From b978959fae1c7449f24706fb3e33630b617a73f0 Mon Sep 17 00:00:00 2001
From: gingerBill <bill@gingerbill.org>
Date: Sun, 24 Mar 2019 20:58:01 +0000
Subject: [PATCH] Improve package strconv

---
 core/fmt/fmt.odin               |   2 +-
 core/strconv/generic_float.odin | 361 +++++++++++++++++++++++++++
 core/strconv/strconv.odin       | 418 ++++++--------------------------
 3 files changed, 430 insertions(+), 351 deletions(-)
 create mode 100644 core/strconv/generic_float.odin

diff --git a/core/fmt/fmt.odin b/core/fmt/fmt.odin
index 8657c6db7..c1d21c00d 100644
--- a/core/fmt/fmt.odin
+++ b/core/fmt/fmt.odin
@@ -3,7 +3,7 @@ package fmt
 import "core:runtime"
 import "core:os"
 import "core:mem"
-import "core:bits"
+import "core:math/bits"
 import "core:unicode/utf8"
 import "core:types"
 import "core:strconv"
diff --git a/core/strconv/generic_float.odin b/core/strconv/generic_float.odin
new file mode 100644
index 000000000..807d7ec04
--- /dev/null
+++ b/core/strconv/generic_float.odin
@@ -0,0 +1,361 @@
+package strconv
+
+using import "core:decimal"
+
+Int_Flag :: enum {
+	Prefix,
+	Plus,
+	Space,
+}
+Int_Flags :: bit_set[Int_Flag];
+
+Decimal_Slice :: struct {
+	digits:        []byte,
+	count:         int,
+	decimal_point: int,
+	neg:           bool,
+}
+
+Float_Info :: struct {
+	mantbits: uint,
+	expbits:  uint,
+	bias:     int,
+}
+
+
+_f16_info := Float_Info{10, 5,   -15};
+_f32_info := Float_Info{23, 8,  -127};
+_f64_info := Float_Info{52, 11, -1023};
+
+
+generic_ftoa :: proc(buf: []byte, val: f64, fmt: byte, prec, bit_size: int) -> []byte {
+	bits: u64;
+	flt: ^Float_Info;
+	switch bit_size {
+	case 32:
+		bits = u64(transmute(u32)f32(val));
+		flt = &_f32_info;
+	case 64:
+		bits = transmute(u64)val;
+		flt = &_f64_info;
+	case:
+		panic("strconv: invalid bit_size");
+	}
+
+	neg  := bits>>(flt.expbits+flt.mantbits) != 0;
+	exp  := int(bits>>flt.mantbits) & (1<<flt.expbits - 1);
+	mant := bits & (u64(1) << flt.mantbits - 1);
+
+	switch exp {
+	case 1<<flt.expbits - 1:
+		s: string;
+		if mant != 0 {
+			s = "NaN";
+		} else if neg {
+			s = "-Inf";
+		} else {
+			s = "+Inf";
+		}
+		n := copy(buf, cast([]byte)s);
+		return buf[:n];
+
+	case 0: // denormalized
+		exp += 1;
+
+	case:
+		mant |= u64(1) << flt.mantbits;
+	}
+
+	exp += flt.bias;
+
+	d_: Decimal;
+	d := &d_;
+	assign(d, mant);
+	shift(d, exp - int(flt.mantbits));
+	digs: Decimal_Slice;
+	shortest := prec < 0;
+	if shortest {
+		round_shortest(d, mant, exp, flt);
+		digs = Decimal_Slice{digits = d.digits[:], count = d.count, decimal_point = d.decimal_point};
+		switch fmt {
+		case 'e', 'E': prec = digs.count-1;
+		case 'f', 'F': prec = max(digs.count-digs.decimal_point, 0);
+		case 'g', 'G': prec = digs.count;
+		}
+	} else {
+		switch fmt {
+		case 'e', 'E': round(d, prec+1);
+		case 'f', 'F': round(d, d.decimal_point+prec);
+		case 'g', 'G':
+			if prec == 0 {
+				prec = 1;
+			}
+			round(d, prec);
