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// Copyright 2018 The xi-editor Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//! Calc start of a backspace delete interval
use xi_rope::{Cursor, Rope};
use crate::config::BufferItems;
use crate::selection::SelRegion;
use crate::view::View;
use xi_unicode::*;
#[allow(clippy::cognitive_complexity)]
pub fn offset_for_delete_backwards(
view: &View,
region: &SelRegion,
text: &Rope,
config: &BufferItems,
) -> usize {
if !region.is_caret() {
region.min()
} else {
// backspace deletes max(1, tab_size) contiguous spaces
let (_, c) = view.offset_to_line_col(&text, region.start);
let tab_off = c % config.tab_size;
let tab_size = config.tab_size;
let tab_size = if tab_off == 0 { tab_size } else { tab_off };
let tab_start = region.start.saturating_sub(tab_size);
let preceded_by_spaces =
region.start > 0 && (tab_start..region.start).all(|i| text.byte_at(i) == b' ');
if preceded_by_spaces && config.translate_tabs_to_spaces && config.use_tab_stops {
tab_start
} else {
#[derive(PartialEq)]
enum State {
Start,
Lf,
BeforeKeycap,
BeforeVsAndKeycap,
BeforeEmojiModifier,
BeforeVSAndEmojiModifier,
BeforeVS,
BeforeEmoji,
BeforeZwj,
BeforeVSAndZWJ,
OddNumberedRIS,
EvenNumberedRIS,
InTagSequence,
Finished,
};
let mut state = State::Start;
let mut tmp_offset = region.end;
let mut delete_code_point_count = 0;
let mut last_seen_vs_code_point_count = 0;
while state != State::Finished && tmp_offset > 0 {
let mut cursor = Cursor::new(&text, tmp_offset);
let code_point = cursor.prev_codepoint().unwrap_or('0');
tmp_offset = text.prev_codepoint_offset(tmp_offset).unwrap_or(0);
match state {
State::Start => {
delete_code_point_count = 1;
if code_point == '\n' {
state = State::Lf;
} else if is_variation_selector(code_point) {
state = State::BeforeVS;
} else if code_point.is_regional_indicator_symbol() {
state = State::OddNumberedRIS;
} else if code_point.is_emoji_modifier() {
state = State::BeforeEmojiModifier;
} else if code_point.is_emoji_combining_enclosing_keycap() {
state = State::BeforeKeycap;
} else if code_point.is_emoji() {
state = State::BeforeEmoji;
} else if code_point.is_emoji_cancel_tag() {
state = State::InTagSequence;
} else {
state = State::Finished;
}
}
State::Lf => {
if code_point == '\r' {
delete_code_point_count += 1;
}
state = State::Finished;
}
State::OddNumberedRIS => {
if code_point.is_regional_indicator_symbol() {
delete_code_point_count += 1;
state = State::EvenNumberedRIS
} else {
state = State::Finished
}
}
State::EvenNumberedRIS => {
if code_point.is_regional_indicator_symbol() {
delete_code_point_count -= 1;
state = State::OddNumberedRIS;
} else {
state = State::Finished;
}
}
State::BeforeKeycap => {
if is_variation_selector(code_point) {
last_seen_vs_code_point_count = 1;
state = State::BeforeVsAndKeycap;
} else {
if is_keycap_base(code_point) {
delete_code_point_count += 1;
}
state = State::Finished;
}
}
State::BeforeVsAndKeycap => {
if is_keycap_base(code_point) {
delete_code_point_count += last_seen_vs_code_point_count + 1;
}
state = State::Finished;
}
State::BeforeEmojiModifier => {
if is_variation_selector(code_point) {
last_seen_vs_code_point_count = 1;
state = State::BeforeVSAndEmojiModifier;
} else {
if code_point.is_emoji_modifier_base() {
delete_code_point_count += 1;
}
state = State::Finished;
}
}
State::BeforeVSAndEmojiModifier => {
if code_point.is_emoji_modifier_base() {
delete_code_point_count += last_seen_vs_code_point_count + 1;
}
state = State::Finished;
}
State::BeforeVS => {
if code_point.is_emoji() {
delete_code_point_count += 1;
state = State::BeforeEmoji;
} else {
if !is_variation_selector(code_point) {
//TODO: UCharacter.getCombiningClass(codePoint) == 0
delete_code_point_count += 1;
}
state = State::Finished;
}
}
State::BeforeEmoji => {
if code_point.is_zwj() {
state = State::BeforeZwj;
} else {
state = State::Finished;
}
}
State::BeforeZwj => {
if code_point.is_emoji() {
delete_code_point_count += 2;
state = if code_point.is_emoji_modifier() {
State::BeforeEmojiModifier
} else {
State::BeforeEmoji
};
} else if is_variation_selector(code_point) {
last_seen_vs_code_point_count = 1;
state = State::BeforeVSAndZWJ;
} else {
state = State::Finished;
}
}
State::BeforeVSAndZWJ => {
if code_point.is_emoji() {
delete_code_point_count += last_seen_vs_code_point_count + 2;
last_seen_vs_code_point_count = 0;
state = State::BeforeEmoji;
} else {
state = State::Finished;
}
}
State::InTagSequence => {
if code_point.is_tag_spec_char() {
delete_code_point_count += 1;
} else if code_point.is_emoji() {
delete_code_point_count += 1;
state = State::Finished;
} else {
delete_code_point_count = 1;
state = State::Finished;
}
}
State::Finished => {
break;
}
}
}
let mut start = region.end;
while delete_code_point_count > 0 {
start = text.prev_codepoint_offset(start).unwrap_or(0);
delete_code_point_count -= 1;
}
start
}
}
}