1 files changed, 192 insertions, 0 deletions
diff --git a/dom/base/XPathGenerator.cpp b/dom/base/XPathGenerator.cpp
new file mode 100644
index 0000000000..ee9134833c
--- /dev/null
+++ b/dom/base/XPathGenerator.cpp
@@ -0,0 +1,192 @@
+/* -*- 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/. */
+
+#include "XPathGenerator.h"
+
+#include "nsGkAtoms.h"
+#include "Element.h"
+#include "nsTArray.h"
+
+/**
+ * Check whether a character is a non-word character. A non-word character is a
+ * character that isn't in ('a'..'z') or in ('A'..'Z') or a number or an
+ * underscore.
+ * */
+bool IsNonWordCharacter(const char16_t& aChar) {
+  if (((char16_t('A') <= aChar) && (aChar <= char16_t('Z'))) ||
+      ((char16_t('a') <= aChar) && (aChar <= char16_t('z'))) ||
+      ((char16_t('0') <= aChar) && (aChar <= char16_t('9'))) ||
+      (aChar == char16_t('_'))) {
+    return false;
+  } else {
+    return true;
+  }
+}
+
+/**
+ * Check whether a string contains a non-word character.
+ * */
+bool ContainNonWordCharacter(const nsAString& aStr) {
+  const char16_t* cur = aStr.BeginReading();
+  const char16_t* end = aStr.EndReading();
+  for (; cur < end; ++cur) {
+    if (IsNonWordCharacter(*cur)) {
+      return true;
+    }
+  }
+  return false;
+}
+
+/**
+ * Get the prefix according to the given namespace and assign the result to
+ * aResult.
+ * */
+void GetPrefix(const nsINode* aNode, nsAString& aResult) {
+  if (aNode->IsXULElement()) {
+    aResult.AssignLiteral(u"xul");
+  } else if (aNode->IsHTMLElement()) {
+    aResult.AssignLiteral(u"xhtml");
+  }
+}
+
+void GetNameAttribute(const nsINode* aNode, nsAString& aResult) {
+  if (aNode->HasName()) {
+    const mozilla::dom::Element* elem = aNode->AsElement();
+    elem->GetAttr(nsGkAtoms::name, aResult);
+  }
+}
+
+/**
+ * Put all sequences of ' in a string in between '," and ",' . And then put
+ * the result string in between concat(' and ').
+ *
+ * For example, a string 'a'' will return result concat('',"'",'a',"''",'')
+ * */
+void GenerateConcatExpression(const nsAString& aStr, nsAString& aResult) {
+  const char16_t* cur = aStr.BeginReading();
+  const char16_t* end = aStr.EndReading();
+
+  // Put all sequences of ' in between '," and ",'
+  nsAutoString result;
+  const char16_t* nonQuoteBeginPtr = nullptr;
+  const char16_t* quoteBeginPtr = nullptr;
+  for (; cur < end; ++cur) {
+    if (char16_t('\'') == *cur) {
+      if (nonQuoteBeginPtr) {
+        result.Append(nonQuoteBeginPtr, cur - nonQuoteBeginPtr);
+        nonQuoteBeginPtr = nullptr;
+      }
+      if (!quoteBeginPtr) {
+        result.AppendLiteral(u"\',\"");
+        quoteBeginPtr = cur;
+      }
+    } else {
+      if (!nonQuoteBeginPtr) {
+        nonQuoteBeginPtr = cur;
+      }
+      if (quoteBeginPtr) {
+        result.Append(quoteBeginPtr, cur - quoteBeginPtr);
+        result.AppendLiteral(u"\",\'");
+        quoteBeginPtr = nullptr;
+      }
+    }
+  }
+
+  if (quoteBeginPtr) {
+    result.Append(quoteBeginPtr, cur - quoteBeginPtr);
+    result.AppendLiteral(u"\",\'");
+  } else if (nonQuoteBeginPtr) {
+    result.Append(nonQuoteBeginPtr, cur - nonQuoteBeginPtr);
+  }
+
+  // Prepend concat(' and append ').
+  aResult.Assign(u"concat(\'"_ns + result + u"\')"_ns);
+}
+
+void XPathGenerator::QuoteArgument(const nsAString& aArg, nsAString& aResult) {
+  if (!aArg.Contains('\'')) {
+    aResult.Assign(u"\'"_ns + aArg + u"\'"_ns);
+  } else if (!aArg.Contains('\"')) {
+    aResult.Assign(u"\""_ns + aArg + u"\""_ns);
+  } else {
+    GenerateConcatExpression(aArg, aResult);
+  }
+}
+
+void XPathGenerator::EscapeName(const nsAString& aName, nsAString& aResult) {
+  if (ContainNonWordCharacter(aName)) {
+    nsAutoString quotedArg;
+    QuoteArgument(aName, quotedArg);
+    aResult.Assign(u"*[local-name()="_ns + quotedArg + u"]"_ns);
+  } else {
+    aResult.Assign(aName);
+  }
+}
+
+void XPathGenerator::Generate(const nsINode* aNode, nsAString& aResult) {
+  if (!aNode->GetParentNode()) {
+    aResult.Truncate();
+    return;
+  }
+
+  nsAutoString nodeNamespaceURI;
+  aNode->GetNamespaceURI(nodeNamespaceURI);
+  const nsString& nodeLocalName = aNode->LocalName();
+
+  nsAutoString prefix;
+  nsAutoString tag;
+  nsAutoString nodeEscapeName;
+  GetPrefix(aNode, prefix);
+  EscapeName(nodeLocalName, nodeEscapeName);
+  if (prefix.IsEmpty()) {
+    tag.Assign(nodeEscapeName);
+  } else {
+    tag.Assign(prefix + u":"_ns + nodeEscapeName);
+  }
+
+  if (aNode->HasID()) {
+    // this must be an element
+    const mozilla::dom::Element* elem = aNode->AsElement();
+    nsAutoString elemId;
+    nsAutoString quotedArgument;
+    elem->GetId(elemId);
+    QuoteArgument(elemId, quotedArgument);
+    aResult.Assign(u"//"_ns + tag + u"[@id="_ns + quotedArgument + u"]"_ns);
+    return;
+  }
+
+  int32_t count = 1;
+  nsAutoString nodeNameAttribute;
+  GetNameAttribute(aNode, nodeNameAttribute);
+  for (const mozilla::dom::Element* e = aNode->GetPreviousElementSibling(); e;
+       e = e->GetPreviousElementSibling()) {
+    nsAutoString elementNamespaceURI;
+    e->GetNamespaceURI(elementNamespaceURI);
+    nsAutoString elementNameAttribute;
+    GetNameAttribute(e, elementNameAttribute);
+    if (e->LocalName().Equals(nodeLocalName) &&
+        elementNamespaceURI.Equals(nodeNamespaceURI) &&
+        (nodeNameAttribute.IsEmpty() ||
+         elementNameAttribute.Equals(nodeNameAttribute))) {
+      ++count;
+    }
+  }
+
+  nsAutoString namePart;
+  nsAutoString countPart;
+  if (!nodeNameAttribute.IsEmpty()) {
+    nsAutoString quotedArgument;
+    QuoteArgument(nodeNameAttribute, quotedArgument);
+    namePart.Assign(u"[@name="_ns + quotedArgument + u"]"_ns);
+  }
+  if (count != 1) {
+    countPart.AssignLiteral(u"[");
+    countPart.AppendInt(count);
+    countPart.AppendLiteral(u"]");
+  }
+  Generate(aNode->GetParentNode(), aResult);
+  aResult.Append(u"/"_ns + tag + namePart + countPart);
+}