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Optimize g_str_has_*() functions to detect const arguments at compile-time
Compilers can emit optimized code for str|strn|mem)cmp(str,"literal") at compile-time. This commit use the preprocessor to introduce this kind of optimization for the functions g_str_has_prefix() and g_str_has_suffix(). Original work by Ben @bdejean Closes issue #24
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@ -2928,9 +2928,8 @@ g_strrstr_len (const gchar *haystack,
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*
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* Since: 2.2
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*/
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gboolean
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g_str_has_suffix (const gchar *str,
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const gchar *suffix)
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gboolean (g_str_has_suffix) (const gchar *str,
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const gchar *suffix)
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{
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gsize str_len;
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gsize suffix_len;
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@ -2958,9 +2957,8 @@ g_str_has_suffix (const gchar *str,
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*
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* Since: 2.2
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*/
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gboolean
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g_str_has_prefix (const gchar *str,
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const gchar *prefix)
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gboolean (g_str_has_prefix) (const gchar *str,
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const gchar *prefix)
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{
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g_return_val_if_fail (str != NULL, FALSE);
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g_return_val_if_fail (prefix != NULL, FALSE);
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@ -33,6 +33,7 @@
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#include <stdarg.h>
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#include <string.h>
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#include <glib/gmacros.h>
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#include <glib/gtypes.h>
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#include <glib/gerror.h>
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@ -139,11 +140,49 @@ gchar * g_strrstr_len (const gchar *haystack,
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const gchar *needle);
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GLIB_AVAILABLE_IN_ALL
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gboolean g_str_has_suffix (const gchar *str,
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const gchar *suffix);
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gboolean (g_str_has_suffix) (const gchar *str,
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const gchar *suffix);
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GLIB_AVAILABLE_IN_ALL
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gboolean g_str_has_prefix (const gchar *str,
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const gchar *prefix);
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gboolean (g_str_has_prefix) (const gchar *str,
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const gchar *prefix);
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#if G_GNUC_CHECK_VERSION (2, 0)
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/* A note on the 'x + !x' terms: These are added to workaround a false
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* warning in gcc 10< which is ignoring the check 'x != NULL' that is
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* set outside of the G_GNUC_EXTENSION scope. Without 'x + !x' it
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* would complain that x may be NULL where strlen() and memcmp()
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* both require non-null arguments. */
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#define g_str_has_prefix(STR, PREFIX) \
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((STR != NULL && PREFIX != NULL && __builtin_constant_p (PREFIX)) ? \
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G_GNUC_EXTENSION ({ \
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const char *const __str = STR; \
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const char *const __prefix = PREFIX; \
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const size_t __str_len = strlen (__str + !__str); \
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const size_t __prefix_len = strlen (__prefix + !__prefix); \
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(__str_len >= __prefix_len) ? \
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memcmp (__str + !__str, \
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__prefix + !__prefix, __prefix_len) == 0 : FALSE; \
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}) \
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: \
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(g_str_has_prefix) (STR, PREFIX))
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#define g_str_has_suffix(STR, SUFFIX) \
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((STR != NULL && SUFFIX != NULL && __builtin_constant_p (SUFFIX)) ? \
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G_GNUC_EXTENSION ({ \
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const char *const __str = STR; \
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const char *const __suffix = SUFFIX; \
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const size_t __str_len = strlen (__str + !__str); \
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const size_t __suffix_len = strlen (__suffix + !__suffix); \
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(__str_len >= __suffix_len) ? \
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memcmp (__str + !__str + __str_len - __suffix_len, \
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__suffix + !__suffix, __suffix_len) == 0 : FALSE; \
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}) \
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: \
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(g_str_has_suffix) (STR, SUFFIX))
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#endif /* G_GNUC_CHECK_VERSION (2, 0) */
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/* String to/from double conversion functions */
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