ch26

examples/ch25-counter-closure.lox

@@ -0,0 +1,13 @@
+fun initCounter() {
+  var privateCounter = 0;
+  fun incr() {
+    privateCounter = privateCounter + 1;
+    return privateCounter;
+  }
+  return incr;
+}
+
+var count = initCounter();
+print(count());
+print(count());
+print(count());

src/compiler.zig

@@ -131,7 +131,7 @@ const FunctionType = enum {
     Script,
 };
 
-const Compiler = struct {
+pub const Compiler = struct {
     function: *ObjFunction,
     type_: FunctionType,
 
@@ -142,7 +142,7 @@ const Compiler = struct {
     upvalues: [U8_COUNT]Upvalue,
     scopeDepth: i16,
 
-    pub fn init(type_: FunctionType, om: *ObjManager, enclosing: *Compiler) !Compiler {
+    pub fn init(type_: FunctionType, om: *ObjManager, enclosing: ?*Compiler) !Compiler {
         var c = Compiler{
             .function = undefined, // see 24.2.1 .. revisit in light of garbage collector
             .type_ = type_,
@@ -171,10 +171,13 @@ pub fn compile(source: []u8, om: *ObjManager) !*ObjFunction {
     // startup -- could be comptime TODO
     initRules();
 
-    // setup the compiler
+    // save reference to object manager
     objManager = om;
-    var compiler = try Compiler.init(FunctionType.Script, objManager, current);
+
+    // setup the compiler
+    var compiler = try Compiler.init(FunctionType.Script, objManager, null);
     current = &compiler;
+    objManager.isCompilerInitialized = true;
 
     scanner = Scanner.init(source);
     parser = Parser{
@@ -900,6 +903,7 @@ fn endCompiler() *ObjFunction {
     } else {
         // we're at the top of the stack, so we're done
         // unsafe warning warning
+        objManager.isCompilerInitialized = false;
         current = undefined;
     }
 
@@ -989,3 +993,16 @@ fn emitByte(byte: u8) void {
 fn tokenString(token: Token) []const u8 {
     return scanner.source[token.start .. token.start + token.length];
 }
+
+// markCompilerRoots is for garbage collection
+pub fn markCompilerRoots() void {
+    if (debug.LOG_GC) print("-- gc: mark compiler roots\n", .{});
+
+    var compiler: *Compiler = current;
+    compiler.function.markObject(objManager);
+
+    while (compiler.enclosing != null) {
+        compiler = compiler.enclosing.?;
+        compiler.function.markObject(objManager);
+    }
+}

src/debug.zig

@@ -1,13 +1,17 @@
 // Debug Flags
 
 // global flag to enable/disable all
-const enable_debugging = false;
+const enable_debugging = true;
 
 // VM (Runtime)
-pub const TRACE_EXECUTION_INCLUDE_INSTRUCTIONS = enable_debugging and true;
+pub const TRACE_EXECUTION_INCLUDE_INSTRUCTIONS = enable_debugging and false;
 pub const TRACE_EXECUTION_SHOW_GET_SET_VARS = enable_debugging and false;
-pub const TRACE_EXECUTION_PRINT_STACK = enable_debugging and true;
+pub const TRACE_EXECUTION_PRINT_STACK = enable_debugging and false;
 
 // Compiler
 pub const PRINT_CODE_AFTER_END_COMPILER = enable_debugging and false; // TODO: try out comptime
 pub const TRACE_PARSER = enable_debugging and false;
+
+// Object Manager (esp Garbage Collection)
+pub const STRESS_GC = enable_debugging and true;
+pub const LOG_GC = enable_debugging and true;