| // Copyright (C) 2009-2010, International Business Machines |
| // Corporation and others. All Rights Reserved. |
| // |
| // Copyright 2007 Google Inc. All Rights Reserved. |
| // Author: sanjay@google.com (Sanjay Ghemawat) |
| // |
| // Abstract interface that consumes a sequence of bytes (ByteSink). |
| // |
| // Used so that we can write a single piece of code that can operate |
| // on a variety of output string types. |
| // |
| // Various implementations of this interface are provided: |
| // ByteSink: |
| // CheckedArrayByteSink Write to a flat array, with bounds checking |
| // StringByteSink Write to an STL string |
| |
| // This code is a contribution of Google code, and the style used here is |
| // a compromise between the original Google code and the ICU coding guidelines. |
| // For example, data types are ICU-ified (size_t,int->int32_t), |
| // and API comments doxygen-ified, but function names and behavior are |
| // as in the original, if possible. |
| // Assertion-style error handling, not available in ICU, was changed to |
| // parameter "pinning" similar to UnicodeString. |
| // |
| // In addition, this is only a partial port of the original Google code, |
| // limited to what was needed so far. The (nearly) complete original code |
| // is in the ICU svn repository at icuhtml/trunk/design/strings/contrib |
| // (see ICU ticket 6765, r25517). |
| |
| #ifndef __BYTESTREAM_H__ |
| #define __BYTESTREAM_H__ |
| |
| /** |
| * \file |
| * \brief C++ API: Interface for writing bytes, and implementation classes. |
| */ |
| |
| #include "unicode/utypes.h" |
| #include "unicode/uobject.h" |
| #include "unicode/std_string.h" |
| |
| U_NAMESPACE_BEGIN |
| |
| /** |
| * A ByteSink can be filled with bytes. |
| * @stable ICU 4.2 |
| */ |
| class U_COMMON_API ByteSink : public UMemory { |
| public: |
| /** |
| * Default constructor. |
| * @stable ICU 4.2 |
| */ |
| ByteSink() { } |
| /** |
| * Virtual destructor. |
| * @stable ICU 4.2 |
| */ |
| virtual ~ByteSink() { } |
| |
| /** |
| * Append "bytes[0,n-1]" to this. |
| * @param bytes the pointer to the bytes |
| * @param n the number of bytes; must be non-negative |
| * @stable ICU 4.2 |
| */ |
| virtual void Append(const char* bytes, int32_t n) = 0; |
| |
| /** |
| * Returns a writable buffer for appending and writes the buffer's capacity to |
| * *result_capacity. Guarantees *result_capacity>=min_capacity. |
| * May return a pointer to the caller-owned scratch buffer which must have |
| * scratch_capacity>=min_capacity. |
| * The returned buffer is only valid until the next operation |
| * on this ByteSink. |
| * |
| * After writing at most *result_capacity bytes, call Append() with the |
| * pointer returned from this function and the number of bytes written. |
| * Many Append() implementations will avoid copying bytes if this function |
| * returned an internal buffer. |
| * |
| * Partial usage example: |
| * int32_t capacity; |
| * char* buffer = sink->GetAppendBuffer(..., &capacity); |
| * ... Write n bytes into buffer, with n <= capacity. |
| * sink->Append(buffer, n); |
| * In many implementations, that call to Append will avoid copying bytes. |
| * |
| * If the ByteSink allocates or reallocates an internal buffer, it should use |
| * the desired_capacity_hint if appropriate. |
| * If a caller cannot provide a reasonable guess at the desired capacity, |
| * it should pass desired_capacity_hint=0. |
| * |
| * If a non-scratch buffer is returned, the caller may only pass |
| * a prefix to it to Append(). |
| * That is, it is not correct to pass an interior pointer to Append(). |
| * |
| * The default implementation always returns the scratch buffer. |
| * |
| * @param min_capacity required minimum capacity of the returned buffer; |
| * must be non-negative |
| * @param desired_capacity_hint desired capacity of the returned buffer; |
| * must be non-negative |
| * @param scratch default caller-owned buffer |
| * @param scratch_capacity capacity of the scratch buffer |
| * @param result_capacity pointer to an integer which will be set to the |
| * capacity of the returned buffer |
| * @return a buffer with *result_capacity>=min_capacity |
| * @stable ICU 4.2 |
| */ |
| virtual char* GetAppendBuffer(int32_t min_capacity, |
| int32_t desired_capacity_hint, |
| char* scratch, int32_t scratch_capacity, |
| int32_t* result_capacity); |
| |
| /** |
| * Flush internal buffers. |
| * Some byte sinks use internal buffers or provide buffering |
| * and require calling Flush() at the end of the stream. |
| * The ByteSink should be ready for further Append() calls after Flush(). |
| * The default implementation of Flush() does nothing. |
| * @stable ICU 4.2 |
| */ |
| virtual void Flush(); |
| |
