#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#if (defined(_WIN32) || defined(_MSDOS) || defined(__IBMC__)) && !(defined S390)
#include <io.h>
#else
#include <unistd.h>
#endif
#include "cpp.h"

/*
 * lexical FSM encoding
 *   when in state state, and one of the characters
 *   in ch arrives, enter nextstate.
 *   States >= S_SELF are either final, or at least require special action.
 *   In 'fsm' there is a line for each state X charset X nextstate.
 *   List chars that overwrite previous entries later (e.g. C_ALPH
 *   can be overridden by '_' by a later entry; and C_XX is the
 *   the universal set, and should always be first.
 *   States above S_SELF are represented in the big table as negative values.
 *   S_SELF and S_SELFB encode the resulting token type in the upper bits.
 *   These actions differ in that S_SELF doesn't have a lookahead char,
 *   S_SELFB does.
 *
 *   The encoding is blown out into a big table for time-efficiency.
 *   Entries have
 *      nextstate: 6 bits; ?\ marker: 1 bit; tokentype: 9 bits.
 */

#define MAXSTATE        32
#define ACT(tok,act)    ((tok<<7)+act)
#define QBSBIT          0100
#define GETACT(st)      (st>>7)&0x1ff

/* character classes */
#define C_WS    1
#define C_ALPH  2
#define C_NUM   3
#define C_EOF   4
#ifdef S390
#define C_XX    6
#else
#define C_XX    5
#endif

enum state
{
    START = 0, NUM1, NUM2, NUM3, ID1, ST1, ST2, ST3, COM1, COM2, COM3, COM4,
    CC1, CC2, WS1, PLUS1, MINUS1, STAR1, SLASH1, PCT1, SHARP1,
    CIRC1, GT1, GT2, LT1, LT2, OR1, AND1, ASG1, NOT1, DOTS1,
    S_SELF = MAXSTATE, S_SELFB, S_EOF, S_NL, S_EOFSTR,
    S_STNL, S_COMNL, S_EOFCOM, S_COMMENT, S_EOB, S_WS, S_NAME
};

int tottok;
int tokkind[256];
struct fsm
{
    int state;                          /* if in this state */
    uchar ch[4];                        /* and see one of these characters */
    int nextstate;                      /* enter this state if +ve */
};

 /*const*/ struct fsm fsm[] = {
    /* start state */
    START, {C_XX}, ACT(UNCLASS, S_SELF),
    START, {' ', '\t', '\v'}, WS1,
    START, {C_NUM}, NUM1,
    START, {'.'}, NUM3,
    START, {C_ALPH}, ID1,
    START, {'L'}, ST1,
    START, {'"'}, ST2,
    START, {'\''}, CC1,
    START, {'/'}, COM1,
    START, {EOFC}, S_EOF,
    START, {'\n'}, S_NL,
    START, {'-'}, MINUS1,
    START, {'+'}, PLUS1,
    START, {'<'}, LT1,
    START, {'>'}, GT1,
    START, {'='}, ASG1,
    START, {'!'}, NOT1,
    START, {'&'}, AND1,
    START, {'|'}, OR1,
    START, {'#'}, SHARP1,
    START, {'%'}, PCT1,
    START, {'['}, ACT(SBRA, S_SELF),
    START, {']'}, ACT(SKET, S_SELF),
    START, {'('}, ACT(LP, S_SELF),
    START, {')'}, ACT(RP, S_SELF),
    START, {'*'}, STAR1,
    START, {','}, ACT(COMMA, S_SELF),
    START, {'?'}, ACT(QUEST, S_SELF),
    START, {':'}, ACT(COLON, S_SELF),
    START, {';'}, ACT(SEMIC, S_SELF),
    START, {'{'}, ACT(CBRA, S_SELF),
    START, {'}'}, ACT(CKET, S_SELF),
    START, {'~'}, ACT(TILDE, S_SELF),
    START, {'^'}, CIRC1,

    /* saw a digit */
    NUM1, {C_XX}, ACT(NUMBER, S_SELFB),
    NUM1, {C_NUM, C_ALPH, '.'}, NUM1,
    NUM1, {'E', 'e'}, NUM2,
    NUM1, {'_'}, ACT(NUMBER, S_SELFB),

