1 files changed, 165 insertions, 72 deletions

diff --git a/xdiff/xmerge.c b/xdiff/xmerge.c
index 82b3573..d9737f0 100644
--- a/xdiff/xmerge.c
+++ b/xdiff/xmerge.c
@@ -30,17 +30,32 @@ typedef struct s_xdmerge {
 	 * 2 = no conflict, take second.
 	 */
 	int mode;
+	/*
+	 * These point at the respective postimages.  E.g. <i1,chg1> is
+	 * how side #1 wants to change the common ancestor; if there is no
+	 * overlap, lines before i1 in the postimage of side #1 appear
+	 * in the merge result as a region touched by neither side.
+	 */
 	long i1, i2;
 	long chg1, chg2;
+	/*
+	 * These point at the preimage; of course there is just one
+	 * preimage, that is from the shared common ancestor.
+	 */
+	long i0;
+	long chg0;
 } xdmerge_t;
 
 static int xdl_append_merge(xdmerge_t **merge, int mode,
-		long i1, long chg1, long i2, long chg2)
+			    long i0, long chg0,
+			    long i1, long chg1,
+			    long i2, long chg2)
 {
 	xdmerge_t *m = *merge;
 	if (m && (i1 <= m->i1 + m->chg1 || i2 <= m->i2 + m->chg2)) {
 		if (mode != m->mode)
 			m->mode = 0;
+		m->chg0 = i0 + chg0 - m->i0;
 		m->chg1 = i1 + chg1 - m->i1;
 		m->chg2 = i2 + chg2 - m->i2;
 	} else {
@@ -49,6 +64,8 @@ static int xdl_append_merge(xdmerge_t **merge, int mode,
 			return -1;
 		m->next = NULL;
 		m->mode = mode;
+		m->i0 = i0;
+		m->chg0 = chg0;
 		m->i1 = i1;
 		m->chg1 = chg1;
 		m->i2 = i2;
@@ -91,11 +108,13 @@ static int xdl_merge_cmp_lines(xdfenv_t *xe1, int i1, xdfenv_t *xe2, int i2,
 	return 0;
 }
 
-static int xdl_recs_copy(xdfenv_t *xe, int i, int count, int add_nl, char *dest)
+static int xdl_recs_copy_0(int use_orig, xdfenv_t *xe, int i, int count, int add_nl, char *dest)
 {
-	xrecord_t **recs = xe->xdf2.recs + i;
+	xrecord_t **recs;
 	int size = 0;
 
+	recs = (use_orig ? xe->xdf1.recs : xe->xdf2.recs) + i;
+
 	if (count < 1)
 		return 0;
 
@@ -113,65 +132,109 @@ static int xdl_recs_copy(xdfenv_t *xe, int i, int count, int add_nl, char *dest)
 	return size;
 }
 
