711 lines
23 KiB
Zig
711 lines
23 KiB
Zig
//! Virtual machine state for story execution.
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const std = @import("std");
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const tokenizer = @import("tokenizer.zig");
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const Ast = @import("Ast.zig");
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const AstGen = @import("AstGen.zig");
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const Module = @import("compile.zig").Module;
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pub const Object = @import("Story/Object.zig");
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const Dumper = @import("Story/Dumper.zig");
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const assert = std.debug.assert;
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const Story = @This();
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allocator: std.mem.Allocator,
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dump_writer: ?*std.Io.Writer = null,
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is_exited: bool = false,
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can_advance: bool = false,
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choice_index: usize = 0,
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current_choices: std.ArrayListUnmanaged(Choice) = .empty,
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code_chunks: std.ArrayListUnmanaged(*Object.Code) = .empty,
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constants_pool: std.ArrayListUnmanaged(Value) = .empty,
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globals: std.StringHashMapUnmanaged(?Value) = .empty,
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stack: std.ArrayListUnmanaged(?Value) = .empty,
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call_stack: std.ArrayListUnmanaged(CallFrame) = .empty,
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stack_max: usize = 128,
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gc_objects: std.SinglyLinkedList = .{},
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// FIXME: This was a hack to keep string bytes alive.
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string_bytes: []const u8 = &.{},
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pub const default_knot_name: [:0]const u8 = "$__main__$";
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pub const Value = union(enum) {
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bool: bool,
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int: i64,
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float: f64,
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object: *Object,
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pub fn tagBytes(v: Value) []const u8 {
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return switch (v) {
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.bool => "Bool",
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.int => "Int",
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.float => "Float",
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.object => "Object",
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};
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}
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pub fn isNumeric(v: Value) bool {
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return v == .int or v == .float;
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}
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pub fn isTruthy(v: Value) bool {
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return switch (v) {
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//.nil => false,
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.bool => |b| b,
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.int => |i| i != 0,
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.float => |f| f != 0.0,
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.object => true,
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};
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}
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pub fn toFloat(v: Value) f64 {
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return switch (v) {
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.int => |i| @floatFromInt(i),
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.float => |f| f,
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else => unreachable,
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};
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}
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pub fn add(lhs: Value, rhs: Value, story: *Story) !Value {
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return arith(lhs, rhs, .add, story);
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}
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pub fn arith(lhs: Value, rhs: Value, op: Opcode, story: *Story) !Value {
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if (lhs.isNumeric() and rhs.isNumeric())
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return numericArith(lhs, rhs, op);
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if (op == .add) {
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if (lhs == .object and lhs.object.tag == .string)
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return concat(lhs, rhs, story);
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if (rhs == .object and rhs.object.tag == .string)
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return concat(lhs, rhs, story);
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}
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return error.TypeError;
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}
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pub fn numericArith(lhs: Value, rhs: Value, op: Story.Opcode) !Value {
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if (!lhs.isNumeric() or !rhs.isNumeric()) return error.TypeError;
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if (lhs == .int and rhs == .int) {
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switch (op) {
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.add => return .{ .int = lhs.int +% rhs.int },
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.sub => return .{ .int = lhs.int -% rhs.int },
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.mul => return .{ .int = lhs.int *% rhs.int },
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.div => {
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if (rhs.int == 0)
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return error.DivisionByZero;
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return .{ .int = @divTrunc(lhs.int, rhs.int) };
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},
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.mod => if (rhs.int == 0)
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return error.DivisionByZero
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else
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return .{ .int = @mod(lhs.int, rhs.int) },
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else => unreachable,
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}
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}
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const l = lhs.toFloat();
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const r = rhs.toFloat();
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switch (op) {
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.add => return .{ .float = l + r },
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.sub => return .{ .float = l - r },
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.mul => return .{ .float = l * r },
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.div => if (r == 0.0)
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return error.DivisionByZero
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else
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return .{ .float = l / r },
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.mod => if (r == 0.0)
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return error.DivisionByZero
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else
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return .{ .float = @mod(l, r) },
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else => unreachable,
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}
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}
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pub fn eql(lhs: Value, rhs: Value) bool {
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return switch (lhs) {
