From 8a26ba535123529322793beb1214d7866ac5831a Mon Sep 17 00:00:00 2001
From: Andre Wagner <andre.nho@gmail.com>
Date: Sat, 9 May 2026 10:37:02 -0500
Subject: [PATCH] .

---
 lua-temp/TODO.md      |  6 +++---
 lua-temp/tests.lua    |  7 ++++---
 lua-temp/tyche-vm.lua | 23 ++++++++++++++++++-----
 3 files changed, 25 insertions(+), 11 deletions(-)

diff --git a/lua-temp/TODO.md b/lua-temp/TODO.md
index 853472c..dc3fbd7 100644
--- a/lua-temp/TODO.md
+++ b/lua-temp/TODO.md
@@ -11,9 +11,9 @@ Progress of the Lua port:
 - [x] Control flow
   - [x] Labels in Assembly
   - [x] Recursion
-- [ ] Strings
-  - [ ] From constants
-  - [ ] Garbage collection
+- [x] Strings
+  - [x] From constants
+  - [x] Garbage collection
 - [ ] Arrays
   - [ ] Garbage collection
 - [ ] Tables
diff --git a/lua-temp/tests.lua b/lua-temp/tests.lua
index 7c6ff6d..9eec2b1 100755
--- a/lua-temp/tests.lua
+++ b/lua-temp/tests.lua
@@ -302,7 +302,7 @@ do TEST "VM: managed strings"
     assert_eq(vm:to_string(-1), "Hello")
 end
 
-do TEST "VM: concatenate strings"
+do TEST "VM: concatenate strings (GC won't delete)"
     local vm = VM.new():load(assemble [[
         .const
             0: "Hello "
@@ -311,6 +311,7 @@ do TEST "VM: concatenate strings"
             pushc   0
             pushc   1
             sum
+            gc
             ret
     ]]):call(0)
 
@@ -319,7 +320,7 @@ do TEST "VM: concatenate strings"
     assert_eq(vm.heap:size(), 1)
 end
 
-do TEST "VM: collect strings"
+do TEST "VM: GC strings"
     local vm = VM.new():load(assemble [[
         .const
             0: "Hello "
@@ -334,7 +335,7 @@ do TEST "VM: collect strings"
             ret
     ]]):call(0)
 
-    print(vm:debug_heap())
+    -- print(vm:debug_heap())
     assert_eq(vm:is(-1, 'nil'), true)
     assert_eq(vm.heap:size(), 0)
 end
diff --git a/lua-temp/tyche-vm.lua b/lua-temp/tyche-vm.lua
index 86380cd..8fb6c61 100644
--- a/lua-temp/tyche-vm.lua
+++ b/lua-temp/tyche-vm.lua
@@ -221,8 +221,8 @@ function Heap.new()
 end
 
 function Heap:add_value(value)
-    local key = math.random(math.mininteger, math.maxinteger)
-    while self.items[key] do key = math.random(math.mininteger, math.maxinteger) end
+    local key = math.random(1, math.maxinteger)
+    while self.items[key] do key = math.random(1, math.maxinteger) end
     self.items[key] = value
     return key
 end
@@ -237,8 +237,21 @@ function Heap:size()
     return n
 end
 
-function Heap:call_gc()
-    -- TODO
+function Heap:call_gc(roots)
+    -- mark
+    local marked = {}
+    for _,v in ipairs(roots) do  -- TODO - recursive, add support to array
+        if v.type == 'string' and v.ref then
+            marked[v.ref] = true
+        end
+    end
+
+    -- sweep
+    for key,_ in pairs(self.items) do
+        if not marked[key] then
+            self.items[key] = nil
+        end
+    end
 end
 
 ----------------------
@@ -527,7 +540,7 @@ function VM:_step()
     --
     
     elseif op.operator == 'gc' then
-        self.heap:call_gc()
+        self.heap:call_gc(self.stack.stack)
 
     --
     -- instruction not found