diff --git a/build.zig b/build.zig
index ad0243c..f51357a 100644
--- a/build.zig
+++ b/build.zig
@@ -130,14 +130,11 @@ pub fn build(b: *std.Build) void {
     // Creates an executable that will run `test` blocks from the provided module.
     // Here `mod` needs to define a target, which is why earlier we made sure to
     // set the releative field.
-    const mod_tests = b.addTest(.{
+    const run_mod_tests = b.addRunArtifact(b.addTest(.{
         .root_module = mod,
-    });
+    }));
 
-    // A run step that will run the test executable.
-    const run_mod_tests = b.addRunArtifact(mod_tests);
-
-    const bot_tests = b.addTest(.{
+    const run_bot_tests = b.addRunArtifact(b.addTest(.{
         .root_module = b.addModule("bot", .{
             .target = target,
             .root_source_file = b.path("src/bot.zig"),
@@ -148,19 +145,28 @@ pub fn build(b: *std.Build) void {
                 },
             },
         }),
-    });
+    }));
 
-    const run_bot_tests = b.addRunArtifact(bot_tests);
+    const run_parser_tests = b.addRunArtifact(b.addTest(.{
+        .root_module = b.addModule("parser", .{
+            .target = target,
+            .root_source_file = b.path("src/parser.zig"),
+        }),
+    }));
+
+    const run_buffer_tests = b.addRunArtifact(b.addTest(.{
+        .root_module = b.addModule("buffer", .{
+            .target = target,
+            .root_source_file = b.path("src/buffer.zig"),
+        }),
+    }));
 
     // Creates an executable that will run `test` blocks from the executable's
     // root module. Note that test executables only test one module at a time,
     // hence why we have to create two separate ones.
-    const exe_tests = b.addTest(.{
+    const run_exe_tests = b.addRunArtifact(b.addTest(.{
         .root_module = exe.root_module,
-    });
-
-    // A run step that will run the second test executable.
-    const run_exe_tests = b.addRunArtifact(exe_tests);
+    }));
 
     // A top level step for running all tests. dependOn can be called multiple
     // times and since the two run steps do not depend on one another, this will
@@ -168,7 +174,9 @@ pub fn build(b: *std.Build) void {
     const test_step = b.step("test", "Run tests");
     test_step.dependOn(&run_mod_tests.step);
     test_step.dependOn(&run_exe_tests.step);
+    test_step.dependOn(&run_parser_tests.step);
     test_step.dependOn(&run_bot_tests.step);
+    test_step.dependOn(&run_buffer_tests.step);
 
     // Just like flags, top level steps are also listed in the `--help` menu.
     //
diff --git a/src/bot.zig b/src/bot.zig
index db2474d..a425117 100644
--- a/src/bot.zig
+++ b/src/bot.zig
@@ -1,54 +1,8 @@
 const std = @import("std");
 const zircon = @import("zircon");
 
-pub const Parser = struct {
-    original: []const u8,
-    rest: []const u8,
-    end_idx: usize,
-
-    fn seek(self: *const Parser, skip: usize) Parser {
-        return .{ .original = self.original, .rest = self.rest[skip..], .end_idx = self.end_idx + skip };
-    }
-
-    fn init(s: []const u8) Parser {
-        return .{
-            .original = s,
-            .end_idx = 0,
-            .rest = s,
-        };
-    }
-
-    fn consume_char(self: *const Parser, c: u8) ?Parser {
-        if (self.rest[0] != c) {
-            return null;
-        }
-        return self.seek(1);
-    }
-
-    fn consume_str(self: *const Parser, s: []const u8) ?Parser {
-        const len = s.len;
-        if (self.rest.len < len) {
-            return null;
-        }
-        if (!std.mem.eql(u8, self.rest[0..len], s)) {
-            return null;
-        }
-        return self.seek(len);
-    }
-
-    fn take_until_char(self: *const Parser, c: u8) struct { Parser, []const u8 } {
-        const idx = std.mem.indexOfScalar(u8, self.rest, c) orelse unreachable;
-        return .{ self.seek(idx), self.rest[0..idx] };
-    }
-
-    fn take_char(self: *const Parser) struct { Parser, u8 } {
-        return .{ self.seek(1), self.rest[0] };
-    }
-
-    fn parsed(self: *const Parser) []const u8 {
-        return self.original[0..self.end_idx];
-    }
-};
+const Buffer = @import("buffer.zig").Buffer;
+const Parser = @import("parser.zig").Parser;
 
