#include "sl.h"
#include "operators.h"
#include "cvalues.h"
#include "ieee754.h"
#include "print.h"
#include "read.h"

#define LOG2_10 3.321928094887362347870319429489

sl_v sl_printreadablysym, sl_printprettysym;
static sl_v widthsym, circlesym;
static sl_v lengthsym, levelsym;
static sl_v radixsym, basesym;
static sl_v ptrradixsym, ptrbasesym;

static inline void
outc(ios *f, char c)
{
	if(ios_putc(f, c) != 1)
		lerrorf(sl_errio, "write failed");
	if(c != '\n')
		sl.hpos += sl_wcwidth(c);
	else
		sl.hpos = 0;
}

static inline void
outsn(ios *f, const char *s, usize n)
{
	if(ios_write(f, s, n) != n)
		lerrorf(sl_errio, "write failed");
	const char *nl = llt_memrchr(s, '\n', n);
	bool err;
	if(nl == nil)
		sl.hpos += u8_strwidth(s, n, &err);
	else if((nl+1-s) < (intptr)n)
		sl.hpos = u8_strwidth(nl+1, s+n-nl-1, &err);
}

static inline void
outs(ios *f, const char *s)
{
	outsn(f, s, strlen(s));
}

#define outsc(f, s) do{ \
	const char vs[] = s; \
	outsn(f, vs, sizeof(vs)-1); \
}while(0)

static int
outindent(ios *f, int n)
{
	// move back to left margin if we get too indented
	if(n > sl.scr_width-12)
		n = 2;
	int n0 = n;
	if(ios_putc(f, '\n') != 1)
		goto err;
	sl.vpos++;
	sl.hpos = n;
	while(n){
		if(ios_putc(f, ' ') != 1)
			goto err;
		n--;
	}
	return n0;
err:
	lerrorf(sl_errio, "write failed");
}

static int
print_radix_prefix(ios *f, bool radix, int base)
{
	if(!radix)
		return 0;
	switch(base){
	case 2: outsc(f, "#b"); return 0;
	case 8: outsc(f, "#o"); return 0;
	case 10: outsc(f, "#d"); return 0;
	case 16: outsc(f, "#x"); return 0;
	default: return ios_printf(f, "#%dr", base);
	}
}

static int
print_num(ios *f, u64int x, int base)
{
	char tmp[64+1];

	if(sl_unlikely(base == 32)){
		u8int d[8] = {x>>56, x>>48, x>>40, x>>32, x>>24, x>>16, x>>8, x};
		int n;
		for(n = 0; n < 7 && d[n] == 0; n++);
		n = enc32(tmp, sizeof(tmp), d+n, sizeof(d)-n);
		return n > 0 ? (int)ios_write(f, tmp, n) : 0;
	}

	char *s = uint2str(tmp, sizeof(tmp), x, base);
	return ios_write(f, s, tmp+sizeof(tmp)-1-s);
}

static void
print_str(ios *f, const char *str, usize sz)
{
	char buf[64];
	u8int c;
	static const char hexdig[] = "0123456789abcdef";

	usize i = 0;
	if(!u8_isvalid(str, sz)){
		// alternate print algorithm that preserves data if it's not UTF-8
		for(; i < sz; i++){
			c = str[i];
			if(c == '\\')
				outsc(f, "\\\\");
			else if(c == '"')
				outsc(f, "\\\"");
			else if(c >= 32 && c < 0x7f)
				outc(f, c);
			else{
				outsc(f, "\\x");
				outc(f, hexdig[c>>4]);
				outc(f, hexdig[c&0xf]);
			}
		}
	}else{
		while(i < sz){
			usize n = u8_escape(buf, sizeof(buf), str, &i, sz, true, false);
			outsn(f, buf, n-1);
		}
	}
}

void
sl_print_chr(ios *f, char c)
{
	outc(f, c);
}

void
sl_print_str(ios *f, const char *s, bool princ)
{
	if(princ)
		outs(f, s);
	else
		print_str(f, s, strlen(s));
}

