src/ftxui/component/input.cpp

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// Copyright 2022 Arthur Sonzogni. All rights reserved.
// Use of this source code is governed by the MIT license that can be found in
// the LICENSE file.
#include <algorithm>   // for max, min
#include <cstddef>     // for size_t
#include <cstdint>     // for uint32_t
#include <functional>  // for function
#include <sstream>     // for basic_istream, stringstream
#include <string>      // for string, basic_string, operator==, getline
#include <utility>     // for move
#include <vector>      // for vector
 
#include "ftxui/component/app.hpp"                // for Component
#include "ftxui/component/component.hpp"          // for Make, Input
#include "ftxui/component/component_base.hpp"     // for ComponentBase
#include "ftxui/component/component_options.hpp"  // for InputOption
#include "ftxui/component/event.hpp"  // for Event, Event::ArrowDown, Event::ArrowLeft, Event::ArrowLeftCtrl, Event::ArrowRight, Event::ArrowRightCtrl, Event::ArrowUp, Event::Backspace, Event::Delete, Event::End, Event::Home, Event::Return
#include "ftxui/component/mouse.hpp"  // for Mouse, Mouse::Left, Mouse::Pressed
#include "ftxui/dom/elements.hpp"  // for operator|, reflect, text, Element, xflex, hbox, Elements, frame, operator|=, vbox, focus, focusCursorBarBlinking, select
#include "ftxui/screen/box.hpp"    // for Box
#include "ftxui/screen/string.hpp"           // for string_width
#include "ftxui/screen/string_internal.hpp"  // for GlyphNext, GlyphPrevious, WordBreakProperty, EatCodePoint, CodepointToWordBreakProperty, IsFullWidth, WordBreakProperty::ALetter, WordBreakProperty::CR, WordBreakProperty::Double_Quote, WordBreakProperty::Extend, WordBreakProperty::ExtendNumLet, WordBreakProperty::Format, WordBreakProperty::Hebrew_Letter, WordBreakProperty::Katakana, WordBreakProperty::LF, WordBreakProperty::MidLetter, WordBreakProperty::MidNum, WordBreakProperty::MidNumLet, WordBreakProperty::Newline, WordBreakProperty::Numeric, WordBreakProperty::Regional_Indicator, WordBreakProperty::Single_Quote, WordBreakProperty::WSegSpace, WordBreakProperty::ZWJ
#include "ftxui/screen/util.hpp"             // for clamp
#include "ftxui/util/ref.hpp"                // for StringRef, Ref
 
namespace ftxui {
 
namespace {
 
std::vector<std::string> SplitLines(std::string_view input) {
  std::vector<std::string> output;
  size_t start = 0;
  size_t end = input.find('\n');
  while (end != std::string_view::npos) {
    output.push_back(std::string(input.substr(start, end - start)));
    start = end + 1;
    end = input.find('\n', start);
  }
  output.push_back(std::string(input.substr(start)));
  return output;
}
 
size_t GlyphWidth(std::string_view input, size_t iter) {
  uint32_t ucs = 0;
  if (!EatCodePoint(input, iter, &iter, &ucs)) {
    return 0;
  }
  if (IsFullWidth(ucs)) {
    return 2;
  }
  return 1;
}
 
bool IsWordCodePoint(uint32_t codepoint) {
  switch (CodepointToWordBreakProperty(codepoint)) {
    case WordBreakProperty::ALetter:
    case WordBreakProperty::Hebrew_Letter:
    case WordBreakProperty::Katakana:
    case WordBreakProperty::Numeric:
      return true;
 
    case WordBreakProperty::CR:
    case WordBreakProperty::Double_Quote:
    case WordBreakProperty::LF:
    case WordBreakProperty::MidLetter:
    case WordBreakProperty::MidNum:
    case WordBreakProperty::MidNumLet:
    case WordBreakProperty::Newline:
    case WordBreakProperty::Single_Quote:
    case WordBreakProperty::WSegSpace:
    // Unexpected/Unsure
    case WordBreakProperty::Extend:
    case WordBreakProperty::ExtendNumLet:
    case WordBreakProperty::Format:
    case WordBreakProperty::Regional_Indicator:
    case WordBreakProperty::ZWJ:
      return false;
  }
  return false;  // NOT_REACHED();
}
 
bool IsWordCharacter(std::string_view input, size_t iter) {
  uint32_t ucs = 0;
  if (!EatCodePoint(input, iter, &iter, &ucs)) {
    return false;
  }
 
  return IsWordCodePoint(ucs);
}
 
// An input box. The user can type text into it.
class InputBase : public ComponentBase, public InputOption {
 public:
  // NOLINTNEXTLINE
  InputBase(InputOption option) : InputOption(std::move(option)) {}
 
 private:
  // Component implementation:
  Element OnRender() override {
    const bool is_focused = Focused();
    const auto focused = (!is_focused && !hovered_) ? focus
                         : insert()                 ? focusCursorBarBlinking
                                                    : focusCursorBlockBlinking;
 
    auto transform_func =
        transform ? transform : InputOption::Default().transform;
 
