1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/intl/icu/source/common/unicode/bytestream.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,257 @@
1.4 +// Copyright (C) 2009-2012, International Business Machines
1.5 +// Corporation and others. All Rights Reserved.
1.6 +//
1.7 +// Copyright 2007 Google Inc. All Rights Reserved.
1.8 +// Author: sanjay@google.com (Sanjay Ghemawat)
1.9 +//
1.10 +// Abstract interface that consumes a sequence of bytes (ByteSink).
1.11 +//
1.12 +// Used so that we can write a single piece of code that can operate
1.13 +// on a variety of output string types.
1.14 +//
1.15 +// Various implementations of this interface are provided:
1.16 +// ByteSink:
1.17 +// CheckedArrayByteSink Write to a flat array, with bounds checking
1.18 +// StringByteSink Write to an STL string
1.19 +
1.20 +// This code is a contribution of Google code, and the style used here is
1.21 +// a compromise between the original Google code and the ICU coding guidelines.
1.22 +// For example, data types are ICU-ified (size_t,int->int32_t),
1.23 +// and API comments doxygen-ified, but function names and behavior are
1.24 +// as in the original, if possible.
1.25 +// Assertion-style error handling, not available in ICU, was changed to
1.26 +// parameter "pinning" similar to UnicodeString.
1.27 +//
1.28 +// In addition, this is only a partial port of the original Google code,
1.29 +// limited to what was needed so far. The (nearly) complete original code
1.30 +// is in the ICU svn repository at icuhtml/trunk/design/strings/contrib
1.31 +// (see ICU ticket 6765, r25517).
1.32 +
1.33 +#ifndef __BYTESTREAM_H__
1.34 +#define __BYTESTREAM_H__
1.35 +
1.36 +/**
1.37 + * \file
1.38 + * \brief C++ API: Interface for writing bytes, and implementation classes.
1.39 + */
1.40 +
1.41 +#include "unicode/utypes.h"
1.42 +#include "unicode/uobject.h"
1.43 +#include "unicode/std_string.h"
1.44 +
1.45 +U_NAMESPACE_BEGIN
1.46 +
1.47 +/**
1.48 + * A ByteSink can be filled with bytes.
1.49 + * @stable ICU 4.2
1.50 + */
1.51 +class U_COMMON_API ByteSink : public UMemory {
1.52 +public:
1.53 + /**
1.54 + * Default constructor.
1.55 + * @stable ICU 4.2
1.56 + */
1.57 + ByteSink() { }
1.58 + /**
1.59 + * Virtual destructor.
1.60 + * @stable ICU 4.2
1.61 + */
1.62 + virtual ~ByteSink();
1.63 +
1.64 + /**
1.65 + * Append "bytes[0,n-1]" to this.
1.66 + * @param bytes the pointer to the bytes
1.67 + * @param n the number of bytes; must be non-negative
1.68 + * @stable ICU 4.2
1.69 + */
1.70 + virtual void Append(const char* bytes, int32_t n) = 0;
1.71 +
1.72 + /**
1.73 + * Returns a writable buffer for appending and writes the buffer's capacity to
1.74 + * *result_capacity. Guarantees *result_capacity>=min_capacity.
1.75 + * May return a pointer to the caller-owned scratch buffer which must have
1.76 + * scratch_capacity>=min_capacity.
1.77 + * The returned buffer is only valid until the next operation
1.78 + * on this ByteSink.
1.79 + *
1.80 + * After writing at most *result_capacity bytes, call Append() with the
1.81 + * pointer returned from this function and the number of bytes written.
1.82 + * Many Append() implementations will avoid copying bytes if this function
1.83 + * returned an internal buffer.
1.84 + *
1.85 + * Partial usage example:
1.86 + * int32_t capacity;
1.87 + * char* buffer = sink->GetAppendBuffer(..., &capacity);
1.88 + * ... Write n bytes into buffer, with n <= capacity.
1.89 + * sink->Append(buffer, n);
1.90 + * In many implementations, that call to Append will avoid copying bytes.