| private: |
| ByteSink(const ByteSink &); // copy constructor not implemented |
| ByteSink &operator=(const ByteSink &); // assignment operator not implemented |
| }; |
| |
| // ------------------------------------------------------------- |
| // Some standard implementations |
| |
| /** |
| * Implementation of ByteSink that writes to a flat byte array, |
| * with bounds-checking: |
| * This sink will not write more than capacity bytes to outbuf. |
| * If more than capacity bytes are Append()ed, then excess bytes are ignored, |
| * and Overflowed() will return true. |
| * Overflow does not cause a runtime error. |
| * @stable ICU 4.2 |
| */ |
| class U_COMMON_API CheckedArrayByteSink : public ByteSink { |
| public: |
| /** |
| * Constructs a ByteSink that will write to outbuf[0..capacity-1]. |
| * @param outbuf buffer to write to |
| * @param capacity size of the buffer |
| * @stable ICU 4.2 |
| */ |
| CheckedArrayByteSink(char* outbuf, int32_t capacity); |
| /** |
| * Returns the sink to its original state, without modifying the buffer. |
| * Useful for reusing both the buffer and the sink for multiple streams. |
| * Resets the state to NumberOfBytesWritten()=NumberOfBytesAppended()=0 |
| * and Overflowed()=FALSE. |
| * @return *this |
| * @draft ICU 4.6 |
| */ |
| virtual CheckedArrayByteSink& Reset(); |
| /** |
| * Append "bytes[0,n-1]" to this. |
| * @param bytes the pointer to the bytes |
| * @param n the number of bytes; must be non-negative |
| * @stable ICU 4.2 |
| */ |
| virtual void Append(const char* bytes, int32_t n); |
| /** |
| * Returns a writable buffer for appending and writes the buffer's capacity to |
| * *result_capacity. For details see the base class documentation. |
| * @param min_capacity required minimum capacity of the returned buffer; |
| * must be non-negative |
| * @param desired_capacity_hint desired capacity of the returned buffer; |
| * must be non-negative |
| * @param scratch default caller-owned buffer |
| * @param scratch_capacity capacity of the scratch buffer |
| * @param result_capacity pointer to an integer which will be set to the |
| * capacity of the returned buffer |
| * @return a buffer with *result_capacity>=min_capacity |
| * @stable ICU 4.2 |
| */ |
| virtual char* GetAppendBuffer(int32_t min_capacity, |
| int32_t desired_capacity_hint, |
| char* scratch, int32_t scratch_capacity, |
| int32_t* result_capacity); |
| /** |
| * Returns the number of bytes actually written to the sink. |
| * @return number of bytes written to the buffer |
| * @stable ICU 4.2 |
| */ |
| int32_t NumberOfBytesWritten() const { return size_; } |
| /** |
| * Returns true if any bytes were discarded, i.e., if there was an |
| * attempt to write more than 'capacity' bytes. |
| * @return TRUE if more than 'capacity' bytes were Append()ed |
| * @stable ICU 4.2 |
| */ |
| UBool Overflowed() const { return overflowed_; } |
| /** |
| * Returns the number of bytes appended to the sink. |
| * If Overflowed() then NumberOfBytesAppended()>NumberOfBytesWritten() |
| * else they return the same number. |
| * @return number of bytes written to the buffer |
| * @draft ICU 4.6 |
| */ |
| int32_t NumberOfBytesAppended() const { return appended_; } |
| private: |
| char* outbuf_; |
| const int32_t capacity_; |
| int32_t size_; |
| int32_t appended_; |
| UBool overflowed_; |
| CheckedArrayByteSink(); ///< default constructor not implemented |
| CheckedArrayByteSink(const CheckedArrayByteSink &); ///< copy constructor not implemented |
| CheckedArrayByteSink &operator=(const CheckedArrayByteSink &); ///< assignment operator not implemented |
| }; |
| |
| #if U_HAVE_STD_STRING |
| |
| /** |
| * Implementation of ByteSink that writes to a "string". |
| * The StringClass is usually instantiated with a std::string. |
| * @stable ICU 4.2 |
| */ |
| template<typename StringClass> |
| class StringByteSink : public ByteSink { |
| public: |
| /** |
| * Constructs a ByteSink that will append bytes to the dest string. |
| * @param dest pointer to string object to append to |
| * @stable ICU 4.2 |
| */ |
| StringByteSink(StringClass* dest) : dest_(dest) { } |
| /** |
| * Append "bytes[0,n-1]" to this. |
| * @param data the pointer to the bytes |
| * @param n the number of bytes; must be non-negative |
| * @stable ICU 4.2 |
| */ |
| virtual void Append(const char* data, int32_t n) { dest_->append(data, n); } |
| private: |
| StringClass* dest_; |
| StringByteSink(); ///< default constructor not implemented |
| StringByteSink(const StringByteSink &); ///< copy constructor not implemented |
| StringByteSink &operator=(const StringByteSink &); ///< assignment operator not implemented |
| }; |
| |
| #endif |
| |
| U_NAMESPACE_END |
| |
| #endif // __BYTESTREAM_H__ |