//
// Copyright (C) 2002-2005  3Dlabs Inc. Ltd.
// Copyright (C) 2013 LunarG, Inc.
// Copyright (C) 2017 ARM Limited.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
//
//    Redistributions of source code must retain the above copyright
//    notice, this list of conditions and the following disclaimer.
//
//    Redistributions in binary form must reproduce the above
//    copyright notice, this list of conditions and the following
//    disclaimer in the documentation and/or other materials provided
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// LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
// ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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/****************************************************************************\
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#ifndef _CRT_SECURE_NO_WARNINGS
#define _CRT_SECURE_NO_WARNINGS
#endif

#include <cstdlib>
#include <cstring>

#include "PpContext.h"
#include "PpTokens.h"
#include "../Scan.h"

namespace glslang {

///////////////////////////////////////////////////////////////////////////////////////////////
/////////////////////////////////// Floating point constants: /////////////////////////////////
///////////////////////////////////////////////////////////////////////////////////////////////

/*
* lFloatConst() - Scan a single- or double-precision floating point constant.  Assumes that the scanner
*         has seen at least one digit, followed by either a decimal '.' or the
*         letter 'e', or a precision ending (e.g., F or LF).
*/

int TPpContext::lFloatConst(int len, int ch, TPpToken* ppToken)
{
    bool HasDecimalOrExponent = false;
    int isDouble = 0;
    bool generateFloat16 = false;
    bool acceptFloat16 = parseContext.intermediate.getSource() == EShSourceHlsl;
    bool isFloat16 = false;
    bool requireHF = false;
    if (
#ifdef AMD_EXTENSIONS
        parseContext.extensionTurnedOn(E_GL_AMD_gpu_shader_half_float) ||
#endif
        parseContext.extensionTurnedOn(E_GL_KHX_shader_explicit_arithmetic_types) ||
        parseContext.extensionTurnedOn(E_GL_KHX_shader_explicit_arithmetic_types_float16)) {
        acceptFloat16 = true;
        generateFloat16 = true;
        requireHF = true;
    }

    const auto saveName = [&](int ch) {
        if (len <= MaxTokenLength)
            ppToken->name[len++] = static_cast<char>(ch);
    };

    // Decimal:

    if (ch == '.') {
        HasDecimalOrExponent = true;
        saveName(ch);
        ch = getChar();

        // 1.#INF or -1.#INF
        if (ch == '#') {
            if ((len <  2) ||
                (len == 2 && ppToken->name[0] != '1') ||
                (len == 3 && ppToken->name[1] != '1' && !(ppToken->name[0] == '-' || ppToken->name[0] == '+')) ||
                (len >  3))
                parseContext.ppError(ppToken->loc, "unexpected use of", "#", "");
            else {
                // we have 1.# or -1.# or +1.#, check for 'INF'
                if ((ch = getChar()) != 'I' ||
                    (ch = getChar()) != 'N' ||
                    (ch = getChar()) != 'F')
                    parseContext.ppError(ppToken->loc, "expected 'INF'", "#", "");
                else {
                    // we have [+-].#INF, and we are targeting IEEE 754, so wrap it up:
                    saveName('I');
                    saveName('N');
                    saveName('F');
                    ppToken->name[len] = '\0';
                    if (ppToken->name[0] == '-')
                        ppToken->i64val = 0xfff0000000000000; // -Infinity
                    else
                        ppToken->i64val = 0x7ff0000000000000; // +Infinity
                    return PpAtomConstFloat;
                }
            }
        }

        while (ch >= '0' && ch <= '9') {
            saveName(ch);
            ch = getChar();
        }
    }

    // Exponent:

    if (ch == 'e' || ch == 'E') {
        HasDecimalOrExponent = true;
        saveName(ch);
        ch = getChar();
        if (ch == '+' || ch == '-') {
            saveName(ch);
            ch = getChar();
        }
        if (ch >= '0' && ch <= '9') {
            while (ch >= '0' && ch <= '9') {
                saveName(ch);
                ch = getChar();
            }
        } else {
            parseContext.ppError(ppToken->loc, "bad character in float exponent", "", "");
        }
    }

