[PATCH v1 8/9] diff --color-moved-ws: modify allow-indentation-change

From

PWPhillip Wood <phillip.wood@talktalk.net>

Date

Nov 16, 2018, 11:03 UTC

Message-ID

<20181116110356.12311-9-phillip.wood@talktalk.net>

In-Reply-To

<20181116110356.12311-1-phillip.wood@talktalk.net>

From: Phillip Wood <phillip.wood@dunelm.org.uk>

-extern int stream_filter(struct stream_filter *,
-                        const char *input, size_t *isize_p,
-                        char *output, size_t *osize_p);
+int stream_filter(struct stream_filter *,
+                 const char *input, size_t *isize_p,
+                 char *output, size_t *osize_p);

[1] Note that before the commit to fix the erroneous coloring of moved
    lines each line was colored as a different block, since that commit
    they are uncolored.

Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
---

Notes:
    Changes since rfc:
     - It now replaces the existing implementation rather than adding a new
       mode.
     - The indentation deltas are now calculated once for each line and
       cached.
     - Optimized the whitespace delta comparison to compare string lengths
       before comparing the actual strings.
     - Modified the calculation of tabs as suggested by Stefan.
     - Split out the blank line handling into a separate commit as suggest
       by Stefan.
     - Fixed some comments pointed out by Stefan.

 diff.c                     | 130 +++++++++++++++++++++----------------
 t/t4015-diff-whitespace.sh |  56 ++++++++++++++++
 2 files changed, 129 insertions(+), 57 deletions(-)

diff --git a/diff.c b/diff.c
index c378ce3daf..89559293e7 100644
--- a/diff.c
+++ b/diff.c
@@ -750,6 +750,8 @@ struct emitted_diff_symbol {
 	const char *line;
 	int len;
 	int flags;
+	int indent_off;
+	int indent_width;
 	enum diff_symbol s;
 };
 #define EMITTED_DIFF_SYMBOL_INIT {NULL}
@@ -780,44 +782,68 @@ struct moved_entry {
 	struct moved_entry *next_line;
 };
 
-/**
- * The struct ws_delta holds white space differences between moved lines, i.e.
- * between '+' and '-' lines that have been detected to be a move.
- * The string contains the difference in leading white spaces, before the
- * rest of the line is compared using the white space config for move
- * coloring. The current_longer indicates if the first string in the
- * comparision is longer than the second.
- */
-struct ws_delta {
-	char *string;
-	unsigned int current_longer : 1;
-};
-#define WS_DELTA_INIT { NULL, 0 }
-
 struct moved_block {
 	struct moved_entry *match;
-	struct ws_delta wsd;
+	int wsd; /* The whitespace delta of this block */
 };
 
 static void moved_block_clear(struct moved_block *b)
 {
-	FREE_AND_NULL(b->wsd.string);
-	b->match = NULL;
+	memset(b, 0, sizeof(*b));
+}
+
+static void fill_es_indent_data(struct emitted_diff_symbol *es)
+{
+	unsigned int off = 0;
+	int width = 0, tab_width = es->flags & WS_TAB_WIDTH_MASK;
+	const char *s = es->line;
+	const int len = es->len;
+
+	/* skip any \v \f \r at start of indentation */
+	while (s[off] == '\f' || s[off] == '\v' ||
+	       (s[off] == '\r' && off < len - 1))
+		off++;
+
+	/* calculate the visual width of indentation */
+	while(1) {
+		if (s[off] == ' ') {
+			width++;
+			off++;
+		} else if (s[off] == '\t') {
+			width += tab_width - (width % tab_width);
+			while (s[++off] == '\t')
+				width += tab_width;
+		} else {
+			break;
+		}
+	}
+
+	es->indent_off = off;
+	es->indent_width = width;
 }
 
 static int compute_ws_delta(const struct emitted_diff_symbol *a,
-			     const struct emitted_diff_symbol *b,
-			     struct ws_delta *out)
+			    const struct emitted_diff_symbol *b,
+			    int *out)
 {
-	const struct emitted_diff_symbol *longer =  a->len > b->len ? a : b;
-	const struct emitted_diff_symbol *shorter = a->len > b->len ? b : a;
-	int d = longer->len - shorter->len;
+	int a_len = a->len,
+	    b_len = b->len,
+	    a_off = a->indent_off,
+	    a_width = a->indent_width,
+	    b_off = b->indent_off,
+	    b_width = b->indent_width;
+	int delta;
 
