1 files changed, 459 insertions, 0 deletions
diff --git a/parser/htmlparser/nsScannerString.h b/parser/htmlparser/nsScannerString.h
new file mode 100644
index 0000000000..195e63e4bb
--- /dev/null
+++ b/parser/htmlparser/nsScannerString.h
@@ -0,0 +1,459 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* 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/. */
+
+#ifndef nsScannerString_h___
+#define nsScannerString_h___
+
+#include "nsString.h"
+#include "nsUnicharUtils.h"  // for nsCaseInsensitiveStringComparator
+#include "mozilla/LinkedList.h"
+#include <algorithm>
+
+/**
+ * NOTE: nsScannerString (and the other classes defined in this file) are
+ * not related to nsAString or any of the other xpcom/string classes.
+ *
+ * nsScannerString is based on the nsSlidingString implementation that used
+ * to live in xpcom/string.  Now that nsAString is limited to representing
+ * only single fragment strings, nsSlidingString can no longer be used.
+ *
+ * An advantage to this design is that it does not employ any virtual
+ * functions.
+ *
+ * This file uses SCC-style indenting in deference to the nsSlidingString
+ * code from which this code is derived ;-)
+ */
+
+class nsScannerIterator;
+class nsScannerSubstring;
+class nsScannerString;
+
+/**
+ * nsScannerBufferList
+ *
+ * This class maintains a list of heap-allocated Buffer objects.  The buffers
+ * are maintained in a circular linked list.  Each buffer has a usage count
+ * that is decremented by the owning nsScannerSubstring.
+ *
+ * The buffer list itself is reference counted.  This allows the buffer list
+ * to be shared by multiple nsScannerSubstring objects.  The reference
+ * counting is not threadsafe, which is not at all a requirement.
+ *
+ * When a nsScannerSubstring releases its reference to a buffer list, it
+ * decrements the usage count of the first buffer in the buffer list that it
+ * was referencing.  It informs the buffer list that it can discard buffers
+ * starting at that prefix.  The buffer list will do so if the usage count of
+ * that buffer is 0 and if it is the first buffer in the list.  It will
+ * continue to prune buffers starting from the front of the buffer list until
+ * it finds a buffer that has a usage count that is non-zero.
+ */
+class nsScannerBufferList {
+ public:
+  /**
+   * Buffer objects are directly followed by a data segment.  The start
+   * of the data segment is determined by increment the |this| pointer
+   * by 1 unit.
+   */
+  class Buffer : public mozilla::LinkedListElement<Buffer> {
+   public:
+    void IncrementUsageCount() { ++mUsageCount; }
+    void DecrementUsageCount() { --mUsageCount; }
+
+    bool IsInUse() const { return mUsageCount != 0; }
+
+    const char16_t* DataStart() const { return (const char16_t*)(this + 1); }
+    char16_t* DataStart() { return (char16_t*)(this + 1); }
+
+    const char16_t* DataEnd() const { return mDataEnd; }
+    char16_t* DataEnd() { return mDataEnd; }
+
+    const Buffer* Next() const { return getNext(); }
+    Buffer* Next() { return getNext(); }
+
+    const Buffer* Prev() const { return getPrevious(); }
+    Buffer* Prev() { return getPrevious(); }
+
+    uint32_t DataLength() const { return mDataEnd - DataStart(); }
+    void SetDataLength(uint32_t len) { mDataEnd = DataStart() + len; }
+
+   private:
+    friend class nsScannerBufferList;
+
+    int32_t mUsageCount;
+    char16_t* mDataEnd;
+  };
+
+  /**
+   * Position objects serve as lightweight pointers into a buffer list.
+   * The mPosition member must be contained with mBuffer->DataStart()
+   * and mBuffer->DataEnd().
