DPF-Plugins/dpf/distrho/extra/String.hpp

/*
 * DISTRHO Plugin Framework (DPF)
 * Copyright (C) 2012-2024 Filipe Coelho <falktx@falktx.com>
 *
 * Permission to use, copy, modify, and/or distribute this software for any purpose with
 * or without fee is hereby granted, provided that the above copyright notice and this
 * permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD
 * TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN
 * NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER
 * IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#ifndef DISTRHO_STRING_HPP_INCLUDED
#define DISTRHO_STRING_HPP_INCLUDED

#include "../DistrhoUtils.hpp"
#include "../extra/ScopedSafeLocale.hpp"

#include <algorithm>

#if __cplusplus >= 201703L
# include <string_view>
#endif

START_NAMESPACE_DISTRHO

// -----------------------------------------------------------------------
// String class

class String
{
public:
    // -------------------------------------------------------------------
    // constructors (no explicit conversions allowed)

    /*
     * Empty string.
     */
    explicit String() noexcept
        : fBuffer(_null()),
          fBufferLen(0),
          fBufferAlloc(false) {}

    /*
     * Simple character.
     */
    explicit String(const char c) noexcept
        : fBuffer(_null()),
          fBufferLen(0),
          fBufferAlloc(false)
    {
        const char ch[2] = { c, '\0' };
        _dup(ch);
    }

    /*
     * Simple char string.
     */
    explicit String(char* const strBuf, const bool reallocData = true) noexcept
        : fBuffer(_null()),
          fBufferLen(0),
          fBufferAlloc(false)
    {
        if (reallocData || strBuf == nullptr)
        {
            _dup(strBuf);
        }
        else
        {
            fBuffer      = strBuf;
            fBufferLen   = std::strlen(strBuf);
            fBufferAlloc = true;
        }
    }

    /*
     * Simple const char string.
     */
    explicit String(const char* const strBuf) noexcept
        : fBuffer(_null()),
          fBufferLen(0),
          fBufferAlloc(false)
    {
        _dup(strBuf);
    }

   #if __cplusplus >= 201703L
    /*
     * std::string_view compatible variant.
     */
    explicit String(const std::string_view& strView) noexcept
        : fBuffer(_null()),
          fBufferLen(0),
          fBufferAlloc(false)
    {
        _dup(strView.data(), strView.size());
    }
   #endif

    /*
     * Integer.
     */
    explicit String(const int value) noexcept
        : fBuffer(_null()),
          fBufferLen(0),
          fBufferAlloc(false)
    {
        char strBuf[0xff+1];
        std::snprintf(strBuf, 0xff, "%d", value);
        strBuf[0xff] = '\0';

        _dup(strBuf);
    }

    /*
     * Unsigned integer, possibly in hexadecimal.
     */
    explicit String(const unsigned int value, const bool hexadecimal = false) noexcept
        : fBuffer(_null()),
          fBufferLen(0),
          fBufferAlloc(false)
    {
        char strBuf[0xff+1];
        std::snprintf(strBuf, 0xff, hexadecimal ? "0x%x" : "%u", value);
        strBuf[0xff] = '\0';

        _dup(strBuf);
    }

    /*
     * Long integer.
     */
    explicit String(const long value) noexcept
        : fBuffer(_null()),
          fBufferLen(0),
          fBufferAlloc(false)
    {
        char strBuf[0xff+1];
        std::snprintf(strBuf, 0xff, "%ld", value);
        strBuf[0xff] = '\0';

        _dup(strBuf);
    }

    /*
     * Long unsigned integer, possibly hexadecimal.
     */
    explicit String(const unsigned long value, const bool hexadecimal = false) noexcept
        : fBuffer(_null()),
          fBufferLen(0),
          fBufferAlloc(false)
    {
        char strBuf[0xff+1];
        std::snprintf(strBuf, 0xff, hexadecimal ? "0x%lx" : "%lu", value);
        strBuf[0xff] = '\0';