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.bool => |l| rhs == .bool and l == rhs.bool,
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.int => |l| switch (rhs) {
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.int => |r| l == r,
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.float => |r| @as(f64, @floatFromInt(l)) == r,
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else => false,
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},
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.float => |l| switch (rhs) {
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.int => |r| l == @as(f64, @floatFromInt(r)),
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.float => |r| l == r,
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else => false,
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},
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.object => |l| rhs == .object and l == rhs.object,
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};
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}
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pub fn compare(lhs: Value, rhs: Value, op: Story.Opcode) !Value {
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return switch (op) {
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.cmp_eq => .{ .bool = lhs.eql(rhs) },
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.cmp_neq => .{ .bool = !lhs.eql(rhs) },
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.cmp_lt, .cmp_gt, .cmp_lte, .cmp_gte => blk: {
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if (!lhs.isNumeric() or !rhs.isNumeric()) return error.TypeError;
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const l = lhs.toFloat();
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const r = rhs.toFloat();
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break :blk .{
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.bool = switch (op) {
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.cmp_lt => l < r,
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.cmp_gt => l > r,
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.cmp_lte => l <= r,
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.cmp_gte => l >= r,
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else => unreachable,
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},
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};
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},
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else => unreachable,
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};
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}
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pub fn logicalNot(lhs: Value) Value {
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return .{ .bool = !lhs.isTruthy() };
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}
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pub fn concat(lhs: Value, rhs: Value, story: *Story) !Value {
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const lhs_object = try Object.String.fromValue(story, lhs);
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const rhs_object = try Object.String.fromValue(story, rhs);
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const str_object = try Object.String.concat(story, lhs_object, rhs_object);
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return .{ .object = &str_object.base };
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}
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pub fn negate(lhs: Value) !Value {
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switch (lhs) {
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.bool => return error.TypeError,
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.int => |int| return .{ .int = -int },
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.float => |float| return .{ .float = -float },
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.object => return error.TypeError,
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}
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}
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};
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pub const CallFrame = struct {
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ip: usize,
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sp: usize,
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callee: *Object.Knot,
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};
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pub const Choice = struct {
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text: std.ArrayListUnmanaged(u8),
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dest_offset: u16,
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};
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pub const Opcode = enum(u8) {
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/// Exit the VM normally.
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exit,
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ret,
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/// Pop a value off the stack, discarding it.
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pop,
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/// Push an object representing the boolean value of "true" to the stack.
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true,
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/// Push an object representing the boolean value of "false" to the stack.
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false,
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/// Pop two values off the stack and calculate their sum.
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/// The result will be pushed to the stack.
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add,
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/// Pop two values off the stack and calculate their difference.
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/// The result will be pushed to the stack.
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sub,
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/// Pop two values off the stack and calculate their product.
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/// The result will be pushed to the stack.
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mul,
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/// Pop two values off the stack and calculate their quotient.
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/// The result will be pushed to the stack.
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div,
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mod,
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neg,
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not,
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cmp_eq,
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cmp_neq,
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cmp_lt,
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cmp_gt,
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cmp_lte,
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cmp_gte,
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/// Jump unconditionally to the target address.
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jmp,
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/// Jump conditionally to the target address if the boolean value at the
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/// top of the stack is true.
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jmp_t,
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/// Jump conditionally to the target address if the boolean value at the
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/// top of the stack is false.
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jmp_f,
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call,
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divert,
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load_const,
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load,
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store,
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load_global,
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store_global,
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load_attr,
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store_attr,
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/// Pop a value off the stack and write it to the content stream.
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stream_push,
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stream_line,
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stream_glue,
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/// Flush the content stream to the story consumer.