    // Suffix:

    if (ch == 'l' || ch == 'L') {
        parseContext.doubleCheck(ppToken->loc, "double floating-point suffix");
        if (! HasDecimalOrExponent)
            parseContext.ppError(ppToken->loc, "float literal needs a decimal point or exponent", "", "");
        int ch2 = getChar();
        if (ch2 != 'f' && ch2 != 'F') {
            ungetChar();
            ungetChar();
        } else {
            saveName(ch);
            saveName(ch2);
            isDouble = 1;
        }
    } else if (acceptFloat16 && (ch == 'h' || ch == 'H')) {
        if (generateFloat16)
            parseContext.float16Check(ppToken->loc, "half floating-point suffix");
        if (!HasDecimalOrExponent)
            parseContext.ppError(ppToken->loc, "float literal needs a decimal point or exponent", "", "");
        if (requireHF) {
            int ch2 = getChar();
            if (ch2 != 'f' && ch2 != 'F') {
                ungetChar();
                ungetChar();
            } else {
                saveName(ch);
                saveName(ch2);
                isFloat16 = generateFloat16;
            }
        } else {
            saveName(ch);
            isFloat16 = generateFloat16;
        }
    } else if (ch == 'f' || ch == 'F') {
        parseContext.profileRequires(ppToken->loc,  EEsProfile, 300, nullptr, "floating-point suffix");
        if (! parseContext.relaxedErrors())
            parseContext.profileRequires(ppToken->loc, ~EEsProfile, 120, nullptr, "floating-point suffix");
        if (! HasDecimalOrExponent)
            parseContext.ppError(ppToken->loc, "float literal needs a decimal point or exponent", "", "");
        saveName(ch);
    } else
        ungetChar();

    // Patch up the name, length, etc.

    if (len > MaxTokenLength) {
        len = MaxTokenLength;
        parseContext.ppError(ppToken->loc, "float literal too long", "", "");
    }
    ppToken->name[len] = '\0';

    // Get the numerical value
    ppToken->dval = strtod(ppToken->name, nullptr);

    // Return the right token type
    if (isDouble)
        return PpAtomConstDouble;
    else if (isFloat16)
        return PpAtomConstFloat16;
    else
        return PpAtomConstFloat;
}

// Recognize a character literal.
//
// The first ' has already been accepted, read the rest, through the closing '.
//
// Always returns PpAtomConstInt.
//
int TPpContext::characterLiteral(TPpToken* ppToken)
{
    ppToken->name[0] = 0;
    ppToken->ival = 0;

    if (parseContext.intermediate.getSource() != EShSourceHlsl) {
        // illegal, except in macro definition, for which case we report the character
        return '\'';
    }

    int ch = getChar();
    switch (ch) {
    case '\'':
        // As empty sequence:  ''
        parseContext.ppError(ppToken->loc, "unexpected", "\'", "");
        return PpAtomConstInt;
    case '\\':
        // As escape sequence:  '\XXX'
        switch (ch = getChar()) {
        case 'a':
            ppToken->ival = 7;
            break;
        case 'b':
            ppToken->ival = 8;
            break;
        case 't':
            ppToken->ival = 9;
            break;
        case 'n':
            ppToken->ival = 10;
            break;
        case 'v':
            ppToken->ival = 11;
            break;
        case 'f':
            ppToken->ival = 12;
            break;
        case 'r':
            ppToken->ival = 13;
            break;
        case 'x':
        case '0':
            parseContext.ppError(ppToken->loc, "octal and hex sequences not supported", "\\", "");
            break;
        default:
            // This catches '\'', '\"', '\?', etc.
            // Also, things like '\C' mean the same thing as 'C'
            // (after the above cases are filtered out).
            ppToken->ival = ch;
            break;
        }
        break;
    default:
        ppToken->ival = ch;
        break;
    }
    ppToken->name[0] = (char)ppToken->ival;
    ppToken->name[1] = '\0';
    ch = getChar();
    if (ch != '\'') {
        parseContext.ppError(ppToken->loc, "expected", "\'", "");
        // Look ahead for a closing '
        do {
            ch = getChar();
        } while (ch != '\'' && ch != EndOfInput && ch != '\n');
    }

