5 files changed, 309 insertions, 148 deletions

diff --git a/src/Buffer.zig b/src/Buffer.zig
index 5bf319c..d0546c0 100644
--- a/src/Buffer.zig
+++ b/src/Buffer.zig
@@ -394,7 +394,8 @@ pub fn nextLine(self: *Buffer) void {
     }
 }
 
-pub fn pageDown(self: *Buffer, screenrows: usize) void {
+pub fn pageDown(self: *Buffer, editor: Editor) void {
+    const screenrows = editor.screenrows;
     self.cy = std.math.clamp(
         self.rowoff + screenrows - 1 - self.config.page_overlap,
         0,
@@ -406,7 +407,8 @@ pub fn pageDown(self: *Buffer, screenrows: usize) void {
     }
 }
 
-pub fn pageUp(self: *Buffer, screenrows: usize) void {
+pub fn pageUp(self: *Buffer, editor: Editor) void {
+    const screenrows = editor.screenrows;
     self.cy = std.math.min(self.rows.items.len, self.rowoff + self.config.page_overlap);
     var i: usize = 0;
     while (i < screenrows) : (i += 1) {
@@ -423,8 +425,11 @@ pub fn previousLine(self: *Buffer) void {
     self.cx = self.rows.items[self.cy].rxToCx(self.config, self.rx);
 }
 
-pub fn recenterTopBottom(self: *Buffer, screenrows: usize) void {
+pub fn recenterTopBottom(self: *Buffer, editor: *Editor) !void {
     // TODO: Currently only recenters
+    try editor.refreshWindowSize();
+
+    const screenrows = editor.screenrows;
     if (self.cy >= screenrows / 2) {
         self.rowoff = self.cy - screenrows / 2;
     } else {
diff --git a/src/Editor.zig b/src/Editor.zig
index d721600..4d90760 100644
--- a/src/Editor.zig
+++ b/src/Editor.zig
@@ -6,8 +6,8 @@ const ArrayList = std.ArrayList;
 const Buffer = es.Buffer;
 const Editor = @This();
 const Key = es.Key;
+const KeyMap = es.KeyMap;
 const KeyReader = es.KeyReader;
-const KeyState = es.key_state.KeyState;
 const StringBuilder = es.StringBuilder;
 const StringHashMap = std.StringHashMap;
 
@@ -22,12 +22,15 @@ screencols: usize,
 statusmsg: ?[]u8,
 statusmsg_time: i64,
 
-current_state: KeyState,
+key_map: KeyMap,
 
 key_reader: KeyReader,
 should_exit: bool,
 
 pub fn init(allocator: Allocator) !Editor {
+    var key_map: ?KeyMap = try KeyMap.defaultMap(allocator);
+    errdefer if (key_map) |*map| map.deinit();
+
     var self = Editor{
         .allocator = allocator,
 
@@ -40,12 +43,13 @@ pub fn init(allocator: Allocator) !Editor {
         .statusmsg = null,
         .statusmsg_time = 0,
 
-        .current_state = es.key_state.defaultState,
+        .key_map = key_map.?,
 
         .key_reader = KeyReader.init(allocator),
         .should_exit = false,
     };
     errdefer self.deinit();
+    key_map = null;
 
     // Initializes .screenrows and .screencols
     try self.refreshWindowSize();
@@ -67,6 +71,8 @@ pub fn deinit(self: *Editor) void {
         self.allocator.free(statusmsg);
     }
 
+    self.key_map.deinit();
+
     self.key_reader.deinit();
 
     self.* = undefined;
@@ -197,7 +203,7 @@ pub fn openFile(self: *Editor) !void {
 
 pub fn processKeypress(self: *Editor) !void {
     const key = try self.key_reader.readKey();
-    try self.current_state(self, self.buffer, key);
+    try self.key_map.keypress(self, self.buffer, key);
 }
 
