Add a new MIME-type package 'mime', with implementation for handling mime-type lookup by path (fine…

pkg/mime/lib/src/magic_number.dart

+// Copyright (c) 2013, 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.
+
+part of mime;
+
+
+class _MagicNumber {
+  final String mimeType;
+  final List<int> numbers;
+  final List<int> mask;
+
+  const _MagicNumber(this.mimeType, this.numbers, {this.mask});
+
+  bool matches(List<int> header) {
+    if (header.length < numbers.length) return false;
+
+    for (int i = 0; i < numbers.length; i++) {
+      if (mask != null) {
+        if ((mask[i] & numbers[i]) != (mask[i] & header[i])) return false;
+      } else {
+        if (numbers[i] != header[i]) return false;
+      }
+    }
+
+    return true;
+  }
+
+}
+
+int _defaultMagicNumbersMaxLength = 16;
+
+List<_MagicNumber> _defaultMagicNumbers = const [
+const _MagicNumber('application/pdf', const [0x25, 0x50, 0x44, 0x46]),
+const _MagicNumber('application/postscript', const [0x25, 0x51]),
+const _MagicNumber('image/gif', const [0x47, 0x49, 0x46, 0x38, 0x37, 0x61]),
+const _MagicNumber('image/gif', const [0x47, 0x49, 0x46, 0x38, 0x39, 0x61]),
+const _MagicNumber('image/jpeg', const [0xFF, 0xD8]),
+const _MagicNumber('image/png',
+                   const [0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A]),
+const _MagicNumber('image/tiff', const [0x49, 0x49, 0x2A, 0x00]),
+const _MagicNumber('image/tiff', const [0x4D, 0x4D, 0x00, 0x2A]),
+const _MagicNumber('video/mp4',
+                   const [0x00, 0x00, 0x00, 0x00, 0x66, 0x74,
+                          0x79, 0x70, 0x33, 0x67, 0x70, 0x35],
+                   mask: const [0xFF, 0xFF, 0xFF, 0x00, 0xFF, 0xFF,
+                                0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF])
+];
+