import FIREFOX_52_6_0esr_RELEASE from mozilla-esr52 hg repo

xpcom/ds/IncrementalTokenizer.cpp

@@ -0,0 +1,195 @@
+/* -*- 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 "mozilla/IncrementalTokenizer.h"
+
+#include "mozilla/AutoRestore.h"
+
+#include "nsIInputStream.h"
+#include "IncrementalTokenizer.h"
+#include <algorithm>
+
+namespace mozilla {
+
+IncrementalTokenizer::IncrementalTokenizer(Consumer aConsumer,
+                                           const char * aWhitespaces,
+                                           const char * aAdditionalWordChars,
+                                           uint32_t aRawMinBuffered)
+  : TokenizerBase(aWhitespaces, aAdditionalWordChars)
+#ifdef DEBUG
+  , mConsuming(false)
+#endif
+  , mNeedMoreInput(false)
+  , mRollback(false)
+  , mInputCursor(0)
+  , mConsumer(aConsumer)
+{
+  mInputFinished = false;
+  mMinRawDelivery = aRawMinBuffered;
+}
+
+nsresult IncrementalTokenizer::FeedInput(const nsACString & aInput)
+{
+  NS_ENSURE_TRUE(mConsumer, NS_ERROR_NOT_INITIALIZED);
+  MOZ_ASSERT(!mInputFinished);
+
+  mInput.Cut(0, mInputCursor);
+  mInputCursor = 0;
+
+  mInput.Append(aInput);
+
+  return Process();
+}
+
+nsresult IncrementalTokenizer::FeedInput(nsIInputStream * aInput, uint32_t aCount)
+{
+  NS_ENSURE_TRUE(mConsumer, NS_ERROR_NOT_INITIALIZED);
+  MOZ_ASSERT(!mInputFinished);
+  MOZ_ASSERT(!mConsuming);
+
+  mInput.Cut(0, mInputCursor);
+  mInputCursor = 0;
+
+  nsresult rv = NS_OK;
+  while (NS_SUCCEEDED(rv) && aCount) {
+    nsCString::index_type remainder = mInput.Length();
+    nsCString::index_type load =
+      std::min<nsCString::index_type>(aCount, PR_UINT32_MAX - remainder);
+
+    if (!load) {
+      // To keep the API simple, we fail if the input data buffer if filled.
+      // It's highly unlikely there will ever be such amout of data cumulated
+      // unless a logic fault in the consumer code.
+      NS_ERROR("IncrementalTokenizer consumer not reading data?");
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
+
+    if (!mInput.SetLength(remainder + load, fallible)) {
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
+
+    nsCString::char_iterator buffer = mInput.BeginWriting() + remainder;
+
+    uint32_t read;
+    rv = aInput->Read(buffer, load, &read);
+    if (NS_SUCCEEDED(rv)) {
+      // remainder + load fits the uint32_t size, so must remainder + read.
+      mInput.SetLength(remainder + read);
+      aCount -= read;
+
+      rv = Process();
+    }
+  }
+
+  return rv;
+}
+
+nsresult IncrementalTokenizer::FinishInput()
+{
+  NS_ENSURE_TRUE(mConsumer, NS_ERROR_NOT_INITIALIZED);
+  MOZ_ASSERT(!mInputFinished);
+  MOZ_ASSERT(!mConsuming);
+
+  mInput.Cut(0, mInputCursor);
+  mInputCursor = 0;
+
+  mInputFinished = true;
+  nsresult rv = Process();
+  mConsumer = nullptr;
+  return rv;
+}
+
+bool IncrementalTokenizer::Next(Token & aToken)
+{
+  // Assert we are called only from the consumer callback
+  MOZ_ASSERT(mConsuming);
+
+  if (mPastEof) {
+    return false;
+  }
+
+  nsACString::const_char_iterator next = Parse(aToken);
+  mPastEof = aToken.Type() == TOKEN_EOF;
+  if (next == mCursor && !mPastEof) {
+    // Not enough input to make a deterministic decision.
+    return false;
+  }
+
+  AssignFragment(aToken, mCursor, next);
+  mCursor = next;
+  return true;
+}
+
+void IncrementalTokenizer::NeedMoreInput()
+{
+  // Assert we are called only from the consumer callback
+  MOZ_ASSERT(mConsuming);
+
+  // When the input has been finished, we can't set the flag to prevent
+  // indefinite wait for more input (that will never come)
+  mNeedMoreInput = !mInputFinished;
+}
+
+void IncrementalTokenizer::Rollback()
+{
+  // Assert we are called only from the consumer callback
+  MOZ_ASSERT(mConsuming);
+
+  mRollback = true;
+}
+
+nsresult IncrementalTokenizer::Process()
+{
+#ifdef DEBUG
+  // Assert we are not re-entered
+  MOZ_ASSERT(!mConsuming);
+
+  AutoRestore<bool> consuming(mConsuming);
+  mConsuming = true;
+#endif
+
+  MOZ_ASSERT(!mPastEof);
+
+  nsresult rv = NS_OK;
+
+  mInput.BeginReading(mCursor);
+  mCursor += mInputCursor;
+  mInput.EndReading(mEnd);
+
+  while (NS_SUCCEEDED(rv) && !mPastEof) {
+    Token token;
+    nsACString::const_char_iterator next = Parse(token);
+    mPastEof = token.Type() == TOKEN_EOF;
+    if (next == mCursor && !mPastEof) {
+      // Not enough input to make a deterministic decision.
+      break;
+    }
+
+    AssignFragment(token, mCursor, next);
+
+    nsACString::const_char_iterator rollback = mCursor;
+    mCursor = next;
+
+    mNeedMoreInput = mRollback = false;
+
+    rv = mConsumer(token, *this);
+    if (NS_FAILED(rv)) {
+      break;
+    }
+    if (mNeedMoreInput || mRollback) {
+      mCursor = rollback;
+      mPastEof = false;
+      if (mNeedMoreInput) {
+        break;
+      }
+    }
+  }
+
+  mInputCursor = mCursor - mInput.BeginReading();
+  return rv;
+}
+
+} // mozilla