add a string replace method

stdlib/string.go

@@ -84,6 +84,25 @@ func Split(in *ast.Token, vt ast.VarTable, ft ast.FuncTable) *ast.Token {
     return res
 }
 
+/* Takes three args
+ * 1. source string
+ * 2. token to be replaced
+ * 3. token to swap in place
+ * All three args are strings
+ * Returns final string
+ */
+func Replace(in *ast.Token, vt ast.VarTable, ft ast.FuncTable) *ast.Token {
+    body := in.Value()
+    sub := in.Next.Value()
+    tok := in.Next.Next.Value()
+
+    body = strings.ReplaceAll(body, sub, tok)
+
+    res := &ast.Token{Tag: ast.STRING}
+    res.Set(body)
+    return res
+}
+
 /* Takes two args, a delimiter and a list of strings
  * Returns the list of strings concatenated together with the delimiter in between each element
  * On error returns nil