+		}
+
+		digs = Decimal_Slice{digits = d.digits[:], count = d.count, decimal_point = d.decimal_point};
+	}
+	return format_digits(buf, shortest, neg, digs, prec, fmt);
+}
+
+
+
+format_digits :: proc(buf: []byte, shortest: bool, neg: bool, digs: Decimal_Slice, prec: int, fmt: byte) -> []byte {
+	Buffer :: struct {
+		b: []byte,
+		n: int,
+	}
+
+	to_bytes :: proc(b: Buffer) -> []byte do return b.b[:b.n];
+	add_bytes :: proc(buf: ^Buffer, bytes: ..byte) {
+		buf.n += copy(buf.b[buf.n:], bytes);
+	}
+
+	b := Buffer{b = buf};
+
+	switch fmt {
+	case 'f', 'F':
+		add_bytes(&b, neg ? '-' : '+');
+
+		// integer, padded with zeros when needed
+		if digs.decimal_point > 0 {
+			m := min(digs.count, digs.decimal_point);
+			add_bytes(&b, ..digs.digits[0:m]);
+			for ; m < digs.decimal_point; m += 1 {
+				add_bytes(&b, '0');
+			}
+		} else {
+			add_bytes(&b, '0');
+		}
+
+
+		// fractional part
+		if prec > 0 {
+			add_bytes(&b, '.');
+			for i in 0..prec-1 {
+				c: byte = '0';
+				if j := digs.decimal_point + i; 0 <= j && j < digs.count {
+					c = digs.digits[j];
+				}
+				add_bytes(&b, c);
+			}
+		}
+		return to_bytes(b);
+
+	case 'e', 'E':
+		add_bytes(&b, neg ? '-' : '+');
+
+		ch := byte('0');
+		if digs.count != 0 {
+			ch = digs.digits[0];
+		}
+		add_bytes(&b, ch);
+
+		if prec > 0 {
+			add_bytes(&b, '.');
+			i := 1;
+			m := min(digs.count, prec+1);
+			if i < m {
+				add_bytes(&b, ..digs.digits[i:m]);
+				i = m;
+			}
+			for ; i <= prec; i += 1 {
+				add_bytes(&b, '0');
+			}
+		}
+
+		add_bytes(&b, fmt);
+		exp := digs.decimal_point-1;
+		if digs.count == 0 {
+			// Zero has exponent of 0
+			exp = 0;
+		}
+
+		ch = '+';
+		if exp < 0 {
+			ch = '-';
+			exp = -exp;
+		}
+		add_bytes(&b, ch);
+
+		switch {
+		case exp < 10:  add_bytes(&b, '0', byte(exp)+'0'); // add prefix 0
+		case exp < 100: add_bytes(&b, byte(exp/10)+'0',  byte(exp%10)+'0');
+		case:           add_bytes(&b, byte(exp/100)+'0', byte(exp/10)%10+'0', byte(exp%10)+'0');
+		}
+
+		return to_bytes(b);
+
+	case 'g', 'G':
+		eprec := prec;
+		if eprec > digs.count && digs.count >= digs.decimal_point {
+			eprec = digs.count;
+		}
+
+		if shortest {
+			eprec = 6;
+		}
+
+		exp := digs.decimal_point - 1;
+		if exp < -4 || exp >= eprec {
+			if prec > digs.count {
+				prec = digs.count;
+			}
+			return format_digits(buf, shortest, neg, digs, prec-1, fmt+'e'-'g'); // keep the same case
+		}
+
+		if prec > digs.decimal_point {
+			prec = digs.count;
+		}
+
+		return format_digits(buf, shortest, neg, digs, max(prec-digs.decimal_point, 0), 'f');
+
+	case:
+		add_bytes(&b, '%', fmt);
+		return to_bytes(b);
+	}
+
+
+}
+
+round_shortest :: proc(d: ^Decimal, mant: u64, exp: int, flt: ^Float_Info) {
+	if mant == 0 { // If mantissa is zero, the number is zero
+		d.count = 0;
+		return;
+	}
+
+	/*
+		10^(dp-nd) > 2^(exp-mantbits)
+		log2(10) * (dp-nd) > exp-mantbits
+		log(2) >~ 0.332
+		332*(dp-nd) >= 100*(exp-mantbits)
