Re: [PATCH v2 2/3] diff: add -I<regex> that ignores matching changes

From: Johannes Schindelin <Johannes.Schindelin@gmx.de>
To: "Michał Kępień" <michal@isc.org>
Cc: git@vger.kernel.org
Subject: Re: [PATCH v2 2/3] diff: add -I<regex> that ignores matching changes
Date: Mon, 12 Oct 2020 13:20:13 +0200 (CEST)	[thread overview]
Message-ID: <nycvar.QRO.7.76.6.2010121315170.50@tvgsbejvaqbjf.bet> (raw)
In-Reply-To: <20201012091751.19594-3-michal@isc.org>

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Hi Michał,

On Mon, 12 Oct 2020, Michał Kępień wrote:

> @@ -5203,6 +5207,22 @@ static int diff_opt_patience(const struct option *opt,
>  	return 0;
>  }
>
> +static int diff_opt_ignore_regex(const struct option *opt,
> +				 const char *arg, int unset)
> +{
> +	struct diff_options *options = opt->value;
> +	regex_t *regex;
> +
> +	BUG_ON_OPT_NEG(unset);
> +	regex = xcalloc(1, sizeof(*regex));
> +	if (regcomp(regex, arg, REG_EXTENDED | REG_NEWLINE))
> +		die("invalid regex: %s", arg);
> +	ALLOC_GROW(options->ignore_regex, options->ignore_regex_nr + 1,
> +		   options->ignore_regex_alloc);
> +	options->ignore_regex[options->ignore_regex_nr++] = regex;

A slightly more elegant way would be to have `ignore_regex` have the type
`regex_t *` and use `ALLOC_GROW_BY()` (which zeroes the newly-added
elements automagically).

> +	return 0;
> +}
> +
>  static int diff_opt_pickaxe_regex(const struct option *opt,
>  				  const char *arg, int unset)
>  {
> [...]
> @@ -5491,6 +5511,9 @@ static void prep_parse_options(struct diff_options *options)
>  		OPT_BIT_F(0, "ignore-blank-lines", &options->xdl_opts,
>  			  N_("ignore changes whose lines are all blank"),
>  			  XDF_IGNORE_BLANK_LINES, PARSE_OPT_NONEG),
> +		OPT_CALLBACK_F('I', NULL, options, N_("<regex>"),
> +			       N_("ignore changes whose all lines match <regex>"),
> +			       0, diff_opt_ignore_regex),
>  		OPT_BIT(0, "indent-heuristic", &options->xdl_opts,
>  			N_("heuristic to shift diff hunk boundaries for easy reading"),
>  			XDF_INDENT_HEURISTIC),

Are we releasing the `ignore_regex` anywhere?

Thanks,
Dscho

> diff --git a/diff.h b/diff.h
> index 11de52e9e9..80dbd3dfdc 100644
> --- a/diff.h
> +++ b/diff.h
> @@ -234,6 +234,10 @@ struct diff_options {
>  	 */
>  	const char *pickaxe;
>
> +	/* see Documentation/diff-options.txt */
> +	regex_t **ignore_regex;
> +	size_t ignore_regex_nr, ignore_regex_alloc;
> +
>  	const char *single_follow;
>  	const char *a_prefix, *b_prefix;
>  	const char *line_prefix;
> diff --git a/xdiff/xdiff.h b/xdiff/xdiff.h
> index 032e3a9f41..883a0d770e 100644
> --- a/xdiff/xdiff.h
> +++ b/xdiff/xdiff.h
> @@ -79,6 +79,10 @@ typedef struct s_mmbuffer {
>  typedef struct s_xpparam {
>  	unsigned long flags;
>
> +	/* See Documentation/diff-options.txt. */
> +	regex_t **ignore_regex;
> +	size_t ignore_regex_nr;
> +
>  	/* See Documentation/diff-options.txt. */
>  	char **anchors;
>  	size_t anchors_nr;
> diff --git a/xdiff/xdiffi.c b/xdiff/xdiffi.c
> index bd035139f9..380eb728ed 100644
> --- a/xdiff/xdiffi.c
> +++ b/xdiff/xdiffi.c
> @@ -998,7 +998,7 @@ static int xdl_call_hunk_func(xdfenv_t *xe, xdchange_t *xscr, xdemitcb_t *ecb,
>  	return 0;
>  }
>
> -static void xdl_mark_ignorable(xdchange_t *xscr, xdfenv_t *xe, long flags)
> +static void xdl_mark_ignorable_lines(xdchange_t *xscr, xdfenv_t *xe, long flags)
>  {
>  	xdchange_t *xch;
>
> @@ -1019,6 +1019,46 @@ static void xdl_mark_ignorable(xdchange_t *xscr, xdfenv_t *xe, long flags)
>  	}
>  }
>
> +static int record_matches_regex(xrecord_t *rec, xpparam_t const *xpp) {
> +	regmatch_t regmatch;
> +	int i;
> +
> +	for (i = 0; i < xpp->ignore_regex_nr; i++)
> +		if (!regexec_buf(xpp->ignore_regex[i], rec->ptr, rec->size, 1,
> +				 &regmatch, 0))
> +			return 1;
> +
> +	return 0;
> +}
> +
> +static void xdl_mark_ignorable_regex(xdchange_t *xscr, const xdfenv_t *xe,
> +				     xpparam_t const *xpp)
> +{
> +	xdchange_t *xch;
> +
> +	for (xch = xscr; xch; xch = xch->next) {
> +		xrecord_t **rec;
> +		int ignore = 1;
> +		long i;
> +
> +		/*
> +		 * Do not override --ignore-blank-lines.
> +		 */
> +		if (xch->ignore)
> +			continue;
> +
> +		rec = &xe->xdf1.recs[xch->i1];
> +		for (i = 0; i < xch->chg1 && ignore; i++)
> +			ignore = record_matches_regex(rec[i], xpp);
> +
> +		rec = &xe->xdf2.recs[xch->i2];
> +		for (i = 0; i < xch->chg2 && ignore; i++)
> +			ignore = record_matches_regex(rec[i], xpp);
> +
> +		xch->ignore = ignore;
> +	}
> +}
> +
>  int xdl_diff(mmfile_t *mf1, mmfile_t *mf2, xpparam_t const *xpp,
>  	     xdemitconf_t const *xecfg, xdemitcb_t *ecb) {
>  	xdchange_t *xscr;
> @@ -1038,7 +1078,10 @@ int xdl_diff(mmfile_t *mf1, mmfile_t *mf2, xpparam_t const *xpp,
>  	}
>  	if (xscr) {
>  		if (xpp->flags & XDF_IGNORE_BLANK_LINES)
> -			xdl_mark_ignorable(xscr, &xe, xpp->flags);
> +			xdl_mark_ignorable_lines(xscr, &xe, xpp->flags);
> +
> +		if (xpp->ignore_regex)
> +			xdl_mark_ignorable_regex(xscr, &xe, xpp);
>
>  		if (ef(&xe, xscr, ecb, xecfg) < 0) {
>
> --
> 2.28.0
>
>