void
sl_print_traverse(sl_v v)
{
	sl_v *bp;
	while(iscons(v)){
		if(ismarked(v)){
			bp = (sl_v*)ptrhash_bp(&sl.printconses, (void*)v);
			if(*bp == (sl_v)HT_NOTFOUND)
				*bp = fixnum(sl.printlabel++);
			return;
		}
		mark_cons(v);
		sl_print_traverse(car_(v));
		v = cdr_(v);
	}
	if(!ismanaged(v) || issym(v))
		return;
	if(ismarked(v)){
		bp = (sl_v*)ptrhash_bp(&sl.printconses, (void*)v);
		if(*bp == (sl_v)HT_NOTFOUND)
			*bp = fixnum(sl.printlabel++);
		return;
	}
	if(isvec(v)){
		if(vec_size(v) > 0)
			mark_cons(v);
		for(int i = 0; i < vec_size(v); i++)
			sl_print_traverse(vec_elt(v, i));
	}else if(isfn(v)){
		mark_cons(v);
		sl_fn *f = ptr(v);
		sl_print_traverse(f->bcode);
		sl_print_traverse(f->vals);
		sl_print_traverse(f->env);
	}else if(iscvalue(v)){
		sl_cv *cv = ptr(v);
		// don't consider shared references to "" and numbers
		if(!valid_numtype(cv_numtype(cv)) && (!cv_isstr(cv) || cv_len(cv) != 0))
			mark_cons(v);
		sl_type *t = cv_class(cv);
		if(t->vtable != nil && t->vtable->print_traverse != nil)
			t->vtable->print_traverse(v);
	}
}

static void
print_sym_name(ios *f, const char *name)
{
	int i;
	bool escape = false, charescape = false;

	if((name[0] == '\0') ||
		(name[0] == '.' && name[1] == '\0') ||
		(name[0] == '#') ||
		sl_read_numtok(name, nil, 0))
		escape = true;
	i = 0;
	while(name[i]){
		if(!symchar(name[i])){
			escape = true;
			if(name[i] == '|' || name[i] == '\\'){
				charescape = true;
				break;
			}
		}
		i++;
	}
	if(escape){
		if(charescape){
			outc(f, '|');
			i = 0;
			while(name[i]){
				if(name[i] == '|' || name[i] == '\\')
					outc(f, '\\');
				outc(f, name[i]);
				i++;
			}
			outc(f, '|');
		}else{
			outc(f, '|');
			outs(f, name);
			outc(f, '|');
		}
	}else{
		outs(f, name);
	}
}

/*
  The following implements a simple pretty-printing algorithm. This is
  an unlimited-width approach that doesn't require an extra pass.
  It uses some heuristics to guess whether an expression is "small",
  and avoids wrapping symbols across lines. The result is high
  performance and nice output for typical code. Quality is poor for
  pathological or deeply-nested expressions, but those are difficult
  to print anyway.
*/
#define SMALL_STR_LEN 24
static inline int
tinyp(sl_v v)
{
	if(issym(v)){
		const char *s = sym_name(v);
		bool err;
		return u8_strwidth(s, strlen(s), &err) < SMALL_STR_LEN;
	}
	if(isstr(v))
		return cv_len(ptr(v)) < SMALL_STR_LEN;
	if(iscvalue(v))
		return valid_numtype(cv_numtype(ptr(v)));
	return isfixnum(v) || isunboxed(v) || isbuiltin(v) || isspecial(v);
}

static bool
smallp(sl_v v)
{
	if(tinyp(v))
		return true;
	if(isnum(v))
		return true;
	if(iscons(v)){
		if(tinyp(car_(v)) &&
		   (tinyp(cdr_(v)) || (iscons(cdr_(v)) && tinyp(car_(cdr_(v))) && cdr_(cdr_(v)) == sl_nil)))
			return true;
		return false;
	}
	if(isvec(v)){
		usize s = vec_size(v);
		return (
			s == 0 ||
			(tinyp(vec_elt(v, 0)) && (s == 1 || (s == 2 && tinyp(vec_elt(v, 1)))))
		);
	}
	return false;
}

static int
specialindent(sl_v head)
{
	// indent these forms 2 spaces, not lined up with the first argument
	if(head == sl_lambda || head == sl_trycatch || head == sl_defsym ||
		head == sl_defmacrosym || head == sl_forsym)
		return 2;
	return -1;
}

static int
lengthestimate(sl_v v)
{
	// get the width of an expression if we can do so cheaply
	if(issym(v)){
		const char *s = sym_name(v);
		bool err;
		return u8_strwidth(s, strlen(s), &err);
	}
	if(isrune(v))
		return 4;
	return -1;
}