1.91 + *
1.92 + * If the ByteSink allocates or reallocates an internal buffer, it should use
1.93 + * the desired_capacity_hint if appropriate.
1.94 + * If a caller cannot provide a reasonable guess at the desired capacity,
1.95 + * it should pass desired_capacity_hint=0.
1.96 + *
1.97 + * If a non-scratch buffer is returned, the caller may only pass
1.98 + * a prefix to it to Append().
1.99 + * That is, it is not correct to pass an interior pointer to Append().
1.100 + *
1.101 + * The default implementation always returns the scratch buffer.
1.102 + *
1.103 + * @param min_capacity required minimum capacity of the returned buffer;
1.104 + * must be non-negative
1.105 + * @param desired_capacity_hint desired capacity of the returned buffer;
1.106 + * must be non-negative
1.107 + * @param scratch default caller-owned buffer
1.108 + * @param scratch_capacity capacity of the scratch buffer
1.109 + * @param result_capacity pointer to an integer which will be set to the
1.110 + * capacity of the returned buffer
1.111 + * @return a buffer with *result_capacity>=min_capacity
1.112 + * @stable ICU 4.2
1.113 + */
1.114 + virtual char* GetAppendBuffer(int32_t min_capacity,
1.115 + int32_t desired_capacity_hint,
1.116 + char* scratch, int32_t scratch_capacity,
1.117 + int32_t* result_capacity);
1.118 +
1.119 + /**
1.120 + * Flush internal buffers.
1.121 + * Some byte sinks use internal buffers or provide buffering
1.122 + * and require calling Flush() at the end of the stream.
1.123 + * The ByteSink should be ready for further Append() calls after Flush().
1.124 + * The default implementation of Flush() does nothing.
1.125 + * @stable ICU 4.2
1.126 + */
1.127 + virtual void Flush();
1.128 +
1.129 +private:
1.130 + ByteSink(const ByteSink &); // copy constructor not implemented
1.131 + ByteSink &operator=(const ByteSink &); // assignment operator not implemented
1.132 +};
1.133 +
1.134 +// -------------------------------------------------------------
1.135 +// Some standard implementations
1.136 +
1.137 +/**
1.138 + * Implementation of ByteSink that writes to a flat byte array,
1.139 + * with bounds-checking:
1.140 + * This sink will not write more than capacity bytes to outbuf.
1.141 + * If more than capacity bytes are Append()ed, then excess bytes are ignored,
1.142 + * and Overflowed() will return true.
1.143 + * Overflow does not cause a runtime error.
1.144 + * @stable ICU 4.2
1.145 + */
1.146 +class U_COMMON_API CheckedArrayByteSink : public ByteSink {
1.147 +public:
1.148 + /**
1.149 + * Constructs a ByteSink that will write to outbuf[0..capacity-1].
1.150 + * @param outbuf buffer to write to
1.151 + * @param capacity size of the buffer
1.152 + * @stable ICU 4.2
1.153 + */
1.154 + CheckedArrayByteSink(char* outbuf, int32_t capacity);
1.155 + /**
1.156 + * Destructor.
1.157 + * @stable ICU 4.2
1.158 + */
1.159 + virtual ~CheckedArrayByteSink();
1.160 + /**
1.161 + * Returns the sink to its original state, without modifying the buffer.
1.162 + * Useful for reusing both the buffer and the sink for multiple streams.
1.163 + * Resets the state to NumberOfBytesWritten()=NumberOfBytesAppended()=0
1.164 + * and Overflowed()=FALSE.
1.165 + * @return *this
1.166 + * @stable ICU 4.6
1.167 + */
1.168 + virtual CheckedArrayByteSink& Reset();
1.169 + /**
1.170 + * Append "bytes[0,n-1]" to this.
1.171 + * @param bytes the pointer to the bytes
1.172 + * @param n the number of bytes; must be non-negative
1.173 + * @stable ICU 4.2
1.174 + */
1.175 + virtual void Append(const char* bytes, int32_t n);
1.176 + /**
1.177 + * Returns a writable buffer for appending and writes the buffer's capacity to
1.178 + * *result_capacity. For details see the base class documentation.