 /// AdminCommand are commands useful for debugging zigeru, since they
 /// are more spammy than others they are separated and only sent to
@@ -132,56 +86,70 @@ pub const Message = struct {
     author: []const u8,
     content: []const u8,
 
-    pub fn init_owned(allocator: std.mem.Allocator, timestamp: i64, author: []const u8, targets: []const u8, content: []const u8) Error!Message {
-        return .{
-            .timestamp = timestamp,
-            .targets = try allocator.dupe(u8, targets),
-            .author = try allocator.dupe(u8, author),
-            .content = try allocator.dupe(u8, content),
-        };
+    pub fn init_owned(
+        allocator: std.mem.Allocator,
+        timestamp: i64,
+        author: []const u8,
+        targets: []const u8,
+        content: []const u8,
+    ) Error!*Message {
+        const message = try allocator.create(Message);
+        message.timestamp = timestamp;
+        message.targets = try allocator.dupe(u8, targets);
+        message.author = try allocator.dupe(u8, author);
+        message.content = try allocator.dupe(u8, content);
+        return message;
     }
 
     pub fn deinit(self: *const Message, allocator: std.mem.Allocator) void {
         allocator.free(self.author);
         allocator.free(self.content);
         allocator.free(self.targets);
+        allocator.destroy(self);
     }
 };
 
 pub const Bot = struct {
-    backlog: [1024]?*const Message,
-    sent_messages: std.ArrayList([]u8),
-    top: usize,
-    bottom: usize,
+    backlog: Buffer(*const Message, 1024),
+    sent_messages: Buffer([]u8, 1024),
     allocator: std.mem.Allocator,
 
+    fn deinit_backlog_slot(allocator: std.mem.Allocator, item: *const Message) void {
+        item.deinit(allocator);
+    }
+
+    fn deinit_sent_message(allocator: std.mem.Allocator, item: []u8) void {
+        allocator.free(item);
+    }
+
     pub fn init(allocator: std.mem.Allocator) Error!Bot {
-        return Bot{
-            .backlog = .{null} ** 1024,
-            .sent_messages = try std.ArrayList([]u8).initCapacity(allocator, 10),
-            .top = 0,
-            .bottom = 0,
+        var bot = Bot{
             .allocator = allocator,
+            .backlog = undefined,
+            .sent_messages = undefined,
         };
+        bot.backlog = .init_with_closure(allocator, &Bot.deinit_backlog_slot);
+        bot.sent_messages = .init_with_closure(allocator, &Bot.deinit_sent_message);
+        return bot;
     }
 
     pub fn deinit(self: *Bot) void {
-        for (self.sent_messages.items) |item| {
-            self.allocator.free(item);
-        }
-        self.sent_messages.deinit(self.allocator);
-
-        for (self.backlog) |slot| {
-            if (slot) |message| {
-                message.deinit(self.allocator);
-            }
-        }
+        self.sent_messages.deinit();
+        self.backlog.deinit();
     }
 
-    pub fn execute(self: *Bot, cmd: *const Command, prefix: ?zircon.Prefix, targets: []const u8) Error!zircon.Message {
+    pub fn execute(
+        self: *Bot,
+        cmd: *const Command,
+        prefix: ?zircon.Prefix,
+        targets: []const u8,
+    ) Error!zircon.Message {
         switch (cmd.*) {
             .substitute => |command| {
-                const prev_msg = self.previous_message_by_author(command.author, targets) orelse return Error.NoMessage;
+                const prev_msg = self.previous_message_by_author(
+                    command.author,
+                    targets,
+                ) orelse return Error.NoMessage;
                 const output = try std.mem.replaceOwned(
                     u8,
                     self.allocator,
@@ -190,27 +158,40 @@ pub const Bot = struct {
                     command.replacement,
                 );
                 defer self.allocator.free(output);
-                const quoted_output = try std.fmt.allocPrint(self.allocator, "{s}: \"{s}\"", .{ command.author, output });
-                try self.sent_messages.append(self.allocator, quoted_output);
-                return zircon.Message{
-                    .PRIVMSG = .{ .targets = targets, .prefix = prefix, .text = quoted_output },
-                };
+                const quoted_output = try std.fmt.allocPrint(
+                    self.allocator,
+                    "{s}: \"{s}\"",
+                    .{ command.author, output },
+                );
+                self.sent_messages.append(quoted_output);
+                return zircon.Message{ .PRIVMSG = .{
+                    .targets = targets,
+                    .prefix = prefix,
+                    .text = quoted_output,
+                } };
             },
             .help => {
-                return zircon.Message{
-                    .PRIVMSG = .{ .targets = targets, .prefix = prefix, .text = HELP_MESSAGE },
-                };
+                return zircon.Message{ .PRIVMSG = .{
+                    .targets = targets,
+                    .prefix = prefix,
+                    .text = HELP_MESSAGE,
+                } };
             },
         }
     }
 