static int
allsmallp(sl_v v)
{
	int n = 1;
	while(iscons(v)){
		if(!smallp(car_(v)))
			return 0;
		v = cdr_(v);
		n++;
		if(n > 25)
			return n;
	}
	return n;
}

static int
indentafter3(sl_v head, sl_v v)
{
	// for certain X always indent (X a b c) after b
	return head == sl_forsym && !allsmallp(cdr_(v));
}

static int
indentafter2(sl_v head, sl_v v)
{
	// for certain X always indent (X a b) after a
	return (head == sl_defsym || head == sl_defmacrosym) && !allsmallp(cdr_(v));
}

static bool
indentevery(sl_v v)
{
	// indent before every subform of a special form, unless every
	// subform is "small"
	sl_v c = car_(v);
	if(c == sl_lambda || c == sl_setqsym)
		return false;
	//if(c == sl.IF) // TODO: others
	//	return !allsmallp(cdr_(v));
	return false;
}

static bool
blockindent(sl_v v)
{
	// in this case we switch to block indent mode, where the head
	// is no longer considered special:
	// (a b c d e
	//  f g h i j)
	return allsmallp(v) > 9;
}

static void
print_cons(ios *f, sl_v v)
{
	sl_v cd;
	const char *op;
	if(iscons(cdr_(v)) && cdr_(cdr_(v)) == sl_nil &&
		!ptrhash_has(&sl.printconses, (void*)cdr_(v)) &&
		((car_(v) == sl_quote     && (op = "'"))  ||
		 (car_(v) == sl_backquote && (op = "`"))  ||
		 (car_(v) == sl_comma     && (op = ","))  ||
		 (car_(v) == sl_commaat   && (op = ",@")) ||
		 (car_(v) == sl_commadot  && (op = ",.")))){
		// special prefix syntax
		unmark_cons(v);
		unmark_cons(cdr_(v));
		outs(f, op);
		sl_print_child(f, car_(cdr_(v)));
		return;
	}
	int startpos = sl.hpos;
	outc(f, '(');
	int newindent = sl.hpos;
	int lastv, n = 0, si, ind, est, nextsmall, thistiny;
	bool always = false, blk = blockindent(v);
	if(!blk)
		always = indentevery(v);
	sl_v head = car_(v);
	int after3 = indentafter3(head, v);
	int after2 = indentafter2(head, v);
	int n_unindented = 1;
	while(1){
		cd = cdr_(v);
		if(sl.print_length >= 0 && n >= sl.print_length){
			outsc(f, "...)");
			break;
		}
		lastv = sl.vpos;
		unmark_cons(v);
		sl_print_child(f, car_(v));
		if(!iscons(cd) || ptrhash_has(&sl.printconses, (void*)cd)){
			if(cd != sl_nil){
				outsc(f, " . ");
				sl_print_child(f, cd);
			}
			outc(f, ')');
			break;
		}

		if(!sl.print_pretty ||
			(head == sl_lambda && n == 0)){
			// never break line before lambda-list
			ind = 0;
		}else{
			est = lengthestimate(car_(cd));
			nextsmall = smallp(car_(cd));
			thistiny = tinyp(car_(v));
			ind = ((sl.vpos > lastv ||
					(sl.hpos>sl.scr_width/2 && !nextsmall && !thistiny && n>0)) ||

				   (sl.hpos > sl.scr_width-4) ||

				   (est != -1 && sl.hpos+est > sl.scr_width-2) ||

				   (head == sl_lambda && !nextsmall) ||

				   (n > 0 && always) ||

				   (n == 2 && after3) ||
				   (n == 1 && after2) ||

				   (n_unindented >= 3 && !nextsmall) ||

				   (n == 0 && !smallp(head)));
		}

		if(ind){
			newindent = outindent(f, newindent);
			n_unindented = 1;
		}else{
			n_unindented++;
			outc(f, ' ');
			if(n == 0){
				// set indent level after printing head
				si = specialindent(head);
				if(si != -1)
					newindent = startpos + si;
				else if(!blk)
					newindent = sl.hpos;
			}
		}
		n++;
		v = cd;
	}
}

static void unboxed_print(ios *f, sl_v v);
static void cvalue_print(ios *f, sl_v v);
static void rune_print(ios *f, Rune r);