    return PpAtomConstInt;
}

//
// Scanner used to tokenize source stream.
//
int TPpContext::tStringInput::scan(TPpToken* ppToken)
{
    int AlreadyComplained = 0;
    int len = 0;
    int ch = 0;
    int ii = 0;
    unsigned long long ival = 0;
    bool enableInt64 = pp->parseContext.version >= 450 &&
                      (pp->parseContext.extensionTurnedOn(E_GL_ARB_gpu_shader_int64) ||
                       pp->parseContext.extensionTurnedOn(E_GL_KHX_shader_explicit_arithmetic_types) ||
                       pp->parseContext.extensionTurnedOn(E_GL_KHX_shader_explicit_arithmetic_types_int64));
    bool enableInt16 = pp->parseContext.version >= 450 &&
                       (
#ifdef AMD_EXTENSIONS
                       pp->parseContext.extensionTurnedOn(E_GL_AMD_gpu_shader_int16) ||
#endif
                       pp->parseContext.extensionTurnedOn(E_GL_KHX_shader_explicit_arithmetic_types) ||
                       pp->parseContext.extensionTurnedOn(E_GL_KHX_shader_explicit_arithmetic_types_int16));
    bool acceptHalf = pp->parseContext.intermediate.getSource() == EShSourceHlsl;
    if (pp->parseContext.version >= 450 &&
        (
#ifdef AMD_EXTENSIONS
         pp->parseContext.extensionTurnedOn(E_GL_AMD_gpu_shader_half_float) ||
#endif
         pp->parseContext.extensionTurnedOn(E_GL_KHX_shader_explicit_arithmetic_types) ||
         pp->parseContext.extensionTurnedOn(E_GL_KHX_shader_explicit_arithmetic_types_float16))) {
        acceptHalf = true;
    }

    const auto floatingPointChar = [&](int ch) { return ch == '.' || ch == 'e' || ch == 'E' ||
                                                                     ch == 'f' || ch == 'F' ||
                                                     (acceptHalf && (ch == 'h' || ch == 'H')); };

    ppToken->ival = 0;
    ppToken->i64val = 0;
    ppToken->space = false;
    ch = getch();
    for (;;) {
        while (ch == ' ' || ch == '\t') {
            ppToken->space = true;
            ch = getch();
        }

        ppToken->loc = pp->parseContext.getCurrentLoc();
        len = 0;
        switch (ch) {
        default:
            // Single character token, including EndOfInput, '#' and '\' (escaped newlines are handled at a lower level, so this is just a '\' token)
            if (ch > PpAtomMaxSingle)
                ch = PpAtomBadToken;
            return ch;

        case 'A': case 'B': case 'C': case 'D': case 'E':
        case 'F': case 'G': case 'H': case 'I': case 'J':
        case 'K': case 'L': case 'M': case 'N': case 'O':
        case 'P': case 'Q': case 'R': case 'S': case 'T':
        case 'U': case 'V': case 'W': case 'X': case 'Y':
        case 'Z': case '_':
        case 'a': case 'b': case 'c': case 'd': case 'e':
        case 'f': case 'g': case 'h': case 'i': case 'j':
        case 'k': case 'l': case 'm': case 'n': case 'o':
        case 'p': case 'q': case 'r': case 's': case 't':
        case 'u': case 'v': case 'w': case 'x': case 'y':
        case 'z':
            do {
                if (len < MaxTokenLength) {
                    ppToken->name[len++] = (char)ch;
                    ch = getch();
                } else {
                    if (! AlreadyComplained) {
                        pp->parseContext.ppError(ppToken->loc, "name too long", "", "");
                        AlreadyComplained = 1;
                    }
                    ch = getch();
                }
            } while ((ch >= 'a' && ch <= 'z') ||
                     (ch >= 'A' && ch <= 'Z') ||
                     (ch >= '0' && ch <= '9') ||
                     ch == '_');