-static int xdl_fill_merge_buffer(xdfenv_t *xe1, const char *name1,
-		xdfenv_t *xe2, const char *name2, xdmerge_t *m, char *dest)
+static int xdl_recs_copy(xdfenv_t *xe, int i, int count, int add_nl, char *dest)
+{
+	return xdl_recs_copy_0(0, xe, i, count, add_nl, dest);
+}
+
+static int xdl_orig_copy(xdfenv_t *xe, int i, int count, int add_nl, char *dest)
+{
+	return xdl_recs_copy_0(1, xe, i, count, add_nl, dest);
+}
+
+static int fill_conflict_hunk(xdfenv_t *xe1, const char *name1,
+			      xdfenv_t *xe2, const char *name2,
+			      int size, int i, int style,
+			      xdmerge_t *m, char *dest)
 {
 	const int marker_size = 7;
 	int marker1_size = (name1 ? strlen(name1) + 1 : 0);
 	int marker2_size = (name2 ? strlen(name2) + 1 : 0);
-	int conflict_marker_size = 3 * (marker_size + 1)
-		+ marker1_size + marker2_size;
-	int size, i1, j;
-
-	for (size = i1 = 0; m; m = m->next) {
-		if (m->mode == 0) {
-			size += xdl_recs_copy(xe1, i1, m->i1 - i1, 0,
-					dest ? dest + size : NULL);
-			if (dest) {
-				for (j = 0; j < marker_size; j++)
-					dest[size++] = '<';
-				if (marker1_size) {
-					dest[size] = ' ';
-					memcpy(dest + size + 1, name1,
-							marker1_size - 1);
-					size += marker1_size;
-				}
-				dest[size++] = '\n';
-			} else
-				size += conflict_marker_size;
-			size += xdl_recs_copy(xe1, m->i1, m->chg1, 1,
-					dest ? dest + size : NULL);
-			if (dest) {
-				for (j = 0; j < marker_size; j++)
-					dest[size++] = '=';
-				dest[size++] = '\n';
-			}
-			size += xdl_recs_copy(xe2, m->i2, m->chg2, 1,
-					dest ? dest + size : NULL);
-			if (dest) {
-				for (j = 0; j < marker_size; j++)
-					dest[size++] = '>';
-				if (marker2_size) {
-					dest[size] = ' ';
-					memcpy(dest + size + 1, name2,
-							marker2_size - 1);
-					size += marker2_size;
-				}
-				dest[size++] = '\n';
-			}
-		} else if (m->mode == 1)
-			size += xdl_recs_copy(xe1, i1, m->i1 + m->chg1 - i1, 0,
-					dest ? dest + size : NULL);
+	int j;
+
+	/* Before conflicting part */
+	size += xdl_recs_copy(xe1, i, m->i1 - i, 0,
+			      dest ? dest + size : NULL);
+
+	if (!dest) {
+		size += marker_size + 1 + marker1_size;
+	} else {
+		for (j = 0; j < marker_size; j++)
+			dest[size++] = '<';
+		if (marker1_size) {
+			dest[size] = ' ';
+			memcpy(dest + size + 1, name1, marker1_size - 1);
+			size += marker1_size;
+		}
+		dest[size++] = '\n';
+	}
+
+	/* Postimage from side #1 */
+	size += xdl_recs_copy(xe1, m->i1, m->chg1, 1,
+			      dest ? dest + size : NULL);
+
+	if (style == XDL_MERGE_DIFF3) {
+		/* Shared preimage */
+		if (!dest) {
+			size += marker_size + 1;
+		} else {
+			for (j = 0; j < marker_size; j++)
+				dest[size++] = '|';
+			dest[size++] = '\n';
+		}
+		size += xdl_orig_copy(xe1, m->i0, m->chg0, 1,
+				      dest ? dest + size : NULL);
+	}
+
+	if (!dest) {
+		size += marker_size + 1;
+	} else {
+		for (j = 0; j < marker_size; j++)
+			dest[size++] = '=';
+		dest[size++] = '\n';
+	}
+
+	/* Postimage from side #2 */
+	size += xdl_recs_copy(xe2, m->i2, m->chg2, 1,
+			      dest ? dest + size : NULL);
+	if (!dest) {
+		size += marker_size + 1 + marker2_size;
+	} else {
+		for (j = 0; j < marker_size; j++)
+			dest[size++] = '>';
+		if (marker2_size) {
+			dest[size] = ' ';
+			memcpy(dest + size + 1, name2, marker2_size - 1);
+			size += marker2_size;
+		}
+		dest[size++] = '\n';
+	}
+	return size;
+}
+
+static int xdl_fill_merge_buffer(xdfenv_t *xe1, const char *name1,
+				 xdfenv_t *xe2, const char *name2,
+				 xdmerge_t *m, char *dest, int style)
+{
+	int size, i;
+
+	for (size = i = 0; m; m = m->next) {
+		if (m->mode == 0)
+			size = fill_conflict_hunk(xe1, name1, xe2, name2,
+						  size, i, style, m, dest);
+		else if (m->mode == 1)
+			size += xdl_recs_copy(xe1, i, m->i1 + m->chg1 - i, 0,
+					      dest ? dest + size : NULL);
 		else if (m->mode == 2)
-			size += xdl_recs_copy(xe2, m->i2 - m->i1 + i1,
-					m->i1 + m->chg2 - i1, 0,
-					dest ? dest + size : NULL);
+			size += xdl_recs_copy(xe2, m->i2 - m->i1 + i,
+					      m->i1 + m->chg2 - i, 0,
+					      dest ? dest + size : NULL);
 		else
 			continue;
-		i1 = m->i1 + m->chg1;
+		i = m->i1 + m->chg1;
 	}
-	size += xdl_recs_copy(xe1, i1, xe1->xdf2.nrec - i1, 0,
-			dest ? dest + size : NULL);
+	size += xdl_recs_copy(xe1, i, xe1->xdf2.nrec - i, 0,
+			      dest ? dest + size : NULL);
 	return size;
 }
 
