jpayne@69: // © 2016 and later: Unicode, Inc. and others.
jpayne@69: // License & terms of use: http://www.unicode.org/copyright.html
jpayne@69: // Copyright (C) 2009-2012, International Business Machines
jpayne@69: // Corporation and others. All Rights Reserved.
jpayne@69: //
jpayne@69: // Copyright 2007 Google Inc. All Rights Reserved.
jpayne@69: // Author: sanjay@google.com (Sanjay Ghemawat)
jpayne@69: //
jpayne@69: // Abstract interface that consumes a sequence of bytes (ByteSink).
jpayne@69: //
jpayne@69: // Used so that we can write a single piece of code that can operate
jpayne@69: // on a variety of output string types.
jpayne@69: //
jpayne@69: // Various implementations of this interface are provided:
jpayne@69: //   ByteSink:
jpayne@69: //      CheckedArrayByteSink    Write to a flat array, with bounds checking
jpayne@69: //      StringByteSink          Write to an STL string
jpayne@69: 
jpayne@69: // This code is a contribution of Google code, and the style used here is
jpayne@69: // a compromise between the original Google code and the ICU coding guidelines.
jpayne@69: // For example, data types are ICU-ified (size_t,int->int32_t),
jpayne@69: // and API comments doxygen-ified, but function names and behavior are
jpayne@69: // as in the original, if possible.
jpayne@69: // Assertion-style error handling, not available in ICU, was changed to
jpayne@69: // parameter "pinning" similar to UnicodeString.
jpayne@69: //
jpayne@69: // In addition, this is only a partial port of the original Google code,
jpayne@69: // limited to what was needed so far. The (nearly) complete original code
jpayne@69: // is in the ICU svn repository at icuhtml/trunk/design/strings/contrib
jpayne@69: // (see ICU ticket 6765, r25517).
jpayne@69: 
jpayne@69: #ifndef __BYTESTREAM_H__
jpayne@69: #define __BYTESTREAM_H__
jpayne@69: 
jpayne@69: /**
jpayne@69:  * \file
jpayne@69:  * \brief C++ API: Interface for writing bytes, and implementation classes.
jpayne@69:  */
jpayne@69: 
jpayne@69: #include "unicode/utypes.h"
jpayne@69: 
jpayne@69: #if U_SHOW_CPLUSPLUS_API
jpayne@69: 
jpayne@69: #include "unicode/uobject.h"
jpayne@69: #include "unicode/std_string.h"
jpayne@69: 
jpayne@69: U_NAMESPACE_BEGIN
jpayne@69: 
jpayne@69: /**
jpayne@69:  * A ByteSink can be filled with bytes.
jpayne@69:  * @stable ICU 4.2
jpayne@69:  */
jpayne@69: class U_COMMON_API ByteSink : public UMemory {
jpayne@69: public:
jpayne@69:   /**
jpayne@69:    * Default constructor.
jpayne@69:    * @stable ICU 4.2
jpayne@69:    */
jpayne@69:   ByteSink() { }
jpayne@69:   /**
jpayne@69:    * Virtual destructor.
jpayne@69:    * @stable ICU 4.2
jpayne@69:    */
jpayne@69:   virtual ~ByteSink();
jpayne@69: 
jpayne@69:   /**
jpayne@69:    * Append "bytes[0,n-1]" to this.
jpayne@69:    * @param bytes the pointer to the bytes
jpayne@69:    * @param n the number of bytes; must be non-negative
jpayne@69:    * @stable ICU 4.2
jpayne@69:    */
jpayne@69:   virtual void Append(const char* bytes, int32_t n) = 0;
jpayne@69: 
jpayne@69: #ifndef U_HIDE_DRAFT_API
jpayne@69:   /**
jpayne@69:    * Appends n bytes to this. Same as Append().
jpayne@69:    * Call AppendU8() with u8"string literals" which are const char * in C++11
jpayne@69:    * but const char8_t * in C++20.
jpayne@69:    * If the compiler does support char8_t as a distinct type,
jpayne@69:    * then an AppendU8() overload for that is defined and will be chosen.
