Add new HttpMultipartFormData, used for parsing a MimeMultipart and extracting either text or binar…

sdk/lib/io/http_multipart_form_data.dart

Index: sdk/lib/io/http_multipart_form_data.dart
diff --git a/sdk/lib/io/http_multipart_form_data.dart b/sdk/lib/io/http_multipart_form_data.dart
new file mode 100644
index 0000000000000000000000000000000000000000..3c9bca41507703661ac83e6b79f6ab4c76f1b102
--- /dev/null
+++ b/sdk/lib/io/http_multipart_form_data.dart
@@ -0,0 +1,73 @@
+// Copyright (c) 2012, 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 dart.io;
+
+
+/**
+ * [:HttpMultipartFormData:] class used for 'upgrading' a [MimeMultipart] by
+ * parsing it as a 'multipart/form-data' part. The following code shows how
+ * it can be used.
+ *
+ *   HttpServer server = ...;
+ *   server.listen((request) {
+ *     String boundary = request.headers.contentType.parameters['boundary'];
+ *     request
+ *         .transform(new MimeMultipartTransformer(boundary))
+ *         .map(HttpMultipartFormData.parse)
+ *         .map((HttpMultipartFormData formData) {
+ *           // form data object available here.
+ *         });
+ *
+ * [:HttpMultipartFormData:] is a Stream, serving either bytes or decoded
+ * Strings. Use [isText] or [isBinary] to see what type of data is provided.
+ */
+abstract class HttpMultipartFormData implements Stream {
+  /**
+   * The parsed [:Content-Type:] header of the [:HttpMultipartFormData:].
+   * Returns [:null:] if not present.
+   */
+  ContentType get contentType;
+
+  /**
+   * The parsed [:Content-Disposition:] header of the [:HttpMultipartFormData:].
+   * This field is always present. Use this to extract e.g. name(form field
+   * name)and filename (client provided name of uploaded file) parameters.
+   */
+  HeaderValue get contentDisposition;
+
+  /**
+   * The parsed [:Content-Transfer-Encoding:] header of the
+   * [:HttpMultipartFormData:]. This field is used to determine how to decode
+   * the data. Returns [:null:] if not present.
+   */
+  HeaderValue get contentTransferEncoding;
+
+  /**
+   * Returns [:true:] if the data is decoded as [String].
+   */
+  bool get isText;
+
+  /**
+   * Returns [:true:] if the data is raw bytes.
+   */
+  bool get isBinary;
+
+  /**
+   * Returns the value for the header named [name]. If there
+   * is no header with the provided name, [:null:] will be returned.
+   *
+   * Use this method to index other headers available in the original
+   * [MimeMultipart].
+   */
+  String value(String name);
+
+  /**
+   * Parse a [MimeMultipart] and return a [HttpMultipartFormData]. If the
+   * [:Content-Disposition:] header is missing or invalid, a [HttpException] is
+   * thrown.
+   */
+  static HttpMultipartFormData parse(MimeMultipart multipart)
+      => _HttpMultipartFormData.parse(multipart);
+}