path: root/shared/loki/SafeFormat.h

////////////////////////////////////////////////////////////////////////////////
// Copyright (c) 2005 by Andrei Alexandrescu
// Copyright (c) 2006 Peter Kümmel
// Permission to use, copy, modify, distribute, and sell this software for any
//     purpose is hereby granted without fee, provided that the above copyright
//     notice appear in all copies and that both that copyright notice and this
//     permission notice appear in supporting documentation.
// The author makes no representations about the suitability of this software
//     for any purpose. It is provided "as is" without express or implied
//     warranty.
////////////////////////////////////////////////////////////////////////////////
#ifndef LOKI_SAFEFORMAT_INC_
#define LOKI_SAFEFORMAT_INC_

// $Id: SafeFormat.h 911 2008-12-15 20:55:24Z syntheticpp $


////////////////////////////////////////////////////////////////////////////////
// This file contains definitions for SafePrintf. SafeScanf coming soon (the
//   design is similar).
// See Alexandrescu, Andrei: Type-safe Formatting, C/C++ Users Journal, Aug 2005
////////////////////////////////////////////////////////////////////////////////

#include <cstdio>
#include <climits>
#include <string>
#include <cstring>
#include <stdexcept>
#include <utility>
#include <cassert>
#include <locale>
#include <iostream>

#include <loki/LokiExport.h>


// long is 32 bit on 64-bit Windows!
// intptr_t used to get 64 bit on Win64
#if defined(_WIN32) || defined(_WIN64)
#  define LOKI_SAFEFORMAT_SIGNED_LONG intptr_t
#  define LOKI_SAFEFORMAT_UNSIGNED_LONG uintptr_t
#else
#  define LOKI_SAFEFORMAT_SIGNED_LONG signed long
#  define LOKI_SAFEFORMAT_UNSIGNED_LONG unsigned long
#endif

// Windows headers could have min/max defined
#ifdef max
#  undef max
#endif
#ifdef min
#  undef min
#endif

namespace Loki
{

// Crude writing method: writes straight to the file, unbuffered
// Must be combined with a buffer to work properly (and efficiently)
LOKI_EXPORT
void write(std::FILE* f, const char* from, const char* to);

// Write to an ostream
LOKI_EXPORT
void write(std::ostream& f, const char* from, const char* to);

// Write to a string
LOKI_EXPORT
void write(std::string& s, const char* from, const char* to);

// Write to a fixed-size buffer
template <class Char>
void write(std::pair<Char*, std::size_t>& s, const Char* from, const Char* to)
{
    assert(from <= to);
    if (from + s.second < to)
        throw std::overflow_error("");
    // s.first: position one past the final copied element
    s.first = std::copy(from, to, s.first);
    // remaining buffer size
    s.second -= to - from;
}

////////////////////////////////////////////////////////////////////////////////
// PrintfState class template
// Holds the formatting state, and implements operator() to format stuff
// Todo: make sure errors are handled properly
////////////////////////////////////////////////////////////////////////////////

template <class Device, class Char>
struct PrintfState
{
    PrintfState(Device dev, const Char* format)
        : device_(dev)
        , format_(format)
        , width_(0)
        , prec_(0)
        , flags_(0)
        , result_(0)
    {
        Advance();
    }

    ~PrintfState()
    {
    }

#define LOKI_PRINTF_STATE_FORWARD(type) \
    PrintfState& operator()(type par) {\
        return (*this)(static_cast< LOKI_SAFEFORMAT_UNSIGNED_LONG >(par)); \
    }

    LOKI_PRINTF_STATE_FORWARD(bool)
    LOKI_PRINTF_STATE_FORWARD(char)
    LOKI_PRINTF_STATE_FORWARD(signed char)
    LOKI_PRINTF_STATE_FORWARD(unsigned char)
    LOKI_PRINTF_STATE_FORWARD(signed short)
    LOKI_PRINTF_STATE_FORWARD(unsigned short)
    LOKI_PRINTF_STATE_FORWARD(signed int)
    LOKI_PRINTF_STATE_FORWARD(signed long)
#if (defined(_WIN32) || defined(_WIN64))
    LOKI_PRINTF_STATE_FORWARD(unsigned long)
#else
    // on Windows already defined by uintptr_t
    LOKI_PRINTF_STATE_FORWARD(unsigned int)
#endif

