feat: loading precompiled sections, strings/constants/knots

src/InternPool.zig

@@ -103,23 +103,23 @@ pub fn getOrPutString(
     gpa: std.mem.Allocator,
     bytes: []const u8,
 ) error{OutOfMemory}!NullTerminatedString {
-    const str_index: u32 = @intCast(ip.string_bytes.items.len);
-    try ip.string_bytes.ensureUnusedCapacity(gpa, bytes.len + 1);
-    ip.string_bytes.appendSliceAssumeCapacity(bytes);
+    const string_bytes = &ip.string_bytes;
+    const str_index: u32 = @intCast(string_bytes.items.len);
+    try string_bytes.appendSlice(gpa, bytes);
 
-    const key: []const u8 = ip.string_bytes.items[str_index..];
+    const key: []const u8 = string_bytes.items[str_index..];
     const gop = try ip.string_table.getOrPutContextAdapted(gpa, key, StringIndexAdapter{
-        .bytes = &ip.string_bytes,
+        .bytes = string_bytes,
     }, StringIndexContext{
-        .bytes = &ip.string_bytes,
+        .bytes = string_bytes,
     });
     if (gop.found_existing) {
-        ip.string_bytes.shrinkRetainingCapacity(str_index);
+        string_bytes.shrinkRetainingCapacity(str_index);
         return @enumFromInt(gop.key_ptr.*);
     } else {
         gop.key_ptr.* = str_index;
-        try ip.string_bytes.append(gpa, 0);
-        return @enumFromInt(gop.key_ptr.*);
+        try string_bytes.append(gpa, 0);
+        return @enumFromInt(str_index);
     }
 }
 

src/Story.zig

@@ -127,7 +127,15 @@ pub const CallFrame = struct {
     bp: usize,
 };
 
-pub const Value = union(enum) {
+pub const ValueType = enum(u8) {
+    nil,
+    bool,
+    int,
+    float,
+    object,
+};
+
+pub const Value = union(ValueType) {
     nil,
     bool: bool,
     int: i64,

src/Story/Dumper.zig

@@ -9,6 +9,31 @@ const Dumper = @This();
 story: *const Story,
 indent_level: usize = 0,
 
+fn dumpStringBytes(dumper: *Dumper, writer: *std.Io.Writer) !void {
+    const bytes = dumper.story.string_bytes;
+    var start: usize = 0;
+    while (start < bytes.len) {
+        const end = std.mem.indexOfScalarPos(u8, bytes, start, 0) orelse break;
+        const str = bytes[start..end];
+
+        try writer.print("[{d:04}] ", .{start});
+        for (str) |b| try writer.print("{x:02} ", .{b});
+        try writer.print("00: {s}\n", .{str});
+        start = end + 1;
+    }
+    return writer.flush();
+}
+
+fn dumpConstants(dumper: *Dumper, writer: *std.Io.Writer) !void {
+    const story = dumper.story;
+    var i: usize = 0;
+    while (i < story.constants_pool.len) : (i += 1) {
+        const global_constant = &story.constants_pool[i];
+        try dumper.dumpValue(writer, global_constant);
+        try writer.writeAll("\n");
+    }
+}
+
 fn dumpSimpleInst(_: *Dumper, w: *std.Io.Writer, offset: usize, op: Opcode) !usize {
     try w.print("{s}\n", .{@tagName(op)});
     return offset + 1;
@@ -312,14 +337,11 @@ pub fn dumpValue(_: Dumper, w: *std.Io.Writer, value: *const Value) !void {
 pub fn dump(story: *Story, writer: *std.Io.Writer) !void {
     var story_dumper: Dumper = .{ .story = story };
 
-    try writer.writeAll("=== Constants ===\n");
+    try writer.writeAll("=== Strings ===\n");
+    try story_dumper.dumpStringBytes(writer);
 
