/* xlread - xlisp expression input routine */
/*        Copyright (c) 1985, by David Michael Betz
          All Rights Reserved
          Permission is granted for unrestricted non-commercial use   */

#include "flp1_xlisp_h"

#ifdef MEGAMAX
overlay "io"
#endif

/* external variables */
extern NODE *s_stdout,*true,*s_dot;
extern NODE *s_quote,*s_function,*s_bquote,*s_comma,*s_comat;
extern NODE *s_rtable,*k_wspace,*k_const,*k_nmacro,*k_tmacro;
extern int xlplevel;
extern char buf[];

/* external routines */
extern FILE *fopen();
extern double atof();
extern ITYPE;

#define WSPACE "\t \f\r\n"
#define CONST1 "!$%&*+-./0123456789:<=>?@[]^_{}~"
#define CONST2 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"

/* forward declarations */
FORWARD NODE *callmacro();
FORWARD NODE *phexnumber(),*pquote(),*plist(),*pvector(),*pname();
FORWARD NODE *tentry();

/* xlload - load a file of xlisp expressions */
int xlload(fname,vflag,pflag)
  char *fname; int vflag,pflag;
{
    NODE ***oldstk,*fptr,*expr;
    char fullname[STRMAX+1];
    CONTEXT cntxt;
    FILE *fp;
    int sts;

    /* create a new stack frame */
    oldstk = xlstack;
    xlstkcheck(2);
    xlsave(fptr);
    xlsave(expr);

    /* create the full file name */
    if (needsdrive(fname)) {
          strcpy(fullname,"FLP1_");
          strcat(fullname,fname);
          fname = fullname;
    }
    /* create the full file name */
    if (needsextension(fname)) {
          strcpy(fullname,fname);
          strcat(fullname,".lsp");
          fname = fullname;
    }

    /* allocate a file node */
    fptr = cvfile(NULL);

    /* print the information line */
    if (vflag)
          { sprintf(buf,"; loading \"%s\"\n",fname); stdputstr(buf); }

    /* open the file */
    if ((fp=fopen(fname,"r")) == NULL) {
          xlstack = oldstk;
          return (FALSE);
    }
    setfile(fptr,fp);

    /* read, evaluate and possibly print each expression in the file */
    xlbegin(&cntxt,CF_ERROR,true);
    if (setjmp(cntxt.c_jmpbuf))
          sts = FALSE;
    else {
          while (xlread(fptr,&expr,FALSE)) {
              expr = xleval(expr);
              if (pflag)
                    stdprint(expr);
          }
          sts = TRUE;
    }
    xlend(&cntxt);

    /* close the file */
    fclose(getfile(fptr));
    setfile(fptr,NULL);

    /* restore the previous stack frame */
    xlstack = oldstk;

    /* return status */
    return (sts);
}

/* xlread - read an xlisp expression */
int xlread(fptr,pval,rflag)
  NODE *fptr,**pval; int rflag;
{
    int sts;

    /* reset the paren nesting level */
    if (!rflag)
          xlplevel = 0;

    /* read an expression */
    while ((sts = readone(fptr,pval)) == FALSE)
          ;

    /* return status */
    return (sts == EOF ? FALSE : TRUE);
}

/* readone - attempt to read a single expression */
int readone(fptr,pval)
  NODE *fptr,**pval;
{
    NODE *val,*type;
    int ch;

    /* get a character and check for EOF */
    if ((ch = xlgetc(fptr)) == EOF)
          return (EOF);

    /* handle white space */
    if ((type = tentry(ch)) == k_wspace)
          return (FALSE);

    /* handle symbol constituents */
    else if (type == k_const) {
          *pval = pname(fptr,ch);
          return (TRUE);
    }

    /* handle read macros */
    else if (consp(type)) {
          if ((val = callmacro(fptr,ch)) && consp(val)) {
              *pval = car(val);
              return (TRUE);
          }
          else
              return (FALSE);
    }

    /* handle illegal characters */
    else
          xlerror("illegal character",cvfixnum((FIXNUM)ch));
}

/* rmhash - read macro for '#' */
NODE *rmhash(args)
  NODE *args;
{
    NODE ***oldstk,*fptr,*mch,*val;
    int ch;

    /* create a new stack frame */
    oldstk = xlstack;
    xlsave1(val);

    /* get the file and macro character */
    fptr = xlgetfile(&args);
    mch = xlmatch(INT,&args);
    xllastarg(args);

    /* make the return value */
    val = consa(NIL);