        _dup(strBuf);
    }

    /*
     * Long long integer.
     */
    explicit String(const long long value) noexcept
        : fBuffer(_null()),
          fBufferLen(0),
          fBufferAlloc(false)
    {
        char strBuf[0xff+1];
        std::snprintf(strBuf, 0xff, "%lld", value);
        strBuf[0xff] = '\0';

        _dup(strBuf);
    }

    /*
     * Long long unsigned integer, possibly hexadecimal.
     */
    explicit String(const unsigned long long value, const bool hexadecimal = false) noexcept
        : fBuffer(_null()),
          fBufferLen(0),
          fBufferAlloc(false)
    {
        char strBuf[0xff+1];
        std::snprintf(strBuf, 0xff, hexadecimal ? "0x%llx" : "%llu", value);
        strBuf[0xff] = '\0';

        _dup(strBuf);
    }

    /*
     * Single-precision floating point number.
     */
    explicit String(const float value) noexcept
        : fBuffer(_null()),
          fBufferLen(0),
          fBufferAlloc(false)
    {
        char strBuf[0xff+1];

        {
            const ScopedSafeLocale ssl;
            std::snprintf(strBuf, 0xff, "%.12g", static_cast<double>(value));
        }

        strBuf[0xff] = '\0';

        _dup(strBuf);
    }

    /*
     * Double-precision floating point number.
     */
    explicit String(const double value) noexcept
        : fBuffer(_null()),
          fBufferLen(0),
          fBufferAlloc(false)
    {
        char strBuf[0xff+1];

        {
            const ScopedSafeLocale ssl;
            std::snprintf(strBuf, 0xff, "%.24g", value);
        }

        strBuf[0xff] = '\0';

        _dup(strBuf);
    }

    // -------------------------------------------------------------------
    // non-explicit constructor

    /*
     * Create string from another string.
     */
    String(const String& str) noexcept
        : fBuffer(_null()),
          fBufferLen(0),
          fBufferAlloc(false)
    {
        _dup(str.fBuffer);
    }

    // -------------------------------------------------------------------
    // destructor

    /*
     * Destructor.
     */
    ~String() noexcept
    {
        DISTRHO_SAFE_ASSERT_RETURN(fBuffer != nullptr,);

        if (fBufferAlloc)
            std::free(fBuffer);

        fBuffer      = nullptr;
        fBufferLen   = 0;
        fBufferAlloc = false;
    }

    // -------------------------------------------------------------------
    // public methods

    /*
     * Get length of the string.
     */
    std::size_t length() const noexcept
    {
        return fBufferLen;
    }

    /*
     * Check if the string is empty.
     */
    bool isEmpty() const noexcept
    {
        return (fBufferLen == 0);
    }

    /*
     * Check if the string is not empty.
     */
    bool isNotEmpty() const noexcept
    {
        return (fBufferLen != 0);
    }

    /*
     * Check if the string contains a specific character, case-sensitive.
     */
    bool contains(const char c) const noexcept
    {
        for (std::size_t i=0; i<fBufferLen; ++i)
        {
            if (fBuffer[i] == c)
                return true;
        }

        return false;
    }

    /*
     * Check if the string contains another string, optionally ignoring case.
     */
    bool contains(const char* const strBuf, const bool ignoreCase = false) const noexcept
    {
        DISTRHO_SAFE_ASSERT_RETURN(strBuf != nullptr, false);

        if (ignoreCase)
        {
#ifdef __USE_GNU
            return (strcasestr(fBuffer, strBuf) != nullptr);
#else
            String tmp1(fBuffer), tmp2(strBuf);