 pub fn prompt(self: *Editor, allocator: Allocator, prompt_str: []const u8) !?[]u8 {
diff --git a/src/KeyMap.zig b/src/KeyMap.zig
new file mode 100644
index 0000000..5c866b8
--- /dev/null
+++ b/src/KeyMap.zig
@@ -0,0 +1,290 @@
+const es = @import("root");
+const std = @import("std");
+
+const Allocator = std.mem.Allocator;
+const AutoHashMap = std.AutoHashMap;
+const Buffer = es.Buffer;
+const Editor = es.Editor;
+const Key = es.Key;
+const KeyMap = @This();
+
+pub const Error = error{
+    MalformedConfig,
+    MisformedTerminalResponse,
+    StreamTooLong,
+} ||
+    std.fmt.ParseIntError ||
+    std.fs.File.OpenError ||
+    std.fs.File.ReadError ||
+    std.fs.File.WriteError ||
+    std.mem.Allocator.Error ||
+    std.os.GetCwdError ||
+    std.os.RealPathError;
+
+pub const BoundFn = fn (*Editor, *Buffer, Key) Error!void;
+
+const Value = union(enum) {
+    bound_fn: BoundFn,
+    submap: AutoHashMap(Key, Value),
+
+    pub fn deinit(self: *Value) void {
+        switch (self.*) {
+            .bound_fn => {},
+            .submap => |*map| {
+                var it = map.valueIterator();
+                while (it.next()) |value| {
+                    value.deinit();
+                }
+
+                map.deinit();
+            },
+        }
+
+        self.* = undefined;
+    }
+};
+
+allocator: Allocator,
+current: ?*AutoHashMap(Key, Value),
+default: ?BoundFn,
+map: AutoHashMap(Key, Value),
+
+pub fn init(allocator: Allocator) KeyMap {
+    return .{
+        .allocator = allocator,
+        .current = null,
+        .default = null,
+        .map = AutoHashMap(Key, Value).init(allocator),
+    };
+}
+
+pub fn defaultMap(allocator: Allocator) !KeyMap {
+    var map = KeyMap.init(allocator);
+    errdefer map.deinit();
+
+    map.default = wrapFn(defaultFn);
+
+    // M-g <*>
+    try map.bind(&.{Key.meta('g'), Key.char('g')}, Buffer.goToLine);
+
+    // M-O <*>
+    try map.bind(&.{Key.meta('O'), Key.char('F')}, Buffer.moveEndOfLine);
+    try map.bind(&.{Key.meta('O'), Key.char('H')}, Buffer.moveBeginningOfLine);
+
+    // C-x C-<*>
+    try map.bind(&.{Key.ctrl('x'), Key.ctrl('b')}, Editor.switchBuffer);
+    try map.bind(&.{Key.ctrl('x'), Key.ctrl('c')}, Editor.saveBuffersExit);
+    try map.bind(&.{Key.ctrl('x'), Key.ctrl('f')}, Editor.openFile);
+    try map.bind(&.{Key.ctrl('x'), Key.ctrl('s')}, Buffer.save);
+
+    // C-x <*>
+    try map.bind(&.{Key.ctrl('x'), Key.char('b')}, Editor.switchBuffer);
+    // TODO: C-x h for help
+    try map.bind(&.{Key.ctrl('x'), Key.char('k')}, Editor.killCurrentBuffer);
+
+    // M-C-<*>
+    try map.bind(&.{Key.meta(Key.ctrl('d'))}, Buffer.backwardDeleteChar);
+
+    // M-<*>
+    // M-g is taken
+    // M-O is taken
+    try map.bind(&.{Key.meta('v')}, Buffer.pageUp);
+
+    // C-<*>
+    try map.bind(&.{Key.ctrl('a')}, Buffer.moveBeginningOfLine);
+    try map.bind(&.{Key.ctrl('b')}, Buffer.backwardChar);
+    try map.bind(&.{Key.ctrl('d')}, Buffer.deleteChar);
+    try map.bind(&.{Key.ctrl('e')}, Buffer.moveEndOfLine);
+    try map.bind(&.{Key.ctrl('f')}, Buffer.forwardChar);
+    try map.bind(&.{Key.ctrl('g')}, Editor.clearStatusMessage);
+    try map.bind(&.{Key.ctrl('i')}, Buffer.indent); // tab
+    try map.bind(&.{Key.ctrl('j')}, Buffer.insertNewline); // line feed
+    try map.bind(&.{Key.ctrl('k')}, Buffer.killLine);
+    try map.bind(&.{Key.ctrl('l')}, Buffer.recenterTopBottom);
+    try map.bind(&.{Key.ctrl('m')}, Buffer.insertNewline); // carriage return
+    try map.bind(&.{Key.ctrl('n')}, Buffer.nextLine);
+    try map.bind(&.{Key.ctrl('p')}, Buffer.previousLine);
+    try map.bind(&.{Key.ctrl('s')}, es.search);
+    // TODO: C-q quotedInsert
+    try map.bind(&.{Key.ctrl('v')}, Buffer.pageDown);
+    // C-x is taken
+
+    // <*>
+    try map.bind(&.{Key.backspace}, Buffer.backwardDeleteChar);
