refactor: using current_chunk()

src/compile.zig

@@ -62,6 +62,10 @@ const Parser = struct {
         };
     }
 
+    inline fn current_chunk(self: *Parser) *Chunk {
+        return self.chunk;
+    }
+
     fn advance(self: *Parser) void {
         self.previous = self.current;
 
@@ -117,7 +121,7 @@ const Parser = struct {
     }
 
     fn emit_byte(self: *Parser, byte: u8) ParsingError!void {
-        self.chunk.write(byte, self.previous.?.line) catch |err| {
+        self.current_chunk().write(byte, self.previous.?.line) catch |err| {
             switch (err) {
                 error.OutOfMemory => return ParsingError.OutOfMemory,
             }
@@ -135,7 +139,7 @@ const Parser = struct {
 
     fn end_parser(self: *Parser) !void {
         if (!self.had_error and self.vm.has_tracing()) {
-            self.chunk.dissassemble("code");
+            self.current_chunk().dissassemble("code");
         }
         try self.emit_return();
     }
@@ -162,7 +166,7 @@ const Parser = struct {
     }
 
     fn make_constant(self: *Parser, value: Value) !u8 {
-        const constant = try self.chunk.add_constant(value);
+        const constant = try self.current_chunk().add_constant(value);
         if (constant > constants.UINT8_MAX) {
             self.error_msg("Too many constants in one chunk.");
             return 0;
@@ -585,11 +589,11 @@ const Parser = struct {
         try self.emit_byte(0xff);
         try self.emit_byte(0xff);
 
-        return self.chunk.count - 2;
+        return self.current_chunk().count - 2;
     }
 
     fn patch_jump(self: *Parser, offset: usize) void {
-        const jump = self.chunk.count - offset - 2;
+        const jump = self.current_chunk().count - offset - 2;
 
         if (jump > constants.UINT16_MAX) {
             self.error_msg("Too much code to jump over.");
@@ -598,8 +602,8 @@ const Parser = struct {
         const b1 = (jump >> 8) & 0xff;
         const b0 = jump & 0xff;
 
-        self.chunk.code[offset] = @intCast(b1);
+        self.current_chunk().code[offset] = @intCast(b1);
-        self.chunk.code[offset + 1] = @intCast(b0);
+        self.current_chunk().code[offset + 1] = @intCast(b0);
     }
 
     fn and_(self: *Parser, can_assign: bool) ParsingError!void {
@@ -624,7 +628,7 @@ const Parser = struct {
     }
 
     fn while_statement(self: *Parser) ParsingError!void {
-        const loop_start = self.chunk.count;
+        const loop_start = self.current_chunk().count;
         self.consume(TokenType.LEFT_PAREN, "Expect '(' after 'while'.");
         try self.expression();
         self.consume(TokenType.RIGHT_PAREN, "Expect ')' after condition.");
@@ -640,7 +644,7 @@ const Parser = struct {
     fn emit_loop(self: *Parser, loop_start: usize) ParsingError!void {
         try self.emit_byte(@intFromEnum(OpCode.OP_LOOP));
 
-        const offset = self.chunk.count - loop_start + 2;
+        const offset = self.current_chunk().count - loop_start + 2;
         if (offset > constants.UINT16_MAX) {
             self.error_msg("Loop body too large.");
         }
@@ -661,7 +665,7 @@ const Parser = struct {
             try self.expression_statement();
         }
 
-        var loop_start = self.chunk.count;
+        var loop_start = self.current_chunk().count;
 
         var exit_jump: ?usize = null;
 
@@ -676,7 +680,7 @@ const Parser = struct {
 
         if (!self.match(TokenType.RIGHT_PAREN)) {
             const body_jump = try self.emit_jump(@intFromEnum(OpCode.OP_JUMP));
-            const increment_start = self.chunk.count;
+            const increment_start = self.current_chunk().count;
             try self.expression();
             try self.emit_byte(@intFromEnum(OpCode.OP_POP));
             self.consume(TokenType.RIGHT_PAREN, "Expect ')' after for clauses.");

src/object.zig

@@ -2,10 +2,13 @@ const std = @import("std");
 const debug = std.debug;
 const Allocator = std.mem.Allocator;
 
+const Chunk = @import("./chunk.zig").Chunk;
+
 const compute_hash = @import("./utils.zig").compute_hash;
 
 pub const ObjType = enum {
     String,
+    Function,
 };
 
 pub const Obj = struct {
@@ -13,8 +16,8 @@ pub const Obj = struct {
     allocator: std.mem.Allocator,
 
     pub const String = struct {
-        chars: []const u8,
         obj: Obj,
+        chars: []const u8,
         hash: u32,
 
         pub fn new(allocator: std.mem.Allocator, chars: []const u8) *String {
@@ -39,6 +42,33 @@ pub const Obj = struct {
         }
     };
 