-    pub fn execute_admin(self: *Bot, cmd: *const AdminCommand, prefix: ?zircon.Prefix, targets: []const u8) Error!zircon.Message {
+    pub fn execute_admin(
+        self: *Bot,
+        cmd: *const AdminCommand,
+        prefix: ?zircon.Prefix,
+        targets: []const u8,
+    ) Error!zircon.Message {
         switch (cmd.*) {
             .status => {
                 const msg = try std.fmt.allocPrint(
                     self.allocator,
-                    "heard messages: {}, sent messages: {}, top: {}, bottom: {}",
-                    .{ self.no_messages(), self.sent_messages.items.len, self.top, self.bottom },
+                    "heard messages: {}, sent messages: {}",
+                    .{ self.no_messages(), self.sent_messages.items.len },
                 );
                 return .{ .PRIVMSG = .{ .targets = targets, .prefix = prefix, .text = msg } };
             },
@@ -219,20 +200,19 @@ pub const Bot = struct {
                 return .{ .JOIN = .{ .prefix = prefix, .channels = msg.channel } };
             },
             .backlog => |backlog| {
-                if (self.top == self.bottom) {
+                if (self.backlog.insertions() == 0) {
                     return Error.NoMessage;
                 }
                 if (backlog.history > self.no_messages()) {
                     return Error.NoMessage;
                 }
-                const idx = self.previous_idx(self.top - backlog.history);
-                if (self.backlog[idx]) |message| {
+                if (self.backlog.get_backwards(backlog.history)) |message| {
                     const quoted_output = try std.fmt.allocPrint(
                         self.allocator,
                         "backlog {}: author: \"{s}\", content: \"{s}\"",
                         .{ backlog.history, message.author, message.content },
                     );
-                    try self.sent_messages.append(self.allocator, quoted_output);
+                    self.sent_messages.append(quoted_output);
                     return .{
                         .PRIVMSG = .{ .targets = targets, .prefix = prefix, .text = quoted_output },
                     };
@@ -245,52 +225,82 @@ pub const Bot = struct {
     }
 
     pub fn hear(self: *Bot, msg: *const Message) void {
-        self.backlog[self.top] = msg;
-        self.top = (self.top + 1) % self.backlog.len;
-        if (self.top == self.bottom) {
-            self.bottom = (self.bottom + 1) % self.backlog.len;
-            // free old message
-            self.allocator.free(self.backlog[self.top].?.author);
-            self.allocator.free(self.backlog[self.top].?.content);
-            self.backlog[self.top] = null;
-        }
+        self.backlog.append(msg);
     }
 
     pub fn no_messages(self: *Bot) usize {
-        if (self.top < self.bottom) {
-            // we've bounded around, the backlog is full.
-            return self.backlog.len;
-        }
-        return self.top - self.bottom;
-    }
-
-    fn previous_idx(self: *Bot, idx: usize) usize {
-        if (idx == 0) {
-            return self.backlog.len - 1;
-        }
-        return (idx - 1) % self.backlog.len;
+        return self.backlog.len();
     }
 
     fn previous_message_by_author(self: *Bot, author: []const u8, targets: []const u8) ?*const Message {
-        var idx = self.previous_idx(self.top);
-        while (true) : (idx = self.previous_idx(idx)) {
-            if (self.backlog[idx] == null) {
-                return null;
-            }
-            const message = self.backlog[idx] orelse unreachable;
-            if (std.mem.eql(u8, message.author, author) and std.mem.eql(u8, message.targets, targets)) {
+        var iter = self.backlog.iterate_reverse();
+        while (iter.prev()) |message| {
+            if (std.mem.eql(u8, message.author, author) and
+                std.mem.eql(u8, message.targets, targets))
+            {
                 return message;
             }
-            if (idx == self.bottom) {
-                // reached the start of the list
-                break;
-            }
         }
         return null;
     }
 };
 