1.179 + * @param min_capacity required minimum capacity of the returned buffer;
1.180 + * must be non-negative
1.181 + * @param desired_capacity_hint desired capacity of the returned buffer;
1.182 + * must be non-negative
1.183 + * @param scratch default caller-owned buffer
1.184 + * @param scratch_capacity capacity of the scratch buffer
1.185 + * @param result_capacity pointer to an integer which will be set to the
1.186 + * capacity of the returned buffer
1.187 + * @return a buffer with *result_capacity>=min_capacity
1.188 + * @stable ICU 4.2
1.189 + */
1.190 + virtual char* GetAppendBuffer(int32_t min_capacity,
1.191 + int32_t desired_capacity_hint,
1.192 + char* scratch, int32_t scratch_capacity,
1.193 + int32_t* result_capacity);
1.194 + /**
1.195 + * Returns the number of bytes actually written to the sink.
1.196 + * @return number of bytes written to the buffer
1.197 + * @stable ICU 4.2
1.198 + */
1.199 + int32_t NumberOfBytesWritten() const { return size_; }
1.200 + /**
1.201 + * Returns true if any bytes were discarded, i.e., if there was an
1.202 + * attempt to write more than 'capacity' bytes.
1.203 + * @return TRUE if more than 'capacity' bytes were Append()ed
1.204 + * @stable ICU 4.2
1.205 + */
1.206 + UBool Overflowed() const { return overflowed_; }
1.207 + /**
1.208 + * Returns the number of bytes appended to the sink.
1.209 + * If Overflowed() then NumberOfBytesAppended()>NumberOfBytesWritten()
1.210 + * else they return the same number.
1.211 + * @return number of bytes written to the buffer
1.212 + * @stable ICU 4.6
1.213 + */
1.214 + int32_t NumberOfBytesAppended() const { return appended_; }
1.215 +private:
1.216 + char* outbuf_;
1.217 + const int32_t capacity_;
1.218 + int32_t size_;
1.219 + int32_t appended_;
1.220 + UBool overflowed_;
1.221 + CheckedArrayByteSink(); ///< default constructor not implemented
1.222 + CheckedArrayByteSink(const CheckedArrayByteSink &); ///< copy constructor not implemented
1.223 + CheckedArrayByteSink &operator=(const CheckedArrayByteSink &); ///< assignment operator not implemented
1.224 +};
1.225 +
1.226 +#if U_HAVE_STD_STRING
1.227 +
1.228 +/**
1.229 + * Implementation of ByteSink that writes to a "string".
1.230 + * The StringClass is usually instantiated with a std::string.
1.231 + * @stable ICU 4.2
1.232 + */
1.233 +template<typename StringClass>
1.234 +class StringByteSink : public ByteSink {
1.235 + public:
1.236 + /**
1.237 + * Constructs a ByteSink that will append bytes to the dest string.
1.238 + * @param dest pointer to string object to append to
1.239 + * @stable ICU 4.2
1.240 + */
1.241 + StringByteSink(StringClass* dest) : dest_(dest) { }
1.242 + /**
1.243 + * Append "bytes[0,n-1]" to this.
1.244 + * @param data the pointer to the bytes
1.245 + * @param n the number of bytes; must be non-negative
1.246 + * @stable ICU 4.2
1.247 + */
1.248 + virtual void Append(const char* data, int32_t n) { dest_->append(data, n); }
1.249 + private:
1.250 + StringClass* dest_;
1.251 + StringByteSink(); ///< default constructor not implemented
1.252 + StringByteSink(const StringByteSink &); ///< copy constructor not implemented
1.253 + StringByteSink &operator=(const StringByteSink &); ///< assignment operator not implemented
1.254 +};
1.255 +
1.256 +#endif
1.257 +
1.258 +U_NAMESPACE_END
1.259 +
1.260 +#endif // __BYTESTREAM_H__