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stream_flush,
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br_push,
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br_table,
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br_dispatch,
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br_select_index,
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_,
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};
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pub fn deinit(story: *Story) void {
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const gpa = story.allocator;
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var next = story.gc_objects.first;
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while (next) |node| {
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const object: *Object = @alignCast(@fieldParentPtr("node", node));
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next = node.next;
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object.destroy(story);
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}
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story.current_choices.deinit(gpa);
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story.constants_pool.deinit(gpa);
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story.globals.deinit(gpa);
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story.stack.deinit(gpa);
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story.call_stack.deinit(gpa);
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gpa.free(story.string_bytes);
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}
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fn isCallStackEmpty(vm: *const Story) bool {
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return vm.call_stack.items.len == 0;
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}
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fn currentFrame(vm: *Story) *CallFrame {
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return &vm.call_stack.items[vm.call_stack.items.len - 1];
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}
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fn peekStack(vm: *Story, offset: usize) ?Value {
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const stack_top = vm.stack.items.len;
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if (stack_top <= offset) return null;
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return vm.stack.items[stack_top - offset - 1];
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}
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fn pushStack(vm: *Story, value: Value) !void {
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const gpa = vm.allocator;
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const stack_top = vm.stack.items.len;
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const max_stack_top = vm.stack_max;
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if (stack_top >= max_stack_top) return error.StackOverflow;
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return vm.stack.append(gpa, value);
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}
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fn popStack(vm: *Story) ?Value {
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return vm.stack.pop() orelse unreachable;
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}
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fn getConstant(story: *Story, frame: *CallFrame, offset: u8) !Value {
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if (offset >= frame.callee.code.constants.len) return error.InvalidArgument;
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const constant_index = frame.callee.code.constants[offset];
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return story.constants_pool.items[constant_index];
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}
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fn getLocal(vm: *Story, frame: *CallFrame, offset: u8) ?Value {
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const stack_top = vm.stack.items.len;
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const stack_offset = frame.sp + offset;
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assert(stack_top > stack_offset);
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return vm.stack.items[stack_offset];
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}
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fn setLocal(vm: *Story, frame: *CallFrame, offset: u8, value: Value) void {
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const stack_top = vm.stack.items.len;
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const stack_offset = frame.sp + offset;
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assert(stack_top > stack_offset);
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vm.stack.items[stack_offset] = value;
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}
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// TODO: This should probably check the constants table first.
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fn getGlobal(vm: *Story, key: Value) !Value {
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switch (key) {
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.object => |object| switch (object.tag) {
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.string => {
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const str_object: *Object.String = @ptrCast(object);
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if (vm.globals.get(str_object.toSlice())) |value| {
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// FIXME: Support for nil
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return value.?;
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}
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return error.InvalidVariable;
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},
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else => return error.TypeError,
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},
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else => return error.TypeError,
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}
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}
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// TODO: This should probably check the constants table first.
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fn setGlobal(vm: *Story, key: Value, value: Value) !void {
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switch (key) {
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.object => |object| switch (object.tag) {
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.string => {
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const str_object: *Object.String = @ptrCast(object);
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return vm.globals.putAssumeCapacity(str_object.toSlice(), value);
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},
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else => return error.TypeError,
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},
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else => return error.TypeError,
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}
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}
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fn execute(vm: *Story) !std.ArrayListUnmanaged(u8) {
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const gpa = vm.allocator;
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errdefer {
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vm.can_advance = false;
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}
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if (vm.isCallStackEmpty()) return .empty;
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var stream_writer = std.Io.Writer.Allocating.init(gpa);
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defer stream_writer.deinit();
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while (true) {
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const frame = vm.currentFrame();
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const code = std.mem.bytesAsSlice(Opcode, frame.callee.code.bytecode);
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if (vm.dump_writer) |w| {
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Dumper.trace(vm, w, frame) catch {};
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}
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switch (code[frame.ip]) {
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.exit => {
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vm.is_exited = true;
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vm.can_advance = false;
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return .empty;
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},
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.true => {
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const value: Value = .{ .bool = true };
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try vm.pushStack(value);
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frame.ip += 1;
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},
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.false => {
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const value: Value = .{ .bool = false };
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try vm.pushStack(value);
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frame.ip += 1;
