last;
-
-	first = 0;
-	last = rename_dst_nr;
-	while (last > first) {
-		int next = (last + first) >> 1;
-		struct diff_rename_dst *dst = &(rename_dst[next]);
-		int cmp = strcmp(two->path, dst->two->path);
-		if (!cmp)
-			return dst;
-		if (cmp < 0) {
-			last = next;
-			continue;
-		}
-		first = next+1;
-	}
-	/* not found */
-	if (!insert_ok)
-		return NULL;
-	/* insert to make it at "first" */
-	if (rename_dst_alloc <= rename_dst_nr) {
-		rename_dst_alloc = alloc_nr(rename_dst_alloc);
-		rename_dst = xrealloc(rename_dst,
-				      rename_dst_alloc * sizeof(*rename_dst));
-	}
-	rename_dst_nr++;
-	if (first < rename_dst_nr)
-		memmove(rename_dst + first + 1, rename_dst + first,
-			(rename_dst_nr - first - 1) * sizeof(*rename_dst));
-	rename_dst[first].two = alloc_filespec(two->path);
-	fill_filespec(rename_dst[first].two, two->sha1, two->mode);
-	rename_dst[first].pair = NULL;
-	return &(rename_dst[first]);
+	struct diff_filespec *two = data;
+	return strcmp(two->path, elem->two->path);
+}
+static void rename_dst_init(struct diff_rename_dst *elem, void* data)
+{
+	struct diff_filespec *two = data;
+	elem->two = alloc_filespec(two->path);
+	fill_filespec(elem->two, two->sha1, two->mode);
+	elem->pair = NULL;
 }
+declare_sorted_array(static, struct diff_rename_dst, rename_dst,
+		     rename_dst_cmp, rename_dst_init)
 
 /* Table of rename/copy src files */
 static struct diff_rename_src {
diff --git a/sorted-array.h b/sorted-array.h
new file mode 100644
index 0000000..03d5d1e
--- /dev/null
+++ b/sorted-array.h
@@ -0,0 +1,36 @@
+#define declare_sorted_array(MAYBESTATIC,ELEMTYPE,LIST,CMP,INIT)	\
+MAYBESTATIC ELEMTYPE *LIST;						\
+MAYBESTATIC int LIST##_nr, LIST##_alloc;				\
+MAYBESTATIC ELEMTYPE *locate_##LIST(void *data, int insert_ok)		\
+{									\
+	int first, last;						\
+									\
+	first = 0;							\
+	last = LIST##_nr;						\
+	while (last > first) {						\
+		int next = (last + first) >> 1;				\
+		ELEMTYPE *nextelem = &(LIST[next]);			\
+		int cmp = CMP(data, nextelem);				\
+		if (!cmp)						\
+			return nextelem;				\
+		if (cmp < 0) {						\
+			last = next;					\
+			continue;					\
+		}							\
+		first = next+1;						\
+	}								\
+	/* not found */							\
+	if (!insert_ok)							\
+		return NULL;						\
+	/* insert to make it at "first" */				\
+	if (LIST##_alloc <= LIST##_nr) {				\
+		LIST##_alloc = alloc_nr(LIST##_alloc);			\
+		LIST = xrealloc(LIST, LIST##_alloc * sizeof(*LIST));	\
+	}								\
+	LIST##_nr++;							\
+	if (first < LIST##_nr)						\
+		memmove(LIST + first + 1, LIST + first,			\
+			(LIST##_nr - first - 1) * sizeof(*LIST));	\
+	INIT(&LIST[first], data);					\
+	return &(LIST[first]);						\
+}
-- 
1.7.2.3