The Tor Browser: comparison intl/icu/source/common/unicode/bytestream.h

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+// 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 &); // 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);
+/**
+* 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(); ///< 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__

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intl/icu/source/common/unicode/bytestream.h