ref: 87f00731e2864debf2efe657de5181fbe5e17a72
dir: /read.c/
enum {
TOK_NONE, TOK_OPEN, TOK_CLOSE, TOK_DOT, TOK_QUOTE, TOK_SYM, TOK_NUM,
TOK_BQ, TOK_COMMA, TOK_COMMAAT, TOK_COMMADOT,
TOK_SHARPDOT, TOK_LABEL, TOK_BACKREF, TOK_SHARPQUOTE, TOK_SHARPOPEN,
TOK_OPENB, TOK_CLOSEB, TOK_SHARPSYM, TOK_GENSYM, TOK_DOUBLEQUOTE
};
#if defined(__plan9__)
static int errno;
#define VLONG_MAX ~(1LL<<63)
#define VLONG_MIN (1LL<<63)
#define UVLONG_MAX (~0ULL)
static mpint *mp_vlong_min, *mp_vlong_max, *mp_uvlong_max;
#endif
static int64_t
strtoll_mp(char *nptr, char **rptr, int base, mpint **mp)
{
int64_t x;
mpint *m;
*mp = nil;
errno = 0;
x = strtoll(nptr, rptr, base);
#if defined(__plan9__)
if((x != VLONG_MAX && x != VLONG_MIN) || *rptr == nptr)
return x;
mpint *c;
m = strtomp(nptr, rptr, base, nil);
if(x == VLONG_MAX){
if(mp_vlong_max == nil)
mp_vlong_max = vtomp(VLONG_MAX, nil);
c = mp_vlong_max;
}else{
if(mp_vlong_min == nil)
mp_vlong_min = vtomp(VLONG_MIN, nil);
c = mp_vlong_min;
}
if(mpcmp(c, m) == 0){
mpfree(m);
m = nil;
}
#else
m = nil;
if(errno == ERANGE && (x == LLONG_MAX || x == LLONG_MIN))
m = strtomp(nptr, rptr, base, nil);
#endif
*mp = m;
return x;
}
static uint64_t
strtoull_mp(char *nptr, char **rptr, int base, mpint **mp)
{
uint64_t x;
mpint *m;
*mp = nil;
errno = 0;
x = strtoull(nptr, rptr, base);
#if defined(__plan9__)
if(x != UVLONG_MAX || *rptr == nptr)
return x;
m = strtomp(nptr, rptr, base, nil);
if(mp_uvlong_max == nil)
mp_uvlong_max = uvtomp(UVLONG_MAX, nil);
if(mpcmp(mp_uvlong_max, m) == 0){
mpfree(m);
m = nil;
}
#else
m = nil;
if(errno == ERANGE && x == ULLONG_MAX)
m = strtomp(nptr, rptr, base, nil);
#endif
*mp = m;
return x;
}
#define F value2c(ios_t*, readstate->source)
// defines which characters are ordinary symbol characters.
// exceptions are '.', which is an ordinary symbol character
// unless it's the only character in the symbol, and '#', which is
// an ordinary symbol character unless it's the first character.
static inline int
symchar(char c)
{
static char *special = "()[]'\";`,\\| \a\b\f\n\r\t\v";
return !strchr(special, c);
}
int
isnumtok_base(char *tok, value_t *pval, int base)
{
char *end;
int64_t i64;
uint64_t ui64;
double d;
mpint *mp = nil;
if(*tok == '\0')
return 0;
if(!((tok[0] == '0' && tok[1] == 'x') || (base >= 15)) && strpbrk(tok, ".eEpP")){
d = strtod(tok, &end);
if(*end == '\0'){
if(pval)
*pval = mk_double(d);
return 1;
}
// floats can end in f or f0
if(end > tok && end[0] == 'f' &&
(end[1] == '\0' ||
(end[1] == '0' && end[2] == '\0'))){
if(pval)
*pval = mk_float((float)d);
return 1;
}
}
if(tok[0] == '+'){
if(!strcmp(tok, "+NaN") || !strcasecmp(tok, "+nan.0")){
if(pval)
