constant folding works

ps3/src/tree.c

@@ -131,8 +131,8 @@ static void node_print(node_t* node, int nesting)
 static node_t* convert_operator(node_t* node)
 {
   assert(node->type == OPERATOR);
-  assert(node->children[0] && node->children[1]);
   if (strcmp(node->data.operator, "or") == 0) {
+    assert(node->children[0] && node->children[1]);
     node_t *one = node_create(NUMBER_LITERAL, 0);
     one->data.number_literal = 1;
     node_t *converted_op = node_create(OPERATOR, 3, node->children[0], one, node->children[1]);
@@ -140,6 +140,7 @@ static node_t* convert_operator(node_t* node)
     node_finalize(node);
     node = converted_op;
   } else if (strcmp(node->data.operator, "and") == 0) {
+    assert(node->children[0] && node->children[1]);
     node_t *zero = node_create(NUMBER_LITERAL, 0);
     zero->data.number_literal = 0;
     node_t *converted_op = node_create(OPERATOR, 3, node->children[0], node->children[1], zero);
@@ -158,92 +159,65 @@ static node_t* constant_fold_operator(node_t* node)
   assert(node->type == OPERATOR);
   for (int i = 0; i < node->n_children; i++)
     assert(node->children[i]->type == NUMBER_LITERAL);
-
-  node_t *a, *b, *c;
+  
+  node_t *a, *b, *c, *result;
   if (node->n_children == 1) {
     a = node->children[0];
+    result = node_create(NUMBER_LITERAL, 0);
     if (strcmp(node->data.operator, "-") == 0) {
-      free(node->data.operator);
-      node->type = NUMBER_LITERAL;
-      node->data.number_literal = -a->data.number_literal;
+      result->data.number_literal = -a->data.number_literal;
     } else if (strcmp(node->data.operator, "!") == 0) {
-      free(node->data.operator);
-      node->type = NUMBER_LITERAL;
-      node->data.number_literal = !a->data.number_literal;
+      result->data.number_literal = !a->data.number_literal;
     } else {
       fprintf(stderr, "folding: unexpected unary operator");
       exit(1);
     }
-    destroy_subtree(a);
   } else if (node->n_children == 2) {
     a = node->children[0];
     b = node->children[1];
+    result = node_create(NUMBER_LITERAL, 0);
     if (strcmp(node->data.operator, "==") == 0) {
-      free(node->data.operator);
-      node->type = NUMBER_LITERAL;
-      node->data.number_literal = a->data.number_literal == b->data.number_literal;
+      result->data.number_literal = a->data.number_literal == b->data.number_literal;
     } else if (strcmp(node->data.operator, "!=") == 0) {
-      free(node->data.operator);
-      node->type = NUMBER_LITERAL;
-      node->data.number_literal = a->data.number_literal != b->data.number_literal;
+      result->data.number_literal = a->data.number_literal != b->data.number_literal;
     } else if (strcmp(node->data.operator, "<") == 0) {
-      free(node->data.operator);
-      node->type = NUMBER_LITERAL;
-      node->data.number_literal = a->data.number_literal < b->data.number_literal;
+      result->data.number_literal = a->data.number_literal < b->data.number_literal;
     } else if (strcmp(node->data.operator, "<=") == 0) {
-      free(node->data.operator);
-      node->type = NUMBER_LITERAL;
-      node->data.number_literal = a->data.number_literal <= b->data.number_literal;
+      result->data.number_literal = a->data.number_literal <= b->data.number_literal;
     } else if (strcmp(node->data.operator, ">") == 0) {
-      free(node->data.operator);
-      node->type = NUMBER_LITERAL;
-      node->data.number_literal = a->data.number_literal > b->data.number_literal;
+      result->data.number_literal = a->data.number_literal > b->data.number_literal;
     } else if (strcmp(node->data.operator, ">=") == 0) {
-      free(node->data.operator);
-      node->type = NUMBER_LITERAL;
-      node->data.number_literal = a->data.number_literal >= b->data.number_literal;
+      result->data.number_literal = a->data.number_literal >= b->data.number_literal;
     } else if (strcmp(node->data.operator, "+") == 0) {
-      free(node->data.operator);
-      node->type = NUMBER_LITERAL;
-      node->data.number_literal = a->data.number_literal + b->data.number_literal;
+      result->data.number_literal = a->data.number_literal + b->data.number_literal;
     } else if (strcmp(node->data.operator, "-") == 0) {
-      free(node->data.operator);
-      node->type = NUMBER_LITERAL;
-      node->data.number_literal = a->data.number_literal - b->data.number_literal;
+      result->data.number_literal = a->data.number_literal - b->data.number_literal;
     } else if (strcmp(node->data.operator, "*") == 0) {
-      free(node->data.operator);
-      node->type = NUMBER_LITERAL;
-      node->data.number_literal = a->data.number_literal * b->data.number_literal;
+      result->data.number_literal = a->data.number_literal * b->data.number_literal;
     } else if (strcmp(node->data.operator, "/") == 0) {
-      free(node->data.operator);
-      node->type = NUMBER_LITERAL;
-      node->data.number_literal = a->data.number_literal / b->data.number_literal;
+      result->data.number_literal = a->data.number_literal / b->data.number_literal;
     } else {
       fprintf(stderr, "folding: unexpected binary operator");
       exit(1);
     }
-    destroy_subtree(a);
-    destroy_subtree(b);
   } else if (node->n_children == 3) {
     a = node->children[0];
     b = node->children[1];
     c = node->children[2];
+    result = node_create(NUMBER_LITERAL, 0);
     if (strcmp(node->data.operator, "?:") == 0) {
-      free(node->data.operator);
-      node->type = NUMBER_LITERAL;
-      node->data.number_literal = a->data.number_literal ? b->data.number_literal : c->data.number_literal;
+      result->data.number_literal = a->data.number_literal ? b->data.number_literal : c->data.number_literal;
     } else {
       fprintf(stderr, "folding: unexpected trinary operator");
       exit(1);
     }
-    destroy_subtree(a);
-    destroy_subtree(b);
-    destroy_subtree(c);
   } else {
     fprintf(stderr, "folding: unexpected number of children: %d", node->n_children);
   }
 
-  return node;
+  destroy_subtree(node);
+  
+  return result;
 }
 
 // Convert PRINTLN_STATEMENT into PRINT_STATEMENT by appending an extra "\n"