jpayne@69:    *
jpayne@69:    * @param bytes the pointer to the bytes
jpayne@69:    * @param n the number of bytes; must be non-negative
jpayne@69:    * @draft ICU 67
jpayne@69:    */
jpayne@69:   inline void AppendU8(const char* bytes, int32_t n) {
jpayne@69:     Append(bytes, n);
jpayne@69:   }
jpayne@69: 
jpayne@69: #if defined(__cpp_char8_t) || defined(U_IN_DOXYGEN)
jpayne@69:   /**
jpayne@69:    * Appends n bytes to this. Same as Append() but for a const char8_t * pointer.
jpayne@69:    * Call AppendU8() with u8"string literals" which are const char * in C++11
jpayne@69:    * but const char8_t * in C++20.
jpayne@69:    * If the compiler does support char8_t as a distinct type,
jpayne@69:    * then this AppendU8() overload for that is defined and will be chosen.
jpayne@69:    *
jpayne@69:    * @param bytes the pointer to the bytes
jpayne@69:    * @param n the number of bytes; must be non-negative
jpayne@69:    * @draft ICU 67
jpayne@69:    */
jpayne@69:   inline void AppendU8(const char8_t* bytes, int32_t n) {
jpayne@69:     Append(reinterpret_cast<const char*>(bytes), n);
jpayne@69:   }
jpayne@69: #endif
jpayne@69: #endif  // U_HIDE_DRAFT_API
jpayne@69: 
jpayne@69:   /**
jpayne@69:    * Returns a writable buffer for appending and writes the buffer's capacity to
jpayne@69:    * *result_capacity. Guarantees *result_capacity>=min_capacity.
jpayne@69:    * May return a pointer to the caller-owned scratch buffer which must have
jpayne@69:    * scratch_capacity>=min_capacity.
jpayne@69:    * The returned buffer is only valid until the next operation
jpayne@69:    * on this ByteSink.
jpayne@69:    *
jpayne@69:    * After writing at most *result_capacity bytes, call Append() with the
jpayne@69:    * pointer returned from this function and the number of bytes written.
jpayne@69:    * Many Append() implementations will avoid copying bytes if this function
jpayne@69:    * returned an internal buffer.
jpayne@69:    *
jpayne@69:    * Partial usage example:
jpayne@69:    *  int32_t capacity;
jpayne@69:    *  char* buffer = sink->GetAppendBuffer(..., &capacity);
jpayne@69:    *  ... Write n bytes into buffer, with n <= capacity.
jpayne@69:    *  sink->Append(buffer, n);
jpayne@69:    * In many implementations, that call to Append will avoid copying bytes.
jpayne@69:    *
jpayne@69:    * If the ByteSink allocates or reallocates an internal buffer, it should use
jpayne@69:    * the desired_capacity_hint if appropriate.
jpayne@69:    * If a caller cannot provide a reasonable guess at the desired capacity,
jpayne@69:    * it should pass desired_capacity_hint=0.
jpayne@69:    *
jpayne@69:    * If a non-scratch buffer is returned, the caller may only pass
jpayne@69:    * a prefix to it to Append().
jpayne@69:    * That is, it is not correct to pass an interior pointer to Append().
jpayne@69:    *
jpayne@69:    * The default implementation always returns the scratch buffer.
jpayne@69:    *
jpayne@69:    * @param min_capacity required minimum capacity of the returned buffer;
jpayne@69:    *                     must be non-negative
jpayne@69:    * @param desired_capacity_hint desired capacity of the returned buffer;
jpayne@69:    *                              must be non-negative
jpayne@69:    * @param scratch default caller-owned buffer
jpayne@69:    * @param scratch_capacity capacity of the scratch buffer
jpayne@69:    * @param result_capacity pointer to an integer which will be set to the
jpayne@69:    *                        capacity of the returned buffer
jpayne@69:    * @return a buffer with *result_capacity>=min_capacity
jpayne@69:    * @stable ICU 4.2
jpayne@69:    */
jpayne@69:   virtual char* GetAppendBuffer(int32_t min_capacity,
jpayne@69:                                 int32_t desired_capacity_hint,
jpayne@69:                                 char* scratch, int32_t scratch_capacity,
jpayne@69:                                 int32_t* result_capacity);
jpayne@69: 
jpayne@69:   /**
jpayne@69:    * Flush internal buffers.
