Re: [PATCH] [RFC] kconfig: menuconfig make "Selected by:" readable

[Paul Bolle <pebolle@tiscali.nl>]

On Thu, 2015-01-22 at 00:00 +0100, Paul Bolle wrote:
> rev_dep expressions can get rather unwieldy, especially if a symbol is
> selected by more than a handful of other symbols. Ie, it's possible to
> have near endless expressions like:
>    A && B && !C || D || F && (G || H) || [...]
> 
> Chop these expressions into actually readable chunks:
>    - A && B && !C
>    - D
>    - F && (G || H)
>    - [...]
> 
> Ie, transform the top level "||" tokens into newlines and prepend each
> line with a minus. This makes the "Selected by:" blurb much easier to
> read.
> 
> Not-yet-signed-off-by: Paul Bolle <pebolle@tiscali.nl>
> ---
> Today I found myself wondering why a certain Kconfig was selected.
> Currently menuconfig's help is of no use in complicated cases. Please
> look at the help of USB or CRYPTO to see what I mean.
> 
> This is a _hack_ to show what might be a better way to do this. It
> parses a stringified version of the reverse dependency, and not the
> actual reverse dependecy expression. But that was easier to cobble
> together.
> 
> One cool improvement would be to change to minus in front of the
> subexpressions to Y or M for those that actually set the symbol. Anyhow,
> other suggestions and feedback is welcome.
> 
>  scripts/kconfig/menu.c | 83 ++++++++++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 81 insertions(+), 2 deletions(-)
> 
> diff --git a/scripts/kconfig/menu.c b/scripts/kconfig/menu.c
> index 72c9dba84c5d..eb73fe77513e 100644
> --- a/scripts/kconfig/menu.c
> +++ b/scripts/kconfig/menu.c
> @@ -613,6 +613,86 @@ static struct property *get_symbol_prop(struct symbol *sym)
>  }
>  
>  /*
> + * Assuming we're just past an opening parenthesis in a NUL terminated string,
> + * find it's closing parenthesis and return its postion. Die otherwise.
> + */
> +static const char *matching_paren(const char *s)
> +{
> +	int lvl = 1;
> +
> +	while (1) {
> +		if (*s == '(')
> +			lvl++;
> +		else if (*s == ')')
> +			lvl--;
> +		if (lvl == 0)
> +			break;
> +		if (*s == '\0')
> +			/* huh? */
> +			exit(1);
> +		s++;
> +	}
> +
> +	return s;
> +}
> +
> +/*
> + * rev_dep expressions can get rather unwieldy, especially if a symbol is
> + * selected by more than a handful of other symbols. Ie, it's possible to
> + * have near endless expressions like:
> + *    A && B && !C || D || F && (G || H) || [...]
> + *
> + * Chop these expressions into actually readable chunks:
> + *    - A && B && !C
> + *    - D
> + *    - F && (G || H)
> + *    - [...]
> + *
> + * Ie, transform the top level "||" tokens into newlines and prepend each line
> + * with a minus. This makes the "Selected by:" blurb much easier to read.
> + */
> +static void rev_dep_gstr_print(struct gstr *gs, struct expr *e)

Charge: posting just before suspending machine and self. Verdict:
guilty.

That should have been
    static void rev_dep_gstr_print(struct expr *e, struct gstr *gs)

> +{
> +	struct gstr tmp = str_new();
> +	const char *prev, *start;
> +	char *beam;
> +
> +	expr_gstr_print(e, &tmp);
> +	prev = start = str_get(&tmp);
> +
> +	str_append(gs, "\n  - ");
> +
> +	while ((beam = index(start, '|'))) {
> +		char *lparen = index(start, '(');
> +
> +		/* don't split "(I || J)" */
> +		if (lparen && (lparen < beam)) {
> +			const char *rparen = matching_paren(++lparen);
> +
> +			/* skip the expression inside parentheses */
> +			start = ++rparen;
> +			continue;
> +		}
> +
> +		/* we can assume we're fed a sane string, so the space before
> +		 * the beam gets turned into a NUL */
> +		*(beam - 1) = '\0';
> +		str_append(gs, prev);
> +		str_append(gs, "\n  - ");
> +		/* assume sane string, so skip the second beam */
> +		beam++;
> +		/* trim */
> +		while (*++beam == ' ')
> +			;
> +		prev = start = beam;
> +	}
> +
> +	str_append(gs, prev);
> +
> +	str_free(&tmp);
> +}
> +
> +/*
>   * head is optional and may be NULL
>   */
>  void get_symbol_str(struct gstr *r, struct symbol *sym,
> @@ -661,8 +741,7 @@ void get_symbol_str(struct gstr *r, struct symbol *sym,
>  		str_append(r, "\n");
>  	if (sym->rev_dep.expr) {
>  		str_append(r, _("  Selected by: "));
> -		expr_gstr_print(sym->rev_dep.expr, r);
> -		str_append(r, "\n");
> +		rev_dep_gstr_print(sym->rev_dep.expr, r);
>  	}
>  	str_append(r, "\n\n");
>  }


Paul Bolle