static bool
print_circle_prefix(ios *f, sl_v v)
{
	sl_v label;
	if((label = (sl_v)ptrhash_get(&sl.printconses, (void*)v)) != (sl_v)HT_NOTFOUND){
		if(!ismarked(v)){
			int n = ios_printf(f, "#%"PRIdPTR"#", (intptr)numval(label));
			if(n < 1)
				lerrorf(sl_errio, "write failed");
			sl.hpos += n;
			return true;
		}
		int n = ios_printf(f, "#%"PRIdPTR"=", (intptr)numval(label));
		if(n < 1)
			lerrorf(sl_errio, "write failed");
		sl.hpos += n;
	}
	if(ismanaged(v))
		unmark_cons(v);
	return false;
}

void
sl_print_child(ios *f, sl_v v)
{
	const char *name;
	if(sl.print_level >= 0 && sl.p_level >= sl.print_level && (iscons(v) || isvec(v) || isfn(v))){
		outc(f, '#');
		return;
	}
	sl.p_level++;

	int n;
	s64int sx;
	switch(tag(v)){
	case TAG_FIXNUM:
		n = print_radix_prefix(f, sl.print_radix, sl.print_base);
		if(n >= 0){
			sl.hpos += n;
			sx = numval(v);
			if(sx < 0){
				outc(f, '-');
				sx = -sx;
			}
			n = print_num(f, sx, sl.print_base);
		}
		if(n < 1)
			lerrorf(sl_errio, "write failed");
		sl.hpos += n;
		break;
	case TAG_UNBOXED:
		unboxed_print(f, v);
		break;
	case TAG_SYM:
		name = sym_name(v);
		if(sl.print_princ)
			outs(f, name);
		else if(ismanaged(v)){
			outsc(f, "#:");
			outs(f, name);
		}else
			print_sym_name(f, name);
		break;
	case TAG_SPECIAL:
		if(v == sl_t)
			outc(f, 'T');
		else if(v == sl_nil)
			outsc(f, "NIL");
		else if(v == sl_eof)
			outsc(f, "#<eof>");
		else if(v == sl_void)
			outsc(f, "#<void>");
		else // unbound, should never happen
			abort();
		break;
	case TAG_FN:
		if(isbuiltin(v)){
			if(!sl.print_princ)
				outsc(f, "#.");
			outs(f, builtins[uintval(v)].name);
		}else{
			assert(isfn(v));
			if(!sl.print_princ){
				if(sl.print_circle && print_circle_prefix(f, v))
					break;
				sl_fn *fn = ptr(v);
				outs(f, "#fn(");
				char *data = cvalue_data(fn->bcode);
				usize i, sz = cvalue_len(fn->bcode);
				for(i = 0; i < sz; i++)
					data[i] += 48;
				sl_print_child(f, fn->bcode);
				for(i = 0; i < sz; i++)
					data[i] -= 48;
				if(fn->vals != sl_emptyvec || fn->env != sl_nil || fn->name != sl_lambda){
					outc(f, ' ');
					sl_print_child(f, fn->vals);
					if(fn->env != sl_nil){
						outc(f, ' ');
						sl_print_child(f, fn->env);
					}
					if(fn->name != sl_lambda){
						outc(f, ' ');
						sl_print_child(f, fn->name);
					}
				}
				outc(f, ' ');
				sl_print_child(f, fixnum(fn->maxstack));
				outc(f, ')');
			}else{
				outs(f, "#<fn>");
			}
		}
		break;
	case TAG_CVALUE:
	case TAG_VEC:
	case TAG_CONS:
		if(!sl.print_princ && sl.print_circle && print_circle_prefix(f, v))
			break;
		if(isvec(v)){
			outs(f, isstruct(v) ? "#S(" : "#(");
			int newindent = sl.hpos, est;
			int i, sz = vec_size(v);
			for(i = 0; i < sz; i++){
				if(sl.print_length >= 0 && i >= sl.print_length){
					outsc(f, "...");
					break;
				}
				sl_print_child(f, vec_elt(v, i));
				if(i < sz-1){
					if(!sl.print_pretty)
						outc(f, ' ');
					else{
						est = lengthestimate(vec_elt(v, i+1));
						if(sl.hpos > sl.scr_width-4 ||
						   (est != -1 && (sl.hpos+est > sl.scr_width-2)) ||
						   (sl.hpos > sl.scr_width/2 && !smallp(vec_elt(v, i+1)) && !tinyp(vec_elt(v, i))))
							newindent = outindent(f, newindent);
						else
							outc(f, ' ');
					}
				}
			}
			outc(f, ')');
			break;
		}
		if(iscvalue(v))
			cvalue_print(f, v);
		else
			print_cons(f, v);
		break;
	}
	sl.p_level--;
}