-    var i: usize = 0;
-    while (i < story.constants_pool.len) : (i += 1) {
-        const global_constant = &story.constants_pool[i];
-        try story_dumper.dumpValue(writer, global_constant);
-        try writer.writeAll("\n");
-    }
+    try writer.writeAll("=== Constants ===\n");
+    try story_dumper.dumpConstants(writer);
 
     try writer.writeAll("\n");
     try writer.writeAll("=== Globals ===\n");

src/Story/Loader.zig

@@ -2,63 +2,237 @@ const std = @import("std");
 const InternPool = @import("../InternPool.zig");
 const Compilation = @import("../compile.zig").Compilation;
 const Story = @import("../Story.zig");
-const Value = Story.Value;
 const Object = Story.Object;
+const Loader = @This();
 
-fn makeValueFromInterned(story: *Story, value: InternPool.Key) !Story.Value {
-    return switch (value) {
-        .bool => |boolean| .{ .bool = boolean },
-        .int => |int| .{ .int = @intCast(int) },
-        .float => |float| .{ .float = @bitCast(float) },
-        .str => |index| blk: {
-            const str_object = try Object.String.create(story, .{
-                .bytes = stringBytes(story, index),
-            });
-            break :blk .{ .object = &str_object.base };
-        },
-    };
-}
-
-fn makeKnotObject(
+gpa: std.mem.Allocator,
 story: *Story,
-    name: []const u8,
-    code: *InternPool.CodeChunk,
-) !*Object.Knot {
-    return Object.Knot.create(story, .{
-        .name = name,
-        .code = try Object.Code.create(story, .{
-            .args_count = @intCast(code.args_count),
-            .locals_count = @intCast(code.locals_count),
-            .stack_size = @intCast(code.stack_size),
-            .constants = try code.constants.toOwnedSlice(story.gpa),
-            .code_bytes = try code.bytecode.toOwnedSlice(story.gpa),
-        }),
-    });
-}
+endian: std.builtin.Endian = .big,
 
-fn makeConstantsPool(mod: *Compilation, story: *Story) ![]const Story.Value {
-    const ip = &mod.intern_pool;
-    const gpa = mod.gpa;
-    var constants_pool: std.ArrayListUnmanaged(Value) = .empty;
-    defer constants_pool.deinit(mod.gpa);
-    try constants_pool.ensureUnusedCapacity(mod.gpa, ip.values.items.len);
+pub const FileHeader = extern struct {
+    magic: [4]u8 = .{ 'I', 'N', 'K', 'C' },
+    version: [2]u8 = .{ 0, 0 },
+    __padding: u16 = 0,
+    sections_count: u32 = 0,
+};
 
-    for (ip.values.items) |value| {
-        const obj = try makeValueFromInterned(story, value);
-        constants_pool.appendAssumeCapacity(obj);
-    }
-    return constants_pool.toOwnedSlice(gpa);
-}
+pub const SectionHeader = extern struct {
+    kind: Tag,
+    flags: u8 = 0,
+    __padding: u16 = 0,
+    size: u32,
 
-fn stringBytes(story: *Story, index: InternPool.NullTerminatedString) [:0]const u8 {
-    const slice = story.string_bytes[@intFromEnum(index)..];
-    return slice[0..std.mem.indexOfScalar(u8, slice, 0).? :0];
-}
+    pub const Tag = enum(u8) {
+        strings,
+        constants,
+        globals,
+        knot,
+        _,
+    };
+};
+
+pub const CodeHeader = extern struct {
+    args_count: u8,
+    locals_count: u8,
+    stack_size: u16,
+    constants_len: u16,
+    bytecode_len: u16,
+};
+
+pub const Constant = enum(u8) {
+    bool,
+    int,
+    float,
+    str_index,
+    _,
+};
 
 pub const Options = struct {
     stack_size: usize,
 };
 