    /* saw possible start of exponent, digits-e */
    NUM2, {C_XX}, ACT(NUMBER, S_SELFB),
    NUM2, {'+', '-'}, NUM1,
    NUM2, {C_NUM, C_ALPH}, NUM1,
    NUM2, {'_'}, ACT(NUMBER, S_SELFB),

    /* saw a '.', which could be a number or an operator */
    NUM3, {C_XX}, ACT(DOT, S_SELFB),
    NUM3, {'.'}, DOTS1,
    NUM3, {C_NUM}, NUM1,

    DOTS1, {C_XX}, ACT(UNCLASS, S_SELFB),
    DOTS1, {C_NUM}, NUM1,
    DOTS1, {'.'}, ACT(ELLIPS, S_SELF),

    /* saw a letter or _ */
    ID1, {C_XX}, ACT(NAME, S_NAME),
    ID1, {C_ALPH, C_NUM}, ID1,

    /* saw L (start of wide string?) */
    ST1, {C_XX}, ACT(NAME, S_NAME),
    ST1, {C_ALPH, C_NUM}, ID1,
    ST1, {'"'}, ST2,
    ST1, {'\''}, CC1,

    /* saw " beginning string */
    ST2, {C_XX}, ST2,
    ST2, {'"'}, ACT(STRING, S_SELF),
    ST2, {'\\'}, ST3,
    ST2, {'\n'}, S_STNL,
    ST2, {EOFC}, S_EOFSTR,

    /* saw \ in string */
    ST3, {C_XX}, ST2,
    ST3, {'\n'}, S_STNL,
    ST3, {EOFC}, S_EOFSTR,

    /* saw ' beginning character const */
    CC1, {C_XX}, CC1,
    CC1, {'\''}, ACT(CCON, S_SELF),
    CC1, {'\\'}, CC2,
    CC1, {'\n'}, S_STNL,
    CC1, {EOFC}, S_EOFSTR,

    /* saw \ in ccon */
    CC2, {C_XX}, CC1,
    CC2, {'\n'}, S_STNL,
    CC2, {EOFC}, S_EOFSTR,

    /* saw /, perhaps start of comment */
    COM1, {C_XX}, ACT(SLASH, S_SELFB),
    COM1, {'='}, ACT(ASSLASH, S_SELF),
    COM1, {'*'}, COM2,
    COM1, {'/'}, COM4,

    /* saw "/*", start of comment */
    COM2, {C_XX}, COM2,
    COM2, {'\n'}, S_COMNL,
    COM2, {'*'}, COM3,
    COM2, {EOFC}, S_EOFCOM,

    /* saw the * possibly ending a comment */
    COM3, {C_XX}, COM2,
    COM3, {'\n'}, S_COMNL,
    COM3, {'*'}, COM3,
    COM3, {'/'}, S_COMMENT,

    /* // comment */
    COM4, {C_XX}, COM4,
    COM4, {'\n'}, S_NL,
    COM4, {EOFC}, S_EOFCOM,

    /* saw white space, eat it up */
    WS1, {C_XX}, S_WS,
    WS1, {'\t', '\v', ' '}, WS1,

    /* saw -, check --, -=, -> */
    MINUS1, {C_XX}, ACT(MINUS, S_SELFB),
    MINUS1, {'-'}, ACT(MMINUS, S_SELF),
    MINUS1, {'='}, ACT(ASMINUS, S_SELF),
    MINUS1, {'>'}, ACT(ARROW, S_SELF),

    /* saw +, check ++, += */
    PLUS1, {C_XX}, ACT(PLUS, S_SELFB),
    PLUS1, {'+'}, ACT(PPLUS, S_SELF),
    PLUS1, {'='}, ACT(ASPLUS, S_SELF),

    /* saw <, check <<, <<=, <= */
    LT1, {C_XX}, ACT(LT, S_SELFB),
    LT1, {'<'}, LT2,
    LT1, {'='}, ACT(LEQ, S_SELF),
    LT2, {C_XX}, ACT(LSH, S_SELFB),
    LT2, {'='}, ACT(ASLSH, S_SELF),

    /* saw >, check >>, >>=, >= */
    GT1, {C_XX}, ACT(GT, S_SELFB),
    GT1, {'>'}, GT2,
    GT1, {'='}, ACT(GEQ, S_SELF),
    GT2, {C_XX}, ACT(RSH, S_SELFB),
    GT2, {'='}, ACT(ASRSH, S_SELF),