-	if (strncmp(longer->line + d, shorter->line, shorter->len))
+	if (a->s == DIFF_SYMBOL_PLUS)
+		delta = a_width - b_width;
+	else
+		delta = b_width - a_width;
+
+	if (a_len - a_off != b_len - b_off ||
+	    memcmp(a->line + a_off, b->line + b_off, a_len - a_off))
 		return 0;
 
-	out->string = xmemdupz(longer->line, d);
-	out->current_longer = (a == longer);
+	*out = delta;
 
 	return 1;
 }
@@ -833,8 +859,11 @@ static int cmp_in_block_with_wsd(const struct diff_options *o,
 	const char *a = cur->es->line,
 		   *b = match->es->line,
 		   *c = l->line;
-	const char *orig_a = a;
-	int wslen;
+	int a_off = cur->es->indent_off,
+	    a_width = cur->es->indent_width,
+	    c_off = l->indent_off,
+	    c_width = l->indent_width;
+	int delta;
 
 	/*
 	 * We need to check if 'cur' is equal to 'match'.  As those
@@ -848,35 +877,20 @@ static int cmp_in_block_with_wsd(const struct diff_options *o,
 	if (al != bl)
 		return 1;
 
-	if (!pmb->wsd.string)
-		/*
-		 * The white space delta is not active? This can happen
-		 * when we exit early in this function.
-		 */
-		return 1;
-
 	/*
-	 * The indent changes of the block are known and stored in
-	 * pmb->wsd; however we need to check if the indent changes of the
-	 * current line are still the same as before.
-	 *
-	 * To do so we need to compare 'l' to 'cur', adjusting the
-	 * one of them for the white spaces, depending which was longer.
+	 * The indent changes of the block are known and stored in pmb->wsd;
+	 * however we need to check if the indent changes of the current line
+	 * match those of the current block and that the text of 'l' and 'cur'
+	 * after the indentation match.
 	 */
+	if (cur->es->s == DIFF_SYMBOL_PLUS)
+		delta = a_width - c_width;
+	else
+		delta = c_width - a_width;
 
-	wslen = strlen(pmb->wsd.string);
-	if (pmb->wsd.current_longer) {
-		c += wslen;
-		cl -= wslen;
-	} else {
-		a += wslen;
-		al -= wslen;
-	}
-
-	if (al != cl || memcmp(orig_a, b, bl) || memcmp(a, c, al))
-		return 1;
-
-	return 0;
+	return !(delta == pmb->wsd && al - a_off == cl - c_off &&
+		 !memcmp(a, b, al) && !
+		 memcmp(a + a_off, c + c_off, al - a_off));
 }
 
 static int moved_entry_cmp(const void *hashmap_cmp_fn_data,
@@ -942,6 +956,9 @@ static void add_lines_to_move_detection(struct diff_options *o,
 			continue;
 		}
 
+		if (o->color_moved_ws_handling &
+		    COLOR_MOVED_WS_ALLOW_INDENTATION_CHANGE)
+			fill_es_indent_data(&o->emitted_symbols->buf[n]);
 		key = prepare_entry(o, n);
 		if (prev_line && prev_line->es->s == o->emitted_symbols->buf[n].s)
 			prev_line->next_line = key;
@@ -1020,8 +1037,7 @@ static int shrink_potential_moved_blocks(struct moved_block *pmb,
 
 		if (lp < pmb_nr && rp > -1 && lp < rp) {
 			pmb[lp] = pmb[rp];
-			pmb[rp].match = NULL;
-			pmb[rp].wsd.string = NULL;
+			memset(&pmb[rp], 0, sizeof(pmb[rp]));
 			rp--;
 			lp++;
 		}
@@ -1141,7 +1157,7 @@ static void mark_color_as_moved(struct diff_options *o,
 							     &pmb[pmb_nr].wsd))
 						pmb[pmb_nr++].match = match;
 				} else {
-					pmb[pmb_nr].wsd.string = NULL;
+					pmb[pmb_nr].wsd = 0;
 					pmb[pmb_nr++].match = match;
 				}
 			}
@@ -1507,7 +1523,7 @@ static void emit_diff_symbol_from_struct(struct diff_options *o,
 static void emit_diff_symbol(struct diff_options *o, enum diff_symbol s,
 			     const char *line, int len, unsigned flags)
 {
-	struct emitted_diff_symbol e = {line, len, flags, s};
+	struct emitted_diff_symbol e = {line, len, flags, 0, 0, s};
 