    // Print (or gobble in case of the "*" specifier) an int
    PrintfState& operator()(LOKI_SAFEFORMAT_UNSIGNED_LONG i)
    {
        if (result_ == -1) return *this; // don't even bother
        // % [flags] [width] [.prec] [modifier] type_char
        // Fetch the flags
        ReadFlags();
        if (*format_ == '*')
        {
            // read the width and get out
            SetWidth(static_cast<size_t>(i));
            ++format_;
            return *this;
        }
        ReadWidth();
        // precision
        if (*format_ == '.')
        {
            // deal with precision
            if (format_[1] == '*')
            {
                // read the precision and get out
                SetPrec(static_cast<size_t>(i));
                format_ += 2;
                return *this;
            }
            ReadPrecision();
        }
        ReadModifiers();
        // input size modifier
        if (ForceShort())
        {
            // short int
            const Char c = *format_;
            if (c == 'x' || c == 'X' || c == 'u' || c == 'o')
            {
                i = static_cast<LOKI_SAFEFORMAT_UNSIGNED_LONG>(static_cast<unsigned short>(i));
            }
        }
        FormatWithCurrentFlags(i);
        return *this;
    }

    PrintfState& operator()(void* n)
    {
        if (result_ == -1) return *this; // don't even bother
        PrintUsing_snprintf(n, "p");
        return *this;
    }

    PrintfState& operator()(double n)
    {
        if (result_ == -1) return *this; // don't even bother
        PrintUsing_snprintf(n, "eEfgG");
        return *this;
    }

    PrintfState& operator()(long double n)
    {
        if (result_ == -1) return *this; // don't even bother
        PrintUsing_snprintf(n, "eEfgG");
        return *this;
    }

    // Store the number of characters printed so far
    PrintfState& operator()(int* pi)
    {
        return StoreCountHelper(pi);
    }

    // Store the number of characters printed so far
    PrintfState& operator()(short* pi)
    {
        return StoreCountHelper(pi);
    }

    // Store the number of characters printed so far
    PrintfState& operator()(long* pi)
    {
        return StoreCountHelper(pi);
    }

    PrintfState& operator()(const std::string& stdstr)
    {
        return operator()(stdstr.c_str());
    }

    PrintfState& operator()(const char* const s)
    {
        if (result_ == -1) return *this;
        ReadLeaders();
        const char fmt = *format_;
        if (fmt == 'p')
        {
            FormatWithCurrentFlags(reinterpret_cast<LOKI_SAFEFORMAT_UNSIGNED_LONG>(s));
            return *this;
        }
        if (fmt != 's')
        {
            result_ = -1;
            return *this;
        }
        const size_t len = std::min(std::strlen(s), prec_);
        if (width_ > len)
        {
            if (LeftJustify())
            {
                Write(s, s + len);
                Fill(' ', width_ - len);
            }
            else
            {
                Fill(' ', width_ - len);
                Write(s, s + len);
            }
        }
        else
        {
            Write(s, s + len);
        }
        Next();
        return *this;
    }

    PrintfState& operator()(const void* const p)
    {
        return (*this)(reinterpret_cast<LOKI_SAFEFORMAT_UNSIGNED_LONG>(p));
    }

