Stefan Beller <sbeller@xxxxxxxxxx> writes:
> In a later patch, I want to propose an option to detect&color
> moved lines in a diff, which cannot be done in a one-pass over
> the diff. Instead we need to go over the whole diff twice,
> because we cannot detect the first line of the two corresponding
> lines (+ and -) that got moved.
>
> So to prepare the diff machinery for two pass algorithms
> (i.e. buffer it all up and then operate on the result),
> move all emissions to places, such that the only emitting
> function is emit_line_0.
>
> This covers emit_rewrite_lines.
>
> Signed-off-by: Stefan Beller <sbeller@xxxxxxxxxx>
> ---
> diff.c | 27 +++++++++++++++++++--------
> 1 file changed, 19 insertions(+), 8 deletions(-)
>
> diff --git a/diff.c b/diff.c
> index 3dda9f3c8e..690794aeb8 100644
> --- a/diff.c
> +++ b/diff.c
> @@ -722,15 +722,25 @@ static void add_line_count(struct strbuf *out, int count)
> static void emit_rewrite_lines(struct emit_callback *ecb,
> int prefix, const char *data, int size)
> {
> - const char *endp = NULL;
> - static const char *nneof = " No newline at end of file\n";
> const char *reset = diff_get_color(ecb->color_diff, DIFF_RESET);
> + struct strbuf sb = STRBUF_INIT;
>
> while (0 < size) {
> int len;
>
> - endp = memchr(data, '\n', size);
> - len = endp ? (endp - data + 1) : size;
> + const char *endp = memchr(data, '\n', size);
> + if (endp)
> + len = endp - data + 1;
> + else {
> + while (0 < size) {
> + strbuf_addch(&sb, *data);
> + size -= len;
> + data += len;
> + }
> + strbuf_addch(&sb, '\n');
> + data = sb.buf;
> + len = sb.len;
> + }
> if (prefix != '+') {
> ecb->lno_in_preimage++;
> emit_del_line(reset, ecb, data, len);
> @@ -741,12 +751,13 @@ static void emit_rewrite_lines(struct emit_callback *ecb,
> size -= len;
> data += len;
> }
> - if (!endp) {
> + if (sb.len) {
> + static const char *nneof = "\\ No newline at end of file\n";
> const char *context = diff_get_color(ecb->color_diff,
> DIFF_CONTEXT);
> - putc('\n', ecb->opt->file);
> - emit_line(ecb->opt, context, reset, 1, '\\',
> - nneof, strlen(nneof));
> + emit_line(ecb->opt, context, reset, 1, 0,
> + nneof, strlen(nneof));
> + strbuf_release(&sb);
The reason why we can lose the LF immediately after the incomplete
line we found in the above loop is because the updated emit_line_0()
adds LF if its input is an incomplete line? Even before this series
started, emit_line_0() was already prepared to see a complete or
incomplete line and emit the "reset" color after the optional EOL
bytes at the end, so emit_line() and emit_{add,del}_line() calls
throughout the code can pass the body of the line with or without
the EOL and right things will happen. Sounds about right.
> }
> }