std::strings:: add the Compare function

std/strings/compare.jule

@@ -0,0 +1,33 @@
+// Copyright 2024 The Jule Programming Language.
+// Use of this source code is governed by a BSD 3-Clause
+// license that can be found in the LICENSE file.
+
+// Returns an integer comparing two strings lexicographically.
+// The result will be 0 if a == b, -1 if a < b, and +1 if a > b.
+//
+// Use compare when you need to perform a three-way comparison (with
+// [slices::SortFunc], for example). It is usually clearer and always faster
+// to use the built-in string comparison operators ==, <, >, and so on.
+fn Compare(a: str, b: str): int {
+    mut l := len(a)
+    if len(b) < l {
+        l = len(b)
+    }
+    mut i := 0
+    for i < l; i++ {
+        c1, c2 := a[i], b[i]
+        if c1 < c2 {
+            ret -1
+        }
+        if c1 > c2 {
+            ret +1
+        }
+    }
+    if len(a) < len(b) {
+        ret -1
+    }
+    if len(a) > len(b) {
+        ret +1
+    }
+    ret 0
+}