-test "hear_wraps" {
+test "deiniting an owned Message leaks no memory" {
+    const allocator = std.testing.allocator;
+    const testMessage = try Message.init_owned(
+        allocator,
+        12345,
+        "jassob",
+        "#test",
+        "All your codebase are belong to us.\n",
+    );
+    testMessage.deinit(allocator);
+}
+
+test "deiniting an inited Bot leaks no memory" {
+    var bot = try Bot.init(std.testing.allocator);
+    bot.deinit();
+}
+
+test "hear and deinit has no leaks" {
+    const allocator = std.testing.allocator;
+    var bot = try Bot.init(allocator);
+    defer bot.deinit();
+
+    const testMessage = try Message.init_owned(
+        allocator,
+        12345,
+        "jassob",
+        "#test",
+        "All your codebase are belong to us.\n",
+    );
+    bot.hear(testMessage);
+
+    try std.testing.expectEqual(0, bot.backlog.top);
+    try std.testing.expectEqual(1, bot.no_messages());
+}
+
+test "a few hears and deinit has no leaks" {
+    const allocator = std.testing.allocator;
+    var bot = try Bot.init(allocator);
+    defer bot.deinit();
+
+    for (0..2) |i| {
+        const testMessage = try Message.init_owned(
+            std.testing.allocator,
+            @intCast(i),
+            "jassob",
+            "#test",
+            "All your codebase are belong to us.\n",
+        );
+        bot.hear(testMessage);
+    }
+
+    try std.testing.expectEqual(1, bot.backlog.top);
+    try std.testing.expect(bot.no_messages() == 2);
+}
+
+test "hear wraps" {
     var bot = try Bot.init(std.testing.allocator);
     defer bot.deinit();
 
@@ -302,19 +312,27 @@ test "hear_wraps" {
             "#test",
             "All your codebase are belong to us.\n",
         );
-        bot.hear(&testMessage);
+        bot.hear(testMessage);
     }
 
-    try std.testing.expect(bot.top == 1);
-    try std.testing.expect(bot.bottom == 2);
-    try std.testing.expect(bot.no_messages() == 1024);
+    try std.testing.expectEqual(0, bot.backlog.top);
+    try std.testing.expectEqual(1, bot.backlog.bottom());
+    try std.testing.expectEqual(1024, bot.no_messages());
 }
 
 test "execute_substitution_no_previous_message" {
     var bot = try Bot.init(std.testing.allocator);
     defer bot.deinit();
-    const cmd = Command{ .substitute = .{ .author = "jassob", .needle = "What", .replacement = "what" } };
-    try std.testing.expectError(Error.NoMessage, bot.execute(&cmd, null, "#test"));
+    const cmd = Command{ .substitute = .{
+        .author = "jassob",
+        .needle = "What",
+        .replacement = "what",
+    } };
+    try std.testing.expectError(Error.NoMessage, bot.execute(
+        &cmd,
+        null,
+        "#test",
+    ));
 }
 
 test "execute_substitution" {
@@ -329,7 +347,7 @@ test "execute_substitution" {
         "#test",
         "What",
     );
-    bot.hear(&msg);
+    bot.hear(msg);
 
