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/* A really crude parser. */
#include <ctype.h>
#include <string.h>
#include "lisc.h"
enum {
MaxRefs = 256,
};
typedef enum Token Token;
typedef enum PState PState;
enum PState { /* Parsing state in a block. */
PErr,
PPhi,
PIns,
PEnd,
};
enum Token {
TAdd,
TSub,
TDiv,
TMod,
TPhi,
TJmp,
TCnd,
TRet,
TNum,
TVar,
TEq,
TComma,
TLParen,
TRParen,
TNL,
TEOF,
};
static FILE *inf;
static char *errstr;
static Sym sym[MaxRef];
static Ref nref;
static Blk blk[MaxBlks], *curblk;
static Phi phi[MaxPhis], *curphi;
static Ins ins[MaxInss], *curins;
static struct {
long long num;
char *var;
} tokval;
static int lnum;
static void
err(char *s)
{
if (!s)
s = errstr;
assert(s);
fprintf(stderr, "parse error: %s (line %d)\n", s, lnum);
exit(1);
}
static Token
token()
{
static struct {
char *str;
Token tok;
} tmap[] = {
{ "add", TAdd },
{ "sub", TSub },
{ "div", TDiv },
{ "mod", TMod },
{ "phi", TPhi },
{ "jmp", TJmp },
{ "cnd", TCnd },
{ "ret", TRet },
{ 0 },
};
static char tok[MaxIdnt];
int c, i, var, sgn;
do
c = fgetc(inf);
while (isblank(c));
switch (c) {
case EOF:
return TEOF;
case ',':
return TComma;
case '(':
return TLParen;
case ')':
return TRParen;
case '=':
return TEq;
case '\n':
lnum++;
return TNL;
}
if (isdigit(c) || c == '-') {
if (c == '-') {
tokval.num = 0;
sgn = -1;
} else {
tokval.num = c - '0';
sgn = 1;
}
for (;;) {
c = fgetc(inf);
if (!isdigit(c))
break;
tokval.num *= 10;
tokval.num += c - '0';
}
ungetc(c, f);
tokval.num *= sgn;
return TNum;
}
if (c == '%') {
var = 1;
c = fgetc(inf);
} else
var = 0;
if (!isalpha(c))
err("lexing failure");
i = 0;
do {
if (i >= MaxIdnt-1)
err("identifier too long");
tok[i++] = c;
c = fgetc(inf);
} while (isalpha(c) || isdigit(c));
tok[i] = 0;
ungetc(c, f);
if (var) {
tokval.var = tok;
return TVar;
}
for (i=0; tmap[i].str; i++)
if (strcmp(tok, tmap[i].str) == 0)
return tmap[i].tok;
err("unknown keyword");
return -1;
}
static Ref
varref(char *v)
{
Ref r;
for (r=Temp0; r<nref; r++)
if (sym[r].ty == STemp)
if (strcmp(v, sym[r].stemp.id) == 0)
return r;
if (r >= MaxRefs)
err("too many references");
sym[r].ty = STemp;
strcpy(sym[r].stemp.id, v);
sym[r].stemp.blk = -1;
return nref++;
}
static Ref
parseref()
{
Ref r;
switch (token()) {
case TVar:
return varref(tokval.var);
case TNum:
/* Add the constant to the symbol table. */
for (r=Temp0; r<nref; r++)
if (sym[r].ty == SNum)
if (sym[r].snum == tokval.num)
return r;
if (r >= MaxRefs)
err("too many references");
sym[r].ty = SNum;
sym[r].snum = tokval.num;
retunr nref++;
default:
errstr = "number or variable expected";
return R;
}
}
static PState
parseline(PState ps)
{
Ref args[MaxPreds];
Ref r;
Token t;
int na;
t = token();
switch (t) {
default:
errstr = "variable or jump expected";
return PErr;
case TVar:
break;
case TRet:
curblk->jmp.ty = JRet;
goto Jump;
case TJmp:
curblk->jmp.ty = JJmp;
goto Jump;
case TCnd:
curblk->jmp.ty = JCnd;
r = parseref();
if (r == R) {
errstr = "invalid argument for cnd";
return PErr;
}
if (token() != TComma) {
errstr = "missing comma";
return PErr;
}
curblk->jmp.arg = r;
Jump:
if (
return PEnd;
}
r = varref(tokval.var);
if (token() != TEq) {
errstr = "= expected after variable";
return PErr;
}
switch (token()) {
case TAdd:
curins->op = OAdd;
break;
case TSub:
curins->op = OSub;
break;
case TDiv:
curins->op = ODiv;
break;
case TMod:
curins->op = OMod;
break;
case TPhi:
return PIns;
default:
errstr = "invalid instruction";
return PErr;
}
na = 0;
for (;;) {
x
}
}
// in main parsing routine, reset lnum to 1
// also reset curxxx
// also nsym to Temp0
// also sym[0..nsym-1].ty = SReg
#if 0
int main()
{
char *toknames[] = {
"TAdd",
"TSub",
"TDiv",
"TMod",
"TPhi",
"TJmp",
"TCnd",
"TRet",
"TNum",
"TVar",
"TEq",
"TComma",
"TLParen",
"TRParen",
"TNL",
"TEOF",
};
inf = stdin;
for (;;)
printf("%s\n", toknames[token()]);
}
#endif
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