fix bug in repeated function calls

ast/eval.go

@@ -43,17 +43,16 @@ func (in *Token) Eval(funcs FuncTable, vars VarTable, cnvtUndefVars bool) *Token
 
     switch in.Tag {
     case BOOL, NUMBER, STRING:
-        res = in
+        res = in.Copy()
 
     case SYMBOL:
         res = GetVar(in.Value(), vars)
         if res == nil {
-            res = in
+            res = in.Copy()
 
             if GetFunction(in.Value(), funcs) == nil {
                 if cnvtUndefVars {
-                    in.Tag = STRING
+                    res.Tag = STRING
-                    res = in
                     break
                 }
 
@@ -63,19 +62,17 @@ func (in *Token) Eval(funcs FuncTable, vars VarTable, cnvtUndefVars bool) *Token
                 return nil
             }
         }
-        res.Next = in.Next
-
 
     case LIST:
         inner := in.Expand()
         if inner == nil {
-            res = in
+            res = in.Copy()
             break
         }
 
         if inner.Tag != SYMBOL {
             in.Direct(inner.Eval(funcs, vars, cnvtUndefVars))
-            res = in
+            res = in.Copy()
             break
         }
 

ast/token.go

@@ -48,6 +48,18 @@ func (t *Token) Append(arg *Token) {
     }
 }
 
+/* Shallow Copy
+ * in case of a LIST,
+ * inner will point to the same list.
+ */
+func (t *Token) Copy() *Token {
+    return &Token{
+        Tag: t.Tag,
+        inner: t.inner,
+        Next: t.Next,
+    }
+}
+
 /* Print function which is better suited for repl.
  * This one prints the SEXPRs as one would write them.
  * Does not evaluate tokens.

stdlib/funcs.go

@@ -60,8 +60,8 @@ func decl_func(input *ast.Token, vars ast.VarTable, funcs ast.FuncTable) *ast.To
 
     ASTSYNCSTATE := ast.SyncTablesWithOSEnviron
     inner := func(in *ast.Token, vt ast.VarTable, ft ast.FuncTable) *ast.Token {
-        in = in.Eval(ft, vt, false)
+        temp := in.Eval(ft, vt, false)
-        if in == nil {
+        if temp == nil {
             log.Log(log.ERR,
                 "error parsing arguments",
                 name.Value())
@@ -70,7 +70,7 @@ func decl_func(input *ast.Token, vars ast.VarTable, funcs ast.FuncTable) *ast.To
 
         ast.SyncTablesWithOSEnviron = false
         key_iter := args.Expand()
-        val_iter := in
+        val_iter := temp
 
         for key_iter != nil {
             if val_iter == nil {