/*
  G W A R T  --  GNU version of Wart

  A small subset of "lex" sufficient for converting the Kermit
  protocol state table from lex notation to C.

  Authors:
    Jeff Damens, Frank da Cruz
    The Kermit Project, Columbia University
    http://www.columbia.edu/kermit/
    kermit@columbia.edu

  Copyright (C) 1984, 1999,
  The Trustees of Columbia University in the City of New York.
  Issued under the GNU General Public License as it existed in 1999.

  This program is free software; you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation; either version 2 of the License, or
  (at your option) any later version.

  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.
*/

/*
 * input format is:
 *  lines to be copied | %state <state names...>
 *  %%
 * <state> | <state,state,...> CHAR  { actions }
 * ...
 *  %%
 *  more lines to be copied
 */

#include <stdio.h>
#include <ctype.h>
#include "gkermit.h"

#define TBL_TYPE "short"		/* C data type of state table */

#define C_L 014				/* Formfeed */

#define SEP 1				/* Token types */
#define LBRACK 2
#define RBRACK 3
#define WORD 4
#define COMMA 5

/* Storage sizes */

#define MAXSTATES 50			/* max number of states */
#define MAXWORD 50			/* max # of chars/word */
#define SBYTES ((MAXSTATES+6)/8)	/* # of bytes for state bitmask */

/* Name of gwart function in generated program */

#ifndef FNAME
#define FNAME "gwart"
#endif /* FNAME */

/* Structure for state information */

struct transx {
    CHAR states[SBYTES];		/* included states */
    int anyst;				/* true if this good from any state */
    CHAR inchr;				/* input character */
    int actno;				/* associated action */
    struct transx *nxt;
};					/* next transition */
typedef struct transx *trans;

/* Function prototypes */

_MYPROTOTYPE( VOID fatal, (char *) );
_MYPROTOTYPE( VOID setwstate, (int, trans) );
_MYPROTOTYPE( int teststate, (int, trans) );
_MYPROTOTYPE( trans rdinput, (FILE *, FILE *) );
_MYPROTOTYPE( VOID initial, (FILE *, FILE *) );
_MYPROTOTYPE( int isin, (char *, int) );
_MYPROTOTYPE( int isword, (int) );
_MYPROTOTYPE( VOID rdword, (FILE *, char *) );
_MYPROTOTYPE( VOID rdstates, (FILE *, FILE *) );
_MYPROTOTYPE( trans newtrans, (void) );
_MYPROTOTYPE( trans rdrules, (FILE *, FILE *) );
_MYPROTOTYPE( VOID statelist, (FILE *, trans) );
_MYPROTOTYPE( VOID copyact, (FILE *, FILE *, int) );
_MYPROTOTYPE( int faction, (trans, int, int) );
_MYPROTOTYPE( VOID emptytbl, (void) );
_MYPROTOTYPE( VOID addaction, (int, int, int) );
_MYPROTOTYPE( VOID writetbl, (FILE *) );
_MYPROTOTYPE( VOID warray, (FILE *, char *, int [], int, char *) );
_MYPROTOTYPE( VOID prolog, (FILE *) );
_MYPROTOTYPE( VOID epilogue, (FILE *) );
_MYPROTOTYPE( VOID copyrest, (FILE *, FILE *) );
_MYPROTOTYPE( int gettoken, (FILE *) );
_MYPROTOTYPE( VOID rdcmnt, (FILE *) );
_MYPROTOTYPE( VOID clrhash, (void) );
_MYPROTOTYPE( int hash, (char *) );
_MYPROTOTYPE( VOID enter, (char *, int) );
_MYPROTOTYPE( int lkup, (char *) );
_MYPROTOTYPE( static char* copy, (char *s) );

/* Variables and tables */

int lines, nstates, nacts;
int tbl[MAXSTATES*96];
char tokval[MAXWORD];
char *tbl_type = TBL_TYPE;

char *txt1 = "\n#define BEGIN state =\n\nint state = 0;\n\nint\n";

char *fname = FNAME;			/* Generated function name goes here */

/* Rest of program... */

char *txt2 = "()\n\
{\n\
    int c,actno;\n\
    extern ";

/* Data type of state table is inserted here (short or int) */

char *txt2a =
" tbl[];\n\
    while (1) {\n\
	c = input() - 32;\n\
	if (c < 0 || c > 95) c = 0;\n";

char *txt2b = "	if ((actno = tbl[c + state*96]) != -1)\n\
	    switch(actno) {\n";

