[PATCH v4 2/5] util: Function to parse boolean term queries
Jani Nikula
jani at nikula.org
Thu Jan 3 09:09:08 PST 2013
On Mon, 31 Dec 2012, Austin Clements <amdragon at MIT.EDU> wrote:
> This parses the subset of Xapian's boolean term quoting rules that are
> used by make_boolean_term. This is provided as a generic string
> utility, but will be used shortly in notmuch restore to parse and
> optimize for ID queries.
> ---
> util/string-util.c | 67 ++++++++++++++++++++++++++++++++++++++++++++++++++++
> util/string-util.h | 15 ++++++++++++
> 2 files changed, 82 insertions(+)
>
> diff --git a/util/string-util.c b/util/string-util.c
> index e4bea21..52c7781 100644
> --- a/util/string-util.c
> +++ b/util/string-util.c
> @@ -22,6 +22,8 @@
> #include "string-util.h"
> #include "talloc.h"
>
> +#include <ctype.h>
> +
> char *
> strtok_len (char *s, const char *delim, size_t *len)
> {
> @@ -96,3 +98,68 @@ make_boolean_term (void *ctx, const char *prefix, const char *term,
>
> return 0;
> }
> +
> +static const char*
> +skip_space (const char *str)
> +{
> + while (*str && isspace (*str))
Pedantic: isspace ((unsigned char) *str)
> + ++str;
> + return str;
> +}
> +
> +int
> +parse_boolean_term (void *ctx, const char *str,
> + char **prefix_out, char **term_out)
> +{
> + *prefix_out = *term_out = NULL;
> +
> + /* Parse prefix */
> + str = skip_space (str);
> + const char *pos = strchr (str, ':');
> + if (! pos)
if (! pos || pos == str) ?
> + goto FAIL;
Could just return 1 here.
> + *prefix_out = talloc_strndup (ctx, str, pos - str);
> + ++pos;
> +
> + /* Implement de-quoting compatible with make_boolean_term. */
> + if (*pos == '"') {
> + char *out = talloc_array (ctx, char, strlen (pos));
> + int closed = 0;
> + *term_out = out;
> + /* Skip the opening quote, find the closing quote, and
> + * un-double doubled internal quotes. */
> + for (++pos; *pos; ) {
> + if (*pos == '"') {
> + ++pos;
> + if (*pos != '"') {
> + /* Found the closing quote. */
> + closed = 1;
> + pos = skip_space (pos);
Is it necessary to accept trailing space?
> + break;
> + }
> + }
> + *out++ = *pos++;
> + }
> + /* Did the term terminate without a closing quote or is there
> + * trailing text after the closing quote? */
> + if (!closed || *pos)
> + goto FAIL;
> + *out = '\0';
> + } else {
> + const char *start = pos;
> + /* Check for text after the boolean term. */
> + while (*pos > ' ' && *pos != ')')
The condition could have *pos there too for clarity, though not strictly
necessary. Would be neat to have a ctype style helper that could be
shared between this and make_boolean_term.
> + ++pos;
> + if (*skip_space (pos))
Is it necessary to accept trailing space?
> + goto FAIL;
> + /* No trailing text; dup the string so the caller can free
> + * it. */
> + *term_out = talloc_strndup (ctx, start, pos - start);
> + }
> + return 0;
> +
> + FAIL:
> + talloc_free (*prefix_out);
> + talloc_free (*term_out);
> + return 1;
> +}
> diff --git a/util/string-util.h b/util/string-util.h
> index b8844a3..8b9fe50 100644
> --- a/util/string-util.h
> +++ b/util/string-util.h
> @@ -33,4 +33,19 @@ char *strtok_len (char *s, const char *delim, size_t *len);
> int make_boolean_term (void *talloc_ctx, const char *prefix, const char *term,
> char **buf, size_t *len);
>
> +/* Parse a boolean term query consisting of a prefix, a colon, and a
> + * term that may be quoted as described for make_boolean_term. If the
> + * term is not quoted, then it ends at the first whitespace or close
> + * parenthesis. str may containing leading or trailing whitespace,
> + * but anything else is considered a parse error. This is compatible
> + * with anything produced by make_boolean_term, and supports a subset
> + * of the quoting styles supported by Xapian (and hence notmuch).
> + * *prefix_out and *term_out will be talloc'd with context ctx.
> + *
> + * Return: 0 on success, non-zero on parse error.
> + */
> +int
> +parse_boolean_term (void *ctx, const char *str,
> + char **prefix_out, char **term_out);
> +
> #endif
> --
> 1.7.10.4
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