    /* check the next character */
    switch (ch = xlgetc(fptr)) {
    case '\'':
                    rplaca(val,pquote(fptr,s_function));
                    break;
    case '(':
                    rplaca(val,pvector(fptr));
                    break;
    case 'x':
    case 'X':
                    rplaca(val,phexnumber(fptr));
                    break;
    case '\\':
                    rplaca(val,cvfixnum((FIXNUM)xlgetc(fptr)));
                    break;
    default:
                    xlerror("illegal character after #",cvfixnum((FIXNUM)ch));
    }

    /* restore the previous stack frame */
    xlstack = oldstk;

    /* return the value */
    return (val);
}

/* rmquote - read macro for '\'' */
NODE *rmquote(args)
  NODE *args;
{
    NODE *fptr,*mch;

    /* get the file and macro character */
    fptr = xlgetfile(&args);
    mch = xlmatch(INT,&args);
    xllastarg(args);

    /* parse the quoted expression */
    return (consa(pquote(fptr,s_quote)));
}

/* rmdquote - read macro for '"' */
NODE *rmdquote(args)
  NODE *args;
{
    int ch,i,d1,d2,d3;
    NODE *fptr,*mch;

    /* get the file and macro character */
    fptr = xlgetfile(&args);
    mch = xlmatch(INT,&args);
    xllastarg(args);

    /* loop looking for a closing quote */
    for (i = 0; i < STRMAX && (ch = checkeof(fptr)) != '"'; i++) {
          switch (ch) {
          case '\\':
                    switch (ch = checkeof(fptr)) {
                    case 'f':
                              ch = '\f';
                              break;
                    case 'n':
                              ch = '\n';
                              break;
                    case 'r':
                              ch = '\r';
                              break;
                    case 't':
                              ch = '\t';
                              break;
                    default:
                              if (ch >= '0' && ch <= '7') {
                                  d1 = ch - '0';
                                  d2 = checkeof(fptr) - '0';
                                  d3 = checkeof(fptr) - '0';
                                  ch = (d1 << 6) + (d2 << 3) + d3;
                              }
                              break;
                    }
          }
          buf[i] = ch;
    }
    buf[i] = 0;

    /* return the new string */
    return (consa(cvstring(buf)));
}

/* rmbquote - read macro for '`' */
NODE *rmbquote(args)
  NODE *args;
{
    NODE *fptr,*mch;

    /* get the file and macro character */
    fptr = xlgetfile(&args);
    mch = xlmatch(INT,&args);
    xllastarg(args);

    /* parse the quoted expression */
    return (consa(pquote(fptr,s_bquote)));
}

/* rmcomma - read macro for ',' */
NODE *rmcomma(args)
  NODE *args;
{
    NODE *fptr,*mch,*sym;

    /* get the file and macro character */
    fptr = xlgetfile(&args);
    mch = xlmatch(INT,&args);
    xllastarg(args);

    /* check the next character */
    if (xlpeek(fptr) == '@') {
          sym = s_comat;
          xlgetc(fptr);
    }
    else
          sym = s_comma;

    /* make the return value */
    return (consa(pquote(fptr,sym)));
}

/* rmlpar - read macro for '(' */
NODE *rmlpar(args)
  NODE *args;
{
    NODE *fptr,*mch;

    /* get the file and macro character */
    fptr = xlgetfile(&args);
    mch = xlmatch(INT,&args);
    xllastarg(args);

    /* make the return value */
    return (consa(plist(fptr)));
}

/* rmrpar - read macro for ')' */
NODE *rmrpar(args)
  NODE *args;
{
    xlfail("misplaced right paren");
}

/* rmsemi - read macro for ';' */
NODE *rmsemi(args)
  NODE *args;
{
    NODE *fptr,*mch;
    int ch;

    /* get the file and macro character */
    fptr = xlgetfile(&args);
    mch = xlmatch(INT,&args);
    xllastarg(args);

    /* skip to end of line */
    while ((ch = xlgetc(fptr)) != EOF && ch != '\n')
          ;

    /* return nil (nothing read) */
    return (NIL);
}

/* phexnumber - parse a hexidecimal number */
LOCAL NODE *phexnumber(fptr)
  NODE *fptr;
{
    long num;
    int ch;

    num = 0L;
    while ((ch = xlpeek(fptr)) != EOF) {
          if (islower(ch)) ch = toupper(ch);
          if (!isdigit(ch) && !(ch >= 'A' && ch <= 'F'))
              break;
          xlgetc(fptr);
          num = num * 16L + (long)(ch <= '9' ? ch - '0' : ch - 'A' + 10);
    }
    return (cvfixnum((FIXNUM)num));
}