/* this program's output goes here, followed by final text... */

char *txt3 = "\n	    }\n    }\n}\n\n";


/*
 * turn on the bit associated with the given state
 *
 */
VOID
setwstate(state,t) int state; trans t; {
    int idx,msk;
    idx = state/8;			/* byte associated with state */
    msk = 0x80 >> (state % 8);		/* bit mask for state */
    t->states[idx] |= msk;
}

/*
 * see if the state is involved in the transition
 *
 */
int
teststate(state,t) int state; trans t; {
    int idx,msk;
    idx = state/8;
    msk = 0x80 >> (state % 8);
    return(t->states[idx] & msk);
}


/*
 * read input from here...
 *
 */

trans
rdinput(infp,outfp) FILE *infp, *outfp; {
    trans x;
    lines = 1;				/* line counter */
    nstates = 0;			/* no states */
    nacts = 0;				/* no actions yet */
    fprintf(outfp,"\n%c* WARNING -- This C source program generated by ",'/');
    fprintf(outfp,"gwart preprocessor. */\n");
    fprintf(outfp,"%c* Do not edit this file; edit the gwart-format ",'/');
    fprintf(outfp,"source file instead, */\n");
    fprintf(outfp,"%c* and then run it through gwart to produce a new ",'/');
    fprintf(outfp,"C source file.     */\n\n");

    initial(infp,outfp);		/* read state names, initial defs */
    prolog(outfp);			/* write out our initial code */
    x = rdrules(infp,outfp);		/* read rules */
    epilogue(outfp);			/* write out epilogue code */
    return(x);
}


/*
 * initial - read initial definitions and state names.  Returns
 * on EOF or %%.
 *
 */
VOID
initial(infp,outfp) FILE *infp, *outfp; {
    int c;
    char wordbuf[MAXWORD];
    while ((c = getc(infp)) != EOF) {
	if (c == '%') {
	    rdword(infp,wordbuf);
	    if (strcmp(wordbuf,"states") == 0)
	      rdstates(infp,outfp);
	    else if (strcmp(wordbuf,"%") == 0) return;
	    else fprintf(outfp,"%%%s",wordbuf);
	}
	else putc(c,outfp);
	if (c == '\n') lines++;
    }
}

/*
 * boolean function to tell if the given character can be part of
 * a word.
 *
 */
int
isin(s,c) char *s; int c; {
    for (; *s != '\0'; s++)
      if (*s == (char) c) return(1);
    return(0);
}
int
isword(c) int c; {
    static char special[] = ".%_-$@";	/* these are allowable */
    return(isalnum(c) || isin(special,c));
}

/*
 * read the next word into the given buffer.
 *
 */
VOID
rdword(fp,buf) FILE *fp; char *buf; {
    int len = 0,c;
    while (isword(c = getc(fp)) && ++len < MAXWORD) *buf++ = (char) c;
    *buf++ = '\0';			/* tie off word */
    ungetc(c,fp);			/* put break char back */
}

/*
 * read state names, up to a newline.
 *
 */
VOID
rdstates(fp,ofp) FILE *fp,*ofp; {
    int c;
    char wordbuf[MAXWORD];
    while ((c = getc(fp)) != EOF && c != '\n') {
	if (isspace(c) || c == C_L) continue;	/* skip whitespace */
	ungetc(c,fp);			/* put char back */
	rdword(fp,wordbuf);		/* read the whole word */
	enter(wordbuf,++nstates);	/* put into symbol tbl */
	fprintf(ofp,"#define %s %d\n",wordbuf,nstates);
    }
    lines++;
}

/*
 * allocate a new, empty transition node
 *
 */
trans
newtrans() {
    trans new;
    int i;
    new = (trans) malloc(sizeof (struct transx));
    for (i=0; i<SBYTES; i++) new->states[i] = 0;
    new->anyst = 0;
    new->nxt = NULL;
    return(new);
}


/*
 * read all the rules.
 *
 */

trans
rdrules(fp,out) FILE *fp,*out; {
    trans head,cur,prev;
    int curtok;
    head = cur = prev = NULL;
    while ((curtok = gettoken(fp)) != SEP)

      switch(curtok) {
	case LBRACK:
	  if (cur == NULL)
	    cur = newtrans();
	  else
	    fatal("duplicate state list");
	  statelist(fp,cur);		/* set states */
	  continue;			/* prepare to read char */

	case WORD:
	  if ((int)strlen(tokval) != 1)
	    fatal("multiple chars in state");
	  if (cur == NULL) {
	      cur = newtrans();
	      cur->anyst = 1;
	  }
	  cur->actno = ++nacts;
	  cur->inchr = (char) (tokval[0] - 32);
	  if (head == NULL)
	    head = cur;
	  else
	    prev->nxt = cur;
	  prev = cur;
	  cur = NULL;
	  copyact(fp,out,nacts);
	  break;
	default: fatal("bad input format");
      }
    return(head);
}

