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05d97932b3
Extracts a TextRange class with a base and extent, and start(), end(), collapsed(), and length() getters. The possibility of reversed base and extent in selections and composing ranges makes reasoning about them complex and increases the chances of errors in the code. This change migrates most uses of base and extent in the text model to start()/end() or position(). The position() method is intended purely as an aid to readability to indicate that a collapsed selection is expected at the call site; it also enforces a debug-time assertion that this is the case.
128 lines
3.9 KiB
C++
128 lines
3.9 KiB
C++
// Copyright 2013 The Flutter Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef FLUTTER_SHELL_PLATFORM_CPP_TEXT_INPUT_MODEL_H_
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#define FLUTTER_SHELL_PLATFORM_CPP_TEXT_INPUT_MODEL_H_
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#include <memory>
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#include <string>
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#include "flutter/shell/platform/common/cpp/text_range.h"
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namespace flutter {
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// Handles underlying text input state, using a simple ASCII model.
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//
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// Ignores special states like "insert mode" for now.
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class TextInputModel {
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public:
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TextInputModel();
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virtual ~TextInputModel();
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// Sets the text.
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//
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// Resets the selection base and extent.
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void SetText(const std::string& text);
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// Attempts to set the text selection.
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//
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// Returns false if the base or extent are out of bounds.
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bool SetSelection(size_t base, size_t extent);
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// Adds a Unicode code point.
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//
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// Either appends after the cursor (when selection base and extent are the
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// same), or deletes the selected text, replacing it with the given
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// code point.
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void AddCodePoint(char32_t c);
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// Adds UTF-16 text.
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//
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// Either appends after the cursor (when selection base and extent are the
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// same), or deletes the selected text, replacing it with the given text.
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void AddText(const std::u16string& text);
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// Adds UTF-8 text.
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//
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// Either appends after the cursor (when selection base and extent are the
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// same), or deletes the selected text, replacing it with the given text.
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void AddText(const std::string& text);
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// Deletes either the selection, or one character ahead of the cursor.
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//
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// Deleting one character ahead of the cursor occurs when the selection base
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// and extent are the same.
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//
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// Returns true if any deletion actually occurred.
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bool Delete();
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// Deletes text near the cursor.
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//
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// A section is made starting at @offset code points past the cursor (negative
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// values go before the cursor). @count code points are removed. The selection
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// may go outside the bounds of the text and will result in only the part
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// selection that covers the available text being deleted. The existing
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// selection is ignored and removed after this operation.
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//
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// Returns true if any deletion actually occurred.
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bool DeleteSurrounding(int offset_from_cursor, int count);
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// Deletes either the selection, or one character behind the cursor.
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//
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// Deleting one character behind the cursor occurs when the selection base
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// and extent are the same.
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//
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// Returns true if any deletion actually occurred.
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bool Backspace();
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// Attempts to move the cursor backward.
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//
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// Returns true if the cursor could be moved. If a selection is active, moves
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// to the start of the selection.
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bool MoveCursorBack();
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// Attempts to move the cursor forward.
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//
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// Returns true if the cursor could be moved. If a selection is active, moves
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// to the end of the selection.
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bool MoveCursorForward();
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// Attempts to move the cursor to the beginning.
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//
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// Returns true if the cursor could be moved.
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bool MoveCursorToBeginning();
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// Attempts to move the cursor to the back.
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//
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// Returns true if the cursor could be moved.
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bool MoveCursorToEnd();
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// Gets the current text as UTF-8.
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std::string GetText() const;
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// Gets the cursor position as a byte offset in UTF-8 string returned from
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// GetText().
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int GetCursorOffset() const;
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// The position where the selection starts.
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int selection_base() const { return selection_.base(); }
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// The position of the cursor.
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int selection_extent() const { return selection_.extent(); }
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private:
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// Deletes the current selection, if any.
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//
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// Returns true if any text is deleted. The selection base and extent are
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// reset to the start of the selected range.
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bool DeleteSelected();
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std::u16string text_;
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TextRange selection_ = TextRange(0);
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};
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} // namespace flutter
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#endif // FLUTTER_SHELL_PLATFORM_CPP_TEXT_INPUT_MODEL_H_
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