+
+/* Decompose FILENAME in four parts: *BASE, *TAB, and *EXT, the fourth
+ part, (the directory) is ranging from FILENAME to the char before
+ *BASE, so we don't need an additional parameter.
+
+ *EXT points to the last period in the basename, or NULL if none.
+
+ If there is no *EXT, *TAB is NULL. Otherwise, *TAB points to
+ `.tab' or `_tab' if present right before *EXT, or is NULL. *TAB
+ cannot be equal to *BASE.
+
+ None are allocated, they are simply pointers to parts of FILENAME.
+ Examples:
+
+ '/tmp/foo.tab.c' -> *BASE = 'foo.tab.c', *TAB = '.tab.c', *EXT =
+ '.c'
+
+ 'foo.c' -> *BASE = 'foo.c', *TAB = NULL, *EXT = '.c'
+
+ 'tab.c' -> *BASE = 'tab.c', *TAB = NULL, *EXT = '.c'
+
+ '.tab.c' -> *BASE = '.tab.c', *TAB = NULL, *EXT = '.c'
+
+ 'foo.tab' -> *BASE = 'foo.tab', *TAB = NULL, *EXT = '.tab'
+
+ 'foo_tab' -> *BASE = 'foo_tab', *TAB = NULL, *EXT = NULL
+
+ 'foo' -> *BASE = 'foo', *TAB = NULL, *EXT = NULL. */
+
+static void
+filename_split (const char *filename,
+ const char **base, const char **tab, const char **ext)
+{
+ *base = base_name (filename);
+
+ /* Look for the extension, i.e., look for the last dot. */
+ *ext = strrchr (*base, '.');
+ *tab = NULL;
+
+ /* If there is an extension, check if there is a `.tab' part right
+ before. */
+ if (*ext)
+ {
+ size_t baselen = *ext - *base;
+ size_t dottablen = 4;
+ if (dottablen < baselen
+ && (strncmp (*ext - dottablen, ".tab", dottablen) == 0
+ || strncmp (*ext - dottablen, "_tab", dottablen) == 0))
+ *tab = *ext - dottablen;
+ }
+}
+