            // line continuation with no token before or after makes len == 0, and need to start over skipping white space, etc.
            if (len == 0)
                continue;

            ppToken->name[len] = '\0';
            ungetch();
            return PpAtomIdentifier;
        case '0':
            ppToken->name[len++] = (char)ch;
            ch = getch();
            if (ch == 'x' || ch == 'X') {
                // must be hexadecimal

                bool isUnsigned = false;
                bool isInt64 = false;
                bool isInt16 = false;
                ppToken->name[len++] = (char)ch;
                ch = getch();
                if ((ch >= '0' && ch <= '9') ||
                    (ch >= 'A' && ch <= 'F') ||
                    (ch >= 'a' && ch <= 'f')) {

                    ival = 0;
                    do {
                        if (ival <= 0x0fffffffu || (enableInt64 && ival <= 0x0fffffffffffffffull)) {
                            ppToken->name[len++] = (char)ch;
                            if (ch >= '0' && ch <= '9') {
                                ii = ch - '0';
                            } else if (ch >= 'A' && ch <= 'F') {
                                ii = ch - 'A' + 10;
                            } else if (ch >= 'a' && ch <= 'f') {
                                ii = ch - 'a' + 10;
                            } else
                                pp->parseContext.ppError(ppToken->loc, "bad digit in hexadecimal literal", "", "");
                            ival = (ival << 4) | ii;
                        } else {
                            if (! AlreadyComplained) {
                                pp->parseContext.ppError(ppToken->loc, "hexadecimal literal too big", "", "");
                                AlreadyComplained = 1;
                            }
                            ival = 0xffffffffffffffffull;
                        }
                        ch = getch();
                    } while ((ch >= '0' && ch <= '9') ||
                             (ch >= 'A' && ch <= 'F') ||
                             (ch >= 'a' && ch <= 'f'));
                } else {
                    pp->parseContext.ppError(ppToken->loc, "bad digit in hexadecimal literal", "", "");
                }
                if (ch == 'u' || ch == 'U') {
                    if (len < MaxTokenLength)
                        ppToken->name[len++] = (char)ch;
                    isUnsigned = true;

                    if (enableInt64) {
                        int nextCh = getch();
                        if ((ch == 'u' || ch == 'U') && (nextCh == 'l' || nextCh == 'L')) {
                            if (len < MaxTokenLength)
                                ppToken->name[len++] = (char)nextCh;
                            isInt64 = true;
                        } else
                            ungetch();
                    }
                    if (enableInt16) {
                        int nextCh = getch();
                        if ((ch == 'u' && nextCh == 's') || (ch == 'U' && nextCh == 'S')) {
                            if (len < MaxTokenLength)
                                ppToken->name[len++] = (char)nextCh;
                            isInt16 = true;
                        } else
                            ungetch();
                    }
                } else if (enableInt64 && (ch == 'l' || ch == 'L')) {
                    if (len < MaxTokenLength)
                        ppToken->name[len++] = (char)ch;
                    isInt64 = true;
                } else if (enableInt16 && (ch == 's' || ch == 'S')) {
                    if (len < MaxTokenLength)
                        ppToken->name[len++] = (char)ch;
                    isInt16 = true;
                } else
                    ungetch();
                ppToken->name[len] = '\0';

                if (isInt64) {
                    ppToken->i64val = ival;
                    return isUnsigned ? PpAtomConstUint64 : PpAtomConstInt64;
                } else if (isInt16) {
                    ppToken->ival = (int)ival;
                    return isUnsigned ? PpAtomConstUint16 : PpAtomConstInt16;
                } else {
                    ppToken->ival = (int)ival;
                    return isUnsigned ? PpAtomConstUint : PpAtomConstInt;
                }
            } else {
                // could be octal integer or floating point, speculative pursue octal until it must be floating point

                bool isUnsigned = false;
                bool isInt64 = false;
                bool isInt16 = false;
                bool octalOverflow = false;
                bool nonOctal = false;
                ival = 0;

