Rewritten UTFDecoder into a function.
This commit is contained in:
Ferdinand Majerech
parent
b060699950
commit
0a625ec7a7
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@ -75,8 +75,9 @@ final class Reader
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uint line_;
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// Current column in file.
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uint column_;
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// Decoder reading data from file and decoding it to UTF-32.
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UTFFastDecoder decoder_;
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// Original Unicode encoding of the data.
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Encoding encoding_;
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version(unittest)
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{
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@ -95,26 +96,26 @@ final class Reader
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this(Stream stream) @trusted //!nothrow
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{
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auto streamBytes = streamToBytesGC(stream);
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auto result = fixUTFByteOrder(streamBytes);
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if(result.bytesStripped > 0)
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auto endianResult = fixUTFByteOrder(streamBytes);
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if(endianResult.bytesStripped > 0)
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{
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throw new ReaderException("Size of UTF-16 or UTF-32 input not aligned "
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"to 2 or 4 bytes, respectively");
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}
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version(unittest) { endian_ = result.endian; }
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decoder_ = UTFFastDecoder(result.array, result.encoding);
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decoder_.decodeAll();
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const msg = decoder_.getAndClearErrorMessage();
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version(unittest) { endian_ = endianResult.endian; }
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encoding_ = endianResult.encoding;
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auto decodeResult = decodeUTF(endianResult.array, endianResult.encoding);
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const msg = decodeResult.errorMessage;
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if(msg !is null)
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{
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throw new ReaderException("UTF decoding error: " ~ msg);
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}
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buffer_ = decoder_.decoded;
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// The part of buffer excluding trailing zeroes.
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buffer_ = decodeResult.decoded;
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// The part of buffer_ excluding trailing zeroes.
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auto noZeros = buffer_;
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while(!noZeros.empty && noZeros.back == '\0') { noZeros.popBack(); }
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enforce(printable(noZeros[]),
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@ -238,191 +239,122 @@ final class Reader
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final size_t charIndex() @safe pure nothrow const @nogc { return charIndex_; }
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/// Get encoding of the input buffer.
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final Encoding encoding() @safe pure nothrow const @nogc { return decoder_.encoding; }
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final Encoding encoding() @safe pure nothrow const @nogc { return encoding_; }
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}
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private:
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alias UTFDecoder UTFFastDecoder;
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struct UTFDecoder
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// Decode an UTF-8/16/32 buffer to UTF-32 (for UTF-32 this does nothing).
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//
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// Params:
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//
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// input = The UTF-8/16/32 buffer to decode.
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// encoding = Encoding of input.
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//
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// Returns:
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//
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// A struct with the following members:
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//
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// $(D string errorMessage) In case of a decoding error, the error message is stored
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// here. If there was no error, errorMessage is NULL. Always
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// check this first before using the other members.
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// $(D dchar[] decoded) A GC-allocated buffer with decoded UTF-32 characters.
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// $(D size_t maxChars) XXX reserved for future
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auto decodeUTF(ubyte[] input, UTFEncoding encoding) @safe pure nothrow
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{
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private:
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// UTF-8 codepoint strides (0xFF are codepoints that can't start a sequence).
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static immutable ubyte[256] utf8Stride =
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[
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1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
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1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
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1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
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1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
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1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
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1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
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1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
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1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
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0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
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0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
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0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
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0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
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2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
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2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
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3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,
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4,4,4,4,4,4,4,4,5,5,5,5,6,6,0xFF,0xFF,
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];
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// Documented in function ddoc.
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struct Result
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{
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string errorMessage;
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// Encoding of the input buffer.
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UTFEncoding encoding_;
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// Maximum number of characters that might be in the buffer.
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size_t maxChars_;
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// Part of the input buffer that has not yet been decoded.
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ubyte[] input_;
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dchar[] decoded;
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}
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// Decoded (UTF-32) version of the entire input_. If input is UTF-32, this is
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// just a reference to input_.
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dchar[] decoded_;
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Result result;
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// Current error message.
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//
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// To be fully nothrow, we use return values and the user (Reader) can check
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// for a detailed error message if they get an error return.