    // read the result
    operator int() const
    {
        return static_cast<int>(result_);
    }

private:
    PrintfState& operator=(const PrintfState&);
    template <typename T>
    PrintfState& StoreCountHelper(T* const pi)
    {
        if (result_ == -1) return *this; // don't even bother
        ReadLeaders();
        const char fmt = *format_;
        if (fmt == 'p')   // pointer
        {
            FormatWithCurrentFlags(reinterpret_cast<LOKI_SAFEFORMAT_UNSIGNED_LONG>(pi));
            return *this;
        }
        if (fmt != 'n')
        {
            result_ = -1;
            return *this;
        }
        assert(pi != 0);
        *pi = result_;
        Next();
        return *this;
    }

    void FormatWithCurrentFlags(const LOKI_SAFEFORMAT_UNSIGNED_LONG i)
    {
        // look at the format character
        Char formatChar = *format_;
        bool isSigned = formatChar == 'd' || formatChar == 'i';
        if (formatChar == 'p')
        {
            formatChar = 'x'; // pointers go to hex
            SetAlternateForm(); // printed with '0x' in front
            isSigned = true; // that's what gcc does
        }
        if (!strchr("cdiuoxX", formatChar))
        {
            result_ = -1;
            return;
        }
        Char buf[
            sizeof(LOKI_SAFEFORMAT_UNSIGNED_LONG) * 3 // digits
            + 1 // sign or ' '
            + 2 // 0x or 0X
            + 1]; // terminating zero
        const Char* const bufEnd = buf + (sizeof(buf) / sizeof(Char));
        Char* bufLast = buf + (sizeof(buf) / sizeof(Char) - 1);
        Char signChar = 0;
        unsigned int base = 10;

        if (formatChar == 'c')
        {
            // Format only one character
            // The 'fill with zeros' flag is ignored
            ResetFillZeros();
            *bufLast = static_cast<char>(i);
        }
        else
        {
            // TODO: inefficient code, refactor
            const bool negative = isSigned && static_cast<LOKI_SAFEFORMAT_SIGNED_LONG>(i) < 0;
            if (formatChar == 'o') base = 8;
            else if (formatChar == 'x' || formatChar == 'X') base = 16;
            bufLast = isSigned
                      ? RenderWithoutSign(static_cast<LOKI_SAFEFORMAT_SIGNED_LONG>(i), bufLast, base,
                                          formatChar == 'X')
                      : RenderWithoutSign(i, bufLast, base,
                                          formatChar == 'X');
            // Add the sign
            if (isSigned)
            {
                negative ? signChar = '-'
                                      : ShowSignAlways() ? signChar = '+'
                                                                      : Blank() ? signChar = ' '
                                                                                             : 0;
            }
        }
        // precision
        size_t
        countDigits = bufEnd - bufLast,
        countZeros = prec_ != size_t(-1) && countDigits < prec_ &&
                     formatChar != 'c'
                     ? prec_ - countDigits
                     : 0,
                     countBase = base != 10 && AlternateForm() && i != 0
                                 ? (base == 16 ? 2 : countZeros > 0 ? 0 : 1)
                                 : 0,
                                 countSign = (signChar != 0),
                                 totalPrintable = countDigits + countZeros + countBase + countSign;
        size_t countPadLeft = 0, countPadRight = 0;
        if (width_ > totalPrintable)
        {
            if (LeftJustify())
            {
                countPadRight = width_ - totalPrintable;
                countPadLeft = 0;
            }
            else
            {
                countPadLeft = width_ - totalPrintable;
                countPadRight = 0;
            }
        }
        if (FillZeros() && prec_ == size_t(-1))
        {
            // pad with zeros and no precision - transfer padding to precision
            countZeros = countPadLeft;
            countPadLeft = 0;
        }
        // ok, all computed, ready to print to device
        Fill(' ', countPadLeft);
        if (signChar != 0) Write(&signChar, &signChar + 1);
        if (countBase > 0) Fill('0', 1);
        if (countBase == 2) Fill(formatChar, 1);
        Fill('0', countZeros);
        Write(bufLast, bufEnd);
        Fill(' ', countPadRight);
        // done, advance
        Next();
    }

    void Write(const Char* b, const Char* e)
    {
        if (result_ < 0) return;
        const LOKI_SAFEFORMAT_SIGNED_LONG x = e - b;
        write(device_, b, e);
        result_ += x;
    }