                // see how much octal-like stuff we can read
                while (ch >= '0' && ch <= '7') {
                    if (len < MaxTokenLength)
                        ppToken->name[len++] = (char)ch;
                    else if (! AlreadyComplained) {
                        pp->parseContext.ppError(ppToken->loc, "numeric literal too long", "", "");
                        AlreadyComplained = 1;
                    }
                    if (ival <= 0x1fffffffu || (enableInt64 && ival <= 0x1fffffffffffffffull)) {
                        ii = ch - '0';
                        ival = (ival << 3) | ii;
                    } else
                        octalOverflow = true;
                    ch = getch();
                }

                // could be part of a float...
                if (ch == '8' || ch == '9') {
                    nonOctal = true;
                    do {
                        if (len < MaxTokenLength)
                            ppToken->name[len++] = (char)ch;
                        else if (! AlreadyComplained) {
                            pp->parseContext.ppError(ppToken->loc, "numeric literal too long", "", "");
                            AlreadyComplained = 1;
                        }
                        ch = getch();
                    } while (ch >= '0' && ch <= '9');
                }
                if (floatingPointChar(ch))
                    return pp->lFloatConst(len, ch, ppToken);

                // wasn't a float, so must be octal...
                if (nonOctal)
                    pp->parseContext.ppError(ppToken->loc, "octal literal digit too large", "", "");

                if (ch == 'u' || ch == 'U') {
                    if (len < MaxTokenLength)
                        ppToken->name[len++] = (char)ch;
                    isUnsigned = true;

                    if (enableInt64) {
                        int nextCh = getch();
                        if ((ch == 'u' || ch == 'U') && (nextCh == 'l' || nextCh == 'L')) {
                            if (len < MaxTokenLength)
                                ppToken->name[len++] = (char)nextCh;
                            isInt64 = true;
                        } else
                            ungetch();
                    }

                    if (enableInt16) {
                        int nextCh = getch();
                        if ((ch == 'u' && nextCh == 's') || (ch == 'U' && nextCh == 'S')) {
                            if (len < MaxTokenLength)
                                ppToken->name[len++] = (char)nextCh;
                            isInt16 = true;
                        } else
                            ungetch();
                    }
                } else if (enableInt64 && (ch == 'l' || ch == 'L')) {
                    if (len < MaxTokenLength)
                        ppToken->name[len++] = (char)ch;
                    isInt64 = true;
                } else if (enableInt16 && (ch == 's' || ch == 'S')) {
                    if (len < MaxTokenLength)
                        ppToken->name[len++] = (char)ch;
                    isInt16 = true;
                } else
                    ungetch();
                ppToken->name[len] = '\0';

                if (octalOverflow)
                    pp->parseContext.ppError(ppToken->loc, "octal literal too big", "", "");

                if (isInt64) {
                    ppToken->i64val = ival;
                    return isUnsigned ? PpAtomConstUint64 : PpAtomConstInt64;
                } else if (isInt16) {
                    ppToken->ival = (int)ival;
                    return isUnsigned ? PpAtomConstUint16 : PpAtomConstInt16;
                } else {
                    ppToken->ival = (int)ival;
                    return isUnsigned ? PpAtomConstUint : PpAtomConstInt;
                }
            }
            break;
        case '1': case '2': case '3': case '4':
        case '5': case '6': case '7': case '8': case '9':
            // can't be hexadecimal or octal, is either decimal or floating point

            do {
                if (len < MaxTokenLength)
                    ppToken->name[len++] = (char)ch;
                else if (! AlreadyComplained) {
                    pp->parseContext.ppError(ppToken->loc, "numeric literal too long", "", "");
                    AlreadyComplained = 1;
                }
                ch = getch();
            } while (ch >= '0' && ch <= '9');
            if (floatingPointChar(ch))
                return pp->lFloatConst(len, ch, ppToken);
            else {
                // Finish handling signed and unsigned integers
                int numericLen = len;
                bool isUnsigned = false;
                bool isInt64 = false;
                bool isInt16 = false;
                if (ch == 'u' || ch == 'U') {
                    if (len < MaxTokenLength)
                        ppToken->name[len++] = (char)ch;
                    isUnsigned = true;

