Upstream ios/web/navigation

ios/web/public/web_state/page_scroll_state.mm

Index: ios/web/public/web_state/page_scroll_state.mm
diff --git a/ios/web/public/web_state/page_scroll_state.mm b/ios/web/public/web_state/page_scroll_state.mm
new file mode 100644
index 0000000000000000000000000000000000000000..b7479fd44c37d95b0ef5da646c59ca991c00716d
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+++ b/ios/web/public/web_state/page_scroll_state.mm
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+// Copyright 2015 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.
+
+#include "ios/web/public/web_state/page_scroll_state.h"
+
+#include <cmath>
+
+namespace web {
+
+namespace {
+// Returns true if:
+// - both |value1| and |value2| are NAN, or
+// - |value1| and |value2| are equal non-NAN values.
+inline bool StateValuesAreEqual(double value1, double value2) {
+  return std::isnan(value1) ? std::isnan(value2) : value1 == value2;
+}
+}  // namespace
+
+PageScrollState::PageScrollState()
+    : scroll_offset_x_(NAN),
+      scroll_offset_y_(NAN),
+      minimum_zoom_scale_(NAN),
+      maximum_zoom_scale_(NAN),
+      zoom_scale_(NAN) {
+}
+
+PageScrollState::PageScrollState(double scroll_offset_x,
+                                 double scroll_offset_y,
+                                 double minimum_zoom_scale,
+                                 double maximum_zoom_scale,
+                                 double zoom_scale)
+    : scroll_offset_x_(scroll_offset_x),
+      scroll_offset_y_(scroll_offset_y),
+      minimum_zoom_scale_(minimum_zoom_scale),
+      maximum_zoom_scale_(maximum_zoom_scale),
+      zoom_scale_(zoom_scale) {
+}
+
+PageScrollState::~PageScrollState() {
+}
+
+bool PageScrollState::IsValid() const {
+  return IsScrollOffsetValid() && IsZoomScaleValid();
+}
+
+bool PageScrollState::IsScrollOffsetValid() const {
+  return !std::isnan(scroll_offset_x_) && !std::isnan(scroll_offset_y_);
+}
+
+bool PageScrollState::IsZoomScaleValid() const {
+  return IsZoomScaleLegacyFormat() ||
+         (!std::isnan(minimum_zoom_scale_) &&
+          !std::isnan(maximum_zoom_scale_) && !std::isnan(zoom_scale_) &&
+          zoom_scale_ >= minimum_zoom_scale_ &&
+          zoom_scale_ <= maximum_zoom_scale_);
+}
+
+bool PageScrollState::IsZoomScaleLegacyFormat() const {
+  return std::isnan(minimum_zoom_scale_) && std::isnan(maximum_zoom_scale_) &&
+         zoom_scale_ > 0.0;
+}
+
+bool PageScrollState::operator==(const PageScrollState& other) const {
+  return StateValuesAreEqual(scroll_offset_x_, other.scroll_offset_x_) &&
+         StateValuesAreEqual(scroll_offset_y_, other.scroll_offset_y_) &&
+         StateValuesAreEqual(minimum_zoom_scale_, other.minimum_zoom_scale_) &&
+         StateValuesAreEqual(maximum_zoom_scale_, other.maximum_zoom_scale_) &&
+         StateValuesAreEqual(zoom_scale_, other.zoom_scale_);
+}
+
+}  // namespace web