Input.cpp

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Author : Olli Etuaho
Date : 2015-08-14 14:16:19
Hash : 26e355b8
Message : Add full support for line continuation in the preprocessor Re-landing earlier change with constant signedness fixed (was causing build issues on Linux). Line continuation in ESSL 3.00 needs to be processed before tokenization, since tokens can span the line continuation. On the other hand, ANGLE's tokenizer keeps track of line numbers, and whenever a line continuation appears the line number still needs to be incremented by one, just like on a regular newline. That's why line continuation is now implemented as follows: when the shader strings are concatenated in Input, they are also checked for line continuation. Whenever line continuation is encountered, the string is cut before that point. When the tokenizer asks for more input, the string starting from the character after line continuation is passed to it, and the line number is incremented from Input. This way the tokenizer can parse tokens that span multiple lines - it never sees the line continuation - but still keeps track of the line number correctly. Relevant spec is in ESSL 3.00 section 3.2 "Source strings". Support for line continuation also applies to ESSL 1.00. ESSL 3.00 spec section 1.5 says that line continuation support is mandated when an ESSL 1.00 shader is used with the OpenGL ES 3.0 API, and is optional when ESSL 1.00 is used with the OpenGL ES 2.0 API. TEST=dEQP-GLES3.functional.shaders.preprocessor.line_continuation.* (all pass), angle_unittests BUG=angleproject:1125 Change-Id: Ic086aacac53cd75bf93c0fda782416501d2f842b Reviewed-on: https://chromium-review.googlesource.com/294200 Reviewed-by: Jamie Madill <jmadill@chromium.org> Tested-by: Olli Etuaho <oetuaho@nvidia.com>

src/compiler/preprocessor/Input.cpp

//
// Copyright (c) 2011 The ANGLE Project Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//

#include "Input.h"

#include <algorithm>
#include <cassert>
#include <cstring>

namespace pp
{

Input::Input() : mCount(0), mString(0)
{
}

Input::Input(size_t count, const char *const string[], const int length[]) :
    mCount(count),
    mString(string)
{
    mLength.reserve(mCount);
    for (size_t i = 0; i < mCount; ++i)
    {
        int len = length ? length[i] : -1;
        mLength.push_back(len < 0 ? std::strlen(mString[i]) : len);
    }
}

const char *Input::skipChar()
{
    // This function should only be called when there is a character to skip.
    assert(mReadLoc.cIndex < mLength[mReadLoc.sIndex]);
    ++mReadLoc.cIndex;
    if (mReadLoc.cIndex == mLength[mReadLoc.sIndex])
    {
        ++mReadLoc.sIndex;
        mReadLoc.cIndex = 0;
    }
    if (mReadLoc.sIndex >= mCount)
    {
        return nullptr;
    }
    return mString[mReadLoc.sIndex] + mReadLoc.cIndex;
}

size_t Input::read(char *buf, size_t maxSize, int *lineNo)
{
    size_t nRead = 0;
    // The previous call to read might have stopped copying the string when encountering a line
    // continuation. Check for this possibility first.
    if (mReadLoc.sIndex < mCount && maxSize > 0)
    {
        const char *c = mString[mReadLoc.sIndex] + mReadLoc.cIndex;
        if ((*c) == '\\')
        {
            c = skipChar();
            if (c != nullptr && (*c) == '\n')
            {
                // Line continuation of backslash + newline.
                skipChar();
                ++(*lineNo);
            }
            else if (c != nullptr && (*c) == '\r')
            {
                // Line continuation. Could be backslash + '\r\n' or just backslash + '\r'.
                c = skipChar();
                if (c != nullptr && (*c) == '\n')
                {
                    skipChar();
                }
                ++(*lineNo);
            }
            else
            {
                // Not line continuation, so write the skipped backslash to buf.
                *buf = '\\';
                ++nRead;
            }
        }
    }

    size_t maxRead = maxSize;
    while ((nRead < maxRead) && (mReadLoc.sIndex < mCount))
    {
        size_t size = mLength[mReadLoc.sIndex] - mReadLoc.cIndex;
        size = std::min(size, maxSize);
        for (size_t i = 0; i < size; ++i)
        {
            // Stop if a possible line continuation is encountered.
            // It will be processed on the next call on input, which skips it
            // and increments line number if necessary.
            if (*(mString[mReadLoc.sIndex] + mReadLoc.cIndex + i) == '\\')
            {
                size = i;
                maxRead = nRead + size;  // Stop reading right before the backslash.
            }
        }
        std::memcpy(buf + nRead, mString[mReadLoc.sIndex] + mReadLoc.cIndex, size);
        nRead += size;
        mReadLoc.cIndex += size;

        // Advance string if we reached the end of current string.
        if (mReadLoc.cIndex == mLength[mReadLoc.sIndex])
        {
            ++mReadLoc.sIndex;
            mReadLoc.cIndex = 0;
        }
    }
    return nRead;
}

}  // namespace pp

kc3-lang/angle/src/compiler/preprocessor/Input.cpp

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kc3-lang/angle /src/compiler/preprocessor/Input.cpp