Add optparse.h

1 files changed, 156 insertions, 0 deletions

diff --git a/lib/optparse/optparse.c b/lib/optparse/optparse.c
new file mode 100644
index 0000000..eaacc52
--- /dev/null
+++ b/lib/optparse/optparse.c
@@ -0,0 +1,156 @@
+#include <stdio.h>
+#include <string.h>
+
+#include "macros.h"
+#include "mbstring.h"
+#include "optparse.h"
+
+#define OPT_MSG_INVALID "invalid option"
+#define OPT_MSG_MISSING "option requires an argument"
+#define OPT_MSG_TOOMANY "option takes no arguments"
+
+#define IS_SHORTOPT(s) ((s)[0] == '-' && (s)[1] != '-' && (s)[1] != '\0')
+#define IS_LONGOPT(s)  ((s)[0] == '-' && (s)[1] == '-' && (s)[2] != '\0')
+
+#define error(st, msg, x) \
+	_Generic((x), const char *: error_s, rune: error_r)((st), (msg), (x))
+
+static bool is_a_match(const char *, const char *);
+static rune error_r(struct optparse *, const char *, rune);
+static rune error_s(struct optparse *, const char *, const char *);
+static rune shortopt(struct optparse *, const struct op_option *, size_t);
+
+void
+optparse_init(struct optparse *st, char **argv)
+{
+	st->argv = argv;
+	st->optind = argv[0] != nullptr;
+	st->subopt = 0;
+	st->optarg = (struct u8view){};
+	st->errmsg[0] = '\0';
+}
+
+rune
+optparse(struct optparse *st, const struct op_option *opts, size_t nopts)
+{
+	st->errmsg[0] = '\0';
+	st->optarg = (struct u8view){};
+
+	const char *opt = st->argv[st->optind];
+	if (opt == nullptr)
+		return 0;
+	if (streq(opt, "--")) {
+		st->optind++;
+		return 0;
+	}
+	if (IS_SHORTOPT(opt))
+		return shortopt(st, opts, nopts);
+	if (!IS_LONGOPT(opt))
+		return 0;
+
+	st->subopt = 0;
+	st->optind++;
+	opt += 2; /* Skip ‘--’ */
+
+	for (size_t i = 0; i < nopts; i++) {
+		struct op_option o = opts[i];
+		if (!is_a_match(opt, o.longopt))
+			continue;
+		switch (o.argtype) {
+		case OPT_NONE:
+			if (strchr(opt, '=') != nullptr)
+				return error(st, OPT_MSG_TOOMANY, opt);
+			break;
+		case OPT_REQ: {
+			const char *p = strchr(opt, '=');
+			if (p == nullptr) {
+				if (st->argv[st->optind] == nullptr)
+					return error(st, OPT_MSG_MISSING, opt);
+				st->optarg.p = st->argv[st->optind++];
+			} else
+				st->optarg.p = p + 1;
+			st->optarg.len = strlen(st->optarg.p);
+		} break;
+		case OPT_OPT: {
+			const char *p = strchr(opt, '=');
+			if (p == nullptr)
+				st->optarg = (struct u8view){};
+			else {
+				st->optarg.p = p + 1;
+				st->optarg.len = strlen(st->optarg.p);
+			}
+		} break;
+		}
+		return o.shortopt;
+	}
+
+	return error(st, OPT_MSG_INVALID, opt);
+}
+
+rune
+shortopt(struct optparse *st, const struct op_option *opts, size_t nopts)
+{
+	rune ch;
+	const char *opt = st->argv[st->optind];
+	st->subopt += u8tor(&ch, opt + st->subopt + 1);
+	if (ch == '\0') {
+		st->subopt = 0;
+		st->optind++;
+		return optparse(st, opts, nopts);
+	}
+	for (size_t i = 0; i < nopts; i++) {
+		if (opts[i].shortopt != ch)
+			continue;
+		if (opts[i].argtype == OPT_NONE)
+			goto out;
+		if (opt[st->subopt + 1] != '\0') {
+			st->optarg.p = opt + st->subopt + 1;
+			st->optarg.len = strlen(st->optarg.p);
+			st->subopt = 0;
+			st->optind++;
+			goto out;
+		}
+		if (opts[i].argtype == OPT_OPT) {
+			st->optarg = (struct u8view){};
+			goto out;
+		}
+		if (st->argv[st->optind + 1] == nullptr) {
+			st->optarg = (struct u8view){};
+			return error(st, OPT_MSG_MISSING, ch);
+		}
+		st->optarg.p = st->argv[st->optind + 1];
+		st->optarg.len = strlen(st->optarg.p);
+		st->optind += 2;
+		goto out;
+	}
+	return error(st, OPT_MSG_INVALID, ch);
+out:
+	return ch;
+}
+
+bool
+is_a_match(const char *u, const char *t)
+{
+	for (; *u && *t && *u != '='; u++, t++) {
+		if (*u != *t)
+			return false;
+	}
+	return *t == '\0' && (*u == '\0' || *u == '=');
+}
+
+rune
+error_s(struct optparse *st, const char *msg, const char *s)
+{
+	const char *p = strchr(s, '=');
+	snprintf(st->errmsg, sizeof(st->errmsg), u8"%s — ‘%.*s’", msg,
+	         (int)(p ? p - s : strlen(s)), s);
+	return -1;
+}
+
+rune
+error_r(struct optparse *st, const char *msg, rune ch)
+{
+	char buf[U8_LEN_MAX + 1] = {};
+	rtou8(buf, ch, sizeof(buf));
+	return error_s(st, msg, buf);
+}