 	if (o->emitted_symbols)
 		append_emitted_diff_symbol(o, &e);
diff --git a/t/t4015-diff-whitespace.sh b/t/t4015-diff-whitespace.sh
index fe8a2ab06e..e023839ba6 100755
--- a/t/t4015-diff-whitespace.sh
+++ b/t/t4015-diff-whitespace.sh
@@ -1901,4 +1901,60 @@ test_expect_success 'compare whitespace delta incompatible with other space opti
 	test_i18ngrep allow-indentation-change err
 '
 
+test_expect_success 'compare mixed whitespace delta across moved blocks' '
+
+	git reset --hard &&
+	tr Q_ "\t " <<-EOF >text.txt &&
+	____Indented text to
+	_Q____be further indented by four spaces across
+	____Qseveral lines
+	QQ____These two lines have had their
+	____indentation reduced by four spaces
+	Qdifferent indentation change
+	____too short
+	EOF
+
+	git add text.txt &&
+	git commit -m "add text.txt" &&
+
+	tr Q_ "\t " <<-EOF >text.txt &&
+	QIndented text to
+	QQbe further indented by four spaces across
+	Q____several lines
+	Q_QThese two lines have had their
+	indentation reduced by four spaces
+	QQdifferent indentation change
+	__Qtoo short
+	EOF
+
+	git -c color.diff.whitespace="normal red" \
+		-c core.whitespace=space-before-tab \
+		diff --color --color-moved --ws-error-highlight=all \
+		--color-moved-ws=allow-indentation-change >actual.raw &&
+	grep -v "index" actual.raw | test_decode_color >actual &&
+
+	cat <<-\EOF >expected &&
+	<BOLD>diff --git a/text.txt b/text.txt<RESET>
+	<BOLD>--- a/text.txt<RESET>
+	<BOLD>+++ b/text.txt<RESET>
+	<CYAN>@@ -1,7 +1,7 @@<RESET>
+	<BOLD;MAGENTA>-<RESET><BOLD;MAGENTA>    Indented text to<RESET>
+	<BOLD;MAGENTA>-<RESET><BRED> <RESET>	<BOLD;MAGENTA>    be further indented by four spaces across<RESET>
+	<BOLD;MAGENTA>-<RESET><BRED>    <RESET>	<BOLD;MAGENTA>several lines<RESET>
+	<BOLD;BLUE>-<RESET>		<BOLD;BLUE>    These two lines have had their<RESET>
+	<BOLD;BLUE>-<RESET><BOLD;BLUE>    indentation reduced by four spaces<RESET>
+	<BOLD;MAGENTA>-<RESET>	<BOLD;MAGENTA>different indentation change<RESET>
+	<RED>-<RESET><RED>    too short<RESET>
+	<BOLD;CYAN>+<RESET>	<BOLD;CYAN>Indented text to<RESET>
+	<BOLD;CYAN>+<RESET>		<BOLD;CYAN>be further indented by four spaces across<RESET>
+	<BOLD;CYAN>+<RESET>	<BOLD;CYAN>    several lines<RESET>
+	<BOLD;YELLOW>+<RESET>	<BRED> <RESET>	<BOLD;YELLOW>These two lines have had their<RESET>
+	<BOLD;YELLOW>+<RESET><BOLD;YELLOW>indentation reduced by four spaces<RESET>
+	<BOLD;CYAN>+<RESET>		<BOLD;CYAN>different indentation change<RESET>
+	<GREEN>+<RESET><BRED>  <RESET>	<GREEN>too short<RESET>
+	EOF
+
+	test_cmp expected actual
+'
+
 test_done

-- 
2.19.1