    // placeholder.
    if (content->empty()) {
      auto element = text(placeholder()) | focused | xflex | frame;
 
      return transform_func({
                 std::move(element), hovered_, is_focused,
                 true  // placeholder
             }) |
             reflect(box_);
    }
 
    Elements elements;
    const std::vector<std::string> lines = SplitLines(*content);
 
    cursor_position() = util::clamp(cursor_position(), 0, (int)content->size());
 
    // Find the line and index of the cursor.
    int cursor_line = 0;
    int cursor_char_index = cursor_position();
    for (const auto& line : lines) {
      if (cursor_char_index <= (int)line.size()) {
        break;
      }
 
      cursor_char_index -= static_cast<int>(line.size() + 1);
      cursor_line++;
    }
 
    if (lines.empty()) {
      elements.push_back(text("") | focused);
    }
 
    elements.reserve(lines.size());
    for (size_t i = 0; i < lines.size(); ++i) {
      const std::string& line = lines[i];
 
      // This is not the cursor line.
      if (int(i) != cursor_line) {
        elements.push_back(Text(line));
        continue;
      }
 
      // The cursor is at the end of the line.
      const std::string cursor_cell = is_focused ? " " : "";
      if (cursor_char_index >= (int)line.size()) {
        elements.push_back(
            hbox({
                Text(line),
                text(cursor_cell) | focused | reflect(cursor_box_),
            }) |
            xflex);
        continue;
      }
 
      // The cursor is on this line.
      const int glyph_start = cursor_char_index;
      const int glyph_end = static_cast<int>(GlyphNext(line, glyph_start));
      const std::string part_before_cursor = line.substr(0, glyph_start);
      const std::string part_at_cursor =
          line.substr(glyph_start, glyph_end - glyph_start);
      const std::string part_after_cursor = line.substr(glyph_end);
      auto element = hbox({
                         Text(part_before_cursor),
                         Text(part_at_cursor) | focused | reflect(cursor_box_),
                         Text(part_after_cursor),
                     }) |
                     xflex;
      elements.push_back(element);
    }
 
    auto element = vbox(std::move(elements)) | frame;
    return transform_func({
               std::move(element), hovered_, is_focused,
               false  // placeholder
           }) |
           xflex | reflect(box_);
  }
 
  Element Text(const std::string& input) {
    if (!password()) {
      return text(input);
    }
 
    const size_t glyph_count = GlyphCount(input);
    std::string out;
    out.reserve(glyph_count * 3);
    for (size_t i = 0; i < glyph_count; ++i) {
      out += "•";
    }
    return text(out);
  }
 
  bool HandleBackspace() {
    if (cursor_position() == 0) {
      return false;
    }
    const size_t start = GlyphPrevious(content(), cursor_position());
    const size_t end = cursor_position();
    content->erase(start, end - start);
    cursor_position() = static_cast<int>(start);
    App::PostEventOrExecute(on_change);
    return true;
  }
 
  bool HandleBackspaceWord() {
    if (cursor_position() == 0) {
      return false;
    }
 
    size_t start = cursor_position();
    const size_t previous = GlyphPrevious(content(), start);
    if (content()[previous] == '\n') {
      start = previous;
    } else {
      // Phase 1: Skip non-word characters going backward (stopping at '\n').
      while (start > 0) {
        const size_t prev = GlyphPrevious(content(), start);
        if (content()[prev] == '\n' || IsWordCharacter(content(), prev)) {
          break;
        }
        start = prev;
      }
 
      // Phase 2: Skip word characters going backward (stopping at '\n').
      while (start > 0) {
        const size_t prev = GlyphPrevious(content(), start);
        if (content()[prev] == '\n' || !IsWordCharacter(content(), prev)) {
          break;
        }
        start = prev;
      }
    }
 
    const size_t end = cursor_position();
    content->erase(start, end - start);
    cursor_position() = static_cast<int>(start);
    App::PostEventOrExecute(on_change);
    return true;
  }
 
  bool HandleDeleteWord() {
    if (cursor_position() == (int)content->size()) {
      return false;
    }
 
    size_t end = cursor_position();
    if (content()[end] == '\n') {
      end++;
    } else {
      // Phase 1: Skip non-word characters going forward (stopping at '\n').
      while (end < content->size() && content()[end] != '\n' &&
             !IsWordCharacter(content(), end)) {
        end = GlyphNext(content(), end);
      }
 