            // memory allocation failed or empty string(s)
            if (tmp1.fBuffer == _null() || tmp2.fBuffer == _null())
                return false;

            tmp1.toLower();
            tmp2.toLower();
            return (std::strstr(tmp1, tmp2) != nullptr);
#endif
        }

        return (std::strstr(fBuffer, strBuf) != nullptr);
    }

    /*
     * Check if character at 'pos' is a digit.
     */
    bool isDigit(const std::size_t pos) const noexcept
    {
        DISTRHO_SAFE_ASSERT_RETURN(pos < fBufferLen, false);

        return (fBuffer[pos] >= '0' && fBuffer[pos] <= '9');
    }

    /*
     * Check if the string starts with the character 'c'.
     */
    bool startsWith(const char c) const noexcept
    {
        DISTRHO_SAFE_ASSERT_RETURN(c != '\0', false);

        return (fBufferLen > 0 && fBuffer[0] == c);
    }

    /*
     * Check if the string starts with the string 'prefix'.
     */
    bool startsWith(const char* const prefix) const noexcept
    {
        DISTRHO_SAFE_ASSERT_RETURN(prefix != nullptr, false);

        const std::size_t prefixLen(std::strlen(prefix));

        if (fBufferLen < prefixLen)
            return false;

        return (std::strncmp(fBuffer, prefix, prefixLen) == 0);
    }

    /*
     * Check if the string ends with the character 'c'.
     */
    bool endsWith(const char c) const noexcept
    {
        DISTRHO_SAFE_ASSERT_RETURN(c != '\0', false);

        return (fBufferLen > 0 && fBuffer[fBufferLen-1] == c);
    }

    /*
     * Check if the string ends with the string 'suffix'.
     */
    bool endsWith(const char* const suffix) const noexcept
    {
        DISTRHO_SAFE_ASSERT_RETURN(suffix != nullptr, false);

        const std::size_t suffixLen(std::strlen(suffix));

        if (fBufferLen < suffixLen)
            return false;

        return (std::strncmp(fBuffer + (fBufferLen-suffixLen), suffix, suffixLen) == 0);
    }

    /*
     * Find the first occurrence of character 'c' in the string.
     * Returns "length()" if the character is not found.
     */
    std::size_t find(const char c, bool* const found = nullptr) const noexcept
    {
        if (fBufferLen == 0 || c == '\0')
        {
            if (found != nullptr)
                *found = false;
            return fBufferLen;
        }

        for (std::size_t i=0; i < fBufferLen; ++i)
        {
            if (fBuffer[i] == c)
            {
                if (found != nullptr)
                    *found = true;
                return i;
            }
        }

        if (found != nullptr)
            *found = false;
        return fBufferLen;
    }

    /*
     * Find the first occurrence of string 'strBuf' in the string.
     * Returns "length()" if the string is not found.
     */
    std::size_t find(const char* const strBuf, bool* const found = nullptr) const noexcept
    {
        if (fBufferLen == 0 || strBuf == nullptr || strBuf[0] == '\0')
        {
            if (found != nullptr)
                *found = false;
            return fBufferLen;
        }

        if (char* const subStrBuf = std::strstr(fBuffer, strBuf))
        {
            const ssize_t ret(subStrBuf - fBuffer);

            if (ret < 0)
            {
                // should never happen!
                d_safe_assert_int("ret >= 0", __FILE__, __LINE__, int(ret));

                if (found != nullptr)
                    *found = false;
                return fBufferLen;
            }

            if (found != nullptr)
                *found = true;
            return static_cast<std::size_t>(ret);
        }

        if (found != nullptr)
            *found = false;
        return fBufferLen;
    }

    /*
     * Find the last occurrence of character 'c' in the string.
     * Returns "length()" if the character is not found.
     */
    std::size_t rfind(const char c, bool* const found = nullptr) const noexcept
    {
        if (fBufferLen == 0 || c == '\0')
        {
            if (found != nullptr)
                *found = false;
            return fBufferLen;
        }

        for (std::size_t i=fBufferLen; i > 0; --i)
        {
            if (fBuffer[i-1] == c)
            {
                if (found != nullptr)
                    *found = true;
                return i-1;
            }
        }

        if (found != nullptr)
            *found = false;
        return fBufferLen;
    }

