string_util: add function strchug_fast()

Replace g_strchug() calls with a cheaper implementation.

src/conf.c

@@ -270,7 +270,7 @@ config_read_block(FILE *fp, int *count, char *string, GError **error_r)
 		}
 
 		(*count)++;
-		line = g_strchug(line);
+		line = strchug_fast(line);
 		if (*line == 0 || *line == CONF_COMMENT)
 			continue;
 
@@ -278,7 +278,7 @@ config_read_block(FILE *fp, int *count, char *string, GError **error_r)
 			/* end of this block; return from the function
 			   (and from this "while" loop) */
 
-			line = g_strchug(line + 1);
+			line = strchug_fast(line + 1);
 			if (*line != 0 && *line != CONF_COMMENT) {
 				config_param_free(ret);
 				g_set_error(error_r, config_quark(), 0,
@@ -356,7 +356,7 @@ config_read_file(const char *file, GError **error_r)
 
 		count++;
 
-		line = g_strchug(string);
+		line = strchug_fast(string);
 		if (*line == 0 || *line == CONF_COMMENT)
 			continue;
 
@@ -402,7 +402,7 @@ config_read_file(const char *file, GError **error_r)
 				return false;
 			}
 
-			line = g_strchug(line + 1);
+			line = strchug_fast(line + 1);
 			if (*line != 0 && *line != CONF_COMMENT) {
 				g_set_error(error_r, config_quark(), 0,
 					    "line %i: Unknown tokens after '{'",

src/playlist/extm3u_playlist_plugin.c

@@ -24,6 +24,7 @@
 #include "uri.h"
 #include "song.h"
 #include "tag.h"
+#include "string_util.h"
 
 #include <glib.h>
 
@@ -89,7 +90,7 @@ extm3u_parse_tag(const char *line)
 		/* 0 means unknown duration */
 		duration = 0;
 
-	name = g_strchug(endptr + 1);
+	name = strchug_fast_c(endptr + 1);
 	if (*name == 0 && duration == 0)
 		/* no information available; don't allocate a tag
 		   object */

src/playlist_database.c

@@ -21,6 +21,7 @@
 #include "playlist_database.h"
 #include "playlist_vector.h"
 #include "text_file.h"
+#include "string_util.h"
 
 #include <string.h>
 #include <stdlib.h>
@@ -62,7 +63,7 @@ playlist_metadata_load(FILE *fp, struct playlist_vector *pv, const char *name,
 		}
 
 		*colon++ = 0;
-		value = g_strchug(colon);
+		value = strchug_fast_c(colon);
 
 		if (strcmp(line, "mtime") == 0)
 			pm.mtime = strtol(value, NULL, 10);

src/song_save.c

@@ -24,6 +24,7 @@
 #include "directory.h"
 #include "tag.h"
 #include "text_file.h"
+#include "string_util.h"
 
 #include <glib.h>
 
@@ -96,7 +97,7 @@ song_load(FILE *fp, struct directory *parent, const char *uri,
 		}
 
 		*colon++ = 0;
-		value = g_strchug(colon);
+		value = strchug_fast_c(colon);
 
 		if ((type = tag_name_parse(line)) != TAG_NUM_OF_ITEM_TYPES) {
 			if (!song->tag) {

src/string_util.c

@@ -24,6 +24,15 @@
 
 #include <assert.h>
 
+const char *
+strchug_fast_c(const char *p)
+{
+	while (*p != 0 && g_ascii_isspace(*p))
+		++p;
+
+	return p;
+}
+
 bool
 string_array_contains(const char *const* haystack, const char *needle)
 {

src/string_util.h

@@ -20,8 +20,49 @@
 #ifndef MPD_STRING_UTIL_H
 #define MPD_STRING_UTIL_H
 
+#include <glib.h>
+
 #include <stdbool.h>
 
+/**
+ * Remove the "const" attribute from a string pointer.  This is a
+ * dirty hack, don't use it unless you know what you're doing!
+ */
+G_GNUC_CONST
+static inline char *
+deconst_string(const char *p)
+{
+	union {
+		const char *in;
+		char *out;
+	} u = {
+		.in = p,
+	};
+
+	return u.out;
+}
+
+/**
+ * Returns a pointer to the first non-whitespace character in the
+ * string, or to the end of the string.
+ *
+ * This is a faster version of g_strchug(), because it does not move
+ * data.
+ */
+G_GNUC_PURE
+const char *
+strchug_fast_c(const char *p);
+
+/**
+ * Same as strchug_fast_c(), but works with a writable pointer.
+ */
+G_GNUC_PURE
+static inline char *
+strchug_fast(char *p)
+{
+	return deconst_string(strchug_fast_c(p));
+}
+
 /**
  * Checks whether a string array contains the specified string.
  *

src/tokenizer.c

@@ -19,6 +19,7 @@
 
 #include "config.h"
 #include "tokenizer.h"
+#include "string_util.h"
 
 #include <stdbool.h>
 #include <assert.h>
@@ -72,7 +73,7 @@ tokenizer_next_word(char **input_p, GError **error_r)
 			/* a whitespace: the word ends here */
 			*input = 0;
 			/* skip all following spaces, too */
-			input = g_strchug(input + 1);
+			input = strchug_fast(input + 1);
 			break;
 		}
 
@@ -126,7 +127,7 @@ tokenizer_next_unquoted(char **input_p, GError **error_r)
 			/* a whitespace: the word ends here */
 			*input = 0;
 			/* skip all following spaces, too */
-			input = g_strchug(input + 1);
+			input = strchug_fast(input + 1);
 			break;
 		}
 
@@ -205,7 +206,7 @@ tokenizer_next_string(char **input_p, GError **error_r)
 	/* finish the string and return it */
 
 	*dest = 0;
-	*input_p = g_strchug(input);
+	*input_p = strchug_fast(input);
 	return word;
 }