static int
double_exponent(double d)
{
	union ieee754_double dl;

	dl.d = d;
	return dl.ieee.exponent - IEEE754_DOUBLE_BIAS;
}

static void
snprint_real(char *s, usize cnt, double r,
             int width, // printf field width, or 0
			 int dec, // # decimal digits desired, recommend 16
             // # of zeros in .00...0x before using scientific notation
             // recommend 3-4 or so
             int max_digs_rt,
             // # of digits left of decimal before scientific notation
             // recommend 10
             int max_digs_lf)
{
	bool keepz = false;
	int mag, sz;

	s[0] = '\0';
	if(width == -1){
		width = 0;
		keepz = true;
	}
	if(isinf(r)){
		strncpy(s, signbit(r) ? "-inf" : "inf", cnt);
		return;
	}
	if(isnan(r)){
		strncpy(s, signbit(r) ? "-nan" : "nan", cnt);
		return;
	}
	if(r == 0){
		strncpy(s, "0", cnt);
		return;
	}

	char num_format[4];
	num_format[0] = 'l';
	num_format[2] = '\0';

	mag = double_exponent(r);
	mag = (int)(((double)mag)/LOG2_10 + 0.5);
	double fpart, temp;
	if(mag > max_digs_lf-1 || mag < -max_digs_rt){
		num_format[1] = 'e';
		temp = r/pow(10, mag); /* see if number will have a decimal */
		fpart = temp - floor(temp); /* when written in scientific notation */
	}else{
		num_format[1] = 'f';
		fpart = r - floor(r);
	}
	if(fpart == 0)
		dec = 0;

	char format[28];
	if(width == 0)
		snprintf(format, sizeof(format), "%%.%d%s", dec, num_format);
	else
		snprintf(format, sizeof(format), "%%%d.%d%s", width, dec, num_format);
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wformat-nonliteral"
	sz = snprintf(s, cnt, format, r);
#pragma GCC diagnostic pop
	/* trim trailing zeros from fractions. not when using scientific
	   notation, since we might have e.g. 1.2000e+100. also not when we
	   need a specific output width */
	if(width == 0 && !keepz){
		if(sz > 2 && fpart){
			char *e = nil;
			if(num_format[1] == 'e'){
				while(s[--sz] != 'e');
				e = s + sz--;
			}
			while(s[sz-1] == '0'){
				s[sz-1] = '\0';
				sz--;
			}
			// don't need trailing .
			if(s[sz-1] == '.')
				s[--sz] = '\0';
			if(num_format[1] == 'e'){
				while(*e)
					s[sz++] = *e++;
				s[sz] = 0;
			}
		}
	}
}

static void
rune_print(ios *f, Rune r)
{
	char seq[UTFmax+1];
	int n, nb = runetochar(seq, &r);
	seq[nb] = '\0';
	if(sl.print_princ){
		outsn(f, seq, nb);
	}else{
		outsc(f, "#\\");
		if(r < nelem(ascii2name))
			outs(f, ascii2name[r]);
		else if(r == 0x7f)
			outsc(f, "delete");
		else{
			if(sl_iswprint(r))
				outs(f, seq);
			else{
				n = ios_printf(f, "x%04"PRIx32, r);
				if(n < 1)
					goto err;
				sl.hpos += n;
			}
		}
	}
	return;
err:
	lerrorf(sl_errio, "write failed");
}

