Commit FS#8314. This adds strnat[case]cmp written by Martin Pool, which respects numbers within strings, and gives a more intuitive

sorting. This also adds a setting, so that the sorting can be used in the file browser. The implementation is very generic, and can possibly 
be used in other places.


git-svn-id: svn://svn.rockbox.org/rockbox/trunk@20155 a1c6a512-1295-4272-9138-f99709370657

1 files changed, 179 insertions, 0 deletions

diff --git a/firmware/common/strnatcmp.c b/firmware/common/strnatcmp.c
new file mode 100644
index 0000000000..84e0d38362
--- /dev/null
+++ b/firmware/common/strnatcmp.c
@@ -0,0 +1,179 @@
+/* -*- mode: c; c-file-style: "k&r" -*-
+
+  strnatcmp.c -- Perform 'natural order' comparisons of strings in C.
+  Copyright (C) 2000, 2004 by Martin Pool <mbp sourcefrog net>
+
+  This software is provided 'as-is', without any express or implied
+  warranty.  In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely, subject to the following restrictions:
+
+  1. The origin of this software must not be misrepresented; you must not
+     claim that you wrote the original software. If you use this software
+     in a product, an acknowledgment in the product documentation would be
+     appreciated but is not required.
+  2. Altered source versions must be plainly marked as such, and must not be
+     misrepresented as being the original software.
+  3. This notice may not be removed or altered from any source distribution.
+*/
+
+
+/* partial change history:
+ *
+ * 2004-10-10 mbp: Lift out character type dependencies into macros.
+ *
+ * Eric Sosman pointed out that ctype functions take a parameter whose
+ * value must be that of an unsigned int, even on platforms that have
+ * negative chars in their default char type.
+ */
+
+#include <ctype.h>
+#include <string.h>
+#include <stdio.h>
+
+#include "strnatcmp.h"
+
+#define assert(x)   /* nothing */
+
+
+/* These are defined as macros to make it easier to adapt this code to
+ * different characters types or comparison functions. */
+static inline int
+nat_isdigit(char a)
+{
+     return isdigit((unsigned char) a);
+}
+
+
+static inline int
+nat_isspace(char a)
+{
+     return a == '0' || isspace((unsigned char) a);
+}
+
+
+static inline char
+nat_toupper(char a)
+{
+     return toupper((unsigned char) a);
+}
+
+
+
+static int
+compare_right(char const *a, char const *b)
+{
+     int bias = 0;
+     
+     /* The longest run of digits wins.  That aside, the greatest
+        value wins, but we can't know that it will until we've scanned
+        both numbers to know that they have the same magnitude, so we
+        remember it in BIAS. */
+     for (;; a++, b++) {
+          if (!nat_isdigit(*a)  &&  !nat_isdigit(*b))
+               return bias;
+          else if (!nat_isdigit(*a))
+               return -1;
+          else if (!nat_isdigit(*b))
+               return +1;
+          else if (*a < *b) {
+               if (!bias)
+                    bias = -1;
+          } else if (*a > *b) {
+               if (!bias)
+                    bias = +1;
+          } else if (!*a  &&  !*b)
+               return bias;
+     }
+
+     return 0;
+}
+
+
+static int
+compare_left(char const *a, char const *b)
+{
+     /* Compare two left-aligned numbers: the first to have a
+        different value wins. */
+     for (;; a++, b++) {
+          if (!nat_isdigit(*a)  &&  !nat_isdigit(*b))
+               return 0;
+          else if (!nat_isdigit(*a))
+               return -1;
+          else if (!nat_isdigit(*b))
+               return +1;
+          else if (*a < *b)
+               return -1;
+          else if (*a > *b)
+               return +1;
+     }
+          
+     return 0;
+}
+
+
+static int strnatcmp0(char const *a, char const *b, int fold_case)
+{
+     int ai, bi;
+     char ca, cb;
+     int fractional, result;
+     
+     assert(a && b);
+     ai = bi = 0;
+     while (1) {
+          ca = a[ai]; cb = b[bi];
+
+          /* skip over leading spaces or zeros */
+          while (nat_isspace(ca))
+               ca = a[++ai];
+
+          while (nat_isspace(cb))
+               cb = b[++bi];
+
+          /* process run of digits */
+          if (nat_isdigit(ca)  &&  nat_isdigit(cb)) {
+               fractional = (ca == '0' || cb == '0');
+
+               if (fractional) {
+                    if ((result = compare_left(a+ai, b+bi)) != 0)
+                         return result;
+               } else {
+                    if ((result = compare_right(a+ai, b+bi)) != 0)
+                         return result;
+               }
+          }
+
+          if (!ca && !cb) {
+               /* The strings compare the same.  Perhaps the caller
+                  will want to call strcmp to break the tie. */
+               return 0;
+          }
+
+          if (fold_case) {
+               ca = nat_toupper(ca);
+               cb = nat_toupper(cb);
+          }
+          
+          if (ca < cb)
+               return -1;
+          else if (ca > cb)
+               return +1;
+
+          ++ai; ++bi;
+     }
+}
+
+
+
+int strnatcmp(const char *a, const char *b) {
+     return strnatcmp0(a, b, 0);
+}
+
+
+/* Compare, recognizing numeric string and ignoring case. */
+int strnatcasecmp(const char *a, const char *b) {
+     return strnatcmp0(a, b, 1);
+}