@@ -323,9 +386,20 @@ static int xdl_simplify_non_conflicts(xdfenv_t *xe1, xdmerge_t *m,
  */
 static int xdl_do_merge(xdfenv_t *xe1, xdchange_t *xscr1, const char *name1,
 		xdfenv_t *xe2, xdchange_t *xscr2, const char *name2,
-		int level, xpparam_t const *xpp, mmbuffer_t *result) {
+		int flags, xpparam_t const *xpp, mmbuffer_t *result) {
 	xdmerge_t *changes, *c;
-	int i1, i2, chg1, chg2;
+	int i0, i1, i2, chg0, chg1, chg2;
+	int level = flags & XDL_MERGE_LEVEL_MASK;
+	int style = flags & XDL_MERGE_STYLE_MASK;
+
+	if (style == XDL_MERGE_DIFF3) {
+		/*
+		 * "diff3 -m" output does not make sense for anything
+		 * more aggressive than XDL_MERGE_EAGER.
+		 */
+		if (XDL_MERGE_EAGER < level)
+			level = XDL_MERGE_EAGER;
+	}
 
 	c = changes = NULL;
 
@@ -333,11 +407,14 @@ static int xdl_do_merge(xdfenv_t *xe1, xdchange_t *xscr1, const char *name1,
 		if (!changes)
 			changes = c;
 		if (xscr1->i1 + xscr1->chg1 < xscr2->i1) {
+			i0 = xscr1->i1;
 			i1 = xscr1->i2;
 			i2 = xscr2->i2 - xscr2->i1 + xscr1->i1;
+			chg0 = xscr1->chg1;
 			chg1 = xscr1->chg2;
 			chg2 = xscr1->chg1;
-			if (xdl_append_merge(&c, 1, i1, chg1, i2, chg2)) {
+			if (xdl_append_merge(&c, 1,
+					     i0, chg0, i1, chg1, i2, chg2)) {
 				xdl_cleanup_merge(changes);
 				return -1;
 			}
@@ -345,18 +422,21 @@ static int xdl_do_merge(xdfenv_t *xe1, xdchange_t *xscr1, const char *name1,
 			continue;
 		}
 		if (xscr2->i1 + xscr2->chg1 < xscr1->i1) {
+			i0 = xscr2->i1;
 			i1 = xscr1->i2 - xscr1->i1 + xscr2->i1;
 			i2 = xscr2->i2;
+			chg0 = xscr2->chg1;
 			chg1 = xscr2->chg1;
 			chg2 = xscr2->chg2;
-			if (xdl_append_merge(&c, 2, i1, chg1, i2, chg2)) {
+			if (xdl_append_merge(&c, 2,
+					     i0, chg0, i1, chg1, i2, chg2)) {
 				xdl_cleanup_merge(changes);
 				return -1;
 			}
 			xscr2 = xscr2->next;
 			continue;
 		}
-		if (level < 1 || xscr1->i1 != xscr2->i1 ||
+		if (level == XDL_MERGE_MINIMAL || xscr1->i1 != xscr2->i1 ||
 				xscr1->chg1 != xscr2->chg1 ||
 				xscr1->chg2 != xscr2->chg2 ||
 				xdl_merge_cmp_lines(xe1, xscr1->i2,
@@ -366,19 +446,25 @@ static int xdl_do_merge(xdfenv_t *xe1, xdchange_t *xscr1, const char *name1,
 			int off = xscr1->i1 - xscr2->i1;
 			int ffo = off + xscr1->chg1 - xscr2->chg1;
 
