ImmutableStringBuilder.h

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//

// Copyright 2018 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.

//

// ImmutableStringBuilder.h: Stringstream-like utility for building pool allocated strings where the

// maximum length is known in advance.

//

#ifndef COMPILER_TRANSLATOR_IMMUTABLESTRINGBUILDER_H_

#define COMPILER_TRANSLATOR_IMMUTABLESTRINGBUILDER_H_

#include "compiler/translator/ImmutableString.h"

namespace sh

class ImmutableStringBuilder

  public:

    ImmutableStringBuilder(size_t maxLength)

        : mPos(0u), mMaxLength(maxLength), mData(AllocateEmptyPoolCharArray(maxLength))

{}

    ImmutableStringBuilder &operator<<(const ImmutableString &str);

    ImmutableStringBuilder &operator<<(const char *str);

    ImmutableStringBuilder &operator<<(const char &c);

    // This invalidates the ImmutableStringBuilder, so it should only be called once.

    operator ImmutableString();

    void appendDecimal(const uint32_t &i);

    template <typename T>

    void appendHex(T number)

        ASSERT(mData != nullptr);

        ASSERT(mPos + sizeof(T) * 2u <= mMaxLength);

        int index = static_cast<int>(sizeof(T)) * 2 - 1;

        // Loop through leading zeroes.

        while (((number >> (index * 4)) & 0xfu) == 0 && index > 0)

            --index;

        // Write the rest of the hex digits.

        while (index >= 0)

            char digit     = static_cast<char>((number >> (index * 4)) & 0xfu);

            char digitChar = (digit < 10) ? (digit + '0') : (digit + ('a' - 10));

            mData[mPos++]  = digitChar;

            --index;

    template <typename T>

    static constexpr size_t GetHexCharCount()

        return sizeof(T) * 2;

  private:

    inline static char *AllocateEmptyPoolCharArray(size_t strLength)

        size_t requiredSize = strLength + 1u;

        return static_cast<char *>(GetGlobalPoolAllocator()->allocate(requiredSize));

    size_t mPos;

    size_t mMaxLength;

    char *mData;

};

// GLSL ES 3.00.6 section 3.9: the maximum length of an identifier is 1024 characters.

constexpr unsigned int kESSLMaxIdentifierLength = 1024u;

}  // namespace sh

#endif  // COMPILER_TRANSLATOR_IMMUTABLESTRINGBUILDER_H_