*pval = mk_double(D_PNAN);
return 1;
}
if(!strcmp(tok, "+Inf") || !strcasecmp(tok, "+inf.0")){
if(pval)
*pval = mk_double(D_PINF);
return 1;
}
}else if(tok[0] == '-'){
if(!strcmp(tok, "-NaN") || !strcasecmp(tok, "-nan.0")){
if(pval)
*pval = mk_double(D_NNAN);
return 1;
}
if(!strcmp(tok, "-Inf") || !strcasecmp(tok, "-inf.0")){
if(pval)
*pval = mk_double(D_NINF);
return 1;
}
i64 = strtoll_mp(tok, &end, base, &mp);
if(pval)
*pval = mp == nil ? return_from_int64(i64) : mk_mpint(mp);
return *end == '\0';
}
ui64 = strtoull_mp(tok, &end, base, &mp);
if(pval)
*pval = mp == nil ? return_from_uint64(ui64) : mk_mpint(mp);
return *end == '\0';
}
static int
isnumtok(char *tok, value_t *pval)
{
return isnumtok_base(tok, pval, 0);
}
static int
read_numtok(char *tok, value_t *pval, int base)
{
return isnumtok_base(tok, pval, base);
}
static uint32_t toktype = TOK_NONE;
static value_t tokval;
static char buf[256];
static char
nextchar(void)
{
int ch;
char c;
ios_t *f = F;
do{
if(f->bpos < f->size){
ch = f->buf[f->bpos++];
}else{
ch = ios_getc(f);
if(ch == IOS_EOF)
return 0;
}
c = (char)ch;
if(c == ';'){
// single-line comment
do{
ch = ios_getc(f);
if(ch == IOS_EOF)
return 0;
}while((char)ch != '\n');
c = (char)ch;
}
}while(c == ' ' || isspace(c));
return c;
}
static void
take(void)
{
toktype = TOK_NONE;
}
static void
accumchar(char c, int *pi)
{
buf[(*pi)++] = c;
if(*pi >= (int)(sizeof(buf)-1))
lerrorf(ParseError, "token too long");
}
// return: 1 if escaped (forced to be symbol)
static int
read_token(char c, int digits)
{
int i = 0, ch, escaped = 0, issym = 0, nc = 0;
while(1){
if(nc != 0){
if(nc != 1)
ios_getc(F);
ch = ios_peekc(F);
if(ch == IOS_EOF)
goto terminate;
c = (char)ch;
}
if(c == '|'){
issym = 1;
escaped = !escaped;
}else if(c == '\\'){
issym = 1;
ios_getc(F);
ch = ios_peekc(F);
if(ch == IOS_EOF)
goto terminate;
accumchar((char)ch, &i);
}else if(!escaped && !(symchar(c) && (!digits || isdigit(c)))){
break;
}else{
accumchar(c, &i);
}
nc++;
}
if(nc == 0)
ios_skip(F, -1);
terminate:
buf[i++] = '\0';
return issym;
}
static value_t do_read_sexpr(value_t label);
static uint32_t
peek(void)
{
char c, *end;
fixnum_t x;
int ch, base;
if(toktype != TOK_NONE)
return toktype;
c = nextchar();
if(ios_eof(F))
return TOK_NONE;
if(c == '(')
toktype = TOK_OPEN;
else if(c == ')')
toktype = TOK_CLOSE;
else if(c == '[')
toktype = TOK_OPENB;
else if(c == ']')
toktype = TOK_CLOSEB;
else if(c == '\'')
toktype = TOK_QUOTE;
else if(c == '`')
toktype = TOK_BQ;
else if(c == '"')
toktype = TOK_DOUBLEQUOTE;
else if(c == '#'){
ch = ios_getc(F); c = (char)ch;
if(ch == IOS_EOF)
lerrorf(ParseError, "invalid read macro");
if(c == '.')