                    if (enableInt64) {
                        int nextCh = getch();
                        if ((ch == 'u' || ch == 'U') && (nextCh == 'l' || nextCh == 'L')) {
                            if (len < MaxTokenLength)
                                ppToken->name[len++] = (char)nextCh;
                            isInt64 = true;
                        } else
                            ungetch();
                    }

                    if (enableInt16) {
                        int nextCh = getch();
                        if ((ch == 'u' && nextCh == 's') || (ch == 'U' && nextCh == 'S')) {
                            if (len < MaxTokenLength)
                                ppToken->name[len++] = (char)nextCh;
                            isInt16 = true;
                        } else
                            ungetch();
                    }
               } else if (enableInt64 && (ch == 'l' || ch == 'L')) {
                    if (len < MaxTokenLength)
                        ppToken->name[len++] = (char)ch;
                    isInt64 = true;
                } else if (enableInt16 && (ch == 's' || ch == 'S')) {
                    if (len < MaxTokenLength)
                        ppToken->name[len++] = (char)ch;
                    isInt16 = true;
                } else
                    ungetch();

                ppToken->name[len] = '\0';
                ival = 0;
                const unsigned oneTenthMaxInt  = 0xFFFFFFFFu / 10;
                const unsigned remainderMaxInt = 0xFFFFFFFFu - 10 * oneTenthMaxInt;
                const unsigned long long oneTenthMaxInt64  = 0xFFFFFFFFFFFFFFFFull / 10;
                const unsigned long long remainderMaxInt64 = 0xFFFFFFFFFFFFFFFFull - 10 * oneTenthMaxInt64;
                const unsigned short oneTenthMaxInt16  = 0xFFFFu / 10;
                const unsigned short remainderMaxInt16 = 0xFFFFu - 10 * oneTenthMaxInt16;
                for (int i = 0; i < numericLen; i++) {
                    ch = ppToken->name[i] - '0';
                    bool overflow = false;
                    if (isInt64)
                        overflow = (ival > oneTenthMaxInt64 || (ival == oneTenthMaxInt64 && (unsigned long long)ch > remainderMaxInt64));
                    else if (isInt16)
                        overflow = (ival > oneTenthMaxInt16 || (ival == oneTenthMaxInt16 && (unsigned short)ch > remainderMaxInt16));
                    else
                        overflow = (ival > oneTenthMaxInt || (ival == oneTenthMaxInt && (unsigned)ch > remainderMaxInt));
                    if (overflow) {
                        pp->parseContext.ppError(ppToken->loc, "numeric literal too big", "", "");
                        ival = 0xFFFFFFFFFFFFFFFFull;
                        break;
                    } else
                        ival = ival * 10 + ch;
                }

                if (isInt64) {
                    ppToken->i64val = ival;
                    return isUnsigned ? PpAtomConstUint64 : PpAtomConstInt64;
                } else if (isInt16) {
                    ppToken->ival = (int)ival;
                    return isUnsigned ? PpAtomConstUint16 : PpAtomConstInt16;
                } else {
                    ppToken->ival = (int)ival;
                    return isUnsigned ? PpAtomConstUint : PpAtomConstInt;
                }
            }
            break;
        case '-':
            ch = getch();
            if (ch == '-') {
                return PpAtomDecrement;
            } else if (ch == '=') {
                return PPAtomSubAssign;
            } else {
                ungetch();
                return '-';
            }
        case '+':
            ch = getch();
            if (ch == '+') {
                return PpAtomIncrement;
            } else if (ch == '=') {
                return PPAtomAddAssign;
            } else {
                ungetch();
                return '+';
            }
        case '*':
            ch = getch();
            if (ch == '=') {
                return PPAtomMulAssign;
            } else {
                ungetch();
                return '*';
            }
        case '%':
            ch = getch();
            if (ch == '=') {
                return PPAtomModAssign;
            } else {
                ungetch();
                return '%';
            }
        case '^':
            ch = getch();
            if (ch == '^') {
                return PpAtomXor;
            } else {
                if (ch == '=')
                    return PpAtomXorAssign;
                else{
                    ungetch();
                    return '^';
                }
            }