    /*
     * Find the last occurrence of string 'strBuf' in the string.
     * Returns "length()" if the string is not found.
     */
    std::size_t rfind(const char* const strBuf, bool* const found = nullptr) const noexcept
    {
        if (found != nullptr)
            *found = false;

        if (fBufferLen == 0 || strBuf == nullptr || strBuf[0] == '\0')
            return fBufferLen;

        const std::size_t strBufLen(std::strlen(strBuf));

        std::size_t ret = fBufferLen;
        const char* tmpBuf = fBuffer;

        for (std::size_t i=0; i < fBufferLen; ++i)
        {
            if (std::strstr(tmpBuf+1, strBuf) == nullptr && std::strncmp(tmpBuf, strBuf, strBufLen) == 0)
            {
                if (found != nullptr)
                    *found = true;
                break;
            }

            --ret;
            ++tmpBuf;
        }

        return fBufferLen-ret;
    }

    /*
     * Clear the string.
     */
    void clear() noexcept
    {
        truncate(0);
    }

    /*
     * Replace all occurrences of character 'before' with character 'after'.
     */
    String& replace(const char before, const char after) noexcept
    {
        DISTRHO_SAFE_ASSERT_RETURN(before != '\0' /* && after != '\0' */, *this);

        for (std::size_t i=0; i < fBufferLen; ++i)
        {
            if (fBuffer[i] == before)
                fBuffer[i] = after;
        }

        return *this;
    }

    /*
     * Remove all occurrences of character 'c', shifting and truncating the string as necessary.
     */
    String& remove(const char c) noexcept
    {
        DISTRHO_SAFE_ASSERT_RETURN(c != '\0', *this);

        if (fBufferLen == 0)
            return *this;

        for (std::size_t i=0; i < fBufferLen; ++i)
        {
            if (fBuffer[i] == c)
            {
                --fBufferLen;
                std::memmove(fBuffer+i, fBuffer+i+1, fBufferLen-i);
            }
        }

        fBuffer[fBufferLen] = '\0';
        return *this;
    }

    /*
     * Truncate the string to size 'n'.
     */
    String& truncate(const std::size_t n) noexcept
    {
        if (n >= fBufferLen)
            return *this;

        fBuffer[n] = '\0';
        fBufferLen = n;

        return *this;
    }

    /*
     * Convert all non-basic characters to '_'.
     */
    String& toBasic() noexcept
    {
        for (std::size_t i=0; i < fBufferLen; ++i)
        {
            if (fBuffer[i] >= '0' && fBuffer[i] <= '9')
                continue;
            if (fBuffer[i] >= 'A' && fBuffer[i] <= 'Z')
                continue;
            if (fBuffer[i] >= 'a' && fBuffer[i] <= 'z')
                continue;
            if (fBuffer[i] == '_')
                continue;

            fBuffer[i] = '_';
        }

        return *this;
    }

    /*
     * Convert all ascii characters to lowercase.
     */
    String& toLower() noexcept
    {
        static constexpr const char kCharDiff = 'a' - 'A';

        for (std::size_t i=0; i < fBufferLen; ++i)
        {
            if (fBuffer[i] >= 'A' && fBuffer[i] <= 'Z')
                fBuffer[i] = static_cast<char>(fBuffer[i] + kCharDiff);
        }

        return *this;
    }

    /*
     * Convert all ascii characters to uppercase.
     */
    String& toUpper() noexcept
    {
        static constexpr const char kCharDiff = 'a' - 'A';

        for (std::size_t i=0; i < fBufferLen; ++i)
        {
            if (fBuffer[i] >= 'a' && fBuffer[i] <= 'z')
                fBuffer[i] = static_cast<char>(fBuffer[i] - kCharDiff);
        }

        return *this;
    }

    /*
     * Create a new string where all non-basic characters are converted to '_'.
     * @see toBasic()
     */
    String asBasic() const noexcept
    {
        String s(*this);
        return s.toBasic();
    }

