Replace StyleRange with BreakList; update RenderText, etc.

ui/gfx/break_list.h

+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef UI_GFX_BREAK_LIST_H_
+#define UI_GFX_BREAK_LIST_H_
+
+#include <limits.h>
+
+#include <vector>
+
+#include "base/basictypes.h"
+#include "base/logging.h"
+#include "ui/base/range/range.h"
+
+namespace gfx {
+
+// BreakLists manage ordered, non-overlapping, and non-repeating ranged values.
+// These may be used to apply ranged colors and styles to text, for an example.
+//
+// Each break stores the start position and value of its associated range.
+// A solitary break at position 0 applies to the entire space [0, INT_MAX).
+// The first break always has position 0, to ensure all positions have a value.
+// The value of the terminal break applies to the range [break.first, INT_MAX).
+// The value of other breaks apply to the range [break.first, (break+1).first).
+template <class T>

[Alexei Svitkine (slow), 2013/01/28 20:52:30]

Nit: change "class" to "typename", since its used with primitives and not
classes.

[msw, 2013/01/29 17:17:25]

Done.

+class BreakList {
+ public:
+  // A BreakList const iterator, typedef'ed for convenience.
+  typedef typename std::vector<std::pair<size_t, T> >::const_iterator

[Alexei Svitkine (slow), 2013/01/28 20:52:30]

Nit: How about typedefing std::pair<size_t, T> to "Break" to make it so it's
just std::vector<Break> to make the code below more readable.

[msw, 2013/01/29 17:17:25]

Done.

+      const_iterator;
+
+  // Initialize a break at position 0 with the default or supplied |value|.
+  BreakList();
+  explicit BreakList(T value);
+
+  const std::vector<std::pair<size_t, T> >& list() const { return list_; }

[Alexei Svitkine (slow), 2013/01/28 20:52:30]

Nit: Instead of naming it |list|, how about |breaks|?

[msw, 2013/01/29 17:17:25]

Done.

+
+  // Clear the list and set a break at position 0 with the supplied |value|.
+  void SetValue(T value);
+
+  // Adjust the list to apply |value| over the supplied |range|.
+  void ApplyValue(T value, const ui::Range& range);
+
+  // Trim any breaks in the range [|position|, INT_MAX).
+  void TrimBreaks(size_t position);
+
+  // Get the break applicable to |position| (at or preceeding |position|).
+  typename std::vector<std::pair<size_t, T> >::iterator GetBreak(
+      size_t position);
+
+  // Get the last position to which the supplied break applies; returns the
+  // start position of the next break, or INT_MAX for the terminal break.
+  size_t GetBreakEnd(const typename BreakList<T>::const_iterator& i) const;
+
+  // Save and restore the list to apply temporary values between calls.
+  void SaveList();

[Alexei Svitkine (slow), 2013/01/28 20:52:30]

I'd prefer if this functionality was outside of this class. Remove
DISALLOW_COPY_AND_ASSIGN(), since this class just wraps a vector of primitives,
which allows copy/assignment and let RenderText do the backup and restore.

[msw, 2013/01/29 17:17:25]

Done.

+  void RestoreList();
+
+  // Comparison functions for testing purposes.
+  bool EqualsValueForTest(T value) const;
+  bool EqualsListForTest(const std::vector<std::pair<size_t, T> >& list) const;

[Alexei Svitkine (slow), 2013/01/28 20:52:30]

I think the convention is to suffix it with "ForTesting" rather than "ForTest".

[msw, 2013/01/29 17:17:25]

Done.

