Import Tcl-core 8.6.6 (as of svn r86089)

compat/strstr.c

@@ -0,0 +1,70 @@
+/*
+ * strstr.c --
+ *
+ *	Source code for the "strstr" library routine.
+ *
+ * Copyright (c) 1988-1993 The Regents of the University of California.
+ * Copyright (c) 1994 Sun Microsystems, Inc.
+ *
+ * See the file "license.terms" for information on usage and redistribution of
+ * this file, and for a DISCLAIMER OF ALL WARRANTIES.
+ */
+
+#include "tcl.h"
+#ifndef NULL
+#define NULL 0
+#endif
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * strstr --
+ *
+ *	Locate the first instance of a substring in a string.
+ *
+ * Results:
+ *	If string contains substring, the return value is the location of the
+ *	first matching instance of substring in string. If string doesn't
+ *	contain substring, the return value is 0. Matching is done on an exact
+ *	character-for-character basis with no wildcards or special characters.
+ *
+ * Side effects:
+ *	None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+char *
+strstr(
+    register char *string,	/* String to search. */
+    char *substring)		/* Substring to try to find in string. */
+{
+    register char *a, *b;
+
+    /*
+     * First scan quickly through the two strings looking for a
+     * single-character match. When it's found, then compare the rest of the
+     * substring.
+     */
+
+    b = substring;
+    if (*b == 0) {
+	return string;
+    }
+    for ( ; *string != 0; string += 1) {
+	if (*string != *b) {
+	    continue;
+	}
+	a = string;
+	while (1) {
+	    if (*b == 0) {
+		return string;
+	    }
+	    if (*a++ != *b++) {
+		break;
+	    }
+	}
+	b = substring;
+    }
+    return NULL;
+}