    /* = */
    ASG1, {C_XX}, ACT(ASGN, S_SELFB),
    ASG1, {'='}, ACT(EQ, S_SELF),

    /* ! */
    NOT1, {C_XX}, ACT(NOT, S_SELFB),
    NOT1, {'='}, ACT(NEQ, S_SELF),

    /* & */
    AND1, {C_XX}, ACT(AND, S_SELFB),
    AND1, {'&'}, ACT(LAND, S_SELF),
    AND1, {'='}, ACT(ASAND, S_SELF),

    /* | */
    OR1, {C_XX}, ACT(OR, S_SELFB),
    OR1, {'|'}, ACT(LOR, S_SELF),
    OR1, {'='}, ACT(ASOR, S_SELF),

    /* # */
    SHARP1, {C_XX}, ACT(SHARP, S_SELFB),
    SHARP1, {'#'}, ACT(DSHARP, S_SELF),

    /* % */
    PCT1, {C_XX}, ACT(PCT, S_SELFB),
    PCT1, {'='}, ACT(ASPCT, S_SELF),

    /* * */
    STAR1, {C_XX}, ACT(STAR, S_SELFB),
    STAR1, {'='}, ACT(ASSTAR, S_SELF),

    /* ^ */
    CIRC1, {C_XX}, ACT(CIRC, S_SELFB),
    CIRC1, {'='}, ACT(ASCIRC, S_SELF),

    -1
};

/* first index is char, second is state */
/* increase #states to power of 2 to encourage use of shift */
short bigfsm[256][MAXSTATE];

void
    expandlex(void)
{
     /* const */ struct fsm *fp;
    int i, j, nstate;

    for (fp = fsm; fp->state >= 0; fp++)
    {
        for (i = 0; fp->ch[i]; i++)
        {
            nstate = fp->nextstate;
            if (nstate >= S_SELF)
                nstate = ~nstate;
            switch (fp->ch[i])
            {

                case C_XX:              /* random characters */
                    for (j = 0; j < 256; j++)
                        bigfsm[j][fp->state] = nstate;
                    continue;
                case C_ALPH:
                    for (j = 0; j <= 256; j++)
#ifdef S390
                        if( isalpha( j ) || (j == '_') )
#else
                        if ('a' <= j && j <= 'z' || 'A' <= j && j <= 'Z'
                            || j == '_')
#endif
                            bigfsm[j][fp->state] = nstate;
                    continue;
                case C_NUM:
                    for (j = '0'; j <= '9'; j++)
                        bigfsm[j][fp->state] = nstate;
                    continue;
                default:
                    bigfsm[fp->ch[i]][fp->state] = nstate;
            }
        }
    }

    /*
     * install special cases for ? (trigraphs),  \ (splicing), runes, and
     * EOB
     */
    for (i = 0; i < MAXSTATE; i++)
    {
        for (j = 0; j < 0xFF; j++)
            if (j == '?' || j == '\\' || j == '\n' || j == '\r')
            {
                if (bigfsm[j][i] > 0)
                    bigfsm[j][i] = ~bigfsm[j][i];
                bigfsm[j][i] &= ~QBSBIT;
            }
        bigfsm[EOB][i] = ~S_EOB;
        if (bigfsm[EOFC][i] >= 0)
            bigfsm[EOFC][i] = ~S_EOF;
    }
}

void
    fixlex(void)
{
    /* do C++ comments? */
    if ((Cplusplus == 0) || (Cflag != 0))
        bigfsm['/'][COM1] = bigfsm['x'][COM1];
}