      // Phase 2: Skip word characters going forward (stopping at '\n').
      while (end < content->size() && content()[end] != '\n' &&
             IsWordCharacter(content(), end)) {
        end = GlyphNext(content(), end);
      }
    }
 
    const size_t start = cursor_position();
    content->erase(start, end - start);
    App::PostEventOrExecute(on_change);
    return true;
  }
 
  // Delete from the beginning of the line to the cursor.
  bool HandleBackspaceLine() {
    if (cursor_position() == 0) {
      return false;
    }
 
    size_t start = cursor_position();
    const size_t previous = GlyphPrevious(content(), start);
    if (content()[previous] == '\n') {
      start = previous;
    } else {
      while (start > 0) {
        const size_t prev = GlyphPrevious(content(), start);
        if (content()[prev] == '\n') {
          break;
        }
        start = prev;
      }
    }
 
    const size_t end = cursor_position();
    content->erase(start, end - start);
    cursor_position() = static_cast<int>(start);
    App::PostEventOrExecute(on_change);
    return true;
  }
 
  bool DeleteImpl() {
    if (cursor_position() == (int)content->size()) {
      return false;
    }
    const size_t start = cursor_position();
    const size_t end = GlyphNext(content(), cursor_position());
    content->erase(start, end - start);
    return true;
  }
 
  bool HandleDelete() {
    if (DeleteImpl()) {
      App::PostEventOrExecute(on_change);
      return true;
    }
    return false;
  }
 
  bool HandleArrowLeft() {
    if (cursor_position() == 0) {
      return false;
    }
 
    cursor_position() =
        static_cast<int>(GlyphPrevious(content(), cursor_position()));
    return true;
  }
 
  bool HandleArrowRight() {
    if (cursor_position() == (int)content->size()) {
      return false;
    }
 
    cursor_position() =
        static_cast<int>(GlyphNext(content(), cursor_position()));
    return true;
  }
 
  size_t CursorColumn() {
    size_t iter = cursor_position();
    int width = 0;
    while (true) {
      if (iter == 0) {
        break;
      }
      iter = GlyphPrevious(content(), iter);
      if (content()[iter] == '\n') {
        break;
      }
      if (password()) {
        width += 1;
      } else {
        width += static_cast<int>(GlyphWidth(content(), iter));
      }
    }
    return width;
  }
 
  // Move the cursor `columns` on the right, if possible.
  void MoveCursorColumn(int columns) {
    while (columns > 0) {
      if (cursor_position() == (int)content().size() ||
          content()[cursor_position()] == '\n') {
        return;
      }
 
      if (password()) {
        columns -= 1;
      } else {
        columns -= static_cast<int>(GlyphWidth(content(), cursor_position()));
      }
      cursor_position() =
          static_cast<int>(GlyphNext(content(), cursor_position()));
    }
  }
 
  bool HandleArrowUp() {
    if (cursor_position() == 0) {
      return false;
    }
 
    const size_t columns = CursorColumn();
 
    // Move cursor at the beginning of 2 lines above.
    while (true) {
      if (cursor_position() == 0) {
        return true;
      }
      const size_t previous = GlyphPrevious(content(), cursor_position());
      if (content()[previous] == '\n') {
        break;
      }
      cursor_position() = static_cast<int>(previous);
    }
    cursor_position() =
        static_cast<int>(GlyphPrevious(content(), cursor_position()));
    while (true) {
      if (cursor_position() == 0) {
        break;
      }
      const size_t previous = GlyphPrevious(content(), cursor_position());
      if (content()[previous] == '\n') {
        break;
      }
      cursor_position() = static_cast<int>(previous);
    }
 
    MoveCursorColumn(static_cast<int>(columns));
    return true;
  }
 
  bool HandleArrowDown() {
    if (cursor_position() == (int)content->size()) {
      return false;
    }
 
    const size_t columns = CursorColumn();
 
    // Move cursor at the beginning of the next line
    while (true) {
      if (content()[cursor_position()] == '\n') {
        break;
      }
      cursor_position() =
          static_cast<int>(GlyphNext(content(), cursor_position()));
      if (cursor_position() == (int)content().size()) {
        return true;
      }
    }
    cursor_position() =
        static_cast<int>(GlyphNext(content(), cursor_position()));
 