+	 */
+	minexp := flt.bias+1;
+	if exp > minexp && 332*(d.decimal_point-d.count) >= 100*(exp - int(flt.mantbits)) {
+		// Number is already its shortest
+		return;
+	}
+
+	upper_: Decimal; upper := &upper_;
+	assign(upper, 2*mant - 1);
+	shift(upper, exp - int(flt.mantbits) - 1);
+
+	mantlo: u64;
+	explo:  int;
+	if mant > 1<<flt.mantbits || exp == minexp {
+		mantlo = mant-1;
+		explo = exp;
+	} else {
+		mantlo = 2*mant - 1;
+		explo = exp-1;
+	}
+	lower_: Decimal; lower := &lower_;
+	assign(lower, 2*mantlo + 1);
+	shift(lower, explo - int(flt.mantbits) - 1);
+
+	inclusive := mant%2 == 0;
+
+	for i in 0..d.count-1 {
+		l: byte = '0'; // lower digit
+		if i < lower.count {
+			l = lower.digits[i];
+		}
+		m := d.digits[i];   // middle digit
+		u: byte = '0'; // upper digit
+		if i < upper.count {
+			u = upper.digits[i];
+		}
+
+		ok_round_down := l != m || inclusive && i+1 == lower.count;
+		ok_round_up   := m != u && (inclusive || m+1 < u || i+1 < upper.count);
+
+		if ok_round_down && ok_round_up {
+			round(d, i+1);
+			return;
+		}
+		if ok_round_down {
+			round_down(d, i+1);
+			return;
+		}
+		if ok_round_up {
+			round_up(d, i+1);
+			return;
+		}
+	}
+
+}
+
+MAX_BASE :: 32;
+digits := "0123456789abcdefghijklmnopqrstuvwxyz";
+
+
+is_integer_negative :: proc(u: u64, is_signed: bool, bit_size: int) -> (unsigned: u64, neg: bool) {
+	if is_signed {
+		switch bit_size {
+		case 8:
+			i := i8(u);
+			neg = i < 0;
+			u = u64(abs(i64(i)));
+		case 16:
+			i := i16(u);
+			neg = i < 0;
+			u = u64(abs(i64(i)));
+		case 32:
+			i := i32(u);
+			neg = i < 0;
+			u = u64(abs(i64(i)));
+		case 64:
+			i := i64(u);
+			neg = i < 0;
+			u = u64(abs(i64(i)));
+		case:
+			panic("is_integer_negative: Unknown integer size");
+		}
+	}
+	return u, neg;
+}
+
+append_bits :: proc(buf: []byte, u: u64, base: int, is_signed: bool, bit_size: int, digits: string, flags: Int_Flags) -> string {
+	if base < 2 || base > MAX_BASE {
+		panic("strconv: illegal base passed to append_bits");
+	}
+
+	neg: bool;
+	a: [129]byte;
+	i := len(a);
+	u, neg = is_integer_negative(u, is_signed, bit_size);
+	b := u64(base);
+	for u >= b {
+		i-=1; a[i] = digits[u % b];
+		u /= b;
+	}
+	i-=1; a[i] = digits[u % b];
+
+	if .Prefix in flags {
+		ok := true;
+		switch base {
+		case  2: i-=1; a[i] = 'b';
+		case  8: i-=1; a[i] = 'o';
+		case 10: i-=1; a[i] = 'd';
+		case 12: i-=1; a[i] = 'z';
+		case 16: i-=1; a[i] = 'x';
+		case: ok = false;
+		}
+		if ok {
+			i-=1; a[i] = '0';
+		}
+	}
+
+	switch {
+	case neg:
+		i-=1; a[i] = '-';
+	case .Plus in flags:
+		i-=1; a[i] = '+';
+	case .Space in flags:
+		i-=1; a[i] = ' ';
+	}
+
+	out := a[i:];
+	copy(buf, out);
+	return string(buf[0:len(out)]);
+}
diff --git a/core/strconv/strconv.odin b/core/strconv/strconv.odin
index 07f506b6d..0b1f10f6c 100644
--- a/core/strconv/strconv.odin
+++ b/core/strconv/strconv.odin
@@ -1,14 +1,6 @@
 package strconv
 
