Line information

src/chunk.zig

@@ -5,10 +5,12 @@ const ValueArray = value.ValueArray;
 
 pub const OpCode = enum(u8) {
     OP_RETURN,
+    OP_CONSTANT,
 };
 
 pub const Chunk = struct {
     code: []u8,
+    lines: []u32,
     count: usize,
     capacity: usize,
     constants: ValueArray,
@@ -21,30 +23,26 @@ pub const Chunk = struct {
             .capacity = 0,
             .allocator = allocator,
             .code = try allocator.alloc(u8, 0),
+            .lines = try allocator.alloc(u32, 0),
             .constants = try ValueArray.init(allocator),
         };
     }
 
     /// Writes a byte to this chunk
-    pub fn write(self: *Chunk, byte: u8) !void {
+    pub fn write(self: *Chunk, byte: u8, line: u32) !void {
         // If the code slice is full
         if (self.count == self.capacity) {
             const old_capacity = self.capacity;
             self.capacity = grow_capacity(old_capacity);
             self.code = try self.allocator.realloc(self.code, self.capacity);
+            self.lines = try self.allocator.realloc(self.lines, self.capacity);
         }
 
         self.code[self.count] = byte;
+        self.lines[self.count] = line;
         self.count += 1;
     }
 
-    /// Reinitializes the state of the chunk.
-    pub fn free_chunck(self: *Chunk) !void {
-        self.count = 0;
-        self.capacity = 0;
-        self.code = try self.allocator.realloc(self.code, 0);
-    }
-
     /// Prints the current state of the chunk to stderr
     pub fn dissasemble_chunk(self: *Chunk, name: []const u8) void {
         print("== {s} ==\n", .{name});
@@ -59,9 +57,17 @@ pub const Chunk = struct {
     fn dissasemble_instruction(self: *Chunk, offset: usize) usize {
         print("{d:0>4} ", .{offset});
 
+        // Print the line number
+        if (offset > 0 and self.lines[offset] == self.lines[offset - 1]) {
+            print("   | ", .{});
+        } else {
+            print("{d: >4} ", .{self.lines[offset]});
+        }
+
         const instruction = self.code[offset];
         switch (instruction) {
             @intFromEnum(OpCode.OP_RETURN) => return simple_instruction("OP_RETURN", offset),
+            @intFromEnum(OpCode.OP_CONSTANT) => return self.constant_instruction("OP_CONSTANT", offset),
             else => {
                 print("unknown opcode {d}\n", .{instruction});
                 return offset + 1;
@@ -76,8 +82,19 @@ pub const Chunk = struct {
     /// Destroys this chunk
     pub fn deinit(self: Chunk) void {
         self.allocator.free(self.code);
+        self.allocator.free(self.lines);
         self.constants.deinit();
     }
+
+    fn constant_instruction(self: *Chunk, comptime name: []const u8, offset: usize) usize {
+        const constant_addr = self.code[offset + 1];
+        const constant_value = self.constants.values[constant_addr];
+
+        print("{s: <16} {d: >4} '", .{ name, constant_addr });
+        print_value(constant_value);
+        print("'\n", .{});
+        return offset + 2;
+    }
 };
 
 fn simple_instruction(comptime name: []const u8, offset: usize) usize {
@@ -85,6 +102,10 @@ fn simple_instruction(comptime name: []const u8, offset: usize) usize {
     return offset + 1;
 }
 
+fn print_value(v: value.Value) void {
+    print("{d}", .{v});
+}
+
 inline fn grow_capacity(old: usize) usize {
     return if (old < 8) 8 else old * 2;
 }

src/main.zig

@@ -1,5 +1,6 @@
 const std = @import("std");
 const chunk = @import("./chunk.zig");
+const OpCode = chunk.OpCode;
 
 pub fn main() !void {
     // Prints to stderr (it's a shortcut based on `std.io.getStdErr()`)
@@ -11,10 +12,12 @@ pub fn main() !void {
     var c = try chunk.Chunk.init(alloc);
     defer c.deinit();
 
-    try c.write(@intFromEnum(chunk.OpCode.OP_RETURN));
-    try c.write(@intFromEnum(chunk.OpCode.OP_RETURN));
+    const constant_idx = try c.add_constant(1.2);
+    try c.write(@intFromEnum(OpCode.OP_CONSTANT), 1);
+    try c.write(@truncate(constant_idx), 1);
+
+    try c.write(@intFromEnum(chunk.OpCode.OP_RETURN), 1);
 
-    _ = try c.add_constant(0.0);
     c.dissasemble_chunk("test chunk");
 }
 
@@ -22,9 +25,8 @@ test "chunk test" {
     var c = try chunk.Chunk.init(std.testing.allocator);
     defer c.deinit();
 
-    try c.write('a');
-    try c.write('b');
-    try c.free_chunck();
-    try c.write('J');
-    try c.write('H');
+    try c.write('a', 0);
+    try c.write('b', 1);
+    try c.write('J', 2);
+    try c.write('H', 3);
 }