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},
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.pop => {
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if (vm.popStack()) |_| {} else return error.InvalidArgument;
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frame.ip += 1;
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},
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.add => {
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const lhs = vm.peekStack(1) orelse return error.Bugged;
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const rhs = vm.peekStack(0) orelse return error.Bugged;
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const value = try Value.add(lhs, rhs, vm);
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_ = vm.popStack();
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_ = vm.popStack();
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try vm.pushStack(value);
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frame.ip += 1;
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},
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.sub, .mul, .div, .mod => |op| {
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const lhs = vm.peekStack(1) orelse return error.Bugged;
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const rhs = vm.peekStack(0) orelse return error.Bugged;
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const value = try Value.arith(lhs, rhs, op, vm);
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_ = vm.popStack();
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_ = vm.popStack();
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try vm.pushStack(value);
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frame.ip += 1;
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},
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.neg => {
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if (vm.popStack()) |arg| {
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const value = try Value.negate(arg);
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try vm.pushStack(value);
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} else {
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return error.InvalidArgument;
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}
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frame.ip += 1;
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},
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.not => {
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if (vm.popStack()) |arg| {
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const value = Value.logicalNot(arg);
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try vm.pushStack(value);
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} else {
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return error.StackOverflow;
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}
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frame.ip += 1;
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},
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.cmp_eq => {
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const lhs = vm.peekStack(1) orelse return error.Bugged;
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const rhs = vm.peekStack(0) orelse return error.Bugged;
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const value = try Value.compare(lhs, rhs, .cmp_eq);
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_ = vm.popStack();
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_ = vm.popStack();
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try vm.pushStack(value);
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frame.ip += 1;
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},
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.cmp_lt, .cmp_gt, .cmp_lte, .cmp_gte => |op| {
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const lhs = vm.peekStack(1) orelse return error.Bugged;
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const rhs = vm.peekStack(0) orelse return error.Bugged;
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const value = try Value.compare(lhs, rhs, op);
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_ = vm.popStack();
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_ = vm.popStack();
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try vm.pushStack(value);
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frame.ip += 1;
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},
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.jmp => {
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const arg_offset = readAddress(code, frame.ip);
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frame.ip += 3 + arg_offset;
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},
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.jmp_t => {
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const arg_offset = readAddress(code, frame.ip);
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frame.ip += 3;
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if (vm.peekStack(0)) |condition| {
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if (condition.isTruthy()) {
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frame.ip += arg_offset;
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}
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} else {
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return error.InvalidArgument;
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}
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},
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.jmp_f => {
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const arg_offset = readAddress(code, frame.ip);
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frame.ip += 3;
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if (vm.peekStack(0)) |condition| {
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if (!condition.isTruthy()) {
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frame.ip += arg_offset;
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}
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} else {
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return error.InvalidArgument;
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}
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},
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.load_const => {
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const index: u8 = @intFromEnum(code[frame.ip + 1]);
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const value = try vm.getConstant(frame, index);
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try vm.pushStack(value);
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frame.ip += 2;
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},
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.load => {
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const arg_offset: u8 = @intFromEnum(code[frame.ip + 1]);
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const value = vm.getLocal(frame, arg_offset) orelse return error.Bugged;
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try vm.pushStack(value);
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frame.ip += 2;
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},
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.store => {
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if (vm.peekStack(0)) |arg| {
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const arg_offset: u8 = @intFromEnum(code[frame.ip + 1]);
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vm.setLocal(frame, arg_offset, arg);
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} else {
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return error.InvalidArgument;
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}
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frame.ip += 2;
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},
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.load_global => {
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const arg_offset: u8 = @intFromEnum(code[frame.ip + 1]);
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const global_name = try vm.getConstant(frame, arg_offset);
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const global_value = try vm.getGlobal(global_name);
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try vm.pushStack(global_value);
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frame.ip += 2;
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},
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.store_global => {
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const arg_offset: u8 = @intFromEnum(code[frame.ip + 1]);
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const global_name = try vm.getConstant(frame, arg_offset);
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if (vm.peekStack(0)) |arg| {
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try vm.setGlobal(global_name, arg);
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_ = vm.popStack();
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try vm.pushStack(arg);
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} else {
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return error.InvalidArgument;
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}
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frame.ip += 2;
|
|
},
|
|
.stream_push => {
|
|
// FIXME: This should be more strict.