toktype = TOK_SHARPDOT;
else if(c == '\'')
toktype = TOK_SHARPQUOTE;
else if(c == '\\'){
uint32_t cval;
if(ios_getutf8(F, &cval) == IOS_EOF)
lerrorf(ParseError, "end of input in character constant");
if(cval == (uint32_t)'u' || cval == (uint32_t)'U' || cval == (uint32_t)'x'){
read_token('u', 0);
if(buf[1] != '\0'){ // not a solitary 'u','U','x'
if(!read_numtok(&buf[1], &tokval, 16))
lerrorf(ParseError, "invalid hex character constant");
cval = numval(tokval);
}
}else if(cval >= 'a' && cval <= 'z'){
read_token((char)cval, 0);
tokval = symbol(buf);
if(buf[1] == '\0') USED(cval); /* one character */
else if(tokval == nulsym) cval = 0x00;
else if(tokval == alarmsym) cval = 0x07;
else if(tokval == backspacesym) cval = 0x08;
else if(tokval == tabsym) cval = 0x09;
else if(tokval == linefeedsym) cval = 0x0A;
else if(tokval == newlinesym) cval = 0x0A;
else if(tokval == vtabsym) cval = 0x0B;
else if(tokval == pagesym) cval = 0x0C;
else if(tokval == returnsym) cval = 0x0D;
else if(tokval == escsym) cval = 0x1B;
else if(tokval == spacesym) cval = 0x20;
else if(tokval == deletesym) cval = 0x7F;
else
lerrorf(ParseError, "unknown character #\\%s", buf);
}
toktype = TOK_NUM;
tokval = mk_wchar(cval);
}else if(c == '('){
toktype = TOK_SHARPOPEN;
}else if(c == '<'){
lerrorf(ParseError, "unreadable object");
}else if(isdigit(c)){
read_token(c, 1);
c = (char)ios_getc(F);
if(c == '#')
toktype = TOK_BACKREF;
else if(c == '=')
toktype = TOK_LABEL;
else
lerrorf(ParseError, "invalid label");
x = strtoll(buf, &end, 10);
if(*end != '\0')
lerrorf(ParseError, "invalid label");
tokval = fixnum(x);
}else if(c == '!'){
// #! single line comment for shbang script support
do{
ch = ios_getc(F);
}while(ch != IOS_EOF && (char)ch != '\n');
return peek();
}else if(c == '|'){
// multiline comment
int commentlevel = 1;
while(1){
ch = ios_getc(F);
hashpipe_gotc:
if(ch == IOS_EOF)
lerrorf(ParseError, "eof within comment");
if((char)ch == '|'){
ch = ios_getc(F);
if((char)ch == '#'){
commentlevel--;
if(commentlevel == 0)
break;
else
continue;
}
goto hashpipe_gotc;
}else if((char)ch == '#'){
ch = ios_getc(F);
if((char)ch == '|')
commentlevel++;
else
goto hashpipe_gotc;
}
}
// this was whitespace, so keep peeking
return peek();
}else if(c == ';'){
// datum comment
(void)do_read_sexpr(UNBOUND); // skip
return peek();
}else if(c == ':'){
// gensym
ch = ios_getc(F);
if((char)ch == 'g')
ch = ios_getc(F);
read_token((char)ch, 0);
x = strtol(buf, &end, 10);
if(*end != '\0' || buf[0] == '\0')
lerrorf(ParseError, "invalid gensym label");
toktype = TOK_GENSYM;
tokval = fixnum(x);
}else if(symchar(c)){
read_token(ch, 0);
if(((c == 'b' && (base = 2)) ||
(c == 'o' && (base = 8)) ||
(c == 'd' && (base = 10)) ||
(c == 'x' && (base = 16))) && (isdigit_base(buf[1], base) || buf[1] == '-')){
if(!read_numtok(&buf[1], &tokval, base))
lerrorf(ParseError, "invalid base %d constant", base);
return (toktype = TOK_NUM);
}
toktype = TOK_SHARPSYM;
tokval = symbol(buf);
}else{
lerrorf(ParseError, "unknown read macro");
}
}else if(c == ','){
toktype = TOK_COMMA;
ch = ios_peekc(F);
if(ch == IOS_EOF)
return toktype;
if((char)ch == '@')
toktype = TOK_COMMAAT;
else if((char)ch == '.')
toktype = TOK_COMMADOT;
else
return toktype;
ios_getc(F);
}else if(c == '{' || c == '}'){
lerrorf(ParseError, "invalid character %c", c);
}else{
if(!read_token(c, 0)){
if(buf[0] == '.' && buf[1] == '\0')
return (toktype = TOK_DOT);
if(read_numtok(buf, &tokval, 0))
return (toktype = TOK_NUM);
}
toktype = TOK_SYM;
tokval = symbol(buf);
}
return toktype;
}
// NOTE: this is NOT an efficient operation. it is only used by the
// reader, and requires at least 1 and up to 3 garbage collections!
