Re: [PATCH 1/2] War on whitespace: first, a bit of retreat.

> This introduces core.whitespace configuration variable that lets
> you specify the definition of "whitespace error".
> 
> Currently there are two kinds of whitespace errors defined:
> 
>  * trailing-space: trailing whitespaces at the end of the line.
> 
>  * space-before-tab: a SP appears immediately before HT in the
>    indent part of the line.

> 
> You can specify the desired types of errors to be detected by
> listing their names (unique abbreviations are accepted)
> separated by comma.  By default, these two errors are always
> detected, as that is the traditional behaviour.  You can disable
> detection of a particular type of error by prefixing a '-' in
> front of the name of the error, like this:
> 
> 	[core]
> 		whitespace = -trailing-space
> 
> This patch teaches the code to output colored diff with
> DIFF_WHITESPACE color to highlight the detected whitespace
> errors to honor the new configuration.
> 
> Signed-off-by: Junio C Hamano <gitster@pobox.com>
> ---
>  cache.h       |    9 +++++++++
>  config.c      |   52 ++++++++++++++++++++++++++++++++++++++++++++++++++++
>  diff.c        |   13 ++++++++-----
>  environment.c |    1 +
>  4 files changed, 70 insertions(+), 5 deletions(-)
> 
> diff --git a/cache.h b/cache.h
> index bfffa05..a6e5988 100644
> --- a/cache.h
> +++ b/cache.h
> @@ -602,4 +602,13 @@ extern int diff_auto_refresh_index;
>  /* match-trees.c */
>  void shift_tree(const unsigned char *, const unsigned char *, unsigned char *, int);
>  
> +/*
> + * whitespace rules.
> + * used by both diff and apply
> + */
> +#define WS_TRAILING_SPACE	01
> +#define WS_SPACE_BEFORE_TAB	02
> +#define WS_DEFAULT_RULE (WS_TRAILING_SPACE|WS_SPACE_BEFORE_TAB)
> +extern unsigned whitespace_rule;
> +
>  #endif /* CACHE_H */
> diff --git a/config.c b/config.c
> index dc3148d..ffb418c 100644
> --- a/config.c
> +++ b/config.c
> @@ -246,6 +246,53 @@ static unsigned long get_unit_factor(const char *end)
>  	die("unknown unit: '%s'", end);
>  }
>  
> +static struct whitespace_rule {
> +	const char *rule_name;
> +	unsigned rule_bits;
> +} whitespace_rule_names[] = {
> +	{ "trailing-space", WS_TRAILING_SPACE },
> +	{ "space-before-tab", WS_SPACE_BEFORE_TAB },
> +};
> +
> +static unsigned parse_whitespace_rule(const char *string)
> +{
> +	unsigned rule = WS_DEFAULT_RULE;
> +
> +	while (string) {
> +		int i;
> +		size_t len;
> +		const char *ep;
> +		int negated = 0;
> +
> +		string = string + strspn(string, ", \t\n\r");
> +		ep = strchr(string, ',');
> +		if (!ep)
> +			len = strlen(string);
> +		else
> +			len = ep - string;
> +
> +		if (*string == '-') {
> +			negated = 1;
> +			string++;
> +			len--;
> +		}
> +		if (!len)
> +			break;
> +		for (i = 0; i < ARRAY_SIZE(whitespace_rule_names); i++) {
> +			if (strncmp(whitespace_rule_names[i].rule_name,
> +				    string, len))
> +				continue;
> +			if (negated)
> +				rule &= ~whitespace_rule_names[i].rule_bits;
> +			else
> +				rule |= whitespace_rule_names[i].rule_bits;
> +			break;
> +		}
> +		string = ep;
> +	}
> +	return rule;
> +}
> +
>  int git_parse_long(const char *value, long *ret)
>  {
>  	if (value && *value) {
> @@ -431,6 +478,11 @@ int git_default_config(const char *var, const char *value)
>  		return 0;
>  	}
>  
> +	if (!strcmp(var, "core.whitespace")) {
> +		whitespace_rule = parse_whitespace_rule(value);
> +		return 0;
> +	}
> +
>  	/* Add other config variables here and to Documentation/config.txt. */
>  	return 0;
>  }
> diff --git a/diff.c b/diff.c
> index a6aaaf7..2112353 100644
> --- a/diff.c
> +++ b/diff.c
> @@ -508,7 +508,8 @@ static void emit_line_with_ws(int nparents,
>  	for (i = col0; i < len; i++) {
>  		if (line[i] == '\t') {
>  			last_tab_in_indent = i;
> -			if (0 <= last_space_in_indent)
> +			if ((whitespace_rule & WS_SPACE_BEFORE_TAB) &&
> +			    0 <= last_space_in_indent)
>  				need_highlight_leading_space = 1;
>  		}
>  		else if (line[i] == ' ')
> @@ -540,10 +541,12 @@ static void emit_line_with_ws(int nparents,
>  	tail = len - 1;
>  	if (line[tail] == '\n' && i < tail)
>  		tail--;
> -	while (i < tail) {
> -		if (!isspace(line[tail]))
> -			break;
> -		tail--;
> +	if (whitespace_rule & WS_TRAILING_SPACE) {
> +		while (i < tail) {
> +			if (!isspace(line[tail]))
> +				break;
> +			tail--;
> +		}
>  	}
>  	if ((i < tail && line[tail + 1] != '\n')) {
>  		/* This has whitespace between tail+1..len */
> diff --git a/environment.c b/environment.c
> index b5a6c69..624dd96 100644
> --- a/environment.c
> +++ b/environment.c
> @@ -35,6 +35,7 @@ int pager_in_use;
>  int pager_use_color = 1;
>  char *editor_program;
>  int auto_crlf = 0;	/* 1: both ways, -1: only when adding git objects */
> +unsigned whitespace_rule = WS_DEFAULT_RULE;
>  
>  /* This is set by setup_git_dir_gently() and/or git_default_config() */
>  char *git_work_tree_cfg;
> -- 
> 1.5.3.5.1452.ga93d
> 
> -
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