refactor: move buffer module to a subdirectory

src/buffer/Selection.zig

@@ -0,0 +1,61 @@
+const std = @import("std");
+const Buffer = @import("Buffer.zig");
+const Cursor = @import("Cursor.zig");
+
+begin: Cursor = Cursor{},
+end: Cursor = Cursor{},
+
+const Self = @This();
+
+pub inline fn eql(self: Self, other: Self) bool {
+    return self.begin.eql(other.begin) and self.end.eql(other.end);
+}
+
+pub fn from_cursor(cursor: *const Cursor) Self {
+    return .{ .begin = cursor.*, .end = cursor.* };
+}
+
+pub fn line_from_cursor(cursor: Cursor, root: Buffer.Root) Self {
+    var begin = cursor;
+    var end = cursor;
+    begin.move_begin();
+    end.move_end(root);
+    end.move_right(root) catch {};
+    return .{ .begin = begin, .end = end };
+}
+
+pub fn empty(self: *const Self) bool {
+    return self.begin.eql(self.end);
+}
+
+pub fn reverse(self: *Self) void {
+    const tmp = self.begin;
+    self.begin = self.end;
+    self.end = tmp;
+}
+
+pub fn normalize(self: *Self) void {
+    if (self.begin.right_of(self.end))
+        self.reverse();
+}
+
+pub fn write(self: *const Self, writer: Buffer.MetaWriter) !void {
+    try self.begin.write(writer);
+    try self.end.write(writer);
+}
+
+pub fn extract(self: *Self, iter: *[]const u8) !bool {
+    if (!try self.begin.extract(iter)) return false;
+    return self.end.extract(iter);
+}
+
+pub fn nudge_insert(self: *Self, nudge: Self) void {
+    self.begin.nudge_insert(nudge);
+    self.end.nudge_insert(nudge);
+}
+
+pub fn nudge_delete(self: *Self, nudge: Self) bool {
+    if (!self.begin.nudge_delete(nudge))
+        return false;
+    return self.end.nudge_delete(nudge);
+}