Make much of gfx::Range[F] constexpr.

ui/gfx/range/range.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_RANGE_RANGE_H_
 #define UI_GFX_RANGE_RANGE_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
+#include <limits>
 #include <ostream>
 #include <string>
 
 #include "build/build_config.h"
 #include "ui/gfx/range/gfx_range_export.h"
 
 #if defined(OS_MACOSX)
 #if __OBJC__
 #import <Foundation/Foundation.h>
 #else
 typedef struct _NSRange NSRange;
 #endif
 #endif  // defined(OS_MACOSX)
 
 #if defined(OS_WIN)
 #include <windows.h>
 #include <richedit.h>
 #endif
 
 namespace gfx {
 
 // A Range contains two integer values that represent a numeric range, like the
 // range of characters in a text selection. A range is made of a start and end
 // position; when they are the same, the Range is akin to a caret. Note that
 // |start_| can be greater than |end_| to respect the directionality of the
 // range.
 class GFX_RANGE_EXPORT Range {
  public:
   // Creates an empty range {0,0}.
-  Range();
+  constexpr Range() : Range(0) {}
 
   // Initializes the range with a start and end.
-  Range(uint32_t start, uint32_t end);
+  constexpr Range(uint32_t start, uint32_t end) : start_(start), end_(end) {}
 
   // Initializes the range with the same start and end positions.
-  explicit Range(uint32_t position);
+  constexpr explicit Range(uint32_t position) : Range(position, position) {}
 
   // Platform constructors.
 #if defined(OS_MACOSX)
   explicit Range(const NSRange& range);
 #elif defined(OS_WIN)
   // The |total_length| paramater should be used if the CHARRANGE is set to
   // {0,-1} to indicate the whole range.
   Range(const CHARRANGE& range, LONG total_length = -1);
 #endif
 
   // Returns a range that is invalid, which is {UINT32_MAX,UINT32_MAX}.
-  static const Range InvalidRange();
+  static constexpr Range InvalidRange() {
+    return Range(std::numeric_limits<uint32_t>::max());
+  }
 
   // Checks if the range is valid through comparison to InvalidRange().
-  bool IsValid() const;
+  constexpr bool IsValid() const { return *this != InvalidRange(); }
 
   // Getters and setters.
-  uint32_t start() const { return start_; }
+  constexpr uint32_t start() const { return start_; }
   void set_start(uint32_t start) { start_ = start; }
 
-  uint32_t end() const { return end_; }
+  constexpr uint32_t end() const { return end_; }
   void set_end(uint32_t end) { end_ = end; }
 
   // Returns the absolute value of the length.
-  uint32_t length() const {
-    return GetMax() - GetMin();
+  constexpr uint32_t length() const { return GetMax() - GetMin(); }
+
+  constexpr bool is_reversed() const { return start() > end(); }
+  constexpr bool is_empty() const { return start() == end(); }
+
+  // Returns the minimum and maximum values.
+  constexpr uint32_t GetMin() const {
+    return start() < end() ? start() : end();
+  }
+  constexpr uint32_t GetMax() const {
+    return start() > end() ? start() : end();
   }
 
-  bool is_reversed() const { return start() > end(); }
-  bool is_empty() const { return start() == end(); }
-
-  // Returns the minimum and maximum values.
-  uint32_t GetMin() const;
-  uint32_t GetMax() const;
-
-  bool operator==(const Range& other) const;
-  bool operator!=(const Range& other) const;
-  bool EqualsIgnoringDirection(const Range& other) const;
+  constexpr bool operator==(const Range& other) const {
+    return start() == other.start() && end() == other.end();
+  }
+  constexpr bool operator!=(const Range& other) const {
+    return !(*this == other);
+  }
+  constexpr bool EqualsIgnoringDirection(const Range& other) const {
+    return GetMin() == other.GetMin() && GetMax() == other.GetMax();
+  }
 
   // Returns true if this range intersects the specified |range|.
-  bool Intersects(const Range& range) const;
+  constexpr bool Intersects(const Range& range) const {
+    return IsValid() && range.IsValid() &&
+           !(range.GetMax() < GetMin() || range.GetMin() >= GetMax());
+  }
 
   // Returns true if this range contains the specified |range|.
-  bool Contains(const Range& range) const;
+  constexpr bool Contains(const Range& range) const {
+    return IsValid() && range.IsValid() && GetMin() <= range.GetMin() &&
+           range.GetMax() <= GetMax();
+  }
 
   // Computes the intersection of this range with the given |range|.
   // If they don't intersect, it returns an InvalidRange().
   // The returned range is always empty or forward (never reversed).
   Range Intersect(const Range& range) const;
 
 #if defined(OS_MACOSX)
   Range& operator=(const NSRange& range);
 
   // NSRange does not store the directionality of a range, so if this
@@ skipping 12 matching lines @@
   // shouldn't exceed UINT32_MAX even on 64 bit builds.
   uint32_t start_;
   uint32_t end_;
 };
 
 GFX_RANGE_EXPORT std::ostream& operator<<(std::ostream& os, const Range& range);
 
 }  // namespace gfx
 
 #endif  // UI_GFX_RANGE_RANGE_H_