feat: [hx] r to replace with a character

If no selection, the character under the cursor is replaced, if
selection, each character is replaced by the typed character.

src/keybind/builtin/helix.json

@@ -379,6 +379,7 @@
             ["N", "extend_search_next"],
             ["*", "extend_search_prev"],
 
+            ["r", "replace"],
             ["P", "paste_clipboard_before"],
             ["R", ["replace_selections_with_clipboard"], ["enter_mode", "normal"]],
             ["p", "paste_after"],
@@ -547,6 +548,17 @@
             ["9", "add_integer_argument_digit", 9]
         ]
     },
+    "mini/replace": {
+        "press": [
+            ["ctrl+g", "mini_mode_cancel"],
+            ["ctrl+c", "mini_mode_cancel"],
+            ["ctrl+l", "scroll_view_center_cycle"],
+            ["tab", "mini_mode_insert_bytes", "\t"],
+            ["enter", "mini_mode_insert_bytes", "\n"],
+            ["escape", "mini_mode_cancel"],
+            ["backspace", "mini_mode_cancel"]
+        ]
+    }, 
     "home": {
         "on_match_failure": "ignore",
         "press": [

src/tui/mode/helix.zig

@@ -441,6 +441,17 @@ const cmds_ = struct {
         try paste_helix(ctx, insert_before);
     }
     pub const paste_clipboard_before_meta: Meta = .{ .description = "Paste from clipboard before selection" };
+
+    pub fn replace_with_character_helix(_: *void, ctx: Ctx) Result {
+        const mv = tui.mainview() orelse return;
+        const ed = mv.get_active_editor() orelse return;
+        var root = ed.buf_root() catch return;
+        root = try ed.with_cursels_mut_once_arg(root, replace_cursel_with_character, ed.allocator, ctx);
+        try ed.update_buf(root);
+        ed.clamp();
+        ed.need_render();
+    }
+    pub const replace_with_character_helix_meta: Meta = .{ .description = "Replace with character" };
 };
 
 fn to_char_helix(ctx: command.Context, move: Editor.cursel_operator_mut_once_arg) command.Result {
@@ -598,6 +609,40 @@ fn move_cursor_word_left_helix(root: Buffer.Root, cursor: *Cursor, metrics: Buff
     }
 }
 
+fn replace_cursel_with_character(ed: *Editor, root: Buffer.Root, cursel: *CurSel, allocator: Allocator, ctx: command.Context) error{Stop}!Buffer.Root {
+    var egc: []const u8 = undefined;
+    if (!(ctx.args.match(.{tp.extract(&egc)}) catch return error.Stop))
+        return error.Stop;
+    const no_selection = try select_char_if_no_selection(cursel, root, ed.metrics);
+    var begin: Cursor = undefined;
+    if (cursel.selection) |*sel| {
+        sel.normalize();
+        begin = sel.*.begin;
+    }
+
+    const sel_length = Editor.cursel_length(root, cursel.*, ed.metrics);
+    const total_length = sel_length * egc.len;
+    var sfa = std.heap.stackFallback(4096, ed.allocator);
+    const sfa_allocator = sfa.get();
+    const replacement = sfa_allocator.alloc(u8, total_length) catch return error.Stop;
+    errdefer allocator.free(replacement);
+    for (0..sel_length) |i| {
+        for (0..egc.len) |j| {
+            replacement[i * egc.len + j] = egc[j];
+        }
+    }
+
+    const root_ = insert_replace_selection(ed, root, cursel, replacement, allocator) catch return error.Stop;
+
+    if (no_selection) {
+        try cursel.cursor.move_left(root, ed.metrics);
+        cursel.disable_selection(root, ed.metrics);
+    } else {
+        cursel.selection = Selection{ .begin = begin, .end = cursel.cursor };
+    }
+    return root_;
+}
+
 fn move_noop(_: Buffer.Root, _: *Cursor, _: Buffer.Metrics) error{Stop}!void {}
 
 fn move_cursor_word_right_end_helix(root: Buffer.Root, cursor: *Cursor, metrics: Buffer.Metrics) error{Stop}!void {
@@ -888,6 +933,21 @@ fn move_cursor_carriage_return(root: Buffer.Root, cursel: CurSel, cursor: *Curso
     try Editor.move_cursor_right(root, cursor, metrics);
 }
 