        case '=':
            ch = getch();
            if (ch == '=') {
                return PpAtomEQ;
            } else {
                ungetch();
                return '=';
            }
        case '!':
            ch = getch();
            if (ch == '=') {
                return PpAtomNE;
            } else {
                ungetch();
                return '!';
            }
        case '|':
            ch = getch();
            if (ch == '|') {
                return PpAtomOr;
            } else if (ch == '=') {
                return PpAtomOrAssign;
            } else {
                ungetch();
                return '|';
            }
        case '&':
            ch = getch();
            if (ch == '&') {
                return PpAtomAnd;
            } else if (ch == '=') {
                return PpAtomAndAssign;
            } else {
                ungetch();
                return '&';
            }
        case '<':
            ch = getch();
            if (ch == '<') {
                ch = getch();
                if (ch == '=')
                    return PpAtomLeftAssign;
                else {
                    ungetch();
                    return PpAtomLeft;
                }
            } else if (ch == '=') {
                return PpAtomLE;
            } else {
                ungetch();
                return '<';
            }
        case '>':
            ch = getch();
            if (ch == '>') {
                ch = getch();
                if (ch == '=')
                    return PpAtomRightAssign;
                else {
                    ungetch();
                    return PpAtomRight;
                }
            } else if (ch == '=') {
                return PpAtomGE;
            } else {
                ungetch();
                return '>';
            }
        case '.':
            ch = getch();
            if (ch >= '0' && ch <= '9') {
                ungetch();
                return pp->lFloatConst(0, '.', ppToken);
            } else {
                ungetch();
                return '.';
            }
        case '/':
            ch = getch();
            if (ch == '/') {
                pp->inComment = true;
                do {
                    ch = getch();
                } while (ch != '\n' && ch != EndOfInput);
                ppToken->space = true;
                pp->inComment = false;

                return ch;
            } else if (ch == '*') {
                ch = getch();
                do {
                    while (ch != '*') {
                        if (ch == EndOfInput) {
                            pp->parseContext.ppError(ppToken->loc, "End of input in comment", "comment", "");
                            return ch;
                        }
                        ch = getch();
                    }
                    ch = getch();
                    if (ch == EndOfInput) {
                        pp->parseContext.ppError(ppToken->loc, "End of input in comment", "comment", "");
                        return ch;
                    }
                } while (ch != '/');
                ppToken->space = true;
                // loop again to get the next token...
                break;
            } else if (ch == '=') {
                return PPAtomDivAssign;
            } else {
                ungetch();
                return '/';
            }
            break;
        case '\'':
            return pp->characterLiteral(ppToken);
        case '"':
            // TODO: If this gets enhanced to handle escape sequences, or
            // anything that is different than what #include needs, then
            // #include needs to use scanHeaderName() for this.
            ch = getch();
            while (ch != '"' && ch != '\n' && ch != EndOfInput) {
                if (len < MaxTokenLength) {
                    ppToken->name[len] = (char)ch;
                    len++;
                    ch = getch();
                } else
                    break;
            };
            ppToken->name[len] = '\0';
            if (ch != '"') {
                ungetch();
                pp->parseContext.ppError(ppToken->loc, "End of line in string", "string", "");
            }
            return PpAtomConstString;
        case ':':
            ch = getch();
            if (ch == ':')
                return PpAtomColonColon;
            ungetch();
            return ':';
        }

        ch = getch();
    }
}

//
// The main functional entry point into the preprocessor, which will
// scan the source strings to figure out and return the next processing token.
//
// Return the token, or EndOfInput when no more tokens.
//
int TPpContext::tokenize(TPpToken& ppToken)
{
    for(;;) {
        int token = scanToken(&ppToken);

        // Handle token-pasting logic
        token = tokenPaste(token, ppToken);

        if (token == EndOfInput) {
            missingEndifCheck();
            return EndOfInput;
        }
        if (token == '#') {
            if (previous_token == '\n') {
                token = readCPPline(&ppToken);
                if (token == EndOfInput) {
                    missingEndifCheck();
                    return EndOfInput;
                }
                continue;
            } else {
                parseContext.ppError(ppToken.loc, "preprocessor directive cannot be preceded by another token", "#", "");
                return EndOfInput;
            }
        }
        previous_token = token;

        if (token == '\n')
            continue;