+   */
+  class Position {
+   public:
+    Position() : mBuffer(nullptr), mPosition(nullptr) {}
+
+    Position(Buffer* buffer, char16_t* position)
+        : mBuffer(buffer), mPosition(position) {}
+
+    inline explicit Position(const nsScannerIterator& aIter);
+
+    inline Position& operator=(const nsScannerIterator& aIter);
+
+    static size_t Distance(const Position& p1, const Position& p2);
+
+    Buffer* mBuffer;
+    char16_t* mPosition;
+  };
+
+  static Buffer* AllocBufferFromString(const nsAString&);
+  static Buffer* AllocBuffer(uint32_t capacity);  // capacity = number of chars
+
+  explicit nsScannerBufferList(Buffer* buf) : mRefCnt(0) {
+    mBuffers.insertBack(buf);
+  }
+
+  void AddRef() { ++mRefCnt; }
+  void Release() {
+    if (--mRefCnt == 0) delete this;
+  }
+
+  void Append(Buffer* buf) { mBuffers.insertBack(buf); }
+  void InsertAfter(Buffer* buf, Buffer* prev) { prev->setNext(buf); }
+  void SplitBuffer(const Position&);
+  void DiscardUnreferencedPrefix(Buffer*);
+
+  Buffer* Head() { return mBuffers.getFirst(); }
+  const Buffer* Head() const { return mBuffers.getFirst(); }
+
+  Buffer* Tail() { return mBuffers.getLast(); }
+  const Buffer* Tail() const { return mBuffers.getLast(); }
+
+ private:
+  friend class nsScannerSubstring;
+
+  ~nsScannerBufferList() { ReleaseAll(); }
+  void ReleaseAll();
+
+  int32_t mRefCnt;
+  mozilla::LinkedList<Buffer> mBuffers;
+};
+
+/**
+ * nsScannerFragment represents a "slice" of a Buffer object.
+ */
+struct nsScannerFragment {
+  typedef nsScannerBufferList::Buffer Buffer;
+
+  const Buffer* mBuffer;
+  const char16_t* mFragmentStart;
+  const char16_t* mFragmentEnd;
+};
+
+/**
+ * nsScannerSubstring is the base class for nsScannerString.  It provides
+ * access to iterators and methods to bind the substring to another
+ * substring or nsAString instance.
+ *
+ * This class owns the buffer list.
+ */
+class nsScannerSubstring {
+ public:
+  typedef nsScannerBufferList::Buffer Buffer;
+  typedef nsScannerBufferList::Position Position;
+  typedef uint32_t size_type;
+
+  nsScannerSubstring();
+  explicit nsScannerSubstring(const nsAString& s);
+
+  ~nsScannerSubstring();
+
+  nsScannerIterator& BeginReading(nsScannerIterator& iter) const;
+  nsScannerIterator& EndReading(nsScannerIterator& iter) const;
+
+  size_type Length() const { return mLength; }
+
+  void Rebind(const nsScannerSubstring&, const nsScannerIterator&,
+              const nsScannerIterator&);
+  void Rebind(const nsAString&);
+
+  bool GetNextFragment(nsScannerFragment&) const;
+  bool GetPrevFragment(nsScannerFragment&) const;
+
+  static inline Buffer* AllocBufferFromString(const nsAString& aStr) {
+    return nsScannerBufferList::AllocBufferFromString(aStr);
+  }
+  static inline Buffer* AllocBuffer(size_type aCapacity) {
+    return nsScannerBufferList::AllocBuffer(aCapacity);
+  }
+
+ protected:
+  void acquire_ownership_of_buffer_list() const {
+    mBufferList->AddRef();
+    mStart.mBuffer->IncrementUsageCount();
+  }
+
+  void release_ownership_of_buffer_list() {
+    if (mBufferList) {
+      mStart.mBuffer->DecrementUsageCount();
+      mBufferList->DiscardUnreferencedPrefix(mStart.mBuffer);
+      mBufferList->Release();
+    }
+  }
+
+  void init_range_from_buffer_list() {
+    mStart.mBuffer = mBufferList->Head();
+    mStart.mPosition = mStart.mBuffer->DataStart();
+
+    mEnd.mBuffer = mBufferList->Tail();
+    mEnd.mPosition = mEnd.mBuffer->DataEnd();
+
+    mLength = Position::Distance(mStart, mEnd);
+  }
+
+  Position mStart;
+  Position mEnd;
+  nsScannerBufferList* mBufferList;
+  size_type mLength;
+
+  friend class nsScannerSharedSubstring;
+};
+
+/**
+ * nsScannerString provides methods to grow and modify a buffer list.
