From: Phillip Wood Date: Sat, 17 Nov 2018 14:59:50 GMT Subject: Re: [PATCH v1 8/9] diff --color-moved-ws: modify allow-indentation-change Message-ID: <42818e32-8774-722d-b46d-9a23f4097315@talktalk.net> In-Reply-To: Hi Stefan On 16/11/2018 21:47, Stefan Beller wrote: > On Fri, Nov 16, 2018 at 3:04 AM Phillip Wood wrote: >> >> From: Phillip Wood >> >> Currently diff --color-moved-ws=allow-indentation-change does not >> support indentation that contains a mix of tabs and spaces. For >> example in commit 546f70f377 ("convert.h: drop 'extern' from function >> declaration", 2018-06-30) the function parameters in the following >> lines are not colored as moved [1]. >> >> -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); >> >> This commit changes the way the indentation is handled to track the >> visual size of the indentation rather than the characters in the >> indentation. This has they benefit that any whitespace errors do not > > s/they/the/ Thanks, well spotted > >> interfer with the move detection (the whitespace errors will still be >> highlighted according to --ws-error-highlight). During the discussion >> of this feature there were concerns about the correct detection of >> indentation for python. However those concerns apply whether or not >> we're detecting moved lines so no attempt is made to determine if the >> indentation is 'pythonic'. >> >> [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 >> --- >> >> 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; > > So this is the trick how we compute the ws related > data only once per line. :-) > > On the other hand, we do not save memory by disabling > the ws detection, but I guess that is not a problem for now. I did wonder about that, but decided the increase was small compared to all the strings that are copied when creating the emitted_diff_symbols. If we want to save memory then we should stop struct emitted_diff_symbol() from carrying a copy of all the strings. > Would it make sense to have the new variables be > unsigned? (Also a comment on what they are, I > needed to read the code to understand off to be > offset into the line, where the content starts, and > width to be the visual width, as I did not recall > the RFC.) Yes a comment would make sense. I don't think I have a strong preference for signed/unsigned, I can change it if you want. Thanks for looking at these so promptly Best Wishes Phillip >> +static void fill_es_indent_data(struct emitted_diff_symbol *es) >> [...] > >> + if (o->color_moved_ws_handling & >> + COLOR_MOVED_WS_ALLOW_INDENTATION_CHANGE) >> + fill_es_indent_data(&o->emitted_symbols->buf[n]); > > Nice. > > By reducing the information kept around to ints, we also do not need > to alloc/free > memory for each line. > >> +++ 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' ' > > Looks good, > > Thanks! > Stefan >