+pub const SectionIterator = struct {
+    bytes: []const u8,
+    index: usize,
+
+    pub const Entry = struct {
+        header: SectionHeader,
+        bytes: []const u8,
+    };
+
+    pub fn next(iter: *SectionIterator) !?Entry {
+        if (iter.index >= iter.bytes.len)
+            return null;
+        if (iter.index + @sizeOf(SectionHeader) > iter.bytes.len)
+            return error.Corrupted;
+
+        const header: SectionHeader = .{
+            .kind = @enumFromInt(iter.bytes[iter.index]),
+            .flags = iter.bytes[iter.index + 1],
+            .__padding = 0,
+            .size = std.mem.readInt(u32, iter.bytes[iter.index + 4 ..][0..4], .big),
+        };
+        const payload_start = iter.index + @sizeOf(SectionHeader);
+        const payload_end = payload_start + header.size;
+
+        if (payload_end > iter.bytes.len)
+            return error.Corrupted;
+
+        const entry: Entry = .{
+            .header = header,
+            .bytes = iter.bytes[payload_start..payload_end],
+        };
+        iter.index = payload_end;
+        return entry;
+    }
+};
+
+pub fn fromCachedCompilation(
+    gpa: std.mem.Allocator,
+    bytes: []const u8,
+    options: Options,
+) !Story {
+    var story: Story = .{
+        .gpa = gpa,
+        .arena = .init(gpa),
+    };
+    errdefer story.deinit();
+
+    story.stack = try gpa.alloc(Story.Value, options.stack_size);
+    story.call_stack = try gpa.alloc(Story.CallFrame, options.stack_size);
+
+    var loader: Loader = .{
+        .gpa = gpa,
+        .story = &story,
+    };
+    var section_iter: SectionIterator = .{
+        .index = @sizeOf(FileHeader),
+        .bytes = bytes,
+    };
+
+    var string_bytes: std.ArrayList(u8) = .empty;
+    defer string_bytes.deinit(gpa);
+
+    var constants_pool: std.ArrayList(Story.Value) = .empty;
+    defer constants_pool.deinit(gpa);
+
+    if (try section_iter.next()) |section| {
+        try string_bytes.appendSlice(gpa, section.bytes);
+        story.string_bytes = try string_bytes.toOwnedSlice(gpa);
+    }
+    if (try section_iter.next()) |section| {
+        var remaining = section.bytes;
+        while (remaining.len > 0) {
+            const tag: Constant = @enumFromInt(remaining[0]);
+            remaining = remaining[1..];
+
+            const value: Story.Value = v: switch (tag) {
+                .bool => {
+                    const v = remaining[0];
+                    remaining = remaining[1..];
+                    break :v .{ .bool = if (v == 1) true else false };
+                },
+                .int => {
+                    const v = std.mem.readInt(i64, remaining[0..8], .big);
+                    remaining = remaining[8..];
+                    break :v .{ .int = @bitCast(v) };
+                },
+                .float => {
+                    const v = std.mem.readInt(i64, remaining[0..8], .big);
+                    remaining = remaining[8..];
+                    break :v .{ .float = @bitCast(v) };
+                },
+                .str_index => {
+                    const str_index = std.mem.readInt(u16, remaining[2..4], .big);
+                    const slice = story.string_bytes[str_index..];
+                    const str_bytes = slice[0..std.mem.indexOfScalar(u8, slice, 0).? :0];