    MoveCursorColumn(static_cast<int>(columns));
    return true;
  }
 
  bool HandleHome() {
    cursor_position() = 0;
    return true;
  }
 
  bool HandleEnd() {
    cursor_position() = static_cast<int>(content->size());
    return true;
  }
 
  bool HandleLineStart() {
    while (cursor_position() > 0) {
      const size_t previous = GlyphPrevious(content(), cursor_position());
      if (content()[previous] == '\n') {
        break;
      }
      cursor_position() = static_cast<int>(previous);
    }
    return true;
  }
 
  bool HandleLineEnd() {
    while (cursor_position() < (int)content->size() &&
           content()[cursor_position()] != '\n') {
      cursor_position() =
          static_cast<int>(GlyphNext(content(), cursor_position()));
    }
    return true;
  }
 
  bool HandleReturn() {
    if (multiline()) {
      HandleCharacter("\n");
    }
    App::PostEventOrExecute(on_enter);
    return true;
  }
 
  bool HandleCharacter(const std::string& character) {
    if (!insert() && cursor_position() < (int)content->size() &&
        content()[cursor_position()] != '\n') {
      DeleteImpl();
    }
    content->insert(cursor_position(), character);
    cursor_position() += static_cast<int>(character.size());
    App::PostEventOrExecute(on_change);
    return true;
  }
 
  bool OnEvent(Event event) override {
    cursor_position() = util::clamp(cursor_position(), 0, (int)content->size());
 
    if (event == Event::Return) {
      return HandleReturn();
    }
    if (event.is_character()) {
      return HandleCharacter(event.character());
    }
    if (event.is_mouse()) {
      return HandleMouse(event);
    }
    if (event == Event::Backspace) {
      return HandleBackspace();
    }
    if (event == Event::BackspaceAlt || event == Event::AltBackspace ||
        event == Event::CtrlW) {
      return HandleBackspaceWord();
    }
    if (event == Event::CtrlU) {
      return HandleBackspaceLine();
    }
    if (event == Event::Delete) {
      return HandleDelete();
    }
    if (event == Event::DeleteAlt || event == Event::DeleteCtrl ||
        event == Event::AltD) {
      return HandleDeleteWord();
    }
    if (event == Event::ArrowLeft) {
      return HandleArrowLeft();
    }
    if (event == Event::ArrowRight) {
      return HandleArrowRight();
    }
    if (event == Event::ArrowUp) {
      return HandleArrowUp();
    }
    if (event == Event::ArrowDown) {
      return HandleArrowDown();
    }
    if (event == Event::Home) {
      return HandleHome();
    }
    if (event == Event::End) {
      return HandleEnd();
    }
    if (event == Event::CtrlA) {
      return HandleLineStart();
    }
    if (event == Event::CtrlE) {
      return HandleLineEnd();
    }
    if (event == Event::ArrowLeftCtrl || event == Event::ArrowLeftAlt ||
        event == Event::AltB) {
      return HandleLeftCtrl();
    }
    if (event == Event::ArrowRightCtrl || event == Event::ArrowRightAlt ||
        event == Event::AltF) {
      return HandleRightCtrl();
    }
    if (event == Event::ArrowUpAlt) {
      return HandleArrowUp();
    }
    if (event == Event::ArrowDownAlt) {
      return HandleArrowDown();
    }
    if (event == Event::Insert) {
      return HandleInsert();
    }
    return false;
  }
 
  bool HandleLeftCtrl() {
    if (cursor_position() == 0) {
      return false;
    }
 
    // Move left, as long as left it not a word.
    while (cursor_position()) {
      const size_t previous = GlyphPrevious(content(), cursor_position());
      if (IsWordCharacter(content(), previous)) {
        break;
      }
      cursor_position() = static_cast<int>(previous);
    }
    // Move left, as long as left is a word character:
    while (cursor_position()) {
      const size_t previous = GlyphPrevious(content(), cursor_position());
      if (!IsWordCharacter(content(), previous)) {
        break;
      }
      cursor_position() = static_cast<int>(previous);
    }
    return true;
  }
 
  bool HandleRightCtrl() {
    if (cursor_position() == (int)content().size()) {
      return false;
    }
 
    // Move right, until entering a word.
    while (cursor_position() < (int)content().size()) {
      cursor_position() =
          static_cast<int>(GlyphNext(content(), cursor_position()));
      if (IsWordCharacter(content(), cursor_position())) {
        break;
      }
    }
    // Move right, as long as right is a word character:
    while (cursor_position() < (int)content().size()) {
      const size_t next = GlyphNext(content(), cursor_position());
      if (!IsWordCharacter(content(), cursor_position())) {
        break;
      }
      cursor_position() = static_cast<int>(next);
    }
 
    return true;
  }
 
  bool HandleMouse(Event event) {
    hovered_ = box_.Contain(event.mouse().x,  //
                            event.mouse().y) &&
               CaptureMouse(event);
    if (!hovered_) {
      return false;
    }
 
    if (event.mouse().button != Mouse::Left) {
      return false;
    }
    if (event.mouse().motion != Mouse::Pressed) {
      return false;
    }
 
