Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 85 insertions, 0 deletions

diff --git a/dom/base/nsAttrValueOrString.h b/dom/base/nsAttrValueOrString.h
new file mode 100644
index 0000000000..9cb3db33c5
--- /dev/null
+++ b/dom/base/nsAttrValueOrString.h
@@ -0,0 +1,85 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * A wrapper to contain either an nsAttrValue or an nsAString. This is useful
+ * because constructing an nsAttrValue from an nsAString can be expensive when
+ * the buffer of the string is not shared.
+ *
+ * This treats nsAttrValueOrString(nullptr) as the empty string,
+ * to help with contexts where a null pointer denotes an empty value.
+ *
+ * Since a raw pointer to the passed-in string is kept, this class should only
+ * be used on the stack.
+ */
+
+#ifndef nsAttrValueOrString_h___
+#define nsAttrValueOrString_h___
+
+#include "nsString.h"
+#include "nsAttrValue.h"
+
+class MOZ_STACK_CLASS nsAttrValueOrString {
+ public:
+  explicit nsAttrValueOrString(const nsAString& aValue)
+      : mAttrValue(nullptr), mStringPtr(&aValue), mCheapString(nullptr) {}
+
+  explicit nsAttrValueOrString(const nsAString* aValue)
+      : mAttrValue(nullptr), mStringPtr(aValue), mCheapString(nullptr) {}
+
+  explicit nsAttrValueOrString(const nsAttrValue& aValue)
+      : mAttrValue(&aValue), mStringPtr(nullptr), mCheapString(nullptr) {}
+
+  explicit nsAttrValueOrString(const nsAttrValue* aValue)
+      : mAttrValue(aValue), mStringPtr(nullptr), mCheapString(nullptr) {}
+
+  void ResetToAttrValue(const nsAttrValue& aValue) {
+    mAttrValue = &aValue;
+    mStringPtr = nullptr;
+    // No need to touch mCheapString here.  If we need to use it, we will reset
+    // it to the rigthe value anyway.
+  }
+
+  /**
+   * Returns a reference to the string value of the contents of this object.
+   *
+   * When this object points to a string or an nsAttrValue of string or atom
+   * type this should be fairly cheap. Other nsAttrValue types will be
+   * serialized the first time this is called and cached from thereon.
+   */
+  const nsAString& String() const;
+
+  /**
+   * Compares the string representation of this object with the string
+   * representation of an nsAttrValue.
+   */
+  bool EqualsAsStrings(const nsAttrValue& aOther) const {
+    if (mStringPtr) {
+      return aOther.Equals(*mStringPtr, eCaseMatters);
+    }
+    return aOther.EqualsAsStrings(*mAttrValue);
+  }
+
+  /*
+   * Returns true if the value stored is empty
+   */
+  bool IsEmpty() const {
+    if (mStringPtr) {
+      return mStringPtr->IsEmpty();
+    }
+    if (mAttrValue) {
+      return mAttrValue->IsEmptyString();
+    }
+    return true;
+  }
+
+ protected:
+  const nsAttrValue* mAttrValue;
+  mutable const nsAString* mStringPtr;
+  mutable nsCheapString mCheapString;
+};
+
+#endif  // nsAttrValueOrString_h___