+ */
+class nsScannerString : public nsScannerSubstring {
+ public:
+  explicit nsScannerString(Buffer*);
+
+  // you are giving ownership to the string, it takes and keeps your
+  // buffer, deleting it when done.
+  // Use AllocBuffer or AllocBufferFromString to create a Buffer object
+  // for use with this function.
+  void AppendBuffer(Buffer*);
+
+  void DiscardPrefix(const nsScannerIterator&);
+  // any other way you want to do this?
+
+  void UngetReadable(const nsAString& aReadable,
+                     const nsScannerIterator& aCurrentPosition);
+};
+
+/**
+ * nsScannerSharedSubstring implements copy-on-write semantics for
+ * nsScannerSubstring.  This class also manages releasing
+ * the reference to the scanner buffer when it is no longer needed.
+ */
+
+class nsScannerSharedSubstring {
+ public:
+  nsScannerSharedSubstring() : mBuffer(nullptr), mBufferList(nullptr) {}
+
+  ~nsScannerSharedSubstring() {
+    if (mBufferList) ReleaseBuffer();
+  }
+
+  // Acquire a copy-on-write reference to the given substring.
+  void Rebind(const nsScannerIterator& aStart, const nsScannerIterator& aEnd);
+
+  // Get a const reference to this string
+  const nsAString& str() const { return mString; }
+
+ private:
+  typedef nsScannerBufferList::Buffer Buffer;
+
+  void ReleaseBuffer();
+
+  nsDependentSubstring mString;
+  Buffer* mBuffer;
+  nsScannerBufferList* mBufferList;
+};
+
+/**
+ * nsScannerIterator works just like nsReadingIterator<CharT> except that
+ * it knows how to iterate over a list of scanner buffers.
+ */
+class nsScannerIterator {
+ public:
+  typedef nsScannerIterator self_type;
+  typedef ptrdiff_t difference_type;
+  typedef char16_t value_type;
+  typedef const char16_t* pointer;
+  typedef const char16_t& reference;
+  typedef nsScannerSubstring::Buffer Buffer;
+
+ protected:
+  nsScannerFragment mFragment;
+  const char16_t* mPosition;
+  const nsScannerSubstring* mOwner;
+
+  friend class nsScannerSubstring;
+  friend class nsScannerSharedSubstring;
+
+ public:
+  // nsScannerIterator();                                       // auto-generate
+  // default constructor is OK nsScannerIterator( const nsScannerIterator& ); //
+  // auto-generated copy-constructor OK nsScannerIterator& operator=( const
+  // nsScannerIterator& );  // auto-generated copy-assignment operator OK
+
+  inline void normalize_forward();
+  inline void normalize_backward();
+
+  pointer get() const { return mPosition; }
+
+  char16_t operator*() const { return *get(); }
+
+  const nsScannerFragment& fragment() const { return mFragment; }
+
+  const Buffer* buffer() const { return mFragment.mBuffer; }
+
+  self_type& operator++() {
+    ++mPosition;
+    normalize_forward();
+    return *this;
+  }
+
+  self_type operator++(int) {
+    self_type result(*this);
+    ++mPosition;
+    normalize_forward();
+    return result;
+  }
+
+  self_type& operator--() {
+    normalize_backward();
+    --mPosition;
+    return *this;
+  }
+
+  self_type operator--(int) {
+    self_type result(*this);
+    normalize_backward();
+    --mPosition;
+    return result;
+  }
+
+  difference_type size_forward() const {
+    return mFragment.mFragmentEnd - mPosition;
+  }
+
+  difference_type size_backward() const {
+    return mPosition - mFragment.mFragmentStart;
+  }
+
+  self_type& advance(difference_type n) {
+    while (n > 0) {
+      difference_type one_hop = std::min(n, size_forward());
+
+      NS_ASSERTION(one_hop > 0,
+                   "Infinite loop: can't advance a reading iterator beyond the "
+                   "end of a string");
+      // perhaps I should |break| if |!one_hop|?
