From: Christian Couder <christian.couder@xxxxxxxxx>
We often accept both a "--key" option and a "--key=<val>" option.
These options currently are parsed using something like:
if (!strcmp(arg, "--key")) {
/* do something */
} else if (skip_prefix(arg, "--key=", &arg)) {
/* do something with arg */
}
which is a bit cumbersome compared to just:
if (skip_to_opt_val(arg, "--key", &arg)) {
/* do something with arg */
}
Note that, when using skip_to_opt_val(), it is not possible any more
to do something different when the first argument is exactly "--key"
than when it is exactly "--key=", but in most cases we already don't
make any difference, which is a good thing.
Note that "opt" in the function name actually means "optional" as
the function can be used to parse any "key=value" string where "key"
is also considered as valid, not just command line options.
Signed-off-by: Christian Couder <chriscool@xxxxxxxxxxxxx>
---
git-compat-util.h | 35 +++++++++++++++++++++++++++++++++++
1 file changed, 35 insertions(+)
Another possibility would be to add a "const char *default"
argument to the function, and to do:
if (!*p) {
*val = default;
return 1;
}
This could make the function more useful in some cases.
I also wonder if the function is too big to be inlined, and
in that case, in which file it should be added.
diff --git a/git-compat-util.h b/git-compat-util.h
index cedad4d581..7ee040388f 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@ -534,6 +534,41 @@ static inline int ends_with(const char *str, const char *suffix)
return strip_suffix(str, suffix, &len);
}
+/*
+ * If the string "str" is the same as the string in "prefix", then the "val"
+ * parameter is set to the empty string and 1 is returned.
+ * If the string "str" begins with the string found in "prefix" and then a
+ * "=" sign, then the "val" parameter is set to "str + strlen(prefix) + 1"
+ * (i.e., to the point in the string right after the prefix and the "=" sign),
+ * and 1 is returned.
+ *
+ * Otherwise, return 0 and leave "val" untouched.
+ *
+ * When we accept both a "--key" and a "--key=<val>" option, this function
+ * can be used instead of !strcmp(arg, "--key") and then
+ * skip_prefix(arg, "--key=", &arg) to parse such an option.
+ */
+static inline int skip_to_opt_val(const char *str, const char *prefix,
+ const char **val)
+{
+ const char *p;
+
+ if (!skip_prefix(str, prefix, &p))
+ return 0;
+
+ if (!*p) {
+ *val = "";
+ return 1;
+ }
+
+ if (*p == '=') {
+ *val = p + 1;
+ return 1;
+ }
+
+ return 0;
+}
+
#define SWAP(a, b) do { \
void *_swap_a_ptr = &(a); \
void *_swap_b_ptr = &(b); \
--
2.15.1.271.g1a4e40aa5d.dirty