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string errorMessage_;
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final switch(encoding)
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{
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case UTFEncoding.UTF_8: result.maxChars = input.length; break;
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case UTFEncoding.UTF_16: result.maxChars = input.length / 2; break;
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case UTFEncoding.UTF_32: result.maxChars = input.length / 2; break;
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}
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public:
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/// Construct a UTFBlockDecoder decoding data from a buffer.
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this(ubyte[] buffer, UTFEncoding encoding) @safe pure nothrow @nogc
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// Decode input_ if it's encoded as UTF-8 or UTF-16.
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//
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// Params:
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//
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// buffer = The input buffer to decode.
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// result = A Result struct to put decoded result and any error messages to.
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//
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// On error, result.errorMessage will be set.
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static void decode(C)(C[] input, ref Result result) @safe pure nothrow
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{
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// End of part of input that contains complete characters that can be decoded.
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const size_t end = endOfLastUTFSequence(input);
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// If end is 0, there are no full chars.
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// This can happen at the end of file if there is an incomplete UTF sequence.
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if(end < input.length)
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{
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input_ = buffer;
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encoding_ = encoding;
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final switch(encoding_)
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{
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case UTFEncoding.UTF_8: maxChars_ = input_.length; break;
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case UTFEncoding.UTF_16: maxChars_ = input_.length / 2; break;
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case UTFEncoding.UTF_32: maxChars_ = input_.length / 2; break;
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}
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result.errorMessage = "Invalid UTF character at the end of input";
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return;
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}
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/// Decode all data passed to the constructor.
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///
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/// On error, getAndClearErrorMessage() will return a non-null string.
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void decodeAll() @safe pure nothrow
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const srclength = input.length;
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try for(size_t srcpos = 0; srcpos < srclength;)
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{
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assert(decoded_ is null, "Calling decodeAll more than once");
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final switch(encoding_)
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const c = input[srcpos];
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if(c < 0x80)
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{
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case UTFEncoding.UTF_8: decode(cast(char[])input_); break;
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case UTFEncoding.UTF_16:
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assert(input_.length % 2 == 0, "UTF-16 buffer size must be even");
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decode(cast(wchar[])input_);
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break;
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case UTFEncoding.UTF_32:
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assert(input_.length % 4 == 0,
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"UTF-32 buffer size must be a multiple of 4");
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// No need to decode anything
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decoded_ = cast(dchar[])input_;
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break;
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result.decoded ~= c;
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++srcpos;
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}
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// XXX This is risky. We rely on the assumption that the scanner only uses
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// peek() to detect the end of the buffer. Should this cause any bugs,
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// revert.
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//
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// The buffer must be zero terminated for scanner to detect its end.
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// if(decoded_.empty || decoded_.back() != '\0')
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// {
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// decoded_ ~= cast(dchar)'\0';
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// }
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}
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/// Get encoding we're decoding from.
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UTFEncoding encoding() const pure @safe nothrow @nogc { return encoding_; }
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/// Get all decoded characters.
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const(dchar[]) decoded() @safe pure nothrow @nogc { return decoded_; }
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/// Get the error message and clear it.
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string getAndClearErrorMessage() @safe pure nothrow @nogc
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{
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const result = errorMessage_;
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errorMessage_ = null;
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return result;
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}
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private:
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// Decode input_ if it's encoded as UTF-8 or UTF-16.
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//
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// On error, errorMessage_ will be set.
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void decode(C)(C[] buffer) @safe pure nothrow
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{
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// End of part of buffer that contains complete characters that can be decoded.
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const size_t end = endOfLastUTFSequence(buffer);
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// If end is 0, there are no full chars.
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// This can happen at the end of file if there is an incomplete UTF sequence.
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if(end < buffer.length)
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else
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{
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errorMessage_ = "Invalid UTF character at the end of buffer";
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return;
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}
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const srclength = buffer.length;
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try for(size_t srcpos = 0; srcpos < srclength;)
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{
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const c = buffer[srcpos];
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if(c < 0x80)
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{
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decoded_ ~= c;
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++srcpos;
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}
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else
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{
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decoded_ ~= std.utf.decode(buffer, srcpos);
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}
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}
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catch(UTFException e)
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{
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errorMessage_ = e.msg;
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return;
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}
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catch(Exception e)
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{
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assert(false, "Unexpected exception in decode(): " ~ e.msg);
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result.decoded ~= std.utf.decode(input, srcpos);
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}
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}
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// Determine the end of last UTF-8 or UTF-16 sequence in a raw buffer.