    template <class Value>
    void PrintUsing_snprintf(Value n, const char* check_fmt_char)
    {
        const Char* const fmt = format_ - 1;
        assert(*fmt == '%');
        // enforce format string validity
        ReadLeaders();
        // enforce format spec
        if (!strchr(check_fmt_char, *format_))
        {
            result_ = -1;
            return;
        }
        // format char validated, copy it to a temp and use legacy sprintf
        ++format_;
        Char fmtBuf[128], resultBuf[1024];
        if (format_  >= fmt + sizeof(fmtBuf) / sizeof(Char))
        {
            result_ = -1;
            return;
        }
        memcpy(fmtBuf, fmt, (format_ - fmt) * sizeof(Char));
        fmtBuf[format_ - fmt] = 0;

        const int stored =
#ifdef _MSC_VER
#if _MSC_VER < 1400
            _snprintf
#else
            _snprintf_s
#endif
#else
            snprintf
#endif
            (resultBuf, sizeof(resultBuf) / sizeof(Char), fmtBuf, n);

        if (stored < 0)
        {
            result_ = -1;
            return;
        }
        Write(resultBuf, resultBuf + strlen(resultBuf));
        Advance(); // output stuff to the next format directive
    }

    void Fill(const Char c, size_t n)
    {
        for (; n > 0; --n)
        {
            Write(&c, &c + 1);
        }
    }

    Char* RenderWithoutSign(LOKI_SAFEFORMAT_UNSIGNED_LONG n, char* bufLast,
                            unsigned int base, bool uppercase)
    {
        const Char hex1st = uppercase ? 'A' : 'a';
        for (;;)
        {
            const LOKI_SAFEFORMAT_UNSIGNED_LONG next = n / base;
            Char c = static_cast<Char>(n - next * base);
            c = static_cast<Char>(c + (c <= 9 ? '0' : static_cast<Char>(hex1st - 10)));
            *bufLast = c;
            n = next;
            if (n == 0) break;
            --bufLast;
        }
        return bufLast;
    }

    char* RenderWithoutSign(LOKI_SAFEFORMAT_SIGNED_LONG n, char* bufLast, unsigned int base,
                            bool uppercase)
    {
        if (n != LONG_MIN)
        {
            return RenderWithoutSign(static_cast<LOKI_SAFEFORMAT_UNSIGNED_LONG>(n < 0 ? -n : n),
                                     bufLast, base, uppercase);
        }
        // annoying corner case
        char* save = bufLast;
        ++n;
        bufLast = RenderWithoutSign(static_cast<LOKI_SAFEFORMAT_UNSIGNED_LONG>(n),
                                    bufLast, base, uppercase);
        --(*save);
        return bufLast;
    }

    void Next()
    {
        ++format_;
        Advance();
    }

    void Advance()
    {
        ResetAll();
        const Char* begin = format_;
        for (;;)
        {
            if (*format_ == '%')
            {
                if (format_[1] != '%')   // It's a format specifier
                {
                    Write(begin, format_);
                    ++format_;
                    break;
                }
                // It's a "%%"
                Write(begin, ++format_);
                begin = ++format_;
                continue;
            }
            if (*format_ == 0)
            {
                Write(begin, format_);
                break;
            }
            ++format_;
        }
    }

    void ReadFlags()
    {
        for (;; ++format_)
        {
            switch (*format_)
            {
                case '-':
                    SetLeftJustify();
                    break;
                case '+':
                    SetShowSignAlways();
                    break;
                case ' ':
                    SetBlank();
                    break;
                case '#':
                    SetAlternateForm();
                    break;
                case '0':
                    SetFillZeros();
                    break;
                default:
                    return;
            }
        }
    }

