Core: introduce new subsurface-string header

First small step to shrinking dive.h.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

core/subsurface-string.h

@@ -0,0 +1,81 @@
+// SPDX-License-Identifier: GPL-2.0
+#ifndef SUBSURFACE_STRING_H
+#define SUBSURFACE_STRING_H
+
+#include <stdbool.h>
+#include <string.h>
+#include <time.h>
+
+// shared generic definitions and macros
+// mostly about strings, but a couple of math macros are here as well
+
+/* Windows has no MIN/MAX macros - so let's just roll our own */
+#define MIN(x, y) ({                \
+	__typeof__(x) _min1 = (x);          \
+	__typeof__(y) _min2 = (y);          \
+	(void) (&_min1 == &_min2);      \
+	_min1 < _min2 ? _min1 : _min2; })
+
+#define MAX(x, y) ({                \
+	__typeof__(x) _max1 = (x);          \
+	__typeof__(y) _max2 = (y);          \
+	(void) (&_max1 == &_max2);      \
+	_max1 > _max2 ? _max1 : _max2; })
+
+#define IS_FP_SAME(_a, _b) (fabs((_a) - (_b)) <= 0.000001 * MAX(fabs(_a), fabs(_b)))
+
+// string handling
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+static inline bool same_string(const char *a, const char *b)
+{
+	return !strcmp(a ?: "", b ?: "");
+}
+
+static inline bool same_string_caseinsensitive(const char *a, const char *b)
+{
+	return !strcasecmp(a ?: "", b ?: "");
+}
+
+static inline bool empty_string(const char *s)
+{
+	return !s || !*s;
+}
+
+static inline bool includes_string_caseinsensitive(const char *haystack, const char *needle)
+{
+	if (!needle)
+		return 1; /* every string includes the NULL string */
+	if (!haystack)
+		return 0; /* nothing is included in the NULL string */
+	int len = strlen(needle);
+	while (*haystack) {
+		if (strncasecmp(haystack, needle, len))
+			return 1;
+		haystack++;
+	}
+	return 0;
+}
+
+static inline char *copy_string(const char *s)
+{
+	return (s && *s) ? strdup(s) : NULL;
+}
+
+#define STRTOD_NO_SIGN 0x01
+#define STRTOD_NO_DOT 0x02
+#define STRTOD_NO_COMMA 0x04
+#define STRTOD_NO_EXPONENT 0x08
+extern double strtod_flags(const char *str, const char **ptr, unsigned int flags);
+
+#define STRTOD_ASCII (STRTOD_NO_COMMA)
+
+#define ascii_strtod(str, ptr) strtod_flags(str, ptr, STRTOD_ASCII)
+
+#ifdef __cplusplus
+}
+#endif
+#endif // SUBSURFACE_STRING_H