/*
 * read a list of (comma-separated) states, set them in the
 * given transition.
 *
 */
VOID
statelist(fp,t) FILE *fp; trans t; {
    int curtok,sval;
    curtok = COMMA;
    while (curtok != RBRACK) {
	if (curtok != COMMA) fatal("missing comma");
	if ((curtok = gettoken(fp)) != WORD) fatal("missing state name");
	if ((sval = lkup(tokval)) == -1) {
	    fprintf(stderr,"state %s undefined\n",tokval);
	    fatal("undefined state");
	}
	setwstate(sval,t);
	curtok = gettoken(fp);
    }
}

/*
 * copy an action from the input to the output file
 *
 */
VOID
copyact(inp,outp,actno) FILE *inp,*outp; int actno; {
    int c,bcnt;
    fprintf(outp,"case %d:\n",actno);
    while (c = getc(inp), (isspace(c) || c == C_L))
      if (c == '\n') lines++;
    if (c == '{') {
	bcnt = 1;
	fputs("    {",outp);
	while (bcnt > 0 && (c = getc(inp)) != EOF) {
	    if (c == '{') bcnt++;
	    else if (c == '}') bcnt--;
	    else if (c == '\n') lines++;
	    putc(c,outp);
	}
	if (bcnt > 0) fatal("action doesn't end");
    } else {
	while (c != '\n' && c != EOF) {
	    putc(c,outp);
	    c = getc(inp);
	}
	lines++;
    }
    fprintf(outp,"\n    break;\n");
}

/*
 * find the action associated with a given character and state.
 * returns -1 if one can't be found.
 *
 */
int
faction(hd,state,chr) trans hd; int state,chr; {
    while (hd != NULL) {
	if (hd->anyst || teststate(state,hd))
	  if (hd->inchr == ('.' - 32) || hd->inchr == (char) chr)
	    return(hd->actno);
	hd = hd->nxt;
    }
    return(-1);
}

/*
 * empty the table...
 *
 */
VOID
emptytbl() {
    int i;
    for (i=0; i<nstates*96; i++) tbl[i] = -1;
}

/*
 * add the specified action to the output for the given state and chr.
 *
 */
VOID
addaction(act,state,chr) int act,state,chr; {
    tbl[state*96 + chr] = act;
}

VOID
writetbl(fp) FILE *fp; {
    warray(fp,"tbl",tbl,96*(nstates+1),TBL_TYPE);
}


/*
 * write an array to the output file, given its name and size.
 *
 */
VOID
warray(fp,nam,cont,siz,typ) FILE *fp; char *nam; int cont[],siz; char *typ; {
    int i;
    fprintf(fp,"%s %s[] = {\n",typ,nam);
    for (i = 0; i < siz - 1; ) {
	fprintf(fp," %2d,",cont[i]);
	if ((++i % 16) == 0) putc('\n',fp);
    }
    fprintf(fp,"%2d\n};\n",cont[siz-1]);
}

int
main(argc,argv) int argc; char **argv; {
    trans head;
    int state,c;
    FILE *infile,*outfile;

    if (argc > 1) {
	if ((infile = fopen(argv[1],"r")) == NULL) {
	    fprintf(stderr,"Can't open %s\n",argv[1]);
	    fatal("unreadable input file");
	}
    } else infile = stdin;

    if (argc > 2) {
	if ((outfile = fopen(argv[2],"w")) == NULL) {
	    fprintf(stderr,"Can't write to %s\n",argv[2]);
	    fatal("bad output file");
	}
    } else outfile = stdout;

    clrhash();				/* empty hash table */
    head = rdinput(infile,outfile);	/* read input file */
    emptytbl();				/* empty our tables */
    for (state = 0; state <= nstates; state++)
      for (c = 1; c < 96; c++)		/* find actions, */
	addaction(faction(head,state,c),state,c); /* add to tbl */
    writetbl(outfile);
    copyrest(infile,outfile);
    printf("%d states, %d actions\n",nstates,nacts);
    exit(0);
}


/*
 * fatal error handler
 *
 */

VOID
fatal(msg) char *msg; {
    fprintf(stderr,"error in line %d: %s\n",lines,msg);
    exit(1);
}