+    try map.bind(&.{Key.delete}, Buffer.deleteChar);
+    try map.bind(&.{Key.down}, Buffer.nextLine);
+    try map.bind(&.{Key.end}, Buffer.moveEndOfLine);
+    try map.bind(&.{Key.home}, Buffer.moveBeginningOfLine);
+    try map.bind(&.{Key.left}, Buffer.backwardChar);
+    try map.bind(&.{Key.page_down}, Buffer.pageDown);
+    try map.bind(&.{Key.page_up}, Buffer.pageUp);
+    try map.bind(&.{Key.right}, Buffer.forwardChar);
+    try map.bind(&.{Key.untab}, Buffer.unindent);
+    try map.bind(&.{Key.up}, Buffer.previousLine);
+
+    return map;
+}
+
+pub fn deinit(self: *KeyMap) void {
+    var it = self.map.valueIterator();
+    while (it.next()) |value| {
+        value.deinit();
+    }
+    self.map.deinit();
+
+    self.* = undefined;
+}
+
+pub fn bind(self: *KeyMap, keys: []const Key, comptime f: anytype) !void {
+    std.debug.assert(keys.len > 0);
+    var map: *AutoHashMap(Key, Value) = &self.map;
+    for (keys[0..keys.len - 1]) |key| {
+        const gop = try map.getOrPut(key);
+        if (!gop.found_existing) {
+            gop.value_ptr.* = .{ .submap = AutoHashMap(Key, Value).init(self.allocator) };
+        }
+
+        switch (gop.value_ptr.*) {
+            .bound_fn => {
+                std.log.err("Attempting to bind a longer chord over a shorter one ({any})", .{keys});
+                return error.KeyBindError;
+            },
+            .submap => |*next_map| map = next_map,
+        }
+    }
+
+    const gop = try map.getOrPut(keys[keys.len - 1]);
+    if (!gop.found_existing) {
+        gop.value_ptr.* = .{ .bound_fn = wrapFn(f) };
+    } else switch (gop.value_ptr.*) {
+        .bound_fn => gop.value_ptr.* = .{ .bound_fn = wrapFn(f) },
+        .submap => {
+            std.log.err("Attempting to bind a shorter chord over a longer one ({any})", .{keys});
+            return error.KeyBindError;
+        },
+    }
+}
+
+pub fn keypress(self: *KeyMap, editor: *Editor, buf: *Buffer, key: Key) !void {
+    const map = self.current orelse &self.map;
+    if (map.getPtr(key)) |value| {
+        switch (value.*) {
+            .bound_fn => |f| {
+                self.current = null;
+                return f(editor, buf, key);
+            },
+            .submap => |*submap| self.current = submap,
+        }
+    } else if (self.current != null) {
+        // TODO: Output the full chord
+        std.log.debug("Unknown chord: ... {}", .{key});
+        try editor.setStatusMessage("Unknown chord: ... {}", .{key});
+        self.current = null;
+    } else if (self.default) |default| {
+        return default(editor, buf, key);
+    } else {
+        std.log.debug("Unknown key: {}", .{key});
+        try editor.setStatusMessage("Unknown key: {}", .{key});
+    }
+}
+
+fn defaultFn(editor: *Editor, buffer: *Buffer, key: Key) !void {
+    if (@enumToInt(key) <= @enumToInt(Key.max_char)) {
+        const char = @intCast(u8, @enumToInt(key));
+        if (std.ascii.isGraph(char) or char == ' ') {
+            try buffer.insertChar(char);
+            return;
+        }
+    }
+
+    std.log.debug("Unknown key: {}", .{key});
+    try editor.setStatusMessage("Unknown key: {}", .{key});
+}
+
+fn wrapFn(comptime f: anytype) BoundFn {
+    comptime {
+        if (@TypeOf(f) == BoundFn) {
+            return f;
+        }
+
+        const fn_info = @typeInfo(@TypeOf(f)).Fn;
+        const should_try = if (fn_info.return_type) |return_type| @typeInfo(return_type) == .ErrorUnion else false;
+
+        const args_info = fn_info.args;
+        var args = [_]type { undefined } ** args_info.len;
+        for (args_info) |arg_info, idx| {
+            args[idx] = arg_info.arg_type.?;
+        }
+
+        if (std.mem.eql(type, &args, &.{*Buffer})) {
+            return struct {
+                pub fn wf(e: *Editor, b: *Buffer, k: Key) Error!void {
