diff --git a/README.md b/README.md index 66d4871..22f3b85 100644 --- a/README.md +++ b/README.md @@ -9,7 +9,7 @@ While reading [Crafting Interpreters](https://craftinginterpreters.com/), after - [x] 16 - Scanning on Demand - [x] 17 - Compiling Expressions - [x] 18 - Types of Values -- [ ] 19 - Strings +- [x] 19 - Strings - [ ] 20 - Hash Tables - [ ] 21 - Global Variables - [ ] 22 - Local Variables diff --git a/src/compile.zig b/src/compile.zig index f59a0dc..9118a42 100644 --- a/src/compile.zig +++ b/src/compile.zig @@ -2,12 +2,16 @@ const std = @import("std"); const debug = std.debug; const Allocator = std.mem.Allocator; +const Obj = @import("./object.zig").Obj; +const ObjType = @import("./object.zig").ObjType; + const OpCode = @import("./opcode.zig").OpCode; const Scanner = @import("./scanner.zig").Scanner; const Token = @import("./scanner.zig").Token; const TokenType = @import("./scanner.zig").TokenType; const Chunk = @import("./chunk.zig").Chunk; const Value = @import("./values.zig").Value; +const VM = @import("./vm.zig").VM; const ParsingError = @import("./errors.zig").ParsingError; @@ -40,8 +44,9 @@ const Parser = struct { had_error: bool, panic_mode: bool, chunk: *Chunk, + vm: *VM, - fn new(scanner: *Scanner, chunk: *Chunk) Parser { + fn new(vm: *VM, scanner: *Scanner, chunk: *Chunk) Parser { return Parser{ .current = null, .previous = null, @@ -49,6 +54,7 @@ const Parser = struct { .had_error = false, .panic_mode = false, .chunk = chunk, + .vm = vm, }; } @@ -232,7 +238,7 @@ const Parser = struct { TokenType.LESS => ParserRule{ .prefix = null, .infix = binary, .precedence = Precedence.Comparison }, TokenType.LESS_EQUAL => ParserRule{ .prefix = null, .infix = binary, .precedence = Precedence.Comparison }, TokenType.IDENTIFIER => ParserRule{ .prefix = null, .infix = null, .precedence = Precedence.None }, - TokenType.STRING => ParserRule{ .prefix = null, .infix = null, .precedence = Precedence.None }, + TokenType.STRING => ParserRule{ .prefix = string, .infix = null, .precedence = Precedence.None }, TokenType.NUMBER => ParserRule{ .prefix = number, .infix = null, .precedence = Precedence.None }, TokenType.AND => ParserRule{ .prefix = null, .infix = null, .precedence = Precedence.None }, TokenType.CLASS => ParserRule{ .prefix = null, .infix = null, .precedence = Precedence.None }, @@ -281,13 +287,22 @@ const Parser = struct { else => unreachable, }; } + + fn string(self: *Parser) ParsingError!void { + const str = self.previous.?.start[1 .. self.previous.?.length - 1]; + var string_obj = Obj.String.new(self.chunk.allocator, str); + + self.vm.add_reference(&string_obj.obj); + + try self.emit_constant(Value.obj_val(&string_obj.obj)); + } }; -pub fn compile(allocator: Allocator, contents: []const u8, chunk: *Chunk) !bool { +pub fn compile(allocator: Allocator, vm: *VM, contents: []const u8, chunk: *Chunk) !bool { _ = allocator; var scanner = Scanner.init(contents); - var parser = Parser.new(&scanner, chunk); + var parser = Parser.new(vm, &scanner, chunk); parser.advance(); try parser.expression(); diff --git a/src/object.zig b/src/object.zig new file mode 100644 index 0000000..760e530 --- /dev/null +++ b/src/object.zig @@ -0,0 +1,67 @@ +const std = @import("std"); +const debug = std.debug; +const Allocator = std.mem.Allocator; + +pub const ObjType = enum { + String, +}; + +pub const Obj = struct { + kind: ObjType, + allocator: std.mem.Allocator, + + pub const String = struct { + chars: []const u8, + obj: Obj, + + pub fn new(allocator: std.mem.Allocator, str: []const u8) *String { + const obj = Obj{ + .kind = ObjType.String, + .allocator = allocator, + }; + + const str_obj = allocator.create(String) catch unreachable; + str_obj.obj = obj; + str_obj.chars = allocator.dupe(u8, str) catch unreachable; + + return str_obj; + } + + pub fn destroy(self: *String) void { + const allocator = self.obj.allocator; + allocator.free(self.chars); + allocator.destroy(self); + } + }; + + pub fn is_type(self: *Obj, kind: ObjType) bool { + return self.kind == kind; + } + + pub fn is_string(self: *Obj) bool { + return self.is_type(ObjType.String); + } + + pub fn print(self: *Obj) void { + switch (self.kind) { + ObjType.String => { + const obj = self.as_string(); + debug.print("{s}", .{obj.chars}); + }, + } + } + + pub fn destroy(self: *Obj) void { + switch (self.kind) { + ObjType.String => { + const obj: *String = @fieldParentPtr("obj", self); + obj.destroy(); + }, + } + } + + pub fn as_string(self: *Obj) *String { + std.debug.assert(self.kind == ObjType.String); + return @fieldParentPtr("obj", self); + } +}; diff --git a/src/values.zig b/src/values.zig index 5ab8c3c..e5f40f0 100644 --- a/src/values.zig +++ b/src/values.zig @@ -3,12 +3,14 @@ const debug = std.debug; const Allocator = std.mem.Allocator; +const Obj = @import("./object.zig").Obj; const utils = @import("./utils.zig"); pub const ValueType = enum { Bool, Nil, Number, + Obj, }; pub const Value = struct { @@ -16,6 +18,7 @@ pub const Value = struct { as: union { boolean: bool, number: f64, + obj: *Obj, }, pub fn bool_val(value: bool) Value { @@ -45,6 +48,15 @@ pub const Value = struct { }; } + pub fn obj_val(obj: *Obj) Value { + return Value{ + .value_type = ValueType.Obj, + .as = .{ + .obj = obj, + }, + }; + } + pub fn as_bool(self: Value) bool { return self.as.boolean; } @@ -53,6 +65,22 @@ pub const Value = struct { return self.as.number; } + pub fn as_obj(self: Value) *Obj { + return self.as.obj; + } + + pub fn as_string(self: Value) *Obj.String { + const obj: *Obj.String = self.as_obj(); + + return obj; + } + + pub fn as_cstring(self: Value) []const u8 { + const obj: *Obj.String = self.as_obj().as_string(); + + return obj.chars; + } + pub fn is_bool(self: Value) bool { return self.value_type == ValueType.Bool; } @@ -65,6 +93,14 @@ pub const Value = struct { return self.value_type == ValueType.Nil; } + pub fn is_obj(self: Value) bool { + return self.value_type == ValueType.Obj; + } + + pub fn is_string(self: Value) bool { + return self.is_obj() and self.as_obj().is_string(); + } + pub fn is_falsey(self: Value) bool { return self.is_nil() or (self.is_bool() and !self.as_bool()); } @@ -78,6 +114,12 @@ pub const Value = struct { ValueType.Nil => true, ValueType.Bool => self.as_bool() == other.as_bool(), ValueType.Number => self.as_number() == other.as_number(), + ValueType.Obj => { + const obj_string0 = self.as_cstring(); + const obj_string1 = other.as_cstring(); + + return std.mem.eql(u8, obj_string0, obj_string1); + }, }; } }; @@ -118,5 +160,6 @@ pub fn print_value(value: Value) void { ValueType.Nil => debug.print("nil", .{}), ValueType.Bool => debug.print("{any}", .{value.as_bool()}), ValueType.Number => debug.print("{d}", .