Source/WTF/icu/unicode/bytestream.h - WebKit - Git at Google

 // © 2016 and later: Unicode, Inc. and others.
 // License & terms of use: http://www.unicode.org/copyright.html
 // Copyright (C) 2009-2012, 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 &) = delete;
   ByteSink &operator=(const ByteSink &) = delete;
 };

 // -------------------------------------------------------------
 // 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);
   /**
    * Destructor.
    * @stable ICU 4.2
    */
   virtual ~CheckedArrayByteSink();
   /**
    * 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
    * @stable 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
    * @stable 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() = delete;
   CheckedArrayByteSink(const CheckedArrayByteSink &) = delete;
   CheckedArrayByteSink &operator=(const CheckedArrayByteSink &) = delete;
 };

 /**
  * 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) { }
   /**
    * Constructs a ByteSink that reserves append capacity and will append bytes to the dest string.
    *
    * @param dest pointer to string object to append to
    * @param initialAppendCapacity capacity beyond dest->length() to be reserve()d
    * @stable ICU 60
    */
   StringByteSink(StringClass* dest, int32_t initialAppendCapacity) : dest_(dest) {
     if (initialAppendCapacity > 0 &&
         (uint32_t)initialAppendCapacity > (dest->capacity() - dest->length())) {
       dest->reserve(dest->length() + initialAppendCapacity);
     }
   }
   /**
    * 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() = delete;
   StringByteSink(const StringByteSink &) = delete;
   StringByteSink &operator=(const StringByteSink &) = delete;
 };

 U_NAMESPACE_END

 #endif  // __BYTESTREAM_H__
	// © 2016 and later: Unicode, Inc. and others.
	// License & terms of use: http://www.unicode.org/copyright.html
	// Copyright (C) 2009-2012, 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 &) = delete;
	ByteSink &operator=(const ByteSink &) = delete;
	};

	// -------------------------------------------------------------
	// 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);
	/**
	* Destructor.
	* @stable ICU 4.2
	*/
	virtual ~CheckedArrayByteSink();
	/**
	* 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
	* @stable 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
	* @stable 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() = delete;
	CheckedArrayByteSink(const CheckedArrayByteSink &) = delete;
	CheckedArrayByteSink &operator=(const CheckedArrayByteSink &) = delete;
	};

	/**
	* 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) { }
	/**
	* Constructs a ByteSink that reserves append capacity and will append bytes to the dest string.
	*
	* @param dest pointer to string object to append to
	* @param initialAppendCapacity capacity beyond dest->length() to be reserve()d
	* @stable ICU 60
	*/
	StringByteSink(StringClass* dest, int32_t initialAppendCapacity) : dest_(dest) {
	if (initialAppendCapacity > 0 &&
	(uint32_t)initialAppendCapacity > (dest->capacity() - dest->length())) {
	dest->reserve(dest->length() + initialAppendCapacity);
	}
	}
	/**
	* 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() = delete;
	StringByteSink(const StringByteSink &) = delete;
	StringByteSink &operator=(const StringByteSink &) = delete;
	};

	U_NAMESPACE_END

	#endif // __BYTESTREAM_H__