VOID
prolog(outfp) FILE *outfp; {
    int c;
    while ((c = *txt1++)     != '\0') putc(c,outfp);
    while ((c = *fname++)    != '\0') putc(c,outfp);
    while ((c = *txt2++)     != '\0') putc(c,outfp);
    while ((c = *tbl_type++) != '\0') putc(c,outfp);
    while ((c = *txt2a++)    != '\0') putc(c,outfp);
    while ((c = *txt2b++)    != '\0') putc(c,outfp);
}

VOID
epilogue(outfp) FILE *outfp; {
    int c;
    while ((c = *txt3++) != '\0') putc(c,outfp);
}

VOID
copyrest(in,out) FILE *in,*out; {
    int c;
    while ((c = getc(in)) != EOF) putc(c,out);
}

/*
 * gettoken - returns token type of next token, sets tokval
 * to the string value of the token if appropriate.
 *
 */

int
gettoken(fp) FILE *fp; {
    int c;
    while (1) {				/* loop if reading comments... */
	do {
	    c = getc(fp);
	    if (c == '\n') lines++;
	} while ((isspace(c) || c == C_L)); /* skip whitespace */
	switch(c) {
	  case EOF:
	    return(SEP);
	  case '%':
	    if ((c = getc(fp)) == '%') return(SEP);
	    tokval[0] = '%';
	    tokval[1] = (char) c;
	    rdword(fp,tokval+2);
	    return(WORD);
	  case '<':
	    return(LBRACK);
	  case '>':
	    return(RBRACK);
	  case ',':
	    return(COMMA);
	  case '/':
	    if ((c = getc(fp)) == '*') {
		rdcmnt(fp);		/* skip over the comment */
		continue;
	    } else {			/* and keep looping */
		ungetc(c,fp);		/* put this back into input */
		c = '/';		/* put character back, fall thru */
	    }

	  default:
	    if (isword(c)) {
		ungetc(c,fp);
		rdword(fp,tokval);
		return(WORD);
	    } else fatal("Invalid character in input");
	}
    }
}

/*
 * skip over a comment
 *
 */

VOID
rdcmnt(fp) FILE *fp; {
    int c,star,prcnt;
    prcnt = star = 0;			/* no star seen yet */
    while (!((c = getc(fp)) == '/' && star)) {
	if (c == EOF || (prcnt && c == '%')) fatal("Unterminated comment");
	prcnt = (c == '%');
	star = (c == '*');
	if (c == '\n') lines++;
    }
}

/*
 * symbol table management for gwart
 *
 * entry points:
 *   clrhash - empty hash table.
 *   enter - enter a name into the symbol table
 *   lkup - find a name's value in the symbol table.
 */
#define HASHSIZE 101			/* # of entries in hash table */

struct sym {
    char *name;				/* symbol name */
    int val;				/* value */
    struct sym *hnxt;			/* next on collision chain */
} *htab[HASHSIZE];			/* the hash table */

/*
 * empty the hash table before using it...
 *
 */
VOID
clrhash() {
    int i;
    for (i=0; i<HASHSIZE; i++) htab[i] = NULL;
}

/*
 * compute the value of the hash for a symbol
 *
 */
int
hash(name) char *name; {
    int sum;
    for (sum = 0; *name != '\0'; name++) sum += (sum + *name);
    sum %= HASHSIZE;			/* take sum mod hashsize */
    if (sum < 0) sum += HASHSIZE;	/* disallow negative hash value */
    return(sum);
}

/*
 * make a private copy of a string...
 *
 */
static char*
copy(s) char *s; {
    char *new;
    new = (char *) malloc((int)strlen(s) + 1);
    strcpy(new,s);
    return(new);
}

/*
 * enter state name into the hash table
 *
 */
VOID
enter(name,svalue) char *name; int svalue; {
    int h;
    struct sym *cur;
    if (lkup(name) != -1) {
	fprintf(stderr,"state \"%s\" appears twice...\n", name);
	exit(1);
    }
    h = hash(name);
    cur = (struct sym *)malloc(sizeof (struct sym));
    cur->name = copy(name);
    cur->val = svalue;
    cur->hnxt = htab[h];
    htab[h] = cur;
}

/*
 * find name in the symbol table, return its value.  Returns -1
 * if not found.
 *
 */
int
lkup(name) char *name; {
    struct sym *cur;
    for (cur = htab[hash(name)]; cur != NULL; cur = cur->hnxt)
      if (strcmp(cur->name,name) == 0) return(cur->val);
    return(-1);
}