/*
 * fill in a row of tokens from input, terminated by NL or END
 * First token is put at trp->lp.
 * Reset is non-zero when the input buffer can be "rewound."
 * The value is a flag indicating that possible macros have
 * been seen in the row.
 */
int
    gettokens(Tokenrow * trp, int reset)
{
    register int c, state, oldstate;
    register uchar *ip;
    register Token *tp, *maxp;
    int runelen;
    Source *s = cursource;
    int nmac = 0;
    extern char outbuf[];

    tp = trp->lp;
    ip = s->inp;
    if (reset)
    {
        s->lineinc = 0;
        if (ip >= s->inl)
        {                               /* nothing in buffer */
            s->inl = s->inb;
            fillbuf(s);
            ip = s->inp = s->inb;
        }
        else
            if (ip >= s->inb + (3 * INS / 4))
            {
                memmove(s->inb, ip, 4 + s->inl - ip);
                s->inl = s->inb + (s->inl - ip);
                ip = s->inp = s->inb;
            }
    }
    maxp = &trp->bp[trp->max];
    runelen = 1;  /* S390: XDBX stürzt ab! */
    for (;;)
    {
continue2:
        if (tp >= maxp)
        {
            trp->lp = tp;
            tp = growtokenrow(trp);
            maxp = &trp->bp[trp->max];
        }
        tp->type = UNCLASS;
        tp->t = ip;
        tp->wslen = 0;
        tp->flag = 0;
        state = START;
        for (;;)
        {
            oldstate = state;

            c = *ip;  /* S390: XDBX stürzt (gelegentlich) ab! */

            if ((state = bigfsm[c][state]) >= 0)
            {
                ip += runelen;
                runelen = 1;
                continue;
            }
            state = ~state;
    reswitch:
            switch (state & 0177)
            {
                case S_SELF:
                    ip += runelen;
                    runelen = 1;
                case S_SELFB:
                    tp->type = GETACT(state);
                    tp->len = ip - tp->t;
                    tp++;
                    goto continue2;

                case S_NAME:            /* like S_SELFB but with nmac check */
                    tp->type = NAME;
                    tp->len = ip - tp->t;
                    nmac |= quicklook(tp->t[0], tp->len > 1 ? tp->t[1] : 0);
                    tp++;
                    goto continue2;

                case S_WS:
                    tp->wslen = ip - tp->t;
                    tp->t = ip;
                    state = START;
                    continue;

                default:
                    if ((state & QBSBIT) == 0)
                    {
                        ip += runelen;
                        runelen = 1;
                        continue;
                    }
                    state &= ~QBSBIT;
                    s->inp = ip;

                    if (c == '\n')
                    {
                        while (s->inp + 1 >= s->inl && fillbuf(s) != EOF); /* S390: XDBX stürzt (manchmal) ab! */

                        if (s->inp[1] == '\r')
                        {
                            memmove(s->inp + 1, s->inp + 2, s->inl - s->inp + 2);
                            s->inl -= 1;
                        }

                        goto reswitch;
                    }

                    if (c == '\r')
                    {
                        while (s->inp + 1 >= s->inl && fillbuf(s) != EOF);

                        if (s->inp[1] == '\n')
                        {
                            memmove(s->inp, s->inp + 1, s->inl - s->inp + 1);
                            s->inl -= 1;
                        }
                        else
                            *s->inp = '\n';

                        state = oldstate;
                        continue;
                    }

                    if (c == '?')
                    {                   /* check trigraph */
                        if (trigraph(s))
                        {
                            state = oldstate;
                            continue;
                        }
                        goto reswitch;
                    }
                    if (c == '\\')
                    {                   /* line-folding */
                        if (foldline(s))
                        {
                            s->lineinc++;
                            state = oldstate;
                            continue;
                        }
                        goto reswitch;
                    }
                    error(WARNING, "Lexical botch in cpp");
                    ip += runelen;
                    runelen = 1;
                    continue;

                case S_EOB:
                    s->inp = ip;
                    fillbuf(cursource);
                    state = oldstate;
                    continue;

                case S_EOF:
                    tp->type = END;
                    tp->len = 0;
                    s->inp = ip;
                    if (tp != trp->bp && (tp - 1)->type != NL && cursource->fd != -1)
                        error(WARNING, "No newline at end of file");
                    trp->lp = tp + 1;
                    return nmac;

                case S_STNL:
                    error(ERROR, "Unterminated string or char const");
                case S_NL:
                    tp->t = ip;
                    tp->type = NL;
                    tp->len = 1;
                    tp->wslen = 0;
                    s->lineinc++;
                    s->inp = ip + 1;
                    trp->lp = tp + 1;
                    return nmac;

                case S_EOFSTR:
                    error(FATAL, "EOF in string or char constant");
                    break;