+
+      mPosition += one_hop;
+      normalize_forward();
+      n -= one_hop;
+    }
+
+    while (n < 0) {
+      normalize_backward();
+      difference_type one_hop = std::max(n, -size_backward());
+
+      NS_ASSERTION(one_hop < 0,
+                   "Infinite loop: can't advance (backward) a reading iterator "
+                   "beyond the end of a string");
+      // perhaps I should |break| if |!one_hop|?
+
+      mPosition += one_hop;
+      n -= one_hop;
+    }
+
+    return *this;
+  }
+};
+
+inline bool SameFragment(const nsScannerIterator& a,
+                         const nsScannerIterator& b) {
+  return a.fragment().mFragmentStart == b.fragment().mFragmentStart;
+}
+
+/**
+ * this class is needed in order to make use of the methods in nsAlgorithm.h
+ */
+template <>
+struct nsCharSourceTraits<nsScannerIterator> {
+  typedef nsScannerIterator::difference_type difference_type;
+
+  static uint32_t readable_distance(const nsScannerIterator& first,
+                                    const nsScannerIterator& last) {
+    return uint32_t(SameFragment(first, last) ? last.get() - first.get()
+                                              : first.size_forward());
+  }
+
+  static const nsScannerIterator::value_type* read(
+      const nsScannerIterator& iter) {
+    return iter.get();
+  }
+
+  static void advance(nsScannerIterator& s, difference_type n) { s.advance(n); }
+};
+
+/**
+ * inline methods follow
+ */
+
+inline void nsScannerIterator::normalize_forward() {
+  while (mPosition == mFragment.mFragmentEnd &&
+         mOwner->GetNextFragment(mFragment))
+    mPosition = mFragment.mFragmentStart;
+}
+
+inline void nsScannerIterator::normalize_backward() {
+  while (mPosition == mFragment.mFragmentStart &&
+         mOwner->GetPrevFragment(mFragment))
+    mPosition = mFragment.mFragmentEnd;
+}
+
+inline bool operator==(const nsScannerIterator& lhs,
+                       const nsScannerIterator& rhs) {
+  return lhs.get() == rhs.get();
+}
+
+inline bool operator!=(const nsScannerIterator& lhs,
+                       const nsScannerIterator& rhs) {
+  return lhs.get() != rhs.get();
+}
+
+inline nsScannerBufferList::Position::Position(const nsScannerIterator& aIter)
+    : mBuffer(const_cast<Buffer*>(aIter.buffer())),
+      mPosition(const_cast<char16_t*>(aIter.get())) {}
+
+inline nsScannerBufferList::Position& nsScannerBufferList::Position::operator=(
+    const nsScannerIterator& aIter) {
+  mBuffer = const_cast<Buffer*>(aIter.buffer());
+  mPosition = const_cast<char16_t*>(aIter.get());
+  return *this;
+}
+
+/**
+ * scanner string utils
+ *
+ * These methods mimic the API provided by nsReadableUtils in xpcom/string.
+ * Here we provide only the methods that the htmlparser module needs.
+ */
+
+inline size_t Distance(const nsScannerIterator& aStart,
+                       const nsScannerIterator& aEnd) {
+  typedef nsScannerBufferList::Position Position;
+  return Position::Distance(Position(aStart), Position(aEnd));
+}
+
+bool CopyUnicodeTo(const nsScannerIterator& aSrcStart,
+                   const nsScannerIterator& aSrcEnd, nsAString& aDest);
+
+bool AppendUnicodeTo(const nsScannerIterator& aSrcStart,
+                     const nsScannerIterator& aSrcEnd, nsAString& aDest);
+
+#endif  // !defined(nsScannerString_h___)