From cd38f358d4f3a5d5437dca9c69d8824ee7d1d18b Mon Sep 17 00:00:00 2001
From: Fredrik Robertsen <fredrikr79@pm.me>
Date: Mon, 23 Feb 2026 18:55:15 +0100
Subject: [PATCH] ps3: task 3

---
 ps3/src/tree.c | 109 ++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 108 insertions(+), 1 deletion(-)

diff --git a/ps3/src/tree.c b/ps3/src/tree.c
index ae33280..c10e657 100644
--- a/ps3/src/tree.c
+++ b/ps3/src/tree.c
@@ -1,4 +1,5 @@
 #include "vslc.h"
+#include "bool.h"
 
 // Global root for abstract syntax tree
 node_t* root;
@@ -132,12 +133,14 @@ static node_t* convert_operator(node_t* node)
   assert(node->type == OPERATOR);
   switch (node->data.operator) {
   case "or":
+    free(node->data.operator);
     node->data.operator = "?:";
     node_t *new = node_create(NUMBER_LITERAL, 0);
     new->data.number_literal = 0;
     append_to_list_node(node, new);
     break;
   case "and":
+    free(node->data.operator);
     node->data.operator = "?:";
     node_t *new = node_create(NUMBER_LITERAL, 0);
     new->data.number_literal = 1;
@@ -154,7 +157,111 @@ static node_t* convert_operator(node_t* node)
 static node_t* constant_fold_operator(node_t* node)
 {
   assert(node->type == OPERATOR);
-  // TODO: Task 3: Implement this function
+  bool b = 1;
+  for (int i = 0; i < node->n_children; i++)
+    b &= node->children[i]->type == NUMBER_LITERAL;
+  if !b return;
+
+  node_t *a, *b, *c;
+  if (node->n_children == 1) {
+    a = node->children[0];
+    switch (node->data.operator) {
+    case "-":
+      free(node->data.operator);
+      node->type = NUMBER_LITERAL;
+      node->data.number_literal = -a->data.number_literal;
+      break;
+    case "!":
+      free(node->data.operator);
+      node->type = NUMBER_LITERAL;
+      node->data.number_literal = !a->data.number_literal;
+      break;
+    default:
+      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];
+    switch (node->data.operator) {
+    case "==":
+      free(node->data.operator);
+      node->type = NUMBER_LITERAL;
+      node->data.number_literal = a->data.number_literal == b->data.number_literal;
+      break;
+    case "!=":
+      free(node->data.operator);
+      node->type = NUMBER_LITERAL;
+      node->data.number_literal = a->data.number_literal != b->data.number_literal;
+      break;
+    case "<":
+      free(node->data.operator);
+      node->type = NUMBER_LITERAL;
+      node->data.number_literal = a->data.number_literal < b->data.number_literal;
+      break;
+    case "<=":
+      free(node->data.operator);
+      node->type = NUMBER_LITERAL;
+      node->data.number_literal = a->data.number_literal <= b->data.number_literal;
+      break;
+    case ">":
+      free(node->data.operator);
+      node->type = NUMBER_LITERAL;
+      node->data.number_literal = a->data.number_literal > b->data.number_literal;
+      break;
+    case ">=":
+      free(node->data.operator);
+      node->type = NUMBER_LITERAL;
+      node->data.number_literal = a->data.number_literal >= b->data.number_literal;
+      break;
+    case "+":
+      free(node->data.operator);
+      node->type = NUMBER_LITERAL;
+      node->data.number_literal = a->data.number_literal + b->data.number_literal;
+      break;
+    case "-":
+      free(node->data.operator);
+      node->type = NUMBER_LITERAL;
+      node->data.number_literal = a->data.number_literal - b->data.number_literal;
+      break;
+    case "*":
+      free(node->data.operator);
+      node->type = NUMBER_LITERAL;
+      node->data.number_literal = a->data.number_literal * b->data.number_literal;
+      break;
+    case "/":
+      free(node->data.operator);
+      node->type = NUMBER_LITERAL;
+      node->data.number_literal = a->data.number_literal / b->data.number_literal;
+      break;
+    default:
+      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];
+    switch (node->data.operator) {
+    case "?:":
+      free(node->data.operator);
+      node->type = NUMBER_LITERAL;
+      node->data.number_literal = a->data.number_literal ? b->data.number_literal : c->data.number_literal;
+      break;
+    default:
+      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;
 }