add a string replace method

ast/func_table.go

@@ -123,11 +123,9 @@ func (f Function) LazyParseFunction(args *Token) bool {
  * calls ParseFunction and increments TimesCalled
  */
 func (f Function) CallFunction(args *Token, vt VarTable, ft FuncTable) *Token {
-    var n_args *Token
+    n_args := args
     if !f.EvalLazy {
         n_args = args.Eval(ft, vt, f.SymLazy)
-    } else {
-        n_args = args
     }
 
     passes := false

stdlib/shell.go

@@ -225,6 +225,11 @@ func LaunchProcess(
  * Example (l vim file.txt)
  */
 func Call(in *ast.Token, vt ast.VarTable, ft ast.FuncTable) *ast.Token {
+    if in == nil {
+        log.Log(log.ERR, "no arguments given", "call")
+        return nil
+    }
+
     if in.Tag == ast.LIST {
         log.Log(log.ERR, "couldnt exec, target bin is a list", "call")
         return nil

stdlib/stdlib.go

@@ -178,6 +178,16 @@ func GenFuncTable() ast.FuncTable {
             },
         },
 
+        "replace": &ast.Function{
+            Function:   Replace,
+            Name:       "replace",
+            Args:   []ast.Token_t{
+                ast.STRING,
+                ast.STRING,
+                ast.STRING,
+            },
+        },
+
         "substr": &ast.Function{
             Function:   Substr,
             Name:       "substr",
@@ -283,6 +293,7 @@ func GenFuncTable() ast.FuncTable {
         "cd": &ast.Function{
             Function:   Cd,
             Name:       "changedir",
+            SymLazy:    true,
             Args:   []ast.Token_t{
                 ast.STRING,
             },

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