static value_t
vector_grow(value_t v)
{
size_t i, s = vector_size(v);
size_t d = vector_grow_amt(s);
PUSH(v);
assert(s+d > s);
value_t newv = alloc_vector(s+d, 1);
v = Stack[SP-1];
for(i = 0; i < s; i++)
vector_elt(newv, i) = vector_elt(v, i);
// use gc to rewrite references from the old vector to the new
Stack[SP-1] = newv;
if(s > 0){
((size_t*)ptr(v))[0] |= 0x1;
vector_elt(v, 0) = newv;
gc(0);
}
return POP();
}
static value_t
read_vector(value_t label, uint32_t closer)
{
value_t v = the_empty_vector, elt;
uint32_t i = 0;
PUSH(v);
if(label != UNBOUND)
ptrhash_put(&readstate->backrefs, (void*)label, (void*)v);
while(peek() != closer){
if(ios_eof(F))
lerrorf(ParseError, "unexpected end of input");
if(i >= vector_size(v)){
v = Stack[SP-1] = vector_grow(v);
if(label != UNBOUND)
ptrhash_put(&readstate->backrefs, (void*)label, (void*)v);
}
elt = do_read_sexpr(UNBOUND);
v = Stack[SP-1];
assert(i < vector_size(v));
vector_elt(v, i) = elt;
i++;
}
take();
if(i > 0)
vector_setsize(v, i);
return POP();
}
static value_t
read_string(void)
{
char *buf, *temp;
char eseq[10];
size_t i = 0, j, sz = 64, ndig;
int c;
value_t s;
uint32_t wc = 0;
buf = malloc(sz);
while(1){
if(i >= sz-4){ // -4: leaves room for longest utf8 sequence
sz *= 2;
temp = realloc(buf, sz);
if(temp == nil){
free(buf);
lerrorf(ParseError, "out of memory reading string");
}
buf = temp;
}
c = ios_getc(F);
if(c == IOS_EOF){
free(buf);
lerrorf(ParseError, "unexpected end of input in string");
}
if(c == '"')
break;
else if(c == '\\'){
c = ios_getc(F);
if(c == IOS_EOF){
free(buf);
lerrorf(ParseError, "end of input in escape sequence");
}
j = 0;
if(octal_digit(c)){
while(1){
eseq[j++] = c;
c = ios_peekc(F);
if(c == IOS_EOF || !octal_digit(c) || j >= 3)
break;
ios_getc(F);
}
eseq[j] = '\0';
wc = strtol(eseq, nil, 8);
// \DDD and \xXX read bytes, not characters
buf[i++] = ((char)wc);
}else if((c == 'x' && (ndig = 2)) || (c == 'u' && (ndig = 4)) || (c == 'U' && (ndig = 8))){
while(1){
c = ios_peekc(F);
if(c == IOS_EOF || !hex_digit(c) || j >= ndig)
break;
eseq[j++] = c;
ios_getc(F);
}
eseq[j] = '\0';
if(j)
wc = strtol(eseq, nil, 16);
if(!j || wc > 0x10ffff){
free(buf);
lerrorf(ParseError, "invalid escape sequence");
}
if(ndig == 2)
buf[i++] = ((char)wc);
else
i += u8_wc_toutf8(&buf[i], wc);
}else{
char esc = read_escape_control_char((char)c);
if(esc == (char)c && !strchr("\\'\"`", esc)){
free(buf);
lerrorf(ParseError, "invalid escape sequence: \\%c", (char)c);
}
buf[i++] = esc;
}
}else{
buf[i++] = c;
}
}
s = cvalue_string(i);
memmove(cvalue_data(s), buf, i);
free(buf);
return s;
}
// build a list of conses. this is complicated by the fact that all conses
// can move whenever a new cons is allocated. we have to refer to every cons
// through a handle to a relocatable pointer (i.e. a pointer on the stack).