+                    const str_object = try Object.String.create(loader.story, .{
+                        .bytes = str_bytes,
+                    });
+                    remaining = remaining[@sizeOf(u16) + @sizeOf(u16) ..];
+                    break :v .{ .object = &str_object.base };
+                },
+                else => return error.MalformedValueTag,
+            };
+            try constants_pool.append(gpa, value);
+        }
+        story.constants_pool = try constants_pool.toOwnedSlice(gpa);
+    }
+    while (try section_iter.next()) |section| {
+        switch (section.header.kind) {
+            .strings => {},
+            .constants => {},
+            .knot => {
+                const knot = try readKnot(&loader, section.bytes);
+                const knot_value: Story.Value = .{ .object = &knot.base };
+                try story.globals.put(gpa, knot.name.toSlice(), knot_value);
+            },
+            else => {},
+        }
+    }
+    if (story.getKnot(Story.default_knot_name)) |knot| {
+        try story.pushStack(.{ .object = &knot.base });
+        try story.divert(knot, 0);
+    }
+    return story;
+}
+
+fn nullTerminatedString(loader: *const Loader, index: u32) []const u8 {
+    const slice = loader.story.string_bytes[index..];
+    return slice[0..std.mem.indexOfScalar(u8, slice, 0).? :0];
+}
+
+fn readKnot(loader: *Loader, bytes: []const u8) !*Object.Knot {
+    const gpa = loader.gpa;
+    const name_index = std.mem.readInt(u32, bytes[0..4], loader.endian);
+    const code_header: CodeHeader = .{
+        .args_count = bytes[4],
+        .locals_count = bytes[5],
+        .stack_size = std.mem.readInt(u16, bytes[6..8], loader.endian),
+        .constants_len = std.mem.readInt(u16, bytes[8..10], loader.endian),
+        .bytecode_len = std.mem.readInt(u16, bytes[10..12], loader.endian),
+    };
+    const constants_start = 12;
+    const constants_end = constants_start + code_header.constants_len;
+    const bytecode_end = constants_end + code_header.bytecode_len;
+
+    if (bytecode_end > bytes.len)
+        return error.InvalidKnotSection;
+
+    var constants: std.ArrayList(u8) = .empty;
+    defer constants.deinit(gpa);
+
+    var bytecode: std.ArrayList(u8) = .empty;
+    defer bytecode.deinit(gpa);
+
+    try constants.appendSlice(gpa, bytes[constants_start..constants_end]);
+    try bytecode.appendSlice(gpa, bytes[constants_end..bytecode_end]);
+
+    return .create(loader.story, .{
+        .name = loader.nullTerminatedString(name_index),
+        .code = try Object.Code.create(loader.story, .{
+            .args_count = code_header.args_count,
+            .locals_count = code_header.locals_count,
+            .stack_size = code_header.stack_size,
+            .constants = try constants.toOwnedSlice(gpa),
+            .code_bytes = try bytecode.toOwnedSlice(gpa),
+        }),
+    });
+}
+
+pub fn fromCompilation(
+    gpa: std.mem.Allocator,
+    mod: *Compilation,
+    options: Options,
+) !Story {
+    var story: Story = .{
+        .gpa = gpa,
+        .arena = .init(gpa),
+    };
+    try fromCompilationCompat(gpa, mod, &story, options);
+    return story;
+}
+
 pub fn fromCompilationCompat(
     gpa: std.mem.Allocator,
     mod: *Compilation,
@@ -111,26 +285,202 @@ pub fn fromCompilationCompat(
     }
 }
 
