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[PATCH v2 6/9] diff --color-moved=zebra: be stricter with color alternation

From
PWPhillip Wood <phillip.wood@talktalk.net>
Date
Nov 23, 2018, 11:16 UTC
Message-ID
<20181123111658.30342-7-phillip.wood@talktalk.net>
In-Reply-To
<20181123111658.30342-1-phillip.wood@talktalk.net>
From: Phillip Wood <phillip.wood@dunelm.org.uk>

Currently when using --color-moved=zebra the color of moved blocks depends on the number of lines separating them. This means that adding an odd number of unmoved lines between blocks that are already separated by one or more unmoved lines will change the color of subsequent moved blocks. This does not make much sense as the blocks were already separated by unmoved lines and causes problems when adding lines to test cases.

Fix this by only using the alternate colors for adjacent moved blocks.
Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
---
 diff.c                     | 27 +++++++++++++++++++--------
 t/t4015-diff-whitespace.sh |  6 +++---
 2 files changed, 22 insertions(+), 11 deletions(-)
diff --git a/diff.c b/diff.c
index 53a7ab5aca..8c08dd68df 100644
--- a/diff.c
+++ b/diff.c
@@ -1038,26 +1038,30 @@ static int shrink_potential_moved_blocks(struct moved_block *pmb,
  * The last block consists of the (n - block_length)'th line up to but not
  * including the nth line.
  *
+ * Returns 0 if the last block is empty or is unset by this function, non zero
+ * otherwise.
+ *
  * NEEDSWORK: This uses the same heuristic as blame_entry_score() in blame.c.
  * Think of a way to unify them.
  */
-static void adjust_last_block(struct diff_options *o, int n, int block_length)
+static int adjust_last_block(struct diff_options *o, int n, int block_length)
 {
 	int i, alnum_count = 0;
 	if (o->color_moved == COLOR_MOVED_PLAIN)
-		return;
+		return block_length;
 	for (i = 1; i < block_length + 1; i++) {
 		const char *c = o->emitted_symbols->buf[n - i].line;
 		for (; *c; c++) {
 			if (!isalnum(*c))
 				continue;
 			alnum_count++;
 			if (alnum_count >= COLOR_MOVED_MIN_ALNUM_COUNT)
-				return;
+				return 1;
 		}
 	}
 	for (i = 1; i < block_length + 1; i++)
 		o->emitted_symbols->buf[n - i].flags &= ~DIFF_SYMBOL_MOVED_LINE;
+	return 0;
 }
 
 /* Find blocks of moved code, delegate actual coloring decision to helper */
@@ -1067,14 +1071,15 @@ static void mark_color_as_moved(struct diff_options *o,
 {
 	struct moved_block *pmb = NULL; /* potentially moved blocks */
 	int pmb_nr = 0, pmb_alloc = 0;
-	int n, flipped_block = 1, block_length = 0;
+	int n, flipped_block = 0, block_length = 0;
 
 
 	for (n = 0; n < o->emitted_symbols->nr; n++) {
 		struct hashmap *hm = NULL;
 		struct moved_entry *key;
 		struct moved_entry *match = NULL;
 		struct emitted_diff_symbol *l = &o->emitted_symbols->buf[n];
+		enum diff_symbol last_symbol = 0;
 
 		switch (l->s) {
 		case DIFF_SYMBOL_PLUS:
@@ -1090,7 +1095,7 @@ static void mark_color_as_moved(struct diff_options *o,
 			free(key);
 			break;
 		default:
-			flipped_block = 1;
+			flipped_block = 0;
 		}
 
 		if (!match) {
@@ -1101,10 +1106,13 @@ static void mark_color_as_moved(struct diff_options *o,
 				moved_block_clear(&pmb[i]);
 			pmb_nr = 0;
 			block_length = 0;
+			flipped_block = 0;
+			last_symbol = l->s;
 			continue;
 		}
 
 		if (o->color_moved == COLOR_MOVED_PLAIN) {
+			last_symbol = l->s;
 			l->flags |= DIFF_SYMBOL_MOVED_LINE;
 			continue;
 		}
@@ -1135,19 +1143,22 @@ static void mark_color_as_moved(struct diff_options *o,
 				}
 			}
 
-			flipped_block = (flipped_block + 1) % 2;
+			if (adjust_last_block(o, n, block_length) &&
+			    pmb_nr && last_symbol != l->s)
+				flipped_block = (flipped_block + 1) % 2;
+			else
+				flipped_block = 0;
 
