[PATCH v3 2/5] util: Function to parse boolean term queries
Mark Walters
markwalters1009 at gmail.com
Sat Dec 29 08:50:51 PST 2012
On Fri, 28 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 | 55 ++++++++++++++++++++++++++++++++++++++++++++++++++++
> util/string-util.h | 11 +++++++++++
> 2 files changed, 66 insertions(+)
>
> diff --git a/util/string-util.c b/util/string-util.c
> index e4bea21..83b4953 100644
> --- a/util/string-util.c
> +++ b/util/string-util.c
> @@ -96,3 +96,58 @@ make_boolean_term (void *ctx, const char *prefix, const char *term,
>
> return 0;
> }
> +
> +int
> +parse_boolean_term (void *ctx, const char *str,
> + char **prefix_out, char **term_out)
> +{
> + *prefix_out = *term_out = NULL;
> +
> + /* Parse prefix */
> + const char *pos = strchr (str, ':');
> + if (! pos)
> + goto FAIL;
> + *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;
> + 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 != ')')
> + ++pos;
> + if (*pos)
> + goto FAIL;
> + /* No trailing text; dup the string so the caller can free
> + * it. */
> + *term_out = talloc_strdup (ctx, start);
> + }
> + return 0;
This looks like it will fail if a line contains trailing white space
(and that seemed to be the case from my experiment). Is that wanted?
If yes we may want to make the error message clearer as I got an error
of the form
Warning: cannot parse query: id:message-id at example.com
and the fact that line contained trailing spaces was not clear.
> +
> + 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..43d49d0 100644
> --- a/util/string-util.h
> +++ b/util/string-util.h
> @@ -33,4 +33,15 @@ 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 produced by make_boolean_term, returning
> + * the prefix in *prefix_out and the term in *term_out. *prefix_out
> + * and *term_out will be talloc'd with context ctx.
> + *
> + * Return: 0 on success, non-zero on parse error (including trailing
> + * data in str).
> + */
I think it would be worth detailing what requirements a boolean term
here should meet to be parsed. In particular, since make_boolean_term
is more restrictive than Xapian we should say whether this is like
make_boolean_term, like Xapian or somewhere in between.
Best wishes
Mark
> +int
> +parse_boolean_term (void *ctx, const char *str,
> + char **prefix_out, char **term_out);
> +
> #endif
> --
> 1.7.10.4
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