From 57ed9226c06b5fbe016e62857fe9662c51da3dfd Mon Sep 17 00:00:00 2001
From: Tom Willemse
Date: Thu, 2 Jun 2022 22:27:43 -0700
Subject: Chapter 25.3 & 25.4

---
 clox/src/compiler.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

(limited to 'clox/src/compiler.c')

diff --git a/clox/src/compiler.c b/clox/src/compiler.c
index 6e98b5e..75ed697 100644
--- a/clox/src/compiler.c
+++ b/clox/src/compiler.c
@@ -42,6 +42,7 @@ typedef struct {
 typedef struct {
   Token name;
   int depth;
+  bool isCaptured;
 } Local;
 
 typedef struct {
@@ -197,6 +198,7 @@ static void initCompiler(Compiler *compiler, FunctionType type) {
 
   Local *local = &current->locals[current->localCount++];
   local->depth = 0;
+  local->isCaptured = false;
   local->name.start = "";
   local->name.length = 0;
 }
@@ -224,7 +226,11 @@ static void endScope() {
 
   while (current->localCount > 0 &&
          current->locals[current->localCount - 1].depth > current->scopeDepth) {
-    emitByte(OP_POP);
+    if (current->locals[current->localCount - 1].isCaptured) {
+      emitByte(OP_CLOSE_UPVALUE);
+    } else {
+      emitByte(OP_POP);
+    }
     current->localCount--;
   }
 }
@@ -740,6 +746,7 @@ static int resolveUpvalue(Compiler *compiler, Token *name) {
 
   int local = resolveLocal(compiler->enclosing, name);
   if (local != -1) {
+    compiler->enclosing->locals[local].isCaptured = true;
     return addUpvalue(compiler, (uint8_t)local, true);
   }
 
@@ -760,6 +767,7 @@ static void addLocal(Token name) {
   Local *local = &current->locals[current->localCount++];
   local->name = name;
   local->depth = -1;
+  local->isCaptured = false;
 }
 
 static void declareVariable() {
-- 
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