|
|
// Its not because theres a bug in when these instructions are
|
|
// emitted.
|
|
if (vm.peekStack(0)) |arg| {
|
|
const str_object = try Object.String.fromValue(vm, arg);
|
|
try stream_writer.writer.writeAll(str_object.toSlice());
|
|
_ = vm.popStack();
|
|
} //else {
|
|
//return error.InvalidArgument;
|
|
//}
|
|
|
|
frame.ip += 1;
|
|
},
|
|
.stream_flush => {
|
|
frame.ip += 1;
|
|
|
|
// FIXME: This is a bit of a hack, but we have to deal with this right now.
|
|
const buffered = stream_writer.writer.buffered();
|
|
if (buffered.len == 0) continue;
|
|
return stream_writer.toArrayList();
|
|
},
|
|
.br_push => {
|
|
const arg_offset = readAddress(code, frame.ip);
|
|
|
|
try vm.current_choices.append(gpa, .{
|
|
.text = stream_writer.toArrayList(),
|
|
.dest_offset = arg_offset,
|
|
});
|
|
frame.ip += 3;
|
|
},
|
|
.br_table => {
|
|
// No-op currently.
|
|
frame.ip += 1;
|
|
},
|
|
.br_select_index => {
|
|
vm.can_advance = false;
|
|
frame.ip += 1;
|
|
return .empty;
|
|
},
|
|
.br_dispatch => {
|
|
const index = vm.choice_index;
|
|
const branch_dispatch = vm.current_choices.items[index];
|
|
defer vm.current_choices.clearRetainingCapacity();
|
|
|
|
frame.ip = branch_dispatch.dest_offset;
|
|
},
|
|
.divert => {
|
|
const arg_offset: u8 = @intFromEnum(code[frame.ip + 1]);
|
|
frame.ip += 2;
|
|
|
|
if (peekStack(vm, arg_offset)) |value| {
|
|
try divertToValue(vm, value);
|
|
} else {
|
|
return error.InvalidArgument;
|
|
}
|
|
},
|
|
.load_attr => {
|
|
const arg_offset: u8 = @intFromEnum(code[frame.ip + 1]);
|
|
frame.ip += 2;
|
|
|
|
if (peekStack(vm, 0)) |value| {
|
|
const knot_object: *Object.Knot = @ptrCast(value.object);
|
|
const arg_value = try vm.getConstant(frame, arg_offset);
|
|
const knot_attr: *Object.String = @ptrCast(arg_value.object);
|
|
|
|
_ = popStack(vm);
|
|
|
|
if (knot_object.members.get(knot_attr.toSlice())) |attr_object| {
|
|
try vm.pushStack(.{ .object = attr_object });
|
|
} else {
|
|
return error.InvalidArgument;
|
|
}
|
|
} else {
|
|
return error.InvalidArgument;
|
|
}
|
|
},
|
|
else => return error.InvalidInstruction,
|
|
}
|
|
}
|
|
}
|
|
|
|
fn readAddress(code: []const Story.Opcode, offset: usize) u16 {
|
|
const arg_offset = std.mem.bytesToValue(u16, code[offset + 1 ..][0..2]);
|
|
return std.mem.bigToNative(u16, arg_offset);
|
|
}
|
|
|
|
pub fn advance(story: *Story, gpa: std.mem.Allocator) ![]const u8 {
|
|
var content = try story.execute();
|
|
return content.toOwnedSlice(gpa);
|
|
}
|
|
|
|
pub fn getKnot(vm: *Story, name: []const u8) ?*Object.Knot {
|
|
const knot: ?*Object.Knot = blk: {
|
|
if (vm.globals.get(name)) |value| {
|
|
// TODO: Do a check here.