// 'weak' means we don't need to accurately reproduce the type, so
// for example #s32(0) can be printed as just 0. this is used
// printing in a context where a type is already implied, e.g. inside
// an array.
static void
cvalue_printdata(ios *f, void *data, usize len, sl_v type, bool weak)
{
	if(type == sl_runesym){
		rune_print(f, *(Rune*)data);
		return;
	}
	if(type == sl_utf8sym && sl.print_princ){
		outc(f, *(u8int*)data);
		return;
	}

	int n = 0;
	if(iscons(type)){
		if(car_(type) != sl_arrsym)
			abort();
		usize i;
		sl_v eltype = car(cdr_(type));
		usize cnt, elsize;
		if(iscons(cdr_(cdr_(type)))){
			cnt = tosize(car_(cdr_(cdr_(type))));
			elsize = cnt ? len/cnt : 0;
		}else{
			// incomplete array type
			elsize = ctype_sizeof(eltype);
			cnt = elsize ? len/elsize : 0;
		}
		if(eltype == sl_utf8sym){
			if(sl.print_princ){
				outsn(f, data, len);
			}else{
				outc(f, '"');
				print_str(f, (char*)data, len);
				outc(f, '"');
			}
			return;
		}else if(eltype == sl_runesym && sl.print_princ){
			char buf[UTFmax+1];
			for(i = 0; i < cnt; i++, data = (char*)data + elsize){
				n = runetochar(buf, (Rune*)data);
				buf[n] = 0;
				outsn(f, buf, n);
			}
			return;
		}
		if(!weak){
			if(eltype == sl_u8sym){
				outsc(f, "#vu8(");
			}else{
				outsc(f, "#arr(");
				sl_print_child(f, eltype);
				if(cnt > 0)
					outc(f, ' ');
			}
		}else{
			outs(f, "#(");
		}
		for(i = 0; i < cnt; i++){
			if(i > 0)
				outc(f, ' ');
			if(sl.print_length >= 0 && i >= (usize)sl.print_length){
				outs(f, "...");
				break;
			}
			cvalue_printdata(f, data, elsize, eltype, true);
			data = (char*)data + elsize;
		}
		outc(f, ')');
		return;
	}

	sl_numtype nt = sym_to_numtype(type);
	if(!valid_numtype(nt))
		abort();
	bool withtype = !weak && !sl.print_princ && nt != T_F64 && nt != T_BIG;
	if(withtype){
		outc(f, '#');
		outs(f, sym_name_(type));
		outc(f, '(');
	}

	if(nt == T_F32 || nt == T_F64){
		char buf[64];
		double d;
		int ndec;
		if(type == sl_f32sym){
			d = *(float*)data;
			ndec = 8;
		}else{
			d = *(double*)data;
			ndec = 16;
		}
		if(!isfinite(d)){
			outc(f, signbit(d) ? '-' : '+');
			if(isinf(d))
				outsc(f, "inf.0");
			else if(isnan(d))
				outsc(f, "nan.0");
			else
				abort();
		}else if(d == 0){
			if(signbit(d))
				outc(f, '-');
			outsc(f, "0.0");
		}else{
			snprint_real(buf, sizeof(buf), d, 0, ndec, 3, 10);
			bool hasdec = strpbrk(buf, ".eE") != nil;
			outs(f, buf);
			if(!hasdec)
				outsc(f, ".0");
		}
	}else{
		u64int x = 0;
		int base;
		bool radix, sign = false;
		switch(nt){
		case T_P32:
			x = *(u32int*)data;
			base = sl.print_ptr_base;
			radix = sl.print_ptr_radix;
			break;
		case T_P64:
			x = *(u64int*)data;
			base = sl.print_ptr_base;
			radix = sl.print_ptr_radix;
			break;
		default:
			base = sl.print_base;
			radix = sl.print_radix;
			if(nt == T_BIG){
				if(base != 10 && (base & (base-1)) != 0)
					lerrorf(sl_errarg, "unsupported print base for bignums: %d", base);
				break;
			}
			if(is_nt_uint(nt))
				x = conv_to_u64(sl_nil, data, nt);
			else{
				s64int sx = conv_to_s64(sl_nil, data, nt);
				if(sx >= 0)
					x = sx;
				else{
					x = -sx;
					sign = true;
				}
			}
			break;
		}