+
+ private:
+#ifndef NDEBUG
+  // Check for ordered breaks [0->length) with no adjacent equivalent values.
+  void CheckList(size_t length);
+#endif
+
+  std::vector<std::pair<size_t, T> > list_;
+  std::vector<std::pair<size_t, T> > saved_list_;
+
+  DISALLOW_COPY_AND_ASSIGN(BreakList);
+};
+
+template<class T>
+BreakList<T>::BreakList() : list_(1, std::pair<size_t, T>(0, T())) {
+}
+
+template<class T>
+BreakList<T>::BreakList(T value) : list_(1, std::pair<size_t, T>(0, value)) {
+}
+
+template<class T>
+void BreakList<T>::SetValue(T value) {
+  list_.clear();
+  list_.push_back(std::pair<size_t, T>(0, value));
+}
+
+template<class T>
+void BreakList<T>::ApplyValue(T value, const ui::Range& range) {
+  if (!range.IsValid() || range.is_empty())
+    return;
+  DCHECK(!list_.empty());
+  DCHECK(!range.is_reversed());
+  DCHECK(ui::Range(0, INT_MAX).Contains(range));
+
+  // Erase any breaks in |range|, then add start and end breaks as needed.
+  typename std::vector<std::pair<size_t, T> >::iterator start =
+      GetBreak(range.start());
+  start += start->first < range.start() ? 1 : 0;
+  typename std::vector<std::pair<size_t, T> >::iterator end =
+      GetBreak(range.end());
+  T trailing_value = end->second;
+  typename std::vector<std::pair<size_t, T> >::iterator i =
+      start == list_.end() ? start : list_.erase(start, end + 1);
+  if (range.start() == 0 || (i - 1)->second != value)
+    i = list_.insert(i, std::pair<size_t, T>(range.start(), value)) + 1;
+  if (trailing_value != value && range.end() != INT_MAX)
+    list_.insert(i, std::pair<size_t, T>(range.end(), trailing_value));
+
+#ifndef NDEBUG
+  CheckList(INT_MAX);
+#endif
+}
+
+template<class T>
+void BreakList<T>::TrimBreaks(size_t length) {
+  for (size_t i = 1; i < list_.size(); ++i)
+    if (list_[i].first >= length)
+      list_.resize(i);
+
+#ifndef NDEBUG
+  CheckList(length);
+#endif
+}
+
+template<class T>
+typename std::vector<std::pair<size_t, T> >::iterator BreakList<T>::GetBreak(
+    size_t position) {
+  typename std::vector<std::pair<size_t, T> >::iterator i = list_.end() - 1;
+  for (; i != list_.begin() && i->first > position; --i);
+  return i;
+}
+
+template<class T>
+size_t BreakList<T>::GetBreakEnd(
+    const typename BreakList<T>::const_iterator& i) const {
+  return (i + 1) == list_.end() ? INT_MAX : (i + 1)->first;
+}
+
+template<class T>
+void BreakList<T>::SaveList() {
+  DCHECK(saved_list_.empty());
+  saved_list_ = list_;
+}
+
+template<class T>
+void BreakList<T>::RestoreList() {
+  DCHECK(!saved_list_.empty());
+  list_ = saved_list_;
+  saved_list_.clear();
+}
+
+template<class T>
+bool BreakList<T>::EqualsValueForTest(T value) const {
+  return list_.size() == 1 && list_[0] == std::pair<size_t, T>(0, value);
+}
+
+template<class T>
+bool BreakList<T>::EqualsListForTest(
+    const std::vector<std::pair<size_t, T> >& list) const {
+  if (list_.size() != list.size())
+    return false;
+  for (size_t i = 0; i < list.size(); ++i)
+    if (list_[i] != list[i])
+      return false;
+  return true;
+}
+
+#ifndef NDEBUG
+template <class T>
+void BreakList<T>::CheckList(size_t length) {
+  DCHECK_EQ(list_[0].first, 0U) << "The first break must be at position 0.";
+  for (size_t i = 0; i < list_.size() - 1; ++i) {
+    DCHECK_LT(list_[i].first, list_[i + 1].first) << "Break out of order.";
+    DCHECK_NE(list_[i].second, list_[i + 1].second) << "Redundant break.";
+  }
+  if (length > 0)
+    DCHECK_LT(list_.back().first, length) << "Break beyond max length.";
+}
+#endif
+
+}  // namespace gfx
+
+#endif  // UI_GFX_BREAK_LIST_H_