    /*
     * Create a new string where all ascii characters are converted lowercase.
     * @see toLower()
     */
    String asLower() const noexcept
    {
        String s(*this);
        return s.toLower();
    }

    /*
     * Create a new string where all ascii characters are converted to uppercase.
     * @see toUpper()
     */
    String asUpper() const noexcept
    {
        String s(*this);
        return s.toUpper();
    }

    /*
     * Direct access to the string buffer (read-only).
     */
    const char* buffer() const noexcept
    {
        return fBuffer;
    }

    /*
     * Get and release the string buffer, while also clearing this string.
     * This allows to keep a pointer to the buffer after this object is deleted.
     * Result must be freed.
     */
    char* getAndReleaseBuffer() noexcept
    {
        char* ret = fBufferLen > 0 ? fBuffer : nullptr;
        fBuffer = _null();
        fBufferLen = 0;
        fBufferAlloc = false;
        return ret;
    }

    // -------------------------------------------------------------------
    // base64 stuff, based on http://www.adp-gmbh.ch/cpp/common/base64.html
    // Copyright (C) 2004-2008 René Nyffenegger

    static String asBase64(const void* const data, const std::size_t dataSize)
    {
        static constexpr const char* const kBase64Chars =
            "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
            "abcdefghijklmnopqrstuvwxyz"
            "0123456789+/";

       #ifndef _MSC_VER
        const std::size_t kTmpBufSize = std::min(d_nextPowerOf2(static_cast<uint32_t>(dataSize/3)), 65536U);
       #else
        constexpr std::size_t kTmpBufSize = 65536U;
       #endif

        const uchar* bytesToEncode((const uchar*)data);

        uint i=0, j=0;
        uint charArray3[3], charArray4[4];

        char strBuf[kTmpBufSize + 1];
        strBuf[kTmpBufSize] = '\0';
        std::size_t strBufIndex = 0;

        String ret;

        for (std::size_t s=0; s<dataSize; ++s)
        {
            charArray3[i++] = *(bytesToEncode++);

            if (i == 3)
            {
                charArray4[0] =  (charArray3[0] & 0xfc) >> 2;
                charArray4[1] = ((charArray3[0] & 0x03) << 4) + ((charArray3[1] & 0xf0) >> 4);
                charArray4[2] = ((charArray3[1] & 0x0f) << 2) + ((charArray3[2] & 0xc0) >> 6);
                charArray4[3] =   charArray3[2] & 0x3f;

                for (i=0; i<4; ++i)
                    strBuf[strBufIndex++] = kBase64Chars[charArray4[i]];

                if (strBufIndex >= kTmpBufSize-7)
                {
                    strBuf[strBufIndex] = '\0';
                    strBufIndex = 0;
                    ret += strBuf;
                }

                i = 0;
            }
        }

        if (i != 0)
        {
            for (j=i; j<3; ++j)
              charArray3[j] = '\0';

            charArray4[0] =  (charArray3[0] & 0xfc) >> 2;
            charArray4[1] = ((charArray3[0] & 0x03) << 4) + ((charArray3[1] & 0xf0) >> 4);
            charArray4[2] = ((charArray3[1] & 0x0f) << 2) + ((charArray3[2] & 0xc0) >> 6);
            charArray4[3] =   charArray3[2] & 0x3f;

            for (j=0; j<4 && i<3 && j<i+1; ++j)
                strBuf[strBufIndex++] = kBase64Chars[charArray4[j]];

            for (; i++ < 3;)
                strBuf[strBufIndex++] = '=';
        }

        if (strBufIndex != 0)
        {
            strBuf[strBufIndex] = '\0';
            ret += strBuf;
        }