/* plist - parse a list */
LOCAL NODE *plist(fptr)
  NODE *fptr;
{
    NODE ***oldstk,*val,*expr,*lastnptr,*nptr;

    /* create a new stack frame */
    oldstk = xlstack;
    xlstkcheck(2);
    xlsave(val);
    xlsave(expr);

    /* increase the paren nesting level */
    ++xlplevel;

    /* keep appending nodes until a closing paren is found */
    lastnptr = NIL;
    for (lastnptr = NIL; nextch(fptr) != ')'; lastnptr = nptr)

          /* get the next expression */
          switch (readone(fptr,&expr)) {
          case EOF:
              badeof(fptr);
          case TRUE:

              /* check for a dotted tail */
              if (expr == s_dot) {

                    /* make sure there's a node */
                    if (lastnptr == NIL)
                        xlfail("invalid dotted pair");

                    /* parse the expression after the dot */
                    if (!xlread(fptr,&expr,TRUE))
                        badeof(fptr);
                    rplacd(lastnptr,expr);

                    /* make sure its followed by a close paren */
                    if (nextch(fptr) != ')')
                        xlfail("invalid dotted pair");

                    /* done with this list */
                    break;
              }

              /* otherwise, handle a normal list element */
              else {
                    nptr = consa(expr);
                    if (lastnptr == NIL)
                        val = nptr;
                    else
                        rplacd(lastnptr,nptr);
              }
              break;
          }

    /* skip the closing paren */
    xlgetc(fptr);

    /* decrease the paren nesting level */
    --xlplevel;

    /* restore the previous stack frame */
    xlstack = oldstk;

    /* return successfully */
    return (val);
}

/* pvector - parse a vector */
LOCAL NODE *pvector(fptr)
  NODE *fptr;
{
    NODE ***oldstk,*list,*expr,*val,*lastnptr,*nptr;
    int len,ch,i;

    /* create a new stack frame */
    oldstk = xlstack;
    xlstkcheck(2);
    xlsave(list);
    xlsave(expr);

    /* keep appending nodes until a closing paren is found */
    lastnptr = NIL; len = 0;
    for (lastnptr = NIL; (ch = nextch(fptr)) != ')'; lastnptr = nptr) {

          /* check for end of file */
          if (ch == EOF)
              badeof(fptr);

          /* get the next expression */
          switch (readone(fptr,&expr)) {
          case EOF:
              badeof(fptr);
          case TRUE:
              nptr = consa(expr);
              if (lastnptr == NIL)
                    list = nptr;
              else
                    rplacd(lastnptr,nptr);
              len++;
              break;
          }
    }

    /* skip the closing paren */
    xlgetc(fptr);

    /* make a vector of the appropriate length */
    val = newvector(len);

    /* copy the list into the vector */
    for (i = 0; i < len; ++i, list = cdr(list))
          setelement(val,i,car(list));

    /* restore the previous stack frame */
    xlstack = oldstk;

    /* return successfully */
    return (val);
}

/* pquote - parse a quoted expression */
LOCAL NODE *pquote(fptr,sym)
  NODE *fptr,*sym;
{
    NODE ***oldstk,*val,*p;

    /* create a new stack frame */
    oldstk = xlstack;
    xlsave1(val);

    /* allocate two nodes */
    val = consa(sym);
    rplacd(val,consa(NIL));

    /* initialize the second to point to the quoted expression */
    if (!xlread(fptr,&p,TRUE))
          badeof(fptr);
    rplaca(cdr(val),p);

    /* restore the previous stack frame */
    xlstack = oldstk;

    /* return the quoted expression */
    return (val);
}

/* pname - parse a symbol name */
LOCAL NODE *pname(fptr,ch)
  NODE *fptr; int ch;
{
    NODE *val,*type;
    int i;

    /* get symbol name */
    for (i = 0; ; xlgetc(fptr)) {
          if (i < STRMAX)
              buf[i++] = (islower(ch) ? toupper(ch) : ch);
          if ((ch = xlpeek(fptr)) == EOF ||
              ((type = tentry(ch)) != k_const &&
             !(consp(type) && car(type) == k_nmacro)))
              break;
    }
    buf[i] = 0;

    /* check for a number or enter the symbol into the oblist */
    return (isnumber(buf,&val) ? val : xlenter(buf,DYNAMIC));
}