jpayne@69:    * Some byte sinks use internal buffers or provide buffering
jpayne@69:    * and require calling Flush() at the end of the stream.
jpayne@69:    * The ByteSink should be ready for further Append() calls after Flush().
jpayne@69:    * The default implementation of Flush() does nothing.
jpayne@69:    * @stable ICU 4.2
jpayne@69:    */
jpayne@69:   virtual void Flush();
jpayne@69: 
jpayne@69: private:
jpayne@69:   ByteSink(const ByteSink &) = delete;
jpayne@69:   ByteSink &operator=(const ByteSink &) = delete;
jpayne@69: };
jpayne@69: 
jpayne@69: // -------------------------------------------------------------
jpayne@69: // Some standard implementations
jpayne@69: 
jpayne@69: /** 
jpayne@69:  * Implementation of ByteSink that writes to a flat byte array,
jpayne@69:  * with bounds-checking:
jpayne@69:  * This sink will not write more than capacity bytes to outbuf.
jpayne@69:  * If more than capacity bytes are Append()ed, then excess bytes are ignored,
jpayne@69:  * and Overflowed() will return true.
jpayne@69:  * Overflow does not cause a runtime error.
jpayne@69:  * @stable ICU 4.2
jpayne@69:  */
jpayne@69: class U_COMMON_API CheckedArrayByteSink : public ByteSink {
jpayne@69: public:
jpayne@69:   /**
jpayne@69:    * Constructs a ByteSink that will write to outbuf[0..capacity-1].
jpayne@69:    * @param outbuf buffer to write to
jpayne@69:    * @param capacity size of the buffer
jpayne@69:    * @stable ICU 4.2
jpayne@69:    */
jpayne@69:   CheckedArrayByteSink(char* outbuf, int32_t capacity);
jpayne@69:   /**
jpayne@69:    * Destructor.
jpayne@69:    * @stable ICU 4.2
jpayne@69:    */
jpayne@69:   virtual ~CheckedArrayByteSink();
jpayne@69:   /**
jpayne@69:    * Returns the sink to its original state, without modifying the buffer.
jpayne@69:    * Useful for reusing both the buffer and the sink for multiple streams.
jpayne@69:    * Resets the state to NumberOfBytesWritten()=NumberOfBytesAppended()=0
jpayne@69:    * and Overflowed()=FALSE.
jpayne@69:    * @return *this
jpayne@69:    * @stable ICU 4.6
jpayne@69:    */
jpayne@69:   virtual CheckedArrayByteSink& Reset();
jpayne@69:   /**
jpayne@69:    * Append "bytes[0,n-1]" to this.
jpayne@69:    * @param bytes the pointer to the bytes
jpayne@69:    * @param n the number of bytes; must be non-negative
jpayne@69:    * @stable ICU 4.2
jpayne@69:    */
jpayne@69:   virtual void Append(const char* bytes, int32_t n);
jpayne@69:   /**
jpayne@69:    * Returns a writable buffer for appending and writes the buffer's capacity to
jpayne@69:    * *result_capacity. For details see the base class documentation.
jpayne@69:    * @param min_capacity required minimum capacity of the returned buffer;
jpayne@69:    *                     must be non-negative
jpayne@69:    * @param desired_capacity_hint desired capacity of the returned buffer;
jpayne@69:    *                              must be non-negative
jpayne@69:    * @param scratch default caller-owned buffer
jpayne@69:    * @param scratch_capacity capacity of the scratch buffer
jpayne@69:    * @param result_capacity pointer to an integer which will be set to the
jpayne@69:    *                        capacity of the returned buffer
jpayne@69:    * @return a buffer with *result_capacity>=min_capacity
jpayne@69:    * @stable ICU 4.2
jpayne@69:    */
jpayne@69:   virtual char* GetAppendBuffer(int32_t min_capacity,
jpayne@69:                                 int32_t desired_capacity_hint,
jpayne@69:                                 char* scratch, int32_t scratch_capacity,
jpayne@69:                                 int32_t* result_capacity);
jpayne@69:   /**
jpayne@69:    * Returns the number of bytes actually written to the sink.