        return ret;
    }

    /*
     * Convert to a URL encoded string.
     */
    String& urlEncode() noexcept
    {
        static constexpr const char* const kHexChars = "0123456789ABCDEF";

        if (fBufferLen == 0)
            return *this;

        char* const newbuf = static_cast<char*>(std::malloc(fBufferLen * 3 + 1));
        DISTRHO_SAFE_ASSERT_RETURN(newbuf != nullptr, *this);

        char* newbufptr = newbuf;

        for (std::size_t i=0; i < fBufferLen; ++i)
        {
            const char c = fBuffer[i];

            switch (c)
            {
            case '!': // 33
            case '#': // 35
            case '$': // 36
            case '&': // 38
            case '\'': // 39
            case '(': // 40
            case ')': // 41
            case '*': // 42
            case '+': // 43
            case ',': // 44
            case '-': // 45
            case '.': // 46
            case '/': // 47
            case '0': // 48
            case '1': // 49
            case '2': // 50
            case '3': // 51
            case '4': // 52
            case '5': // 53
            case '6': // 54
            case '7': // 55
            case '8': // 56
            case '9': // 57
            case ':': // 58
            case ';': // 59
            case '=': // 61
            case '?': // 63
            case '@': // 64
            case 'A': // 65
            case 'B': // 66
            case 'C': // 67
            case 'D': // 68
            case 'E': // 69
            case 'F': // 70
            case 'G': // 71
            case 'H': // 72
            case 'I': // 73
            case 'J': // 74
            case 'K': // 75
            case 'L': // 76
            case 'M': // 77
            case 'N': // 78
            case 'O': // 79
            case 'P': // 80
            case 'Q': // 81
            case 'R': // 82
            case 'S': // 83
            case 'T': // 84
            case 'U': // 85
            case 'V': // 86
            case 'W': // 87
            case 'X': // 88
            case 'Y': // 89
            case 'Z': // 90
            case '[': // 91
            case ']': // 93
            case '_': // 95
            case 'a': // 97
            case 'b': // 98
            case 'c': // 99
            case 'd': // 100
            case 'e': // 101
            case 'f': // 102
            case 'g': // 103
            case 'h': // 104
            case 'i': // 105
            case 'j': // 106
            case 'k': // 107
            case 'l': // 108
            case 'm': // 109
            case 'n': // 110
            case 'o': // 111
            case 'p': // 112
            case 'q': // 113
            case 'r': // 114
            case 's': // 115
            case 't': // 116
            case 'u': // 117
            case 'v': // 118
            case 'w': // 119
            case 'x': // 120
            case 'y': // 121
            case 'z': // 122
            case '~': // 126
                *newbufptr++ = c;
                break;
            default:
                *newbufptr++ = '%';
                *newbufptr++ = kHexChars[(c >> 4) & 0xf];
                *newbufptr++ = kHexChars[c & 0xf];
                break;
            }
        }

        *newbufptr = '\0';

        std::free(fBuffer);
        fBuffer = newbuf;
        fBufferLen = std::strlen(newbuf);
        fBufferAlloc = true;

        return *this;
    }

    /*
     * Convert to a URL decoded string.
     */
    String& urlDecode() noexcept
    {
        if (fBufferLen == 0)
            return *this;

        char* const newbuf = static_cast<char*>(std::malloc(fBufferLen + 1));
        DISTRHO_SAFE_ASSERT_RETURN(newbuf != nullptr, *this);

        char* newbufptr = newbuf;

        for (std::size_t i=0; i < fBufferLen; ++i)
        {
            const char c = fBuffer[i];

            if (c == '%')
            {
                DISTRHO_SAFE_ASSERT_CONTINUE(fBufferLen > i + 2);

                char c1 = fBuffer[i + 1];
                char c2 = fBuffer[i + 2];
                i += 2;

                /**/ if (c1 >= '0' && c1 <= '9')
                    c1 -= '0';
                else if (c1 >= 'A' && c1 <= 'Z')
                    c1 -= 'A' - 10;
                else if (c1 >= 'a' && c1 <= 'z')
                    c1 -= 'a' - 10;
                else
                    continue;

