Move flat_buffer and api_signature into front_end.

pkg/analyzer/lib/src/summary/api_signature.dart

-// Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-
-library analyzer.src.summary.api_signature;
-
-import 'dart:convert';
-import 'dart:typed_data';
-
-import 'package:convert/convert.dart';
-import 'package:crypto/crypto.dart';
-
-/**
- * An instance of [ApiSignature] collects data in the form of primitive types
- * (strings, ints, bools, etc.) from a summary "builder" object, and uses them
- * to generate an MD5 signature of a the non-informative parts of the summary
- * (i.e. those parts representing the API of the code being summarized).
- *
- * Note that the data passed to the MD5 signature algorithm is untyped.  So, for
- * instance, an API signature built from a sequence of `false` booleans is
- * likely to match an API signature built from a sequence of zeros.  The caller
- * should take this into account; e.g. if a data structure may be represented
- * either by a boolean or an int, the caller should encode a tag distinguishing
- * the two representations before encoding the data.
- */
-class ApiSignature {
-  /**
-   * Version number of the code in this class.  Any time this class is changed
-   * in a way that affects the data collected in [_data], this version number
-   * should be incremented, so that a summary signed by a newer version of the
-   * signature algorithm won't accidentally have the same signature as a summary
-   * signed by an older version.
-   */
-  static const int _VERSION = 0;
-
-  /**
-   * Data accumulated so far.
-   */
-  ByteData _data = new ByteData(4096);
-
-  /**
-   * Offset into [_data] where the next byte should be written.
-   */
-  int _offset = 0;
-
-  /**
-   * Create an [ApiSignature] which is ready to accept data.
-   */
-  ApiSignature() {
-    addInt(_VERSION);
-  }
-
-  /**
-   * For testing only: create an [ApiSignature] which doesn't include any
-   * version information.  This makes it easier to unit tests, since the data
-   * is stable even if [_VERSION] is changed.
-   */
-  ApiSignature.unversioned();
-
-  /**
-   * Collect a boolean value.
-   */
-  void addBool(bool b) {
-    _makeRoom(1);
-    _data.setUint8(_offset, b ? 1 : 0);
-    _offset++;
-  }
-
-  /**
-   * Collect a sequence of arbitrary bytes.  Note that the length is not
-   * collected, so for example `addBytes([1, 2]);` will have the same effect as
-   * `addBytes([1]); addBytes([2]);`.
-   */
-  void addBytes(List<int> bytes) {
-    int length = bytes.length;
-    _makeRoom(length);
-    for (int i = 0; i < length; i++) {
-      _data.setUint8(_offset + i, bytes[i]);
-    }
-    _offset += length;
-  }
-
-  /**
-   * Collect a double-precision floating point value.
-   */
-  void addDouble(double d) {
-    _makeRoom(8);
-    _data.setFloat64(_offset, d, Endianness.LITTLE_ENDIAN);
-    _offset += 8;
-  }
-
-  /**
-   * Collect a 32-bit unsigned integer value.
-   */
-  void addInt(int i) {
-    _makeRoom(4);
-    _data.setUint32(_offset, i, Endianness.LITTLE_ENDIAN);
-    _offset += 4;
-  }
-
-  /**
-   * Collect a string.
-   */
-  void addString(String s) {
-    List<int> bytes = UTF8.encode(s);
-    addInt(bytes.length);
-    addBytes(bytes);
-  }
-
-  /**
-   * Collect the given [Uint32List].
-   */
-  void addUint32List(Uint32List data) {
-    addBytes(data.buffer.asUint8List());
-  }
-
-  /**
-   * For testing only: retrieve the internal representation of the data that
-   * has been collected.
-   */
-  List<int> getBytes_forDebug() {
-    return new Uint8List.view(_data.buffer, 0, _offset).toList();
-  }
-
-  /**
-   * Return the bytes of the MD5 hash of the data collected so far.
-   */
-  List<int> toByteList() {
-    return md5.convert(new Uint8List.view(_data.buffer, 0, _offset)).bytes;
-  }
-
-  /**
-   * Return a hex-encoded MD5 signature of the data collected so far.
-   */
-  String toHex() {
-    return hex.encode(toByteList());
-  }
-
-  /**
-   * Ensure that [spaceNeeded] bytes can be added to [_data] at [_offset]
-   * (copying it to a larger object if necessary).
-   */
-  void _makeRoom(int spaceNeeded) {
-    int oldLength = _data.lengthInBytes;
-    if (_offset + spaceNeeded > oldLength) {
-      int newLength = 2 * (_offset + spaceNeeded);
-      ByteData newData = new ByteData(newLength);
-      new Uint8List.view(newData.buffer)
-          .setRange(0, oldLength, new Uint8List.view(_data.buffer));
-      _data = newData;
-    }
-  }
-}