+                    _ = e;
+                    _ = k;
+                    if (should_try) {
+                        _ = try f(b);
+                    } else {
+                        _ = f(b);
+                    }
+                }
+            }.wf;
+        } else if (std.mem.eql(type, &args, &.{*Editor})) {
+            return struct {
+                pub fn wf(e: *Editor, b: *Buffer, k: Key) Error!void {
+                    _ = b;
+                    _ = k;
+                    if (should_try) {
+                        _ = try f(e);
+                    } else {
+                        _ = f(e);
+                    }
+                }
+            }.wf;
+        } else if (std.mem.eql(type, &args, &.{*Editor, *Buffer})) {
+            return struct {
+                pub fn wf(e: *Editor, b: *Buffer, k: Key) Error!void {
+                    _ = k;
+                    if (should_try) {
+                        _ = try f(e, b);
+                    } else {
+                        _ = f(e, b);
+                    }
+                }
+            }.wf;
+        } else if (std.mem.eql(type, &args, &.{*Buffer, *Editor})) {
+            return struct {
+                pub fn wf(e: *Editor, b: *Buffer, k: Key) Error!void {
+                    _ = k;
+                    if (should_try) {
+                        _ = try f(b, e);
+                    } else {
+                        _ = f(b, e);
+                    }
+                }
+            }.wf;
+        } else if (std.mem.eql(type, &args, &.{*Buffer, Editor})) {
+            return struct {
+                pub fn wf(e: *Editor, b: *Buffer, k: Key) Error!void {
+                    _ = k;
+                    if (should_try) {
+                        _ = try f(b, e.*);
+                    } else {
+                        _ = f(b, e.*);
+                    }
+                }
+            }.wf;
+        } else if (std.mem.eql(type, &args, &.{*Editor, *Buffer, Key})) {
+            return struct {
+                pub fn wf(e: *Editor, b: *Buffer, k: Key) Error!void {
+                    if (should_try) {
+                        _ = try f(e, b, k);
+                    } else {
+                        _ = f(e, b, k);
+                    }
+                }
+            }.wf;
+        }
+
+        @compileError("How to wrap " ++ @typeName(@TypeOf(f)));
+    }
+}
diff --git a/src/key_state.zig b/src/key_state.zig
deleted file mode 100644
index 818dded..0000000
--- a/src/key_state.zig
+++ /dev/null
@@ -1,140 +0,0 @@
-const es = @import("root");
-const std = @import("std");
-
-const Buffer = es.Buffer;
-const Editor = es.Editor;
-const Key = es.Key;
-
-pub const Error = error{
-    MalformedConfig,
-    MisformedTerminalResponse,
-    StreamTooLong,
-} ||
-    std.mem.Allocator.Error ||
-    std.fmt.ParseIntError ||
-    std.fs.File.OpenError ||
-    std.fs.File.ReadError ||
-    std.fs.File.WriteError ||
-    std.os.GetCwdError ||
-    std.os.RealPathError;
-pub const KeyState = fn (*Editor, *Buffer, Key) Error!void;
-
-fn mgState(editor: *Editor, buf: *Buffer, key: Key) Error!void {
-    editor.current_state = defaultState;
-    editor.clearStatusMessage();
-
-    switch (key) {
-        // ========== <*> ==========
-        Key.char('g') => try buf.goToLine(editor),
-
-        else => {
-            std.log.debug("Unknown chord: M-g {}", .{key});
-            try editor.setStatusMessage("Unknown chord: M-g {}", .{key});
-        },
-    }
-}
-
-fn mOState(editor: *Editor, buf: *Buffer, key: Key) Error!void {
-    editor.current_state = defaultState;
-    editor.clearStatusMessage();
-
-    switch (key) {
-        // ========== <*> ==========
-        Key.char('F') => buf.moveEndOfLine(),
-        Key.char('H') => buf.moveBeginningOfLine(),
-