                /**/ if (c2 >= '0' && c2 <= '9')
                    c2 -= '0';
                else if (c2 >= 'A' && c2 <= 'Z')
                    c2 -= 'A' - 10;
                else if (c2 >= 'a' && c2 <= 'z')
                    c2 -= 'a' - 10;
                else
                    continue;

                *newbufptr++ = c1 << 4 | c2;
            }
            else
            {
                *newbufptr++ = c;
            }
        }

        *newbufptr = '\0';

        std::free(fBuffer);
        fBuffer = newbuf;
        fBufferLen = std::strlen(newbuf);
        fBufferAlloc = true;

        return *this;
    }

    // -------------------------------------------------------------------
    // public operators

    operator const char*() const noexcept
    {
        return fBuffer;
    }

    char operator[](const std::size_t pos) const noexcept
    {
        if (pos < fBufferLen)
            return fBuffer[pos];

        d_safe_assert("pos < fBufferLen", __FILE__, __LINE__);

        static char fallback;
        fallback = '\0';
        return fallback;
    }

    char& operator[](const std::size_t pos) noexcept
    {
        if (pos < fBufferLen)
            return fBuffer[pos];

        d_safe_assert("pos < fBufferLen", __FILE__, __LINE__);

        static char fallback;
        fallback = '\0';
        return fallback;
    }

    bool operator==(const char* const strBuf) const noexcept
    {
        return (strBuf != nullptr && std::strcmp(fBuffer, strBuf) == 0);
    }

    bool operator==(const String& str) const noexcept
    {
        return operator==(str.fBuffer);
    }

    bool operator!=(const char* const strBuf) const noexcept
    {
        return !operator==(strBuf);
    }

    bool operator!=(const String& str) const noexcept
    {
        return !operator==(str.fBuffer);
    }

    String& operator=(const char* const strBuf) noexcept
    {
        _dup(strBuf);

        return *this;
    }

    String& operator=(const String& str) noexcept
    {
        _dup(str.fBuffer);

        return *this;
    }

    String& operator+=(const char* const strBuf) noexcept
    {
        if (strBuf == nullptr || strBuf[0] == '\0')
            return *this;

        const std::size_t strBufLen = std::strlen(strBuf);

        // for empty strings, we can just take the appended string as our entire data
        if (isEmpty())
        {
            _dup(strBuf, strBufLen);
            return *this;
        }

        // we have some data ourselves, reallocate to add the new stuff
        char* const newBuf = static_cast<char*>(std::realloc(fBuffer, fBufferLen + strBufLen + 1));
        DISTRHO_SAFE_ASSERT_RETURN(newBuf != nullptr, *this);

        std::memcpy(newBuf + fBufferLen, strBuf, strBufLen + 1);

        fBuffer = newBuf;
        fBufferLen += strBufLen;

        return *this;
    }

    String& operator+=(const String& str) noexcept
    {
        return operator+=(str.fBuffer);
    }

    String operator+(const char* const strBuf) noexcept
    {
        if (strBuf == nullptr || strBuf[0] == '\0')
            return *this;
        if (isEmpty())
            return String(strBuf);

        const std::size_t strBufLen = std::strlen(strBuf);
        const std::size_t newBufSize = fBufferLen + strBufLen;
        char* const newBuf = static_cast<char*>(std::malloc(newBufSize + 1));
        DISTRHO_SAFE_ASSERT_RETURN(newBuf != nullptr, String());

        std::memcpy(newBuf, fBuffer, fBufferLen);
        std::memcpy(newBuf + fBufferLen, strBuf, strBufLen + 1);

        return String(newBuf, false);
    }

    String operator+(const String& str) noexcept
    {
        return operator+(str.fBuffer);
    }