                case S_COMNL:
                    s->lineinc++;
                    state = COM2;
                    ip += runelen;
                    runelen = 1;
                    continue;

                case S_EOFCOM:
                    error(WARNING, "EOF inside comment");
                    --ip;
                case S_COMMENT:
                    if (!Cflag)
                    {
                        tp->t = ++ip;
                        tp->t[-1] = ' ';
                        tp->wslen = 1;
                        state = START;
                        continue;
                    }
                    else
                    {
                        runelen = 1;
                        s->lineinc = 0;;
                        tp->type = COMMENT;
                        tp->flag |= XTWS;
                    }
            }
            break;
        }
        ip += runelen;
        runelen = 1;
        tp->len = ip - tp->t;
        tp++;
    }
}

/* have seen ?; handle the trigraph it starts (if any) else 0 */
int
    trigraph(Source * s)
{
    int c;

    while (s->inp + 2 >= s->inl && fillbuf(s) != EOF);
    ;
    if (s->inp[1] != '?')
        return 0;
    c = 0;
    switch (s->inp[2])
    {
        case '=':
            c = '#';
            break;
        case '(':
            c = '[';
            break;
        case '/':
            c = '\\';
            break;
        case ')':
            c = ']';
            break;
        case '\'':
            c = '^';
            break;
        case '<':
            c = '{';
            break;
        case '!':
            c = '|';
            break;
        case '>':
            c = '}';
            break;
        case '-':
            c = '~';
            break;
    }
    if (c)
    {
        *s->inp = c;
        memmove(s->inp + 1, s->inp + 3, s->inl - s->inp + 2);
        s->inl -= 2;
    }
    return c;
}

int
    foldline(Source * s)
{
    int n = 1;

    /* skip pending wihite spaces */
    while ((s->inp[n] == ' ') || (s->inp[n] == '\t'))
    {
        n++;
        if ((s->inp + n >= s->inl) && (fillbuf(s) == EOF))
            break;
    }

    /* refill buffer */
    while (s->inp + (n + 1) >= s->inl && fillbuf(s) != EOF);

    /* skip DOS line ends */
    if (((s->inp[n] == '\r') && (s->inp[n+1] == '\n')) ||
        ((s->inp[n] == '\n') && (s->inp[n+1] == '\r')))
        n++;

    if ((s->inp[n] == '\n') || (s->inp[n] == '\r'))
    {
        memmove(s->inp, s->inp + n + 1, s->inl - s->inp + n + 2);
        s->inl -= n + 1;
        return 1;
    }
    return 0;
}

int
    fillbuf(Source * s)
{
    int n;

    if (s->fd < 0 || (n = read(s->fd, (char *) s->inl, INS / 8)) <= 0)
        n = 0;
    s->inl += n;
    s->inl[0] = s->inl[1] = s->inl[2] = s->inl[3] = EOB;
    if (n == 0)
    {
        s->inl[0] = s->inl[1] = s->inl[2] = s->inl[3] = EOFC;
        return EOF;
    }
    return 0;
}

/*
 * Push down to new source of characters.
 * If fd>0 and str==NULL, then from a file `name';
 * if fd==-1 and str, then from the string.
 */
Source *
    setsource(char *name, int path, int fd, char *str, int wrap)
{
    Source *s = new(Source);
    int len;

    s->line = 1;
    s->lineinc = 0;
    s->fd = fd;
    s->filename = name;
    s->next = cursource;
    s->ifdepth = 0;
    s->pathdepth = path;
    s->wrap = wrap;

    cursource = s;

    if (s->wrap)
        genwrap(0);

    /* slop at right for EOB */
    if (str)
    {
        len = strlen(str);
        s->inb = domalloc(len + 4);
        s->inp = s->inb;
        strncpy((char *) s->inp, str, len);
    }
    else
    {
        s->inb = domalloc(INS + 4);
        s->inp = s->inb;
        len = 0;
    }
    s->inl = s->inp + len;
    s->inl[0] = s->inl[1] = EOB;

    return s;
}

void
    unsetsource(void)
{
    Source *s = cursource;

    if (s->wrap)
        genwrap(1);

    if (s->fd >= 0)
    {
        close(s->fd);
        dofree(s->inb);
    }
    cursource = s->next;
    dofree(s);
}