static void
read_list(value_t *pval, value_t label, uint32_t closer)
{
value_t c, *pc;
uint32_t t;
PUSH(NIL);
pc = &Stack[SP-1]; // to keep track of current cons cell
t = peek();
while(t != closer){
if(ios_eof(F))
lerrorf(ParseError, "unexpected end of input");
c = mk_cons(); car_(c) = cdr_(c) = NIL;
if(iscons(*pc))
cdr_(*pc) = c;
else{
*pval = c;
if(label != UNBOUND)
ptrhash_put(&readstate->backrefs, (void*)label, (void*)c);
}
*pc = c;
c = do_read_sexpr(UNBOUND); // must be on separate lines due to
car_(*pc) = c; // undefined evaluation order
t = peek();
if(t == TOK_DOT){
take();
c = do_read_sexpr(UNBOUND);
cdr_(*pc) = c;
t = peek();
if(ios_eof(F))
lerrorf(ParseError, "unexpected end of input");
if(t != closer){
take();
lerrorf(ParseError, "expected '%c'", closer == TOK_CLOSEB ? ']' : ')');
}
}
}
take();
c = POP();
USED(c);
}
// label is the backreference we'd like to fix up with this read
static value_t
do_read_sexpr(value_t label)
{
value_t v, sym, oldtokval, *head;
value_t *pv;
uint32_t t;
char c;
t = peek();
take();
switch(t){
case TOK_CLOSE:
lerrorf(ParseError, "unexpected ')'");
case TOK_CLOSEB:
lerrorf(ParseError, "unexpected ']'");
case TOK_DOT:
lerrorf(ParseError, "unexpected '.'");
case TOK_SYM:
case TOK_NUM:
return tokval;
case TOK_COMMA:
head = &COMMA; goto listwith;
case TOK_COMMAAT:
head = &COMMAAT; goto listwith;
case TOK_COMMADOT:
head = &COMMADOT; goto listwith;
case TOK_BQ:
head = &BACKQUOTE; goto listwith;
case TOK_QUOTE:
head = "E;
listwith:
v = cons_reserve(2);
car_(v) = *head;
cdr_(v) = tagptr(((cons_t*)ptr(v))+1, TAG_CONS);
car_(cdr_(v)) = cdr_(cdr_(v)) = NIL;
PUSH(v);
if(label != UNBOUND)
ptrhash_put(&readstate->backrefs, (void*)label, (void*)v);
v = do_read_sexpr(UNBOUND);
car_(cdr_(Stack[SP-1])) = v;
return POP();
case TOK_SHARPQUOTE:
// femtoLisp doesn't need symbol-function, so #' does nothing
return do_read_sexpr(label);
case TOK_OPEN:
PUSH(NIL);
read_list(&Stack[SP-1], label, TOK_CLOSE);
return POP();
case TOK_OPENB:
PUSH(NIL);
read_list(&Stack[SP-1], label, TOK_CLOSEB);
return POP();
case TOK_SHARPSYM:
sym = tokval;
if(sym == tsym || sym == Tsym)
return FL_T;
if(sym == fsym || sym == Fsym)
return FL_F;
// constructor notation
c = nextchar();
if(c != '('){
take();
lerrorf(ParseError, "expected argument list for %s", symbol_name(tokval));
}
PUSH(NIL);
read_list(&Stack[SP-1], UNBOUND, TOK_CLOSE);
if(sym == vu8sym){
sym = arraysym;
Stack[SP-1] = fl_cons(uint8sym, Stack[SP-1]);
}else if(sym == fnsym){
sym = FUNCTION;
}
v = symbol_value(sym);
if(v == UNBOUND)
unbound_error(sym);
return fl_apply(v, POP());
case TOK_SHARPOPEN:
return read_vector(label, TOK_CLOSE);
case TOK_SHARPDOT:
// eval-when-read
// evaluated expressions can refer to existing backreferences, but they
// cannot see pending labels. in other words:
// (... #2=#.#0# ... ) OK
// (... #2=#.(#2#) ... ) DO NOT WANT
sym = do_read_sexpr(UNBOUND);
if(issymbol(sym)){
v = symbol_value(sym);
if(v == UNBOUND)
unbound_error(sym);
return v;
}
return fl_toplevel_eval(sym);
case TOK_LABEL:
// create backreference label
if(ptrhash_has(&readstate->backrefs, (void*)tokval))
lerrorf(ParseError, "label %"PRIdPTR" redefined", numval(tokval));
oldtokval = tokval;
v = do_read_sexpr(tokval);
ptrhash_put(&readstate->backrefs, (void*)oldtokval, (void*)v);
return v;
case TOK_BACKREF:
// look up backreference
v = (value_t)ptrhash_get(&readstate->backrefs, (void*)tokval);
if(v == (value_t)HT_NOTFOUND)
lerrorf(ParseError, "undefined label %"PRIdPTR, numval(tokval));
return v;
case TOK_GENSYM:
pv = (value_t*)ptrhash_bp(&readstate->gensyms, (void*)tokval);
if(*pv == (value_t)HT_NOTFOUND)
*pv = gensym();
return *pv;
case TOK_DOUBLEQUOTE:
return read_string();
}
return FL_UNSPECIFIED;
}
value_t
fl_read_sexpr(value_t f)
{
value_t v;
fl_readstate_t state;
state.prev = readstate;
htable_new(&state.backrefs, 8);
htable_new(&state.gensyms, 8);
state.source = f;
readstate = &state;
assert(toktype == TOK_NONE);
fl_gc_handle(&tokval);
v = do_read_sexpr(UNBOUND);
fl_free_gc_handles(1);
readstate = state.prev;
free_readstate(&state);
return v;
}