        // expand macros
        if (token == PpAtomIdentifier && MacroExpand(&ppToken, false, true) != 0)
            continue;

        switch (token) {
        case PpAtomIdentifier:
        case PpAtomConstInt:
        case PpAtomConstUint:
        case PpAtomConstFloat:
        case PpAtomConstInt64:
        case PpAtomConstUint64:
        case PpAtomConstInt16:
        case PpAtomConstUint16:
        case PpAtomConstDouble:
        case PpAtomConstFloat16:
            if (ppToken.name[0] == '\0')
                continue;
            break;
        case PpAtomConstString:
            if (parseContext.intermediate.getSource() != EShSourceHlsl) {
                // HLSL allows string literals.
                parseContext.ppError(ppToken.loc, "string literals not supported", "\"\"", "");
                continue;
            }
            break;
        case '\'':
            parseContext.ppError(ppToken.loc, "character literals not supported", "\'", "");
            continue;
        default:
            strcpy(ppToken.name, atomStrings.getString(token));
            break;
        }

        return token;
    }
}

//
// Do all token-pasting related combining of two pasted tokens when getting a
// stream of tokens from a replacement list. Degenerates to no processing if a
// replacement list is not the source of the token stream.
//
int TPpContext::tokenPaste(int token, TPpToken& ppToken)
{
    // starting with ## is illegal, skip to next token
    if (token == PpAtomPaste) {
        parseContext.ppError(ppToken.loc, "unexpected location", "##", "");
        return scanToken(&ppToken);
    }

    int resultToken = token; // "foo" pasted with "35" is an identifier, not a number

    // ## can be chained, process all in the chain at once
    while (peekPasting()) {
        TPpToken pastedPpToken;

        // next token has to be ##
        token = scanToken(&pastedPpToken);
        assert(token == PpAtomPaste);

        // This covers end of macro expansion
        if (endOfReplacementList()) {
            parseContext.ppError(ppToken.loc, "unexpected location; end of replacement list", "##", "");
            break;
        }

        // get the token after the ##
        token = scanToken(&pastedPpToken);

        // This covers end of argument expansion
        if (token == tMarkerInput::marker) {
            parseContext.ppError(ppToken.loc, "unexpected location; end of argument", "##", "");
            break;
        }

        // get the token text
        switch (resultToken) {
        case PpAtomIdentifier:
            // already have the correct text in token.names
            break;
        case '=':
        case '!':
        case '-':
        case '~':
        case '+':
        case '*':
        case '/':
        case '%':
        case '<':
        case '>':
        case '|':
        case '^':
        case '&':
        case PpAtomRight:
        case PpAtomLeft:
        case PpAtomAnd:
        case PpAtomOr:
        case PpAtomXor:
            strcpy(ppToken.name, atomStrings.getString(resultToken));
            strcpy(pastedPpToken.name, atomStrings.getString(token));
            break;
        default:
            parseContext.ppError(ppToken.loc, "not supported for these tokens", "##", "");
            return resultToken;
        }

        // combine the tokens
        if (strlen(ppToken.name) + strlen(pastedPpToken.name) > MaxTokenLength) {
            parseContext.ppError(ppToken.loc, "combined tokens are too long", "##", "");
            return resultToken;
        }
        strncat(ppToken.name, pastedPpToken.name, MaxTokenLength - strlen(ppToken.name));

        // correct the kind of token we are making, if needed (identifiers stay identifiers)
        if (resultToken != PpAtomIdentifier) {
            int newToken = atomStrings.getAtom(ppToken.name);
            if (newToken > 0)
                resultToken = newToken;
            else
                parseContext.ppError(ppToken.loc, "combined token is invalid", "##", "");
        }
    }

    return resultToken;
}

// Checks if we've seen balanced #if...#endif
void TPpContext::missingEndifCheck()
{
    if (ifdepth > 0)
        parseContext.ppError(parseContext.getCurrentLoc(), "missing #endif", "", "");
}

} // end namespace glslang