+    pub const Function = struct {
+        obj: Obj,
+        arity: usize,
+        chunk: *Chunk,
+        name: *Obj.String,
+
+        pub fn new(allocator: std.mem.Allocator) *Function {
+            const obj = Obj{
+                .kind = ObjType.Function,
+                .allocator = allocator,
+            };
+
+            const function_obj = allocator.create(Function) catch unreachable;
+            function_obj.obj = obj;
+            function_obj.arity = 0;
+            function_obj.chunk = Chunk.new(allocator);
+
+            return function_obj;
+        }
+
+        pub fn destroy(self: *Function) void {
+            const allocator = self.obj.allocator;
+            self.chunk.deinit();
+            allocator.destroy(self);
+        }
+    };
+
     pub fn is_type(self: *Obj, kind: ObjType) bool {
         return self.kind == kind;
     }
@@ -47,12 +77,20 @@ pub const Obj = struct {
         return self.is_type(ObjType.String);
     }
 
+    pub fn is_function(self: *Obj) bool {
+        return self.is_function(ObjType.Function);
+    }
+
     pub fn print(self: *Obj) void {
         switch (self.kind) {
             ObjType.String => {
                 const obj = self.as_string();
                 debug.print("{s}", .{obj.chars});
             },
+            ObjType.Function => {
+                const obj = self.as_function();
+                debug.print("<fn {s}>", .{obj.name.chars});
+            },
         }
     }
 
@@ -62,6 +100,10 @@ pub const Obj = struct {
                 const obj: *String = @fieldParentPtr("obj", self);
                 obj.destroy();
             },
+            ObjType.Function => {
+                const obj: *Function = @fieldParentPtr("obj", self);
+                obj.destroy();
+            },
         }
     }
 
@@ -69,4 +111,9 @@ pub const Obj = struct {
         std.debug.assert(self.kind == ObjType.String);
         return @fieldParentPtr("obj", self);
     }
+
+    pub fn as_function(self: *Obj) *Function {
+        std.debug.assert(self.kind == ObjType.Function);
+        return @fieldParentPtr("obj", self);
+    }
 };

src/vm.zig

@@ -61,6 +61,10 @@ pub const VM = struct {
         self.references.deinit();
     }
 
+    inline fn current_chunk(self: *VM) *Chunk {
+        return self.chunk.?;
+    }
+
     pub fn set_trace(self: *VM, tracing: bool) void {
         self.tracing = tracing;
     }
@@ -96,7 +100,7 @@ pub const VM = struct {
                     }
                     debug.print("\n", .{});
                 }
-                _ = self.chunk.?.dissassemble_instruction(self.ip.?);
+                _ = self.current_chunk().dissassemble_instruction(self.ip.?);
             }
 
             const instruction = self.read_byte();
@@ -209,7 +213,7 @@ pub const VM = struct {
     // XXX In the book, we're using a ptr to data directly, to avoid dereferencing to a given offset
     // How to do that in Zig?
     pub fn read_byte(self: *VM) u8 {
-        const ret = self.chunk.?.code[self.ip.?];
+        const ret = self.current_chunk().code[self.ip.?];
         self.ip.? += 1;
 
         return ret;
@@ -218,11 +222,11 @@ pub const VM = struct {
     pub fn read_short(self: *VM) u16 {
         self.ip.? += 2;
 
-        return (@as(u16, self.chunk.?.code[self.ip.? - 2]) << 8) | (@as(u16, self.chunk.?.code[self.ip.? - 1]));
+        return (@as(u16, self.current_chunk().code[self.ip.? - 2]) << 8) | (@as(u16, self.current_chunk().code[self.ip.? - 1]));
     }
 
     pub fn read_constant(self: *VM) Value {
-        return self.chunk.?.constants.values[read_byte(self)];
+        return self.current_chunk().constants.values[read_byte(self)];
     }
 
     pub fn push(self: *VM, value: Value) !void {
@@ -269,7 +273,7 @@ pub const VM = struct {
         const b = self.pop().as_cstring();
         const a = self.pop().as_cstring();
 
-        const concat_str = try std.mem.concat(self.chunk.?.allocator, u8, &.{ a, b });
+        const concat_str = try std.mem.concat(self.current_chunk().allocator, u8, &.{ a, b });
 
         var string_obj = self.take_string(concat_str);
 
@@ -284,7 +288,7 @@ pub const VM = struct {
 
     pub fn runtime_error(self: *VM, err_msg: []const u8) void {
         const instruction = self.ip.?;
-        const line = self.chunk.?.lines[instruction];
+        const line = self.current_chunk().lines[instruction];
 
         debug.print("err: {s}\n", .{err_msg});
         debug.print("[line {d}] in script\n", .{line});