-pub fn fromCompilation(
+pub const Builder = struct {
     gpa: std.mem.Allocator,
-    mod: *Compilation,
-    options: Options,
-) !Story {
-    var story: Story = .{
-        .gpa = gpa,
-        .arena = .init(gpa),
-    };
-    try fromCompilationCompat(gpa, mod, &story, options);
-    return story;
+    intern_pool: *const InternPool,
+    endian: std.builtin.Endian = .big,
+
+    pub const Section = struct {
+        builder: *Builder,
+        header: SectionHeader,
+        bytes: std.ArrayList(u8) = .empty,
+
+        fn addConstant(self: *Section, value: InternPool.Key) !void {
+            const gpa = self.builder.gpa;
+            const bytes = &self.bytes;
+            switch (value) {
+                .bool => |v| {
+                    const size: u32 = 1 + @sizeOf(bool);
+                    self.header.size += size;
+
+                    try bytes.ensureUnusedCapacity(gpa, size);
+                    bytes.appendAssumeCapacity(@intFromEnum(Constant.bool));
+                    bytes.appendAssumeCapacity(@intFromBool(v));
+                },
+                .int => |v| {
+                    const size: u32 = 1 + @sizeOf(i64);
+                    self.header.size += size;
+
+                    try bytes.ensureUnusedCapacity(gpa, size);
+                    bytes.appendAssumeCapacity(@intFromEnum(Constant.int));
+                    bytes.appendSliceAssumeCapacity(
+                        &std.mem.toBytes(std.mem.nativeToBig(i64, v)),
+                    );
+                },
+                .float => |v| {
+                    const size: u32 = 1 + @sizeOf(u64);
+                    self.header.size += size;
+
+                    try bytes.ensureUnusedCapacity(gpa, size);
+                    bytes.appendAssumeCapacity(@intFromEnum(Constant.float));
+                    bytes.appendSliceAssumeCapacity(
+                        &std.mem.toBytes(std.mem.nativeToBig(u64, v)),
+                    );
+                },
+                .str => |index| {
+                    const slice = self.builder.intern_pool.string_bytes.items[@intFromEnum(index)..];
+                    const str_bytes = slice[0..std.mem.indexOfScalar(u8, slice, 0).? :0];
+                    const str_len: u16 = @intCast(str_bytes.len);
+                    const size: u32 = 1 + @sizeOf(u16) + @sizeOf(u16);
+                    self.header.size += size;
+
+                    try bytes.ensureUnusedCapacity(gpa, size);
+                    bytes.appendAssumeCapacity(@intFromEnum(Constant.str_index));
+                    bytes.appendSliceAssumeCapacity(
+                        &std.mem.toBytes(std.mem.nativeToBig(u16, str_len)),
+                    );
+                    bytes.appendSliceAssumeCapacity(
+                        &std.mem.toBytes(std.mem.nativeToBig(u16, @intCast(@intFromEnum(index)))),
+                    );
+                },
+            }
         }
 