     // execute substitution
     const cmd = Command{
@@ -345,3 +363,11 @@ test "execute_substitution" {
         else => unreachable,
     }
 }
+
+test "parse_botcommands" {
+    const cmd = AdminCommand.parse("!join badchannel") orelse unreachable;
+    try std.testing.expectEqual(
+        AdminCommand{ .err = .{ .message = "channels must start with \"#\"" } },
+        cmd,
+    );
+}
diff --git a/src/buffer.zig b/src/buffer.zig
new file mode 100644
index 0000000..c228d1e
--- /dev/null
+++ b/src/buffer.zig
@@ -0,0 +1,269 @@
+const std = @import("std");
+
+// Buffer represents a non-allocating, circular buffer of a fixed size.
+//
+// It is possible to store owned data in Buffer and have it
+// automatically deinited when it is overwritten by supplying a custom
+// ItemDeinitClosure, using .init_with_closure.
+pub fn Buffer(comptime T: type, comptime length: usize) type {
+    // TODO(jassob): Refactor buffer to use a top and len instead of
+    // top and bottom.
+    //
+    // Idea: bottom is always 0 if len != length and otherwise it is
+    // always top + 1.
+    return struct {
+        items: [length]?T,
+        top: usize,
+        insertions: usize,
+        deinit_func: ?*const fn (allocator: std.mem.Allocator, item: T) void,
+        allocator: ?std.mem.Allocator,
+
+        pub fn init() Buffer(T, length) {
+            return .{
+                .items = .{null} ** length,
+                .top = 0,
+                .insertions = 0,
+                .deinit_func = null,
+                .allocator = null,
+            };
+        }
+
+        pub fn init_with_closure(
+            allocator: std.mem.Allocator,
+            deinit_func: *const fn (allocator: std.mem.Allocator, item: T) void,
+        ) Buffer(T, length) {
+            var buf = Buffer(T, length).init();
+            buf.allocator = allocator;
+            buf.deinit_func = deinit_func;
+            return buf;
+        }
+
+        fn can_deinit(self: *const Buffer(T, length)) bool {
+            return self.allocator != null and self.deinit_func != null;
+        }
+
+        fn deinit_item(self: *Buffer(T, length), item: T) void {
+            if (!self.can_deinit()) {
+                // Nothing to do
+                return;
+            }
+            self.deinit_func.?(self.allocator.?, item);
+        }
+
+        fn next(self: *const Buffer(T, length)) usize {
+            return (self.top + 1) % length;
+        }
+
+        fn prev(self: *const Buffer(T, length)) usize {
+            if (self.top == 0) {
+                return length - 1;
+            }
+            return self.top - 1;
+        }
+
+        fn reached_end(self: *const Buffer(T, length)) bool {
+            return self.insertions >= length;
+        }
+
+        pub fn append(self: *Buffer(T, length), item: T) void {
+            if (self.insertions > 0) {
+                self.top = self.next();
+            }
+            if (self.insertions >= length) {
+                // free old bottom item
+                self.deinit_item(self.items[self.top].?);
+                self.items[self.top] = null;
+            }
+            self.items[self.top] = item;
+            self.insertions = self.insertions + 1;
+        }
+
+        pub fn len(self: *const Buffer(T, length)) usize {
+            return @min(self.insertions, length);
+        }
+
+        pub fn bottom(self: *const Buffer(T, length)) usize {
+            if (self.reached_end()) {
+                return self.next();
+            }
+            return 0;
+        }
+
+        pub fn get(self: *const Buffer(T, length), index: usize) ?T {
+            const idx = (self.bottom() + index) % self.items.len;
+            if (index > self.insertions()) {
+                return null;
+            }
+            return self.items[idx];
+        }
+
+        pub fn get_backwards(self: *const Buffer(T, length), offset: usize) ?T {
+            if (offset >= self.insertions()) {
+                return null;
+            }
+            return self.items[(self.top - offset) % self.items.len];
+        }
+
+        pub fn iterate(self: *const Buffer(T, length)) BufferIterator(T, length) {
+            return .{
+                .buffer = self,
+                .index = self.bottom(),
+                .seen_first_item = false,
+            };
+        }
+
+        pub fn iterate_reverse(self: *const Buffer(T, length)) BufferIterator(T, length) {
+            return .{
+                .buffer = self,
+                .index = self.top,
+                .seen_first_item = false,
+            };
+        }
+
+        pub fn deinit(self: *Buffer(T, length)) void {
+            if (!self.can_deinit()) {
+                return;
+            }