-			adjust_last_block(o, n, block_length);
 			block_length = 0;
 		}
 
 		if (pmb_nr) {
 			block_length++;
-
 			l->flags |= DIFF_SYMBOL_MOVED_LINE;
 			if (flipped_block && o->color_moved != COLOR_MOVED_BLOCKS)
 				l->flags |= DIFF_SYMBOL_MOVED_LINE_ALT;
 		}
+		last_symbol = l->s;
 	}
 	adjust_last_block(o, n, block_length);
 
diff --git a/t/t4015-diff-whitespace.sh b/t/t4015-diff-whitespace.sh
index eee81a1987..fe8a2ab06e 100755
--- a/t/t4015-diff-whitespace.sh
+++ b/t/t4015-diff-whitespace.sh
@@ -1802,14 +1802,14 @@ test_expect_success 'only move detection ignores white spaces' '
 	<BOLD;MAGENTA>-a long line to exceed per-line minimum<RESET>
 	<BOLD;MAGENTA>-another long line to exceed per-line minimum<RESET>
 	<RED>-original file<RESET>
-	<BOLD;YELLOW>+<RESET>Q<BOLD;YELLOW>a long line to exceed per-line minimum<RESET>
-	<BOLD;YELLOW>+<RESET>Q<BOLD;YELLOW>another long line to exceed per-line minimum<RESET>
+	<BOLD;CYAN>+<RESET>Q<BOLD;CYAN>a long line to exceed per-line minimum<RESET>
+	<BOLD;CYAN>+<RESET>Q<BOLD;CYAN>another long line to exceed per-line minimum<RESET>
 	<GREEN>+<RESET><GREEN>new file<RESET>
 	EOF
 	test_cmp expected actual
 '
 
-test_expect_failure 'compare whitespace delta across moved blocks' '
+test_expect_success 'compare whitespace delta across moved blocks' '
 
 	git reset --hard &&
 	q_to_tab <<-\EOF >text.txt &&
-- 
2.19.1.1690.g258b440b18
Previous: Phillip WoodNext: Phillip Wood
Message 33 of 44 in “diff --color-moved-ws: allow mixed spaces and tabs in indentation change”
  1. 0/3 diff --color-moved-ws: allow mixed spaces and tabs in indentation changePhillip Wood, Sep 24, 2018
  2. 1/3 xdiff-interface: make xdl_blankline() availablePhillip Wood, Sep 24, 2018
  3. Stefan BellerSep 24, 2018
  4. 2/3 diff.c: remove unused variablesPhillip Wood, Sep 24, 2018
  5. 3/3 diff: add --color-moved-ws=allow-mixed-indentation-changePhillip Wood, Sep 24, 2018
  6. Stefan BellerSep 25, 2018
  7. 3/3 diff: add --color-moved-ws=allow-mixed-indentation-changePhillip Wood, Oct 9, 2018
  8. Stefan BellerOct 9, 2018
  9. Phillip WoodOct 10, 2018
  10. Stefan BellerOct 10, 2018
  11. Phillip WoodSep 24, 2018
  12. 0/9 diff --color-moved-ws fixes and enhancmentPhillip Wood, Nov 16, 2018
  13. 1/9 diff: document --no-color-movedPhillip Wood, Nov 16, 2018
  14. 7/9 diff --color-moved-ws: optimize allow-indentation-changePhillip Wood, Nov 16, 2018
  15. Stefan BellerNov 16, 2018
  16. Phillip WoodNov 17, 2018
  17. 4/9 diff --color-moved-ws: demonstrate false positivesPhillip Wood, Nov 16, 2018
  18. 8/9 diff --color-moved-ws: modify allow-indentation-changePhillip Wood, Nov 16, 2018
  19. Stefan BellerNov 16, 2018
  20. Phillip WoodNov 17, 2018
  21. 6/9 diff --color-moved=zebra: be stricter with color alternationPhillip Wood, Nov 16, 2018
  22. 9/9 diff --color-moved-ws: handle blank linesPhillip Wood, Nov 16, 2018
  23. Stefan BellerNov 20, 2018
  24. Phillip WoodNov 21, 2018
  25. 5/9 diff --color-moved-ws: fix false positivesPhillip Wood, Nov 16, 2018
  26. 3/9 diff: allow --no-color-moved-wsPhillip Wood, Nov 16, 2018
  27. 2/9 diff: use whitespace consistentlyPhillip Wood, Nov 16, 2018
  28. Stefan BellerNov 16, 2018
  29. 0/9 diff --color-moved-ws fixes and enhancmentPhillip Wood, Nov 23, 2018
  30. 1/9 diff: document --no-color-movedPhillip Wood, Nov 23, 2018
  31. 5/9 diff --color-moved-ws: fix false positivesPhillip Wood, Nov 23, 2018
  32. 4/9 diff --color-moved-ws: demonstrate false positivesPhillip Wood, Nov 23, 2018
  33. 6/9 diff --color-moved=zebra: be stricter with color alternationPhillip Wood, Nov 23, 2018
  34. 7/9 diff --color-moved-ws: optimize allow-indentation-changePhillip Wood, Nov 23, 2018
  35. 8/9 diff --color-moved-ws: modify allow-indentation-changePhillip Wood, Nov 23, 2018
  36. 9/9 diff --color-moved-ws: handle blank linesPhillip Wood, Nov 23, 2018
  37. 3/9 diff: allow --no-color-moved-wsPhillip Wood, Nov 23, 2018
  38. 2/9 Use "whitespace" consistentlyPhillip Wood, Nov 23, 2018
  39. Stefan BellerNov 26, 2018
  40. Phillip WoodNov 27, 2018
  41. Phillip WoodJan 8, 2019
  42. Junio C HamanoJan 8, 2019
  43. Stefan BellerJan 10, 2019
  44. Junio C HamanoJan 10, 2019

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