-pub fn fromCachedCompilation(
-    gpa: std.mem.Allocator,
-    bytes: []const u8,
-    options: Options,
-) !Story {
-    _ = gpa;
-    _ = bytes;
-    _ = options;
-    return error.NotImplemented;
+        fn addKnot(self: *Section, knot: InternPool.Knot) !void {
+            const builder = self.builder;
+            const gpa = builder.gpa;
+            const bytes = &self.bytes;
+            const section_size = @sizeOf(u32) + @sizeOf(CodeHeader) +
+                knot.code_chunk.constants.items.len +
+                knot.code_chunk.bytecode.items.len;
+            self.header.size += @intCast(section_size);
+
+            const string_const = builder.intern_pool.values.items[@intFromEnum(knot.name_index)];
+            const string_index = string_const.str;
+            try bytes.ensureUnusedCapacity(gpa, section_size);
+
+            const code_header: CodeHeader = .{
+                .args_count = @intCast(knot.code_chunk.args_count),
+                .locals_count = @intCast(knot.code_chunk.locals_count),
+                .stack_size = @intCast(knot.code_chunk.stack_size),
+                .constants_len = @intCast(knot.code_chunk.constants.items.len),
+                .bytecode_len = @intCast(knot.code_chunk.bytecode.items.len),
+            };
+            bytes.appendSliceAssumeCapacity(
+                &std.mem.toBytes(std.mem.nativeToBig(u32, @intFromEnum(string_index))),
+            );
+            bytes.appendAssumeCapacity(code_header.args_count);
+            bytes.appendAssumeCapacity(code_header.locals_count);
+            bytes.appendSliceAssumeCapacity(
+                &std.mem.toBytes(std.mem.nativeToBig(u16, code_header.stack_size)),
+            );
+            bytes.appendSliceAssumeCapacity(
+                &std.mem.toBytes(std.mem.nativeToBig(u16, code_header.constants_len)),
+            );
+            bytes.appendSliceAssumeCapacity(
+                &std.mem.toBytes(std.mem.nativeToBig(u16, code_header.bytecode_len)),
+            );
+            bytes.appendSliceAssumeCapacity(knot.code_chunk.constants.items);
+            bytes.appendSliceAssumeCapacity(knot.code_chunk.bytecode.items);
+        }
+    };
+
+    fn makeSection(self: *Builder, tag: SectionHeader.Tag) Section {
+        return .{
+            .builder = self,
+            .header = .{ .kind = tag, .size = 0 },
+        };
+    }
+};
+
+pub fn writeFile(comp: *Compilation, writer: *std.Io.Writer) !void {
+    const endian: std.builtin.Endian = .big;
+    const gpa = comp.gpa;
+    const ip = &comp.intern_pool;
+    var bytes: std.ArrayList(u8) = .empty;
+    defer bytes.deinit(comp.gpa);
+
+    var builder: Builder = .{
+        .gpa = gpa,
+        .intern_pool = ip,
+        .endian = endian,
+    };
+    const file_header: FileHeader = .{
+        .sections_count = @intCast(2 + comp.knots.items.len),
+    };
+
+    try writer.writeStruct(file_header, endian);
+
+    var strings_section = builder.makeSection(.strings);
+    defer strings_section.bytes.deinit(gpa);
+    try strings_section.bytes.appendSlice(gpa, ip.string_bytes.items);
+    strings_section.header.size += @intCast(ip.string_bytes.items.len);
+    try writer.writeStruct(strings_section.header, endian);
+    try writer.writeAll(strings_section.bytes.items);
+
+    var const_section = builder.makeSection(.constants);
+    defer const_section.bytes.deinit(gpa);
+    for (ip.values.items) |value| {
+        try const_section.addConstant(value);
+    }
+    try writer.writeStruct(const_section.header, endian);
+    try writer.writeAll(const_section.bytes.items);
+
+    for (comp.knots.items) |knot| {
+        var knot_section = builder.makeSection(.knot);
+        try knot_section.addKnot(knot);
+        try writer.writeStruct(knot_section.header, endian);
+        try writer.writeAll(knot_section.bytes.items);
+    }
+    try writer.flush();
+}
+
+fn makeValueFromInterned(story: *Story, value: InternPool.Key) !Story.Value {
+    return switch (value) {
+        .bool => |boolean| .{ .bool = boolean },
+        .int => |int| .{ .int = @intCast(int) },
+        .float => |float| .{ .float = @bitCast(float) },
+        .str => |index| blk: {
+            const str_object = try Object.String.create(story, .{
+                .bytes = stringBytes(story, index),
+            });
+            break :blk .{ .object = &str_object.base };
+        },
+    };
+}
+
+fn makeConstantsPool(mod: *Compilation, story: *Story) ![]const Story.Value {
+    const ip = &mod.intern_pool;
+    const gpa = mod.gpa;
+    var constants_pool: std.ArrayList(Story.Value) = .empty;
+    defer constants_pool.deinit(mod.gpa);
+    try constants_pool.ensureUnusedCapacity(mod.gpa, ip.values.items.len);
+
+    for (ip.values.items) |value| {
+        const obj = try makeValueFromInterned(story, value);
+        constants_pool.appendAssumeCapacity(obj);
+    }
+    return constants_pool.toOwnedSlice(gpa);
+}
+
+fn makeKnotObject(
+    story: *Story,
+    name: []const u8,
+    code: *InternPool.CodeChunk,
+) !*Object.Knot {
+    return .create(story, .{
+        .name = name,
+        .code = try .create(story, .{
+            .args_count = @intCast(code.args_count),
+            .locals_count = @intCast(code.locals_count),
+            .stack_size = @intCast(code.stack_size),
+            .constants = try code.constants.toOwnedSlice(story.gpa),
+            .code_bytes = try code.bytecode.toOwnedSlice(story.gpa),
+        }),
+    });
+}
+
+fn stringBytes(story: *Story, index: InternPool.NullTerminatedString) [:0]const u8 {
+    const slice = story.string_bytes[@intFromEnum(index)..];
+    return slice[0..std.mem.indexOfScalar(u8, slice, 0).? :0];
 }