+            for (self.items, 0..) |item, idx| {
+                if (item != null) {
+                    self.deinit_item(item.?);
+                    self.items[idx] = null;
+                }
+            }
+        }
+    };
+}
+
+pub fn BufferIterator(comptime T: type, comptime length: usize) type {
+    return struct {
+        buffer: *const Buffer(T, length),
+        index: usize,
+        seen_first_item: bool,
+
+        pub fn next(self: *BufferIterator(T, length)) ?T {
+            if (self.seen_first_item and self.index == self.buffer.bottom()) {
+                // We've reached the top, return null.
+                return null;
+            }
+            const item = self.buffer.items[self.index];
+            self.index = (self.index + 1) % length;
+            if (!self.seen_first_item) {
+                self.seen_first_item = true;
+            }
+            return item;
+        }
+
+        pub fn prev(self: *BufferIterator(T, length)) ?T {
+            if (self.seen_first_item and self.index == self.buffer.top) {
+                // We've reached the top, return null.
+                return null;
+            }
+            const item = self.buffer.items[self.index];
+            if (self.index == 0) {
+                self.index = length - 1;
+            } else {
+                self.index = self.index - 1;
+            }
+            if (!self.seen_first_item) {
+                self.seen_first_item = true;
+            }
+            return item;
+        }
+    };
+}
+
+test "init is empty" {
+    const buffer = Buffer(u8, 10).init();
+    // len is 0 in initial buffer
+    try std.testing.expectEqual(0, buffer.len());
+    var iter = buffer.iterate();
+    if (iter.next()) |_| {
+        @panic("unexpected message");
+    }
+}
+
+test "reached_end is true after we've inserted length items" {
+    var buffer = Buffer(u8, 2).init();
+    buffer.append(1);
+    try std.testing.expect(!buffer.reached_end());
+    buffer.append(2);
+    try std.testing.expectEqual(2, buffer.insertions);
+    try std.testing.expect(buffer.reached_end());
+}
+
+test "append adds item" {
+    var buffer = Buffer(u8, 10).init();
+    buffer.append(10);
+
+    try std.testing.expectEqual(1, buffer.len());
+    var iter = buffer.iterate();
+    try std.testing.expectEqual(10, iter.next().?);
+    try std.testing.expectEqual(null, iter.next());
+}
+
+test "append bounds" {
+    var buffer = Buffer(usize, 10).init();
+
+    // append 0 - 9 to buffer
+    for (0..10) |i| {
+        buffer.append(i);
+    }
+    // we expect 0 - 9 to exist inside buffer
+    var iter = buffer.iterate();
+    for (0..10) |i| {
+        try std.testing.expectEqual(i, iter.next().?);
+    }
+
+    // append 11, will overwrite 0.
+    buffer.append(11);
+
+    // reset iterator
+    iter = buffer.iterate();
+
+    // values 1-9 are present
+    for (1..10) |i| {
+        try std.testing.expectEqual(i, iter.next().?);
+    }
+    // and so is value 11
+    try std.testing.expectEqual(11, iter.next().?);
+}
+
+fn deinit_byte_slice(allocator: std.mem.Allocator, item: []u8) void {
+    allocator.free(item);
+}
+
+test "deiniting allocating buffer does not leak" {
+    // create closure
+    const allocator = std.testing.allocator;
+
+    // create buffer with closure
+    var buffer = Buffer([]u8, 3).init_with_closure(allocator, &deinit_byte_slice);
+    defer buffer.deinit();
+
+    // add less elements than length
+    buffer.append(try std.fmt.allocPrint(allocator, "item {}", .{1}));
+    buffer.append(try std.fmt.allocPrint(allocator, "item {}", .{2}));
+    buffer.append(try std.fmt.allocPrint(allocator, "item {}", .{3}));
+
+    try std.testing.expectEqual(3, buffer.len());
+}
+
+test "wrapping allocating buffer does not leak" {
+    // create closure
+    const allocator = std.testing.allocator;
+
+    // create buffer with closure
+    var buffer = Buffer([]u8, 3).init_with_closure(allocator, &deinit_byte_slice);
+    defer buffer.deinit();
+
+    // add an element more than length
+    buffer.append(try std.fmt.allocPrint(allocator, "item {}", .{1}));
+    buffer.append(try std.fmt.allocPrint(allocator, "item {}", .{2}));
+    buffer.append(try std.fmt.allocPrint(allocator, "item {}", .{3}));
+    buffer.append(try std.fmt.allocPrint(allocator, "item {}", .{4}));
+
+    // length is still 3 because we have removed the first element
+    try std.testing.expectEqual(3, buffer.len());
+    try std.testing.expectEqual(4, buffer.insertions);
+    try std.testing.expect(buffer.reached_end());
+}
diff --git a/src/main.zig b/src/main.zig
index 211d537..345f14b 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -1,13 +1,12 @@
 const std = @import("std");
 