		// this combination makes no sense - it's impossible to read it back correctly
		if(withtype && !radix && base != 10)
			lerrorf(sl_errarg, "print: non-fixnum, non-default base and radix disabled");

		if((n = print_radix_prefix(f, radix, base)) < 0)
			lerrorf(sl_errio, "write failed");
		sl.hpos += n;
		if(nt == T_BIG){
			mpint *i = *(mpint**)data;
			char *s = mptoa(i, base, nil, 0);
			if(s == nil)
				lerrorf(sl_errmem, "no memory for a bignum printout");
			n = ios_write(f, s, strlen(s));
			MEM_FREE(s);
		}else{
			if(sign)
				outc(f, '-');
			n = print_num(f, x, base);
		}
	}

	if(n < 0)
		lerrorf(sl_errio, "write failed");
	sl.hpos += n;
	if(withtype)
		outc(f, ')');
}

static void
unboxed_print(ios *f, sl_v a)
{
	if(isrune(a)){
		rune_print(f, torune(a));
		return;
	}
	assert(isubnum(a));
	sl_numtype nt = ubnumtype(a);
	sl_fx v = ubnumval(a);
	sl_v typesym = unboxedtypesyms[nt];
	cvalue_printdata(f, ubnumptr(v, nt), unboxedtypes[nt]->size, typesym, false);
}

static void
cvalue_print(ios *f, sl_v v)
{
	sl_cv *cv = ptr(v);
	void *data = cvalue_data(v);
	sl_v label;

	if(cv_class(cv) == sl_builtintype){
		label = (sl_v)ptrhash_get(&slvm.reverse_dlsym_lookup, cv);
		assert(label != (sl_v)HT_NOTFOUND);
		if(sl.print_princ){
			outs(f, sym_name(label));
		}else{
			outsc(f, "#fn(");
			outs(f, sym_name(label));
			outc(f, ')');
		}
	}else if(cv_class(cv)->vtable != nil && cv_class(cv)->vtable->print != nil){
		cv_class(cv)->vtable->print(v, f);
	}else{
		sl_v type = cv_type(cv);
		usize len = cv_len(cv);
		cvalue_printdata(f, data, len, type, false);
	}
}

static void
set_print_width(void)
{
	sl_v v = sym_value(widthsym);
	if(isfixnum(v))
		sl.scr_width = numval(v);
	else if(isubnum(v))
		sl.scr_width = ubnumval(v);
}

static sl_fx
getbase(sl_v sym)
{
	sl_v v = sym_value(sym);
	if(!isnum(v))
		type_error(sym_name(sym), "num", v);
	sl_fx base = tooffset(v);
	if(base < 2 || base > 36)
		lerrorf(sl_errarg, "unsupported print base: %d", (int)base);
	return base;
}

void
sl_print(ios *f, sl_v v)
{
	sl.print_circle = sym_value(circlesym) != sl_nil;
	sl.print_pretty = sym_value(sl_printprettysym) != sl_nil;
	if(sl.print_pretty)
		set_print_width();
	sl.print_princ = sym_value(sl_printreadablysym) == sl_nil;

	sl_v pl = sym_value(lengthsym);
	sl.print_length = isnum(pl) ? tooffset(pl) : -1;

	pl = sym_value(levelsym);
	sl.print_level = isnum(pl) ? tooffset(pl) : -1;
	sl.p_level = 0;

	sl.print_base = getbase(basesym);
	sl.print_radix = sym_value(radixsym) != sl_nil;
	sl.print_ptr_base = getbase(ptrbasesym);
	sl.print_ptr_radix = sym_value(ptrradixsym) != sl_nil;

	sl.printlabel = 0;
	if(!sl.print_princ)
		sl_print_traverse(v);
	sl.hpos = sl.vpos = 0;

	sl_print_child(f, v);

	if(sl.print_level >= 0 || sl.print_length >= 0)
		memset(sl.consflags, 0, 4*bitvector_nwords(slvm.heapsize/sizeof(sl_cons)));

	if((iscons(v) || isvec(v) || isfn(v) || iscvalue(v)) && !isstr(v))
		htable_reset(&sl.printconses, 32);
}

void
sl_print_init(void)
{
	set(sl_printprettysym = mk_csym("*print-pretty*"), sl_t);
	set(sl_printreadablysym = mk_csym("*print-readably*"), sl_t);
	set(circlesym = mk_csym("*print-circle*"), sl_nil);
	set(widthsym = mk_csym("*print-width*"), fixnum(sl.scr_width));
	set(lengthsym = mk_csym("*print-length*"), sl_nil);
	set(levelsym = mk_csym("*print-level*"), sl_nil);
	set(radixsym = mk_csym("*print-radix*"), sl_nil);
	set(basesym = mk_csym("*print-base*"), fixnum(10));
	set(ptrradixsym = mk_csym("*print-ptr-radix*"), sl_t);
	set(ptrbasesym = mk_csym("*print-ptr-base*"), fixnum(16));
}