src/compile.zig

@@ -81,10 +81,11 @@ pub const Compilation = struct {
     arena: std.heap.ArenaAllocator,
     tree: Ast,
     ir: Ir,
-    globals: std.ArrayListUnmanaged(InternPool.Global) = .empty,
-    knots: std.ArrayListUnmanaged(InternPool.Knot) = .empty,
-    stitches: std.ArrayListUnmanaged(InternPool.Stitch) = .empty,
-    errors: *std.ArrayListUnmanaged(Error),
+    globals: std.ArrayList(InternPool.Global) = .empty,
+    knots: std.ArrayList(InternPool.Knot) = .empty,
+    stitches: std.ArrayList(InternPool.Stitch) = .empty,
+    code_chunks: std.ArrayList(*InternPool.CodeChunk) = .empty,
+    errors: *std.ArrayList(Error),
     intern_pool: InternPool = .{},
     work_queue: WorkQueue = .{},
 
@@ -291,9 +292,9 @@ pub const Compilation = struct {
         cu: *Compilation,
         arena: std.mem.Allocator,
     ) error{OutOfMemory}!*InternPool.CodeChunk {
-        _ = cu;
         const chunk = try arena.create(InternPool.CodeChunk);
         chunk.* = .{};
+        try cu.code_chunks.append(cu.gpa, chunk);
         return chunk;
     }
 
@@ -338,11 +339,20 @@ pub const Compilation = struct {
 
     pub fn deinit(mod: *Compilation) void {
         const gpa = mod.gpa;
-        mod.arena.deinit();
+
+        var i: usize = 0;
+        while (i < mod.code_chunks.items.len) : (i += 1) {
+            const chunk = mod.code_chunks.items[i];
+            chunk.bytecode.deinit(gpa);
+            chunk.constants.deinit(gpa);
+        }
+
         mod.intern_pool.deinit(gpa);
         mod.globals.deinit(gpa);
         mod.knots.deinit(gpa);
         mod.stitches.deinit(gpa);
+        mod.code_chunks.deinit(gpa);
+        mod.arena.deinit();
         mod.* = undefined;
     }
 };

src/main.zig

@@ -9,7 +9,6 @@ const fatal = std.process.fatal;
 
 var stdin_buffer: [4096]u8 align(std.heap.page_size_min) = undefined;
 var stdout_buffer: [4096]u8 align(std.heap.page_size_min) = undefined;
-var stderr_buffer: [4096]u8 align(std.heap.page_size_min) = undefined;
 var debug_allocator: std.heap.DebugAllocator(.{}) = .init;
 
 const ArgsIterator = struct {
@@ -64,6 +63,7 @@ fn mainArgs(
     var dump_trace: bool = false;
     var use_stdin: bool = false;
     var use_color: bool = false;
+    const stack_size = 128;
 
     var args_iter: ArgsIterator = .{
         .args = args_list[1..],
@@ -98,7 +98,19 @@ fn mainArgs(
         }
     }
 
+    const stdout = std.Io.File.stdout();
+    var stdout_writer = stdout.writer(io, &stdout_buffer);
+    const log_writer = &stdout_writer.interface;
+
     const filename = source_path orelse "<STDIN>";
+    const file_ext: FileExtension = f: {
+        const bytes = std.fs.path.extension(filename);
+        if (std.mem.eql(u8, bytes, ".ink")) break :f .ink;
+        if (std.mem.eql(u8, bytes, ".inkc")) break :f .inkc;
+        return error.InvalidFileExtension;
+    };
+    var story: Story = story: switch (file_ext) {
+        .ink => {
             const source_bytes: [:0]const u8 = s: {
                 var f = if (source_path) |p| file: {
                     break :file std.Io.Dir.cwd().openFile(io, p, .{}) catch |err| {
@@ -113,19 +125,6 @@ fn mainArgs(
                 };
             };
 
-    const stderr = std.Io.File.stderr();
-    var stderr_writer = stderr.writer(io, &stderr_buffer);
-    const io_w = &stderr_writer.interface;
-    const stack_size = 128;
-
-    const file_ext: FileExtension = f: {
-        const bytes = std.fs.path.extension(filename);
-        if (std.mem.eql(u8, bytes, ".ink")) break :f .ink;
-        if (std.mem.eql(u8, bytes, ".inkc")) break :f .inkc;
-        return error.InvalidFileExtension;
-    };
-    switch (file_ext) {
-        .ink => {
             var tree = try Ast.parse(gpa, arena, source_bytes, filename, 0);
             defer tree.deinit(gpa);
 