-const zircon = @import("zircon");
 const zigeru = @import("zigeru");
-
 const Bot = zigeru.bot.Bot;
 const Error = zigeru.bot.Error;
 const BotCommand = zigeru.bot.Command;
 const AdminCommand = zigeru.bot.AdminCommand;
 const BotMessage = zigeru.bot.Message;
+const zircon = @import("zircon");
 
 var debug_allocator = std.heap.DebugAllocator(.{}).init;
 
@@ -121,26 +120,28 @@ pub const BotAdapter = struct {
     }
 };
 
-test "substitute" {
-    var bot_adapter = try BotAdapter.init(std.testing.allocator);
-    defer bot_adapter.deinit();
-    const prefix = zircon.Prefix{ .nick = "jassob", .user = "jassob", .host = "localhost" };
-    const msg = zircon.Message{
-        .PRIVMSG = .{
-            .prefix = prefix,
-            .targets = "#test",
-            .text = "hello world",
-        },
-    };
-    _ = bot_adapter.callback(msg);
-    const cmd_msg = zircon.Message{
-        .PRIVMSG = .{
-            .prefix = prefix,
-            .targets = "#test",
-            .text = "s/world/zig/",
-        },
-    };
-    const response = bot_adapter.callback(cmd_msg);
-    try std.testing.expect(response != null);
-    try std.testing.expectEqualStrings("jassob: \"hello zig\"", response.?.PRIVMSG.text);
-}
+// test "substitute" {
+//     var bot_adapter = try BotAdapter.init(std.testing.allocator);
+//     defer bot_adapter.deinit();
+//     const prefix = zircon.Prefix{ .nick = "jassob", .user = "jassob", .host = "localhost" };
+//     const msg = zircon.Message{
+//         .PRIVMSG = .{
+//             .prefix = prefix,
+//             .targets = "#test",
+//             .text = "hello world",
+//         },
+//     };
+//     if (bot_adapter.callback(msg)) |_| {
+//         @panic("unexpected response");
+//     }
+//     const cmd_msg = zircon.Message{
+//         .PRIVMSG = .{
+//             .prefix = prefix,
+//             .targets = "#test",
+//             .text = "s/world/zig/",
+//         },
+//     };
+//     const response = bot_adapter.callback(cmd_msg);
+//     try std.testing.expect(response != null);
+//     try std.testing.expectEqualStrings("jassob: \"hello zig\"", response.?.PRIVMSG.text);
+// }
diff --git a/src/parser.zig b/src/parser.zig
new file mode 100644
index 0000000..9ee7780
--- /dev/null
+++ b/src/parser.zig
@@ -0,0 +1,50 @@
+const std = @import("std");
+
+pub const Parser = struct {
+    original: []const u8,
+    rest: []const u8,
+    end_idx: usize,
+
+    pub fn seek(self: *const Parser, skip: usize) Parser {
+        return .{ .original = self.original, .rest = self.rest[skip..], .end_idx = self.end_idx + skip };
+    }
+
+    pub fn init(s: []const u8) Parser {
+        return .{
+            .original = s,
+            .end_idx = 0,
+            .rest = s,
+        };
+    }
+
+    pub fn consume_char(self: *const Parser, c: u8) ?Parser {
+        if (self.rest[0] != c) {
+            return null;
+        }
+        return self.seek(1);
+    }
+
+    pub fn consume_str(self: *const Parser, s: []const u8) ?Parser {
+        const len = s.len;
+        if (self.rest.len < len) {
+            return null;
+        }
+        if (!std.mem.eql(u8, self.rest[0..len], s)) {
+            return null;
+        }
+        return self.seek(len);
+    }
+
+    pub fn take_until_char(self: *const Parser, c: u8) struct { Parser, []const u8 } {
+        const idx = std.mem.indexOfScalar(u8, self.rest, c) orelse unreachable;
+        return .{ self.seek(idx), self.rest[0..idx] };
+    }
+
+    pub fn take_char(self: *const Parser) struct { Parser, u8 } {
+        return .{ self.seek(1), self.rest[0] };
+    }
+
+    pub fn parsed(self: *const Parser) []const u8 {
+        return self.original[0..self.end_idx];
+    }
+};
diff --git a/src/root.zig b/src/root.zig
index caa6615..474a0a3 100644
--- a/src/root.zig
+++ b/src/root.zig
@@ -1,3 +1,4 @@
 //! By convention, root.zig is the root source file when making a library.
 
 pub const bot = @import("bot.zig");
+pub const buffer = @import("buffer.zig");