{value.as_number()}), + ValueType.Obj => value.as_obj().print(), } } diff --git a/src/vm.zig b/src/vm.zig index a5943a7..835455d 100644 --- a/src/vm.zig +++ b/src/vm.zig @@ -5,6 +5,7 @@ const Allocator = std.mem.Allocator; const Chunk = @import("./chunk.zig").Chunk; const OpCode = @import("./opcode.zig").OpCode; const Value = @import("./values.zig").Value; +const Obj = @import("./object.zig").Obj; const compile = @import("./compile.zig").compile; @@ -24,24 +25,30 @@ pub const VM = struct { chunk: ?*Chunk, ip: ?usize, stack: std.ArrayList(Value), + // Keeping creating objects in references to destroy objects on cleaning. + // In the book, a linked list between objects is used to handle this. + references: std.ArrayList(*Obj), pub fn new(allocator: Allocator) VM { return VM{ .chunk = null, .ip = null, .stack = std.ArrayList(Value).init(allocator), + .references = std.ArrayList(*Obj).init(allocator), }; } pub fn free(self: *VM) void { self.stack.deinit(); + self.clean_references(); + self.references.deinit(); } pub fn interpret(self: *VM, allocator: Allocator, content: []const u8) !InterpretResult { var chunk = Chunk.new(allocator); defer chunk.deinit(); - const res = try compile(allocator, content, &chunk); + const res = try compile(allocator, self, content, &chunk); if (!res) { return InterpretResult.COMPILE_ERROR; } @@ -77,7 +84,13 @@ pub const VM = struct { @intFromEnum(OpCode.OP_NIL) => try self.push(Value.nil_val()), @intFromEnum(OpCode.OP_FALSE) => try self.push(Value.bool_val(false)), @intFromEnum(OpCode.OP_TRUE) => try self.push(Value.bool_val(true)), - @intFromEnum(OpCode.OP_ADD), @intFromEnum(OpCode.OP_SUBSTRACT), @intFromEnum(OpCode.OP_MULTIPLY), @intFromEnum(OpCode.OP_DIVIDE), @intFromEnum(OpCode.OP_LESS), @intFromEnum(OpCode.OP_GREATER) => { + @intFromEnum(OpCode.OP_ADD), + @intFromEnum(OpCode.OP_SUBSTRACT), + @intFromEnum(OpCode.OP_MULTIPLY), + @intFromEnum(OpCode.OP_DIVIDE), + @intFromEnum(OpCode.OP_LESS), + @intFromEnum(OpCode.OP_GREATER), + => { const res = try self.binary_op(@enumFromInt(instruction)); if (res != InterpretResult.OK) { return res; @@ -133,8 +146,13 @@ pub const VM = struct { } pub fn binary_op(self: *VM, op: OpCode) !InterpretResult { + if (op == OpCode.OP_ADD and self.peek(0).is_string() and self.peek(1).is_string()) { + try self.concatenate(); + return InterpretResult.OK; + } + if (!self.peek(0).is_number() or !self.peek(0).is_number()) { - self.runtime_error("Operands must be numbers"); + self.runtime_error("Operands must be two numbers or two strings"); return InterpretResult.RUNTIME_ERROR; } @@ -156,6 +174,20 @@ pub const VM = struct { return InterpretResult.OK; } + pub fn concatenate(self: *VM) !void { + 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 }); + defer self.chunk.?.allocator.free(concat_str); + + var string_obj = Obj.String.new(self.chunk.?.allocator, concat_str); + + self.add_reference(&string_obj.obj); + + try self.push(Value.obj_val(&string_obj.obj)); + } + pub fn peek(self: *VM, distance: usize) Value { return self.stack.items[self.stack.items.len - 1 - distance]; } @@ -167,4 +199,15 @@ pub const VM = struct { debug.print("err: {s}\n", .{err_msg}); debug.print("[line {d}] in script\n", .{line}); } + + pub fn add_reference(self: *VM, obj: *Obj) void { + // XXX TODO catch unreachable to prevents + self.references.append(obj) catch unreachable; + } + + pub fn clean_references(self: *VM) void { + for (self.references.items) |item| { + item.destroy(); + } + } };