|
|
break :blk @ptrCast(value.?.object);
|
|
}
|
|
break :blk null;
|
|
};
|
|
return knot;
|
|
}
|
|
|
|
// TODO(Brett): Add arguments?
|
|
fn divertToKnot(vm: *Story, knot: *Object.Knot) !void {
|
|
const gpa = vm.allocator;
|
|
const stack_ptr = vm.stack.items.len - knot.code.args_count;
|
|
const stack_needed = knot.code.stack_size;
|
|
|
|
try vm.stack.ensureUnusedCapacity(gpa, stack_needed);
|
|
try vm.call_stack.ensureUnusedCapacity(gpa, 1);
|
|
|
|
vm.call_stack.appendAssumeCapacity(.{
|
|
.callee = knot,
|
|
.ip = 0,
|
|
.sp = stack_ptr,
|
|
});
|
|
vm.stack.appendNTimesAssumeCapacity(null, stack_needed);
|
|
vm.can_advance = true;
|
|
}
|
|
|
|
fn divertToValue(vm: *Story, value: Value) !void {
|
|
switch (value) {
|
|
.object => |object| switch (object.tag) {
|
|
.knot => try divertToKnot(vm, @ptrCast(object)),
|
|
else => return error.TypeError,
|
|
},
|
|
else => return error.TypeError,
|
|
}
|
|
}
|
|
|
|
fn divert(vm: *Story, knot_name: []const u8) !void {
|
|
return if (getKnot(vm, knot_name)) |knot| {
|
|
return divertToKnot(vm, knot);
|
|
} else return error.InvalidPath;
|
|
}
|
|
|
|
pub const LoadOptions = struct {
|
|
dump_writer: ?*std.Io.Writer = null,
|
|
error_writer: *std.Io.Writer,
|
|
use_color: bool = true,
|
|
dump_ast: bool = false,
|
|
dump_ir: bool = false,
|
|
dump_trace: bool = false,
|
|
};
|
|
|
|
pub fn selectChoiceIndex(story: *Story, index: usize) !void {
|
|
if (index >= story.current_choices.items.len) return error.InvalidChoice;
|
|
story.choice_index = index;
|
|
story.can_advance = true;
|
|
}
|
|
|
|
pub fn dump(story: *Story, writer: *std.Io.Writer) !void {
|
|
return Dumper.dump(story, writer);
|
|
}
|
|
|
|
pub fn loadFromString(
|
|
gpa: std.mem.Allocator,
|
|
source_bytes: [:0]const u8,
|
|
options: LoadOptions,
|
|
) !Story {
|
|
var arena_allocator = std.heap.ArenaAllocator.init(gpa);
|
|
defer arena_allocator.deinit();
|
|
|
|
const arena = arena_allocator.allocator();
|
|
var comp = try Module.compile(gpa, arena, .{
|
|
.source_bytes = source_bytes,
|
|
.filename = "<STDIN>",
|
|
.dump_writer = options.dump_writer,
|
|
.dump_use_color = options.use_color,
|
|
.dump_ast = options.dump_ast,
|
|
.dump_ir = options.dump_ir,
|
|
});
|
|
defer comp.deinit();
|
|
|
|
if (comp.errors.items.len > 0) {
|
|
for (comp.errors.items) |err| {
|
|
try comp.renderError(options.error_writer, err);
|
|
}
|
|
return error.LoadFailed;
|
|
}
|
|
|
|
var story: Story = .{
|
|
.allocator = gpa,
|
|
.can_advance = false,
|
|
.dump_writer = if (options.dump_trace) options.dump_writer else null,
|
|
};
|
|
errdefer story.deinit();
|
|
try comp.setupStoryRuntime(gpa, &story);
|
|
if (story.getKnot(Story.default_knot_name)) |knot| {
|
|
try story.divertToKnot(knot);
|
|
story.can_advance = true;
|
|
}
|
|
return story;
|
|
}
|