/* tentry - get a readtable entry */
LOCAL NODE *tentry(ch)
  int ch;
{
    NODE *rtable;
    rtable = getvalue(s_rtable);
    if (!vectorp(rtable) || ch < 0 || ch >= getsize(rtable))
          return (NIL);
    return (getelement(rtable,ch));
}

/* nextch - look at the next non-blank character */
LOCAL int nextch(fptr)
  NODE *fptr;
{
    int ch;

    /* return and save the next non-blank character */
    while ((ch = xlpeek(fptr)) != EOF && isspace(ch))
          xlgetc(fptr);
    return (ch);
}

/* checkeof - get a character and check for end of file */
LOCAL int checkeof(fptr)
  NODE *fptr;
{
    int ch;

    if ((ch = xlgetc(fptr)) == EOF)
          badeof(fptr);
    return (ch);
}

/* badeof - unexpected eof */
LOCAL badeof(fptr)
  NODE *fptr;
{
    xlgetc(fptr);
    xlfail("unexpected EOF");
}

/* isnumber - check if this string is a number */
int isnumber(str,pval)
  char *str; NODE **pval;
{
    int dl,dr;
    char *p;

    /* initialize */
    p = str; dl = dr = 0;

    /* check for a sign */
    if (*p == '+' || *p == '-')
          p++;

    /* check for a string of digits */
    while (isdigit(*p))
          p++, dl++;

    /* check for a decimal point */
    if (*p == '.') {
          p++;
          while (isdigit(*p))
              p++, dr++;
    }

    /* check for an exponent */
    if ((dl || dr) && *p == 'E') {
          p++;

          /* check for a sign */
          if (*p == '+' || *p == '-')
              p++;

          /* check for a string of digits */
          while (isdigit(*p))
              p++, dr++;
    }

    /* make sure there was at least one digit and this is the end */
    if ((dl == 0 && dr == 0) || *p)
          return (FALSE);

    /* convert the string to an integer and return successfully */
    if (*str == '+') ++str;
    if (str[strlen(str)-1] == '.') str[strlen(str)-1] = 0;
    *pval = (dr ? cvflonum(atof(str)) : cvfixnum(ICNV(str)));
    return (TRUE);
}

/* defmacro - define a read macro */
defmacro(ch,type,fun)
  int ch; NODE *type,*(*fun)();
{
    NODE *p;
    p = consa(type);
    setelement(getvalue(s_rtable),ch,p);
    rplacd(p,cvsubr(fun,SUBR));
}

/* callmacro - call a read macro */
NODE *callmacro(fptr,ch)
  NODE *fptr; int ch;
{
    NODE ***oldstk,*fun,*args,*val;

    /* create a new stack frame */
    oldstk = xlstack;
    xlstkcheck(2);
    xlsave(fun);
    xlsave(args);

    /* get the macro function */
    fun = cdr(getelement(getvalue(s_rtable),ch));

    /* create the argument list */
    args = consa(fptr);
    rplacd(args,consa(NIL));
    rplaca(cdr(args),cvfixnum((FIXNUM)ch));

    /* apply the macro function to the arguments */
    val = xlapply(fun,args);

    /* restore the previous stack frame */
    xlstack = oldstk;

    /* return the result */
    return (val);
}

/* needsextension - determine if a filename needs an extension */
int needsextension(name)
  char *name;
{
    while (*name)
          if (*name++ == '.')
              return (FALSE);
    return (TRUE);
}

/* needsdrive - determine if a filename needs a drive */
int needsdrive(name)
  char *name;
{
    while (*name)
          if (*name++ == '_')
              return (FALSE);
    return (TRUE);
}

/* xlrinit - initialize the reader */
xlrinit()
{
    NODE *rtable;
    char *p;
    int ch;

    /* create the read table */
    rtable = newvector(256);
    setvalue(s_rtable,rtable);

    /* initialize the readtable */
    for (p = WSPACE; ch = *p++; )
          setelement(rtable,ch,k_wspace);
    for (p = CONST1; ch = *p++; )
          setelement(rtable,ch,k_const);
    for (p = CONST2; ch = *p++; )
          setelement(rtable,ch,k_const);

    /* install the read macros */
    defmacro('#', k_nmacro,rmhash);
    defmacro('\'',k_tmacro,rmquote);
    defmacro('"', k_tmacro,rmdquote);
    defmacro('`', k_tmacro,rmbquote);
    defmacro(',', k_tmacro,rmcomma);
    defmacro('(', k_tmacro,rmlpar);
    defmacro(')', k_tmacro,rmrpar);
    defmacro(';', k_tmacro,rmsemi);
}