+			i0 = xscr1->i1;
 			i1 = xscr1->i2;
 			i2 = xscr2->i2;
-			if (off > 0)
+			if (off > 0) {
+				i0 -= off;
 				i1 -= off;
+			}
 			else
 				i2 += off;
+			chg0 = xscr1->i1 + xscr1->chg1 - i0;
 			chg1 = xscr1->i2 + xscr1->chg2 - i1;
 			chg2 = xscr2->i2 + xscr2->chg2 - i2;
-			if (ffo > 0)
-				chg2 += ffo;
-			else
+			if (ffo < 0) {
+				chg0 -= ffo;
 				chg1 -= ffo;
-			if (xdl_append_merge(&c, 0, i1, chg1, i2, chg2)) {
+			} else
+				chg2 += ffo;
+			if (xdl_append_merge(&c, 0,
+					     i0, chg0, i1, chg1, i2, chg2)) {
 				xdl_cleanup_merge(changes);
 				return -1;
 			}
@@ -395,11 +481,14 @@ static int xdl_do_merge(xdfenv_t *xe1, xdchange_t *xscr1, const char *name1,
 	while (xscr1) {
 		if (!changes)
 			changes = c;
+		i0 = xscr1->i1;
 		i1 = xscr1->i2;
 		i2 = xscr1->i1 + xe2->xdf2.nrec - xe2->xdf1.nrec;
+		chg0 = xscr1->chg1;
 		chg1 = xscr1->chg2;
 		chg2 = xscr1->chg1;
-		if (xdl_append_merge(&c, 1, i1, chg1, i2, chg2)) {
+		if (xdl_append_merge(&c, 1,
+				     i0, chg0, i1, chg1, i2, chg2)) {
 			xdl_cleanup_merge(changes);
 			return -1;
 		}
@@ -408,11 +497,14 @@ static int xdl_do_merge(xdfenv_t *xe1, xdchange_t *xscr1, const char *name1,
 	while (xscr2) {
 		if (!changes)
 			changes = c;
+		i0 = xscr2->i1;
 		i1 = xscr2->i1 + xe1->xdf2.nrec - xe1->xdf1.nrec;
 		i2 = xscr2->i2;
+		chg0 = xscr2->chg1;
 		chg1 = xscr2->chg1;
 		chg2 = xscr2->chg2;
-		if (xdl_append_merge(&c, 2, i1, chg1, i2, chg2)) {
+		if (xdl_append_merge(&c, 2,
+				     i0, chg0, i1, chg1, i2, chg2)) {
 			xdl_cleanup_merge(changes);
 			return -1;
 		}
@@ -421,16 +513,17 @@ static int xdl_do_merge(xdfenv_t *xe1, xdchange_t *xscr1, const char *name1,
 	if (!changes)
 		changes = c;
 	/* refine conflicts */
-	if (level > 1 &&
+	if (XDL_MERGE_ZEALOUS <= level &&
 	    (xdl_refine_conflicts(xe1, xe2, changes, xpp) < 0 ||
-	     xdl_simplify_non_conflicts(xe1, changes, level > 2) < 0)) {
+	     xdl_simplify_non_conflicts(xe1, changes,
+					XDL_MERGE_ZEALOUS < level) < 0)) {
 		xdl_cleanup_merge(changes);
 		return -1;
 	}
 	/* output */
 	if (result) {
 		int size = xdl_fill_merge_buffer(xe1, name1, xe2, name2,
-			changes, NULL);
+			changes, NULL, style);
 		result->ptr = xdl_malloc(size);
 		if (!result->ptr) {
 			xdl_cleanup_merge(changes);
@@ -438,14 +531,14 @@ static int xdl_do_merge(xdfenv_t *xe1, xdchange_t *xscr1, const char *name1,
 		}
 		result->size = size;
 		xdl_fill_merge_buffer(xe1, name1, xe2, name2, changes,
-				result->ptr);
+				      result->ptr, style);
 	}
 	return xdl_cleanup_merge(changes);
 }
 
 int xdl_merge(mmfile_t *orig, mmfile_t *mf1, const char *name1,
 		mmfile_t *mf2, const char *name2,
-		xpparam_t const *xpp, int level, mmbuffer_t *result) {
+		xpparam_t const *xpp, int flags, mmbuffer_t *result) {
 	xdchange_t *xscr1, *xscr2;
 	xdfenv_t xe1, xe2;
 	int status;
@@ -482,7 +575,7 @@ int xdl_merge(mmfile_t *orig, mmfile_t *mf1, const char *name1,
 		} else {
 			status = xdl_do_merge(&xe1, xscr1, name1,
 					      &xe2, xscr2, name2,
-					      level, xpp, result);
+					      flags, xpp, result);
 		}
 		xdl_free_script(xscr1);
 		xdl_free_script(xscr2);