[PATCH 1/4] diff.c: emit_line_0 to take string instead of first sign

[Stefan Beller <sbeller@google.com>]

By providing a string as the first part of the emission we can extend
it later more easily.

While at it, document emit_line_0.

Signed-off-by: Stefan Beller <sbeller@google.com>
---
 diff.c | 28 +++++++++++++++++-----------
 1 file changed, 17 insertions(+), 11 deletions(-)

diff --git a/diff.c b/diff.c
index af9316c8f91..b3cb73eb69a 100644
--- a/diff.c
+++ b/diff.c
@@ -621,9 +621,15 @@ static void check_blank_at_eof(mmfile_t *mf1, mmfile_t *mf2,
 	ecbdata->blank_at_eof_in_postimage = (at - l2) + 1;
 }
 
+/*
+ * Emits
+ * <set_sign> <first> <reset> <set> <second> <reset> LF
+ * if they are present. 'first' is a NULL terminated string,
+ * 'second' is a buffer of length 'len'.
+ */
 static void emit_line_0(struct diff_options *o,
 			const char *set_sign, const char *set, const char *reset,
-			int first, const char *line, int len)
+			const char *first, const char *second, int len)
 {
 	int has_trailing_newline, has_trailing_carriage_return;
 	int reverse = !!set && !!set_sign;
@@ -633,11 +639,11 @@ static void emit_line_0(struct diff_options *o,
 
 	fputs(diff_line_prefix(o), file);
 
-	has_trailing_newline = (len > 0 && line[len-1] == '\n');
+	has_trailing_newline = (len > 0 && second[len-1] == '\n');
 	if (has_trailing_newline)
 		len--;
 
-	has_trailing_carriage_return = (len > 0 && line[len-1] == '\r');
+	has_trailing_carriage_return = (len > 0 && second[len-1] == '\r');
 	if (has_trailing_carriage_return)
 		len--;
 
@@ -655,7 +661,7 @@ static void emit_line_0(struct diff_options *o,
 	}
 
 	if (first)
-		fputc(first, file);
+		fputs(first, file);
 
 	if (!len)
 		goto end_of_line;
@@ -666,7 +672,7 @@ static void emit_line_0(struct diff_options *o,
 		fputs(set, file);
 		needs_reset = 1;
 	}
-	fwrite(line, len, 1, file);
+	fwrite(second, len, 1, file);
 	needs_reset |= len > 0;
 
 end_of_line:
@@ -681,7 +687,7 @@ static void emit_line_0(struct diff_options *o,
 static void emit_line(struct diff_options *o, const char *set, const char *reset,
 		      const char *line, int len)
 {
-	emit_line_0(o, set, NULL, reset, 0, line, len);
+	emit_line_0(o, set, NULL, reset, NULL, line, len);
 }
 
 enum diff_symbol {
@@ -1201,7 +1207,7 @@ static void dim_moved_lines(struct diff_options *o)
 static void emit_line_ws_markup(struct diff_options *o,
 				const char *set_sign, const char *set,
 				const char *reset,
-				char sign, const char *line, int len,
+				const char *sign, const char *line, int len,
 				unsigned ws_rule, int blank_at_eof)
 {
 	const char *ws = NULL;
@@ -1244,7 +1250,7 @@ static void emit_diff_symbol_from_struct(struct diff_options *o,
 		context = diff_get_color_opt(o, DIFF_CONTEXT);
 		reset = diff_get_color_opt(o, DIFF_RESET);
 		putc('\n', o->file);
-		emit_line_0(o, context, NULL, reset, '\\',
+		emit_line_0(o, context, NULL, reset, "\\",
 			    nneof, strlen(nneof));
 		break;
 	case DIFF_SYMBOL_SUBMODULE_HEADER:
@@ -1282,7 +1288,7 @@ static void emit_diff_symbol_from_struct(struct diff_options *o,
 			else if (c == '-')
 				set = diff_get_color_opt(o, DIFF_FILE_OLD);
 		}
-		emit_line_ws_markup(o, set_sign, set, reset, ' ', line, len,
+		emit_line_ws_markup(o, set_sign, set, reset, " ", line, len,
 				    flags & (DIFF_SYMBOL_CONTENT_WS_MASK), 0);
 		break;
 	case DIFF_SYMBOL_PLUS:
@@ -1325,7 +1331,7 @@ static void emit_diff_symbol_from_struct(struct diff_options *o,
 				set = diff_get_color_opt(o, DIFF_CONTEXT_BOLD);
 			flags &= ~DIFF_SYMBOL_CONTENT_WS_MASK;
 		}
-		emit_line_ws_markup(o, set_sign, set, reset, '+', line, len,
+		emit_line_ws_markup(o, set_sign, set, reset, "+", line, len,
 				    flags & DIFF_SYMBOL_CONTENT_WS_MASK,
 				    flags & DIFF_SYMBOL_CONTENT_BLANK_LINE_EOF);
 		break;
@@ -1368,7 +1374,7 @@ static void emit_diff_symbol_from_struct(struct diff_options *o,
 			else
 				set = diff_get_color_opt(o, DIFF_CONTEXT_DIM);
 		}
-		emit_line_ws_markup(o, set_sign, set, reset, '-', line, len,
+		emit_line_ws_markup(o, set_sign, set, reset, "-", line, len,
 				    flags & DIFF_SYMBOL_CONTENT_WS_MASK, 0);
 		break;
 	case DIFF_SYMBOL_WORDS_PORCELAIN:
-- 
2.18.0.865.gffc8e1a3cd6-goog