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      1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef NET_BASE_UPLOAD_ELEMENT_READER_H_
      6 #define NET_BASE_UPLOAD_ELEMENT_READER_H_
      7 
      8 #include "base/basictypes.h"
      9 #include "net/base/completion_callback.h"
     10 #include "net/base/net_export.h"
     11 
     12 namespace net {
     13 
     14 class IOBuffer;
     15 class UploadBytesElementReader;
     16 class UploadFileElementReader;
     17 
     18 // An interface to read an upload data element.
     19 class NET_EXPORT UploadElementReader {
     20  public:
     21   UploadElementReader() {}
     22   virtual ~UploadElementReader() {}
     23 
     24   // Returns this instance's pointer as UploadBytesElementReader when possible,
     25   // otherwise returns NULL.
     26   virtual const UploadBytesElementReader* AsBytesReader() const;
     27 
     28   // Returns this instance's pointer as UploadFileElementReader when possible,
     29   // otherwise returns NULL.
     30   virtual const UploadFileElementReader* AsFileReader() const;
     31 
     32   // Initializes the instance synchronously when possible, otherwise does
     33   // initialization aynschronously, returns ERR_IO_PENDING and runs callback.
     34   // Calling this method again after a Init() success results in resetting the
     35   // state.
     36   virtual int Init(const CompletionCallback& callback) = 0;
     37 
     38   // Returns the byte-length of the element.  For files that do not exist, 0
     39   // is returned.  This is done for consistency with Mozilla.
     40   virtual uint64 GetContentLength() const = 0;
     41 
     42   // Returns the number of bytes remaining to read.
     43   virtual uint64 BytesRemaining() const = 0;
     44 
     45   // Returns true if the upload element is entirely in memory.
     46   // The default implementation returns false.
     47   virtual bool IsInMemory() const;
     48 
     49   // Reads up to |buf_length| bytes synchronously and returns the number of
     50   // bytes read or error code when possible, otherwise, returns ERR_IO_PENDING
     51   // and runs |callback| with the result. |buf_length| must be greater than 0.
     52   virtual int Read(IOBuffer* buf,
     53                    int buf_length,
     54                    const CompletionCallback& callback) = 0;
     55 
     56  private:
     57   DISALLOW_COPY_AND_ASSIGN(UploadElementReader);
     58 };
     59 
     60 }  // namespace net
     61 
     62 #endif  // NET_BASE_UPLOAD_ELEMENT_READER_H_
     63