    void ParseDecimalSizeT(size_t& dest)
    {
        if (!std::isdigit(*format_, std::locale())) return;
        size_t r = 0;
        do
        {
            // TODO: inefficient - rewrite
            r *= 10;
            r += *format_ - '0';
            ++format_;
        }
        while (std::isdigit(*format_, std::locale()));
        dest = r;
    }

    void ReadWidth()
    {
        ParseDecimalSizeT(width_);
    }

    void ReadPrecision()
    {
        assert(*format_ == '.');
        ++format_;
        ParseDecimalSizeT(prec_);
    }

    void ReadModifiers()
    {
        switch (*format_)
        {
            case 'h':
                SetForceShort();
                ++format_;
                break;
            case 'l':
                ++format_;
                break;
                // more (C99 and platform-specific modifiers) to come
        }
    }

    void ReadLeaders()
    {
        ReadFlags();
        ReadWidth();
        if (*format_ == '.') ReadPrecision();
        ReadModifiers();
    }

    enum
    {
        leftJustify = 1,
        showSignAlways = 2,
        blank = 4,
        alternateForm = 8,
        fillZeros = 16,
        forceShort = 32
    };

    bool LeftJustify() const { return (flags_ & leftJustify) != 0; }
    bool ShowSignAlways() const { return (flags_ & showSignAlways) != 0; }
    void SetWidth(size_t w) { width_  = w; }
    void SetLeftJustify() { flags_  |= leftJustify; }
    void SetShowSignAlways() { flags_ |= showSignAlways; }
    bool Blank() const { return (flags_ & blank) != 0; }
    bool AlternateForm() const { return (flags_ & alternateForm) != 0; }
    bool FillZeros() const { return (flags_ & fillZeros) != 0; }
    bool ForceShort() const { return (flags_ & forceShort) != 0; }

    void SetPrec(size_t p) { prec_ = p; }
    void SetBlank() { flags_ |= blank; }
    void SetAlternateForm() { flags_ |=  alternateForm; }
    void SetFillZeros() { flags_ |= fillZeros; }
    void ResetFillZeros() { flags_ &= ~fillZeros; }
    void SetForceShort() { flags_ |= forceShort; }

    void ResetAll()
    {
        assert(result_ != EOF);
        width_ = 0;
        prec_ = size_t(-1);
        flags_ = 0;
    }

    // state
    Device device_;
    const Char* format_;
    size_t width_;
    size_t prec_;
    unsigned int flags_;
    LOKI_SAFEFORMAT_SIGNED_LONG result_;
};

LOKI_EXPORT
PrintfState<std::FILE*, char> Printf(const char* format);

LOKI_EXPORT
PrintfState<std::FILE*, char> Printf(const std::string& format);

LOKI_EXPORT
PrintfState<std::FILE*, char> FPrintf(std::FILE* f, const char* format);

LOKI_EXPORT
PrintfState<std::FILE*, char> FPrintf(std::FILE* f, const std::string& format);

LOKI_EXPORT
PrintfState<std::ostream&, char> FPrintf(std::ostream& f, const char* format);

LOKI_EXPORT
PrintfState<std::ostream&, char> FPrintf(std::ostream& f, const std::string& format);

LOKI_EXPORT
PrintfState<std::string&, char> SPrintf(std::string& s, const char* format);

LOKI_EXPORT
PrintfState<std::string&, char> SPrintf(std::string& s, const std::string& format);

template <class T, class Char>
PrintfState<T&, Char> XPrintf(T& device, const Char* format)
{
    return PrintfState<T&, Char>(device, format);
}

template <class T>
PrintfState<T&, char> XPrintf(T& device, const std::string& format)
{
    return PrintfState<T&, char>(device, format.c_str());
}

template <class Char, std::size_t N>
PrintfState<std::pair<Char*, std::size_t>, Char>
BufPrintf(Char (&buf)[N], const Char* format)
{
    std::pair<Char*, std::size_t> temp(buf, N);
    return PrintfState<std::pair<Char*, std::size_t>, Char>(temp, format);
}

}// namespace Loki


#endif // end file guardian