third_party/WebKit/Source/core/style/GridPosition.h

/*
 * Copyright (C) 2012 Google Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above
 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
 * distribution.
 *     * Neither the name of Google Inc. nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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 */

#ifndef GridPosition_h
#define GridPosition_h

#include "wtf/Allocator.h"
#include "wtf/text/WTFString.h"

namespace blink {

enum GridPositionType {
  AutoPosition,
  ExplicitPosition,      // [ <integer> || <string> ]
  SpanPosition,          // span && [ <integer> || <string> ]
  NamedGridAreaPosition  // <ident>
};

class GridPosition {
  DISALLOW_NEW();

 public:
  GridPosition() : m_type(AutoPosition), m_integerPosition(0) {}

  bool isPositive() const { return integerPosition() > 0; }

  GridPositionType type() const { return m_type; }
  bool isAuto() const { return m_type == AutoPosition; }
  bool isSpan() const { return m_type == SpanPosition; }
  bool isNamedGridArea() const { return m_type == NamedGridAreaPosition; }

  void setExplicitPosition(int position, const AtomicString& namedGridLine) {
    m_type = ExplicitPosition;
    m_integerPosition = position;
    m_namedGridLine = namedGridLine;
  }

  void setAutoPosition() {
    m_type = AutoPosition;
    m_integerPosition = 0;
  }

  // 'span' values cannot be negative, yet we reuse the <integer> position which
  // can be. This means that we have to convert the span position to an integer,
  // losing some precision here. It shouldn't be an issue in practice though.
  void setSpanPosition(int position, const AtomicString& namedGridLine) {
    m_type = SpanPosition;
    m_integerPosition = position;
    m_namedGridLine = namedGridLine;
  }

  void setNamedGridArea(const AtomicString& namedGridArea) {
    m_type = NamedGridAreaPosition;
    m_namedGridLine = namedGridArea;
  }

  int integerPosition() const {
    ASSERT(type() == ExplicitPosition);
    return m_integerPosition;
  }

  AtomicString namedGridLine() const {
    ASSERT(type() == ExplicitPosition || type() == SpanPosition ||
           type() == NamedGridAreaPosition);
    return m_namedGridLine;
  }

  int spanPosition() const {
    ASSERT(type() == SpanPosition);
    return m_integerPosition;
  }

  bool operator==(const GridPosition& other) const {
    return m_type == other.m_type &&
           m_integerPosition == other.m_integerPosition &&
           m_namedGridLine == other.m_namedGridLine;
  }

  bool shouldBeResolvedAgainstOppositePosition() const {
    return isAuto() || isSpan();
  }

 private:
  GridPositionType m_type;
  int m_integerPosition;
  AtomicString m_namedGridLine;
};

}  // namespace blink

#endif  // GridPosition_h