    TakeFocus();
 
    if (content->empty()) {
      cursor_position() = 0;
      return true;
    }
 
    // Find the line and index of the cursor.
    std::vector<std::string> lines = SplitLines(*content);
    int cursor_line = 0;
    int cursor_char_index = cursor_position();
    for (const auto& line : lines) {
      if (cursor_char_index <= (int)line.size()) {
        break;
      }
 
      cursor_char_index -= static_cast<int>(line.size() + 1);
      cursor_line++;
    }
    const int cursor_column =
        password()
            ? GlyphCount(lines[cursor_line].substr(0, cursor_char_index))
            : string_width(lines[cursor_line].substr(0, cursor_char_index));
 
    int new_cursor_column = cursor_column + event.mouse().x - cursor_box_.x_min;
    int new_cursor_line = cursor_line + event.mouse().y - cursor_box_.y_min;
 
    // Fix the new cursor position:
    new_cursor_line = std::max(std::min(new_cursor_line, (int)lines.size()), 0);
 
    const std::string empty_string;
    const std::string& line = new_cursor_line < (int)lines.size()
                                  ? lines[new_cursor_line]
                                  : empty_string;
    new_cursor_column =
        util::clamp(new_cursor_column, 0,
                    password() ? GlyphCount(line) : string_width(line));
 
    if (new_cursor_column == cursor_column &&  //
        new_cursor_line == cursor_line) {
      return false;
    }
 
    // Convert back the new_cursor_{line,column} toward cursor_position:
    cursor_position() = 0;
    for (int i = 0; i < new_cursor_line; ++i) {
      cursor_position() += static_cast<int>(lines[i].size() + 1);
    }
    while (new_cursor_column > 0) {
      if (password()) {
        new_cursor_column -= 1;
      } else {
        new_cursor_column -=
            static_cast<int>(GlyphWidth(content(), cursor_position()));
      }
      cursor_position() =
          static_cast<int>(GlyphNext(content(), cursor_position()));
    }
 
    App::PostEventOrExecute(on_change);
    return true;
  }
 
  bool HandleInsert() {
    insert() = !insert();
    return true;
  }
 
  bool Focusable() const final { return true; }
 
  bool hovered_ = false;
 
  Box box_;
  Box cursor_box_;
};
 
}  // namespace
 
/// @brief An input box for editing text.
/// @param option Additional optional parameters.
/// @ingroup component
/// @see InputBase
///
/// ### Example
///
/// ```cpp
/// auto screen = App::FitComponent();
/// std::string content= "";
/// std::string placeholder = "placeholder";
/// Component input = Input({
///   .content = &content,
///   .placeholder = &placeholder,
/// })
/// screen.Loop(input);
/// ```
///
/// ### Output
///
/// ```bash
/// placeholder
/// ```
Component Input(InputOption option) {
  return Make<InputBase>(std::move(option));
}
 
/// @brief An input box for editing text.
/// @param content The editable content.
/// @param option Additional optional parameters.
/// @ingroup component
/// @see InputBase
///
/// ### Example
///
/// ```cpp
/// auto screen = App::FitComponent();
/// std::string content= "";
/// std::string placeholder = "placeholder";
/// Component input = Input(content, {
///   .placeholder = &placeholder,
///   .password = true,
/// })
/// screen.Loop(input);
/// ```
///
/// ### Output
///
/// ```bash
/// placeholder
/// ```
Component Input(StringRef content, InputOption option) {
  option.content = std::move(content);
  return Make<InputBase>(std::move(option));
}
 
/// @brief An input box for editing text.
/// @param content The editable content.
/// @param placeholder The placeholder text.
/// @param option Additional optional parameters.
/// @ingroup component
/// @see InputBase
///
/// ### Example
///
/// ```cpp
/// auto screen = App::FitComponent();
/// std::string content= "";
/// std::string placeholder = "placeholder";
/// Component input = Input(content, placeholder);
/// screen.Loop(input);
/// ```
///
/// ### Output
///
/// ```bash
/// placeholder
/// ```
Component Input(StringRef content, StringRef placeholder, InputOption option) {
  option.content = std::move(content);
  option.placeholder = std::move(placeholder);
  return Make<InputBase>(std::move(option));
}
 
}  // namespace ftxui