@@ -136,16 +135,17 @@ fn mainArgs(
             defer errors.deinit(gpa);
 
             if (dump_ast) {
-                try io_w.writeAll("=== AST ===\n");
-                try tree.render(gpa, io_w, .{
+                try log_writer.writeAll("=== AST ===\n");
+                try tree.render(gpa, log_writer, .{
                     .use_color = use_color,
                 });
-                try io_w.flush();
+                try log_writer.flush();
             }
             if (dump_ir) {
-                try io_w.writeAll("=== IR ===\n");
-                try ir.render(io_w);
-                try io_w.flush();
+                try log_writer.writeAll("=== IR ===\n");
+                try ir.dumpInfo(log_writer);
+                try ir.render(log_writer);
+                try log_writer.flush();
             }
 
             var cu = Compilation.build(gpa, tree, ir, &errors) catch |err| switch (err) {
@@ -155,41 +155,62 @@ fn mainArgs(
 
             if (cu.hasCompileErrors()) {
                 for (cu.errors.items) |err| {
-                    try cu.renderError(io_w, err);
+                    try cu.renderError(log_writer, err);
                 }
-            } else if (output_path) |_| {
-                return error.NotImplemented;
-            } else {
-                var story: Story = try .fromCompilation(gpa, &cu, .{
+            }
+            if (output_path) |path| {
+                const file = try std.Io.Dir.cwd().createFile(io, path, .{});
+                defer file.close(io);
+                var file_writer = file.writer(io, &.{});
+                try Story.Loader.writeFile(&cu, &file_writer.interface);
+                try file_writer.interface.flush();
+                return;
+            }
+            break :story try .fromCompilation(gpa, &cu, .{
                 .stack_size = stack_size,
             });
-                defer story.deinit();
-                if (dump_story) {
-                    try story.dump(io_w);
-                }
-                if (dump_trace) {
-                    story.dump_writer = io_w;
-                }
-                return if (!compile_only) run(io, gpa, &story);
-            }
         },
         .inkc => {
-            var story: Story = try .fromCachedCompilation(gpa, source_bytes, .{
+            const source_bytes: [:0]const u8 = s: {
+                var f = if (source_path) |p| file: {
+                    break :file std.Io.Dir.cwd().openFile(io, p, .{}) catch |err| {
+                        fatal("unable to open file '{s}': {s}", .{ p, @errorName(err) });
+                    };
+                } else std.Io.File.stdin();
+                defer if (source_path != null) f.close(io);
+
+                var file_reader: std.Io.File.Reader = f.reader(io, &stdin_buffer);
+                break :s ink.readSourceFileToEndAlloc(arena, &file_reader) catch |err| {
+                    fatal("unable to load file '{s}': {s}", .{ filename, @errorName(err) });
+                };
+            };
+
+            break :story try .fromCachedCompilation(gpa, source_bytes, .{
                 .stack_size = stack_size,
             });
-            defer story.deinit();
-            return if (!compile_only) run(io, gpa, &story);
         },
-    }
-}
+    };
+    defer story.deinit();
+
+    if (dump_story) try story.dump(log_writer);
+    if (dump_trace) story.dump_writer = log_writer;
 
-fn run(io: std.Io, _: std.mem.Allocator, story: *Story) !void {
     const stdin = std.Io.File.stdin();
     var stdin_reader = stdin.reader(io, &stdin_buffer);
-    const stdout = std.Io.File.stdin();
-    var stdout_writer = stdout.writer(io, &stdout_buffer);
-    const reader = &stdin_reader.interface;
-    const writer = &stdout_writer.interface;
+    return if (!compile_only) run(gpa, &story, .{
+        .reader = &stdin_reader.interface,
+        .writer = log_writer,
+    });
+}
+
+pub const RunOptions = struct {
+    reader: *std.Io.Reader,
+    writer: *std.Io.Writer,
+};
+
+fn run(_: std.mem.Allocator, story: *Story, options: RunOptions) !void {
+    const reader = options.reader;
+    const writer = options.writer;
 
     while (!story.is_exited and story.can_advance) {
         while (try story.advance()) |content| {