jpayne@69:    * @return number of bytes written to the buffer
jpayne@69:    * @stable ICU 4.2
jpayne@69:    */
jpayne@69:   int32_t NumberOfBytesWritten() const { return size_; }
jpayne@69:   /**
jpayne@69:    * Returns true if any bytes were discarded, i.e., if there was an
jpayne@69:    * attempt to write more than 'capacity' bytes.
jpayne@69:    * @return TRUE if more than 'capacity' bytes were Append()ed
jpayne@69:    * @stable ICU 4.2
jpayne@69:    */
jpayne@69:   UBool Overflowed() const { return overflowed_; }
jpayne@69:   /**
jpayne@69:    * Returns the number of bytes appended to the sink.
jpayne@69:    * If Overflowed() then NumberOfBytesAppended()>NumberOfBytesWritten()
jpayne@69:    * else they return the same number.
jpayne@69:    * @return number of bytes written to the buffer
jpayne@69:    * @stable ICU 4.6
jpayne@69:    */
jpayne@69:   int32_t NumberOfBytesAppended() const { return appended_; }
jpayne@69: private:
jpayne@69:   char* outbuf_;
jpayne@69:   const int32_t capacity_;
jpayne@69:   int32_t size_;
jpayne@69:   int32_t appended_;
jpayne@69:   UBool overflowed_;
jpayne@69: 
jpayne@69:   CheckedArrayByteSink() = delete;
jpayne@69:   CheckedArrayByteSink(const CheckedArrayByteSink &) = delete;
jpayne@69:   CheckedArrayByteSink &operator=(const CheckedArrayByteSink &) = delete;
jpayne@69: };
jpayne@69: 
jpayne@69: /** 
jpayne@69:  * Implementation of ByteSink that writes to a "string".
jpayne@69:  * The StringClass is usually instantiated with a std::string.
jpayne@69:  * @stable ICU 4.2
jpayne@69:  */
jpayne@69: template<typename StringClass>
jpayne@69: class StringByteSink : public ByteSink {
jpayne@69:  public:
jpayne@69:   /**
jpayne@69:    * Constructs a ByteSink that will append bytes to the dest string.
jpayne@69:    * @param dest pointer to string object to append to
jpayne@69:    * @stable ICU 4.2
jpayne@69:    */
jpayne@69:   StringByteSink(StringClass* dest) : dest_(dest) { }
jpayne@69:   /**
jpayne@69:    * Constructs a ByteSink that reserves append capacity and will append bytes to the dest string.
jpayne@69:    * 
jpayne@69:    * @param dest pointer to string object to append to
jpayne@69:    * @param initialAppendCapacity capacity beyond dest->length() to be reserve()d
jpayne@69:    * @stable ICU 60
jpayne@69:    */
jpayne@69:   StringByteSink(StringClass* dest, int32_t initialAppendCapacity) : dest_(dest) {
jpayne@69:     if (initialAppendCapacity > 0 &&
jpayne@69:         (uint32_t)initialAppendCapacity > (dest->capacity() - dest->length())) {
jpayne@69:       dest->reserve(dest->length() + initialAppendCapacity);
jpayne@69:     }
jpayne@69:   }
jpayne@69:   /**
jpayne@69:    * Append "bytes[0,n-1]" to this.
jpayne@69:    * @param data the pointer to the bytes
jpayne@69:    * @param n the number of bytes; must be non-negative
jpayne@69:    * @stable ICU 4.2
jpayne@69:    */
jpayne@69:   virtual void Append(const char* data, int32_t n) { dest_->append(data, n); }
jpayne@69:  private:
jpayne@69:   StringClass* dest_;
jpayne@69: 
jpayne@69:   StringByteSink() = delete;
jpayne@69:   StringByteSink(const StringByteSink &) = delete;
jpayne@69:   StringByteSink &operator=(const StringByteSink &) = delete;
jpayne@69: };
jpayne@69: 
jpayne@69: U_NAMESPACE_END
jpayne@69: 
jpayne@69: #endif /* U_SHOW_CPLUSPLUS_API */
jpayne@69: 
jpayne@69: #endif  // __BYTESTREAM_H__