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size_t endOfLastUTFSequence(C)(const C[] buffer)
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@safe pure nothrow const @nogc
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catch(UTFException e)
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{
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static if(is(C == char))
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{
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for(long end = buffer.length - 1; end >= 0; --end)
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{
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const stride = utf8Stride[buffer[cast(size_t)end]];
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if(stride != 0xFF)
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{
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// If stride goes beyond end of the buffer, return end.
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// Otherwise the last sequence ends at buffer.length, so we can
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// return that. (Unless there is an invalid code point, which is
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// caught at decoding)
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return (stride > buffer.length - end) ? cast(size_t)end : buffer.length;
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}
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}
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return 0;
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}
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else static if(is(C == wchar))
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{
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// TODO this is O(N), which is slow. Find out if we can somehow go
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// from the end backwards with UTF-16.
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size_t end = 0;
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while(end < buffer.length)
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{
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const s = stride(buffer, end);
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if(s + end > buffer.length) { break; }
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end += s;
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}
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return end;
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}
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result.errorMessage = e.msg;
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return;
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}
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catch(Exception e)
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{
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assert(false, "Unexpected exception in decode(): " ~ e.msg);
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}
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}
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final switch(encoding)
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{
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case UTFEncoding.UTF_8: decode(cast(char[])input, result); break;
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case UTFEncoding.UTF_16:
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assert(input.length % 2 == 0, "UTF-16 buffer size must be even");
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decode(cast(wchar[])input, result);
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break;
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case UTFEncoding.UTF_32:
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assert(input.length % 4 == 0,
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"UTF-32 buffer size must be a multiple of 4");
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// No need to decode anything
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result.decoded = cast(dchar[])input;
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break;
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}
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if(result.errorMessage !is null) { return result; }
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// XXX This is risky. We rely on the assumption that the scanner only uses
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// peek() to detect the end of the buffer. Should this cause any bugs,
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// revert.
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//
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// The buffer must be zero terminated for scanner to detect its end.
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// if(result.decoded.empty || result.decoded.back() != '\0')
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// {
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// result.decoded ~= cast(dchar)'\0';
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// }
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return result;
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}
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/// Determine if all characters in an array are printable.
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///
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/// Params: chars = Characters to check.
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@ -443,6 +375,62 @@ bool printable(const dchar[] chars) @safe pure nothrow @nogc
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return true;
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}
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// Determine the end of last UTF-8 or UTF-16 sequence in a raw buffer.
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size_t endOfLastUTFSequence(C)(const C[] buffer)
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@safe pure nothrow @nogc
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{
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// UTF-8 codepoint strides (0xFF are codepoints that can't start a sequence).
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static immutable ubyte[256] utf8Stride =
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[
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1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
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1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
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1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
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1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
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1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
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1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
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1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
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1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
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0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
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0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
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0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
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0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
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2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
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2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
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3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,
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4,4,4,4,4,4,4,4,5,5,5,5,6,6,0xFF,0xFF,
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];
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static if(is(C == char))
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{
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for(long end = buffer.length - 1; end >= 0; --end)
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{
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const stride = utf8Stride[buffer[cast(size_t)end]];
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if(stride != 0xFF)
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{
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// If stride goes beyond end of the buffer, return end.
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// Otherwise the last sequence ends at buffer.length, so we can
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// return that. (Unless there is an invalid code point, which is
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// caught at decoding)
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return (stride > buffer.length - end) ? cast(size_t)end : buffer.length;
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}
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}
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return 0;
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}
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else static if(is(C == wchar))
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{
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// TODO this is O(N), which is slow. Find out if we can somehow go
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// from the end backwards with UTF-16.
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size_t end = 0;
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while(end < buffer.length)
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{
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const s = stride(buffer, end);
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if(s + end > buffer.length) { break; }
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end += s;
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}
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return end;
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}
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}
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// Unittests.
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import std.stream;
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