    // needed for std::map compatibility
    bool operator<(const String& str) const noexcept
    {
        return std::strcmp(fBuffer, str.fBuffer) < 0;
    }

    // -------------------------------------------------------------------

private:
    char*       fBuffer;      // the actual string buffer
    std::size_t fBufferLen;   // string length
    bool        fBufferAlloc; // wherever the buffer is allocated, not using _null()

    /*
     * Static null string.
     * Prevents allocation for new and/or empty strings.
     */
    static char* _null() noexcept
    {
        static char sNull = '\0';
        return &sNull;
    }

    /*
     * Helper function.
     * Called whenever the string needs to be allocated.
     *
     * Notes:
     * - Allocates string only if 'strBuf' is not null and new string contents are different
     * - If 'strBuf' is null, 'size' must be 0
     */
    void _dup(const char* const strBuf, const std::size_t size = 0) noexcept
    {
        if (strBuf != nullptr)
        {
            // don't recreate string if contents match
            if (std::strcmp(fBuffer, strBuf) == 0)
                return;

            if (fBufferAlloc)
                std::free(fBuffer);

            fBufferLen = (size > 0) ? size : std::strlen(strBuf);
            fBuffer    = static_cast<char*>(std::malloc(fBufferLen + 1));

            if (fBuffer == nullptr)
            {
                fBuffer      = _null();
                fBufferLen   = 0;
                fBufferAlloc = false;
                return;
            }

            fBufferAlloc = true;

            std::strcpy(fBuffer, strBuf);
            fBuffer[fBufferLen] = '\0';
        }
        else
        {
            DISTRHO_SAFE_ASSERT_UINT(size == 0, static_cast<uint>(size));

            // don't recreate null string
            if (! fBufferAlloc)
                return;

            DISTRHO_SAFE_ASSERT(fBuffer != nullptr);
            std::free(fBuffer);

            fBuffer      = _null();
            fBufferLen   = 0;
            fBufferAlloc = false;
        }
    }

    DISTRHO_PREVENT_HEAP_ALLOCATION
};

// -----------------------------------------------------------------------

static inline
String operator+(const String& strBefore, const char* const strBufAfter) noexcept
{
    if (strBufAfter == nullptr || strBufAfter[0] == '\0')
        return strBefore;
    if (strBefore.isEmpty())
        return String(strBufAfter);

    const std::size_t strBeforeLen = strBefore.length();
    const std::size_t strBufAfterLen = std::strlen(strBufAfter);
    const std::size_t newBufSize = strBeforeLen + strBufAfterLen;
    char* const newBuf = static_cast<char*>(malloc(newBufSize + 1));
    DISTRHO_SAFE_ASSERT_RETURN(newBuf != nullptr, String());

    std::memcpy(newBuf, strBefore.buffer(), strBeforeLen);
    std::memcpy(newBuf + strBeforeLen, strBufAfter, strBufAfterLen + 1);

    return String(newBuf, false);
}

static inline
String operator+(const char* const strBufBefore, const String& strAfter) noexcept
{
    if (strAfter.isEmpty())
        return String(strBufBefore);
    if (strBufBefore == nullptr || strBufBefore[0] == '\0')
        return strAfter;

    const std::size_t strBufBeforeLen = std::strlen(strBufBefore);
    const std::size_t strAfterLen = strAfter.length();
    const std::size_t newBufSize = strBufBeforeLen + strAfterLen;
    char* const newBuf = static_cast<char*>(malloc(newBufSize + 1));
    DISTRHO_SAFE_ASSERT_RETURN(newBuf != nullptr, String());

    std::memcpy(newBuf, strBufBefore, strBufBeforeLen);
    std::memcpy(newBuf + strBufBeforeLen, strAfter.buffer(), strAfterLen + 1);

    return String(newBuf, false);
}

// -----------------------------------------------------------------------

END_NAMESPACE_DISTRHO

#endif // DISTRHO_STRING_HPP_INCLUDED