+fn select_char_if_no_selection(cursel: *CurSel, root: Buffer.Root, metrics: Buffer.Metrics) !bool {
+    if (cursel.selection) |*sel_| {
+        const sel: *Selection = sel_;
+        if (sel.*.empty()) {
+            sel.*.begin = .{ .row = cursel.cursor.row, .col = cursel.cursor.col + 1, .target = cursel.cursor.target + 1 };
+            return true;
+        }
+        return false;
+    } else {
+        const sel = try cursel.enable_selection(root, metrics);
+        sel.begin = .{ .row = cursel.cursor.row, .col = cursel.cursor.col + 1, .target = cursel.cursor.target + 1 };
+        return true;
+    }
+}
+
 fn is_cursel_from_extend_line_below(cursel: CurSel) bool {
     if (cursel.selection) |sel_| {
         var sel = sel_;

src/tui/mode/mini/replace.zig

@@ -0,0 +1,87 @@
+const std = @import("std");
+const tp = @import("thespian");
+const log = @import("log");
+const input = @import("input");
+const keybind = @import("keybind");
+const command = @import("command");
+const EventHandler = @import("EventHandler");
+
+const tui = @import("../../tui.zig");
+
+const Allocator = @import("std").mem.Allocator;
+
+const Self = @This();
+
+const Commands = command.Collection(cmds);
+
+allocator: Allocator,
+commands: Commands = undefined,
+
+pub fn create(allocator: Allocator, ctx: command.Context) !struct { tui.Mode, tui.MiniMode } {
+    var operation_command: []const u8 = undefined;
+    _ = ctx.args.match(.{tp.extract(&operation_command)}) catch return error.InvalidReplaceArgument;
+
+    const self = try allocator.create(Self);
+    errdefer allocator.destroy(self);
+    self.* = .{
+        .allocator = allocator,
+    };
+    try self.commands.init(self);
+    var mode = try keybind.mode("mini/replace", allocator, .{
+        .insert_command = "mini_mode_insert_bytes",
+    });
+    mode.event_handler = EventHandler.to_owned(self);
+    return .{ mode, .{ .name = self.name() } };
+}
+
+pub fn deinit(self: *Self) void {
+    self.commands.deinit();
+    self.allocator.destroy(self);
+}
+
+fn name(_: *Self) []const u8 {
+    return "🗘 replace";
+}
+
+pub fn receive(_: *Self, _: tp.pid_ref, _: tp.message) error{Exit}!bool {
+    return false;
+}
+
+fn execute_operation(_: *Self, ctx: command.Context) command.Result {
+    try command.executeName("replace_with_character_helix", ctx);
+    try command.executeName("exit_mini_mode", .{});
+}
+
+const cmds = struct {
+    pub const Target = Self;
+    const Ctx = command.Context;
+    const Meta = command.Metadata;
+    const Result = command.Result;
+
+    pub fn mini_mode_insert_code_point(self: *Self, ctx: Ctx) Result {
+        var code_point: u32 = 0;
+        if (!try ctx.args.match(.{tp.extract(&code_point)}))
+            return error.InvalidRepaceInsertCodePointArgument;
+
+        log.logger("replace").print("replacement '{d}'", .{code_point});
+        var buf: [6]u8 = undefined;
+        const bytes = input.ucs32_to_utf8(&[_]u32{code_point}, &buf) catch return error.InvalidReplaceCodePoint;
+        log.logger("replace").print("replacement '{s}'", .{buf[0..bytes]});
+        return self.execute_operation(ctx);
+    }
+    pub const mini_mode_insert_code_point_meta: Meta = .{ .description = "🗘 Replace" };
+
+    pub fn mini_mode_insert_bytes(self: *Self, ctx: Ctx) Result {
+        var bytes: []const u8 = undefined;
+        if (!try ctx.args.match(.{tp.extract(&bytes)}))
+            return error.InvalidReplaceInsertBytesArgument;
+        log.logger("replace").print("replacement '{s}'", .{bytes});
+        return self.execute_operation(ctx);
+    }
+    pub const mini_mode_insert_bytes_meta: Meta = .{ .arguments = &.{.string} };
+
+    pub fn mini_mode_cancel(_: *Self, _: Ctx) Result {
+        command.executeName("exit_mini_mode", .{}) catch {};
+    }
+    pub const mini_mode_cancel_meta: Meta = .{ .description = "Cancel replace" };
+};

src/tui/tui.zig

@@ -1167,6 +1167,11 @@ const cmds = struct {
     }
     pub const move_to_char_meta: Meta = .{ .description = "Move to character" };
 
+    pub fn replace(self: *Self, ctx: Ctx) Result {
+        return enter_mini_mode(self, @import("mode/mini/replace.zig"), ctx);
+    }
+    pub const replace_meta: Meta = .{ .description = "Replace with character" };
+
     pub fn open_file(self: *Self, ctx: Ctx) Result {
         if (get_active_selection(self.allocator)) |text| {
             defer self.allocator.free(text);