-        else => {
-            std.log.debug("Unknown chord: M-O {}", .{key});
-            try editor.setStatusMessage("Unknown chord: M-O {}", .{key});
-        },
-    }
-}
-
-fn cxState(editor: *Editor, buf: *Buffer, key: Key) Error!void {
-    editor.current_state = defaultState;
-    editor.clearStatusMessage();
-
-    switch (key) {
-        // ========== C-<*> ==========
-        Key.ctrl('b'), Key.char('b') => try editor.switchBuffer(),
-        Key.ctrl('c') => try editor.saveBuffersExit(),
-        Key.ctrl('f') => try editor.openFile(),
-        Key.ctrl('g') => {},
-        Key.ctrl('s') => try buf.save(editor),
-
-        // ========== <*> ==========
-        Key.char('k') => _ = try editor.killCurrentBuffer(),
-
-        else => {
-            std.log.debug("Unknown chord: C-x {}", .{key});
-            try editor.setStatusMessage("Unknown chord: C-x {}", .{key});
-        },
-    }
-}
-
-pub fn defaultState(editor: *Editor, buf: *Buffer, key: Key) Error!void {
-    switch (key) {
-        // ========== M-C-<*> ==========
-        Key.meta(Key.ctrl('d')), Key.backspace => try buf.backwardDeleteChar(),
-
-        // ========== M-<*> ==========
-        Key.meta('g') => {
-            editor.current_state = mgState;
-            try editor.setStatusMessage("M-g-", .{});
-        },
-        Key.meta('O') => editor.current_state = mOState,
-        Key.meta('v'), Key.page_up => buf.pageUp(editor.screenrows),
-
-        // ========== C-<*> ==========
-        Key.ctrl('a'), Key.home => buf.moveBeginningOfLine(),
-        Key.ctrl('b'), Key.left => buf.backwardChar(),
-        Key.ctrl('d'), Key.delete => try buf.deleteChar(),
-        Key.ctrl('e'), Key.end => buf.moveEndOfLine(),
-        Key.ctrl('f'), Key.right => buf.forwardChar(),
-        Key.ctrl('g') => editor.clearStatusMessage(),
-
-        // TODO: C-h help
-
-        // tab
-        Key.ctrl('i') => try buf.indent(),
-        // line feed
-        Key.ctrl('j') => try buf.insertNewline(),
-        Key.ctrl('k') => try buf.killLine(),
-
-        Key.ctrl('l') => {
-            try editor.refreshWindowSize();
-            buf.recenterTopBottom(editor.screenrows);
-        },
-
-        // carriage return
-        Key.ctrl('m') => try buf.insertNewline(),
-        Key.ctrl('n'), Key.down => buf.nextLine(),
-        Key.ctrl('p'), Key.up => buf.previousLine(),
-        Key.ctrl('s') => try es.search(editor, buf),
-
-        // TODO: C-q quotedInsert
-
-        Key.ctrl('v'), Key.page_down => buf.pageDown(editor.screenrows),
-
-        Key.ctrl('x') => {
-            editor.current_state = cxState;
-            try editor.setStatusMessage("C-x-", .{});
-        },
-
-        // ========== <*> ==========
-        Key.untab => try buf.unindent(),
-
-        else => {
-            if (@enumToInt(key) <= @enumToInt(Key.max_char)) {
-                const char = @intCast(u8, @enumToInt(key));
-                if (std.ascii.isGraph(char) or std.ascii.isSpace(char)) {
-                    try buf.insertChar(char);
-                    return;
-                }
-            }
-
-            std.log.debug("Unknown key: {}", .{key});
-            try editor.setStatusMessage("Unknown key: {}", .{key});
-        },
-    }
-}
diff --git a/src/main.zig b/src/main.zig
index 176aadd..7a3f007 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -5,8 +5,8 @@ pub const Editor = @import("Editor.zig");
 pub const files = @import("files.zig");
 pub const Highlight = @import("highlight.zig").Highlight;
 pub const Key = @import("key.zig").Key;
+pub const KeyMap = @import("KeyMap.zig");
 pub const KeyReader = @import("KeyReader.zig");
-pub const key_state = @import("key_state.zig");
 pub const RawMode = @import("RawMode.zig");
 pub const Row = @import("Row.zig");
 pub const search = @import("search.zig").search;