-using import "core:decimal"
-
-Int_Flag :: enum {
-	Prefix,
-	Plus,
-	Space,
-}
-Int_Flags :: bit_set[Int_Flag];
-
+import "core:unicode/utf8"
 
 parse_bool :: proc(s: string) -> (result: bool = false, ok: bool) {
 	switch s {
@@ -204,363 +196,89 @@ append_uint :: proc(buf: []byte, u: u64, base: int) -> string {
 append_int :: proc(buf: []byte, i: i64, base: int) -> string {
 	return append_bits(buf, u64(i), base, true, 8*size_of(int), digits, nil);
 }
-itoa :: proc(buf: []byte, i: int) -> string do return append_int(buf, i64(i), 10);
+
+itoa :: proc(buf: []byte, i: int) -> string {
+	return append_int(buf, i64(i), 10);
+}
+atoi :: proc(s: string) -> int {
+	return parse_int(s);
+}
 
 append_float :: proc(buf: []byte, f: f64, fmt: byte, prec, bit_size: int) -> string {
 	return string(generic_ftoa(buf, f, fmt, prec, bit_size));
 }
 
 
+quote :: proc(buf: []byte, s: string) -> string {
+	write_byte :: inline proc(buf: []byte, i: ^int, bytes: ..byte) {
+		n := copy(buf[i^:], bytes[:]);
+		i^ += n;
+	}
 
+	c :: '"';
+	i := 0;
 
-Decimal_Slice :: struct {
-	digits:        []byte,
-	count:         int,
-	decimal_point: int,
-	neg:           bool,
+	write_byte(buf, &i, c);
+	for width := 0; len(s) > 0; s = s[width:] {
+		r := rune(s[0]);
+		width = 1;
+		if r >= utf8.RUNE_SELF {
+			r, width = utf8.decode_rune_in_string(s);
+		}
+		if width == 1 && r == utf8.RUNE_ERROR {
+			write_byte(buf, &i, '\\', 'x');
+			write_byte(buf, &i, digits[s[0]>>4]);
+			write_byte(buf, &i, digits[s[0]&0xf]);
+		}
+		s := quote_rune(buf[i:], r);
+		i += len(s);
+	}
+	write_byte(buf, &i, c);
+	return string(buf[:i]);
 }
 
-Float_Info :: struct {
-	mantbits: uint,
-	expbits:  uint,
-	bias:     int,
-}
+quote_rune :: proc(buf: []byte, r: rune) -> string {
+	write_byte :: inline proc(buf: []byte, i: ^int, bytes: ..byte) {
+		n := copy(buf[i^:], bytes[:]);
+		i^ += n;
+	}
+	write_string :: inline proc(buf: []byte, i: ^int, s: string) {
+		n := copy(buf[i^:], cast([]byte)s);
+		i^ += n;
+	}
+	write_rune :: inline proc(buf: []byte, i: ^int, r: rune) {
+		b, w := utf8.encode_rune(r);
+		n := copy(buf[i^:], b[:w]);
+		i^ += n;
+	}
 
+	i := 0;
+	write_byte(buf, &i, '\'');
 
-_f16_info := Float_Info{10, 5,   -15};
-_f32_info := Float_Info{23, 8,  -127};
-_f64_info := Float_Info{52, 11, -1023};
-
-
-generic_ftoa :: proc(buf: []byte, val: f64, fmt: byte, prec, bit_size: int) -> []byte {
-	bits: u64;
-	flt: ^Float_Info;
-	switch bit_size {
-	case 32:
-		bits = u64(transmute(u32)f32(val));
-		flt = &_f32_info;
-	case 64:
-		bits = transmute(u64)val;
-		flt = &_f64_info;
+	switch r {
+	case '\a': write_string(buf, &i, "\\a");
+	case '\b': write_string(buf, &i, "\\b");
+	case '\e': write_string(buf, &i, "\\e");
+	case '\f': write_string(buf, &i, "\\f");
+	case '\n': write_string(buf, &i, "\\n");
+	case '\r': write_string(buf, &i, "\\r");
+	case '\t': write_string(buf, &i, "\\t");
+	case '\v': write_string(buf, &i, "\\v");
 	case:
-		panic("strconv: invalid bit_size");
-	}
-
-	neg  := bits>>(flt.expbits+flt.mantbits) != 0;
-	exp  := int(bits>>flt.mantbits) & (1<<flt.expbits - 1);
-	mant := bits & (u64(1) << flt.mantbits - 1);
-
-	switch exp {
-	case 1<<flt.expbits - 1:
-		s: string;
-		if mant != 0 {
-			s = "NaN";
-		} else if neg {
-			s = "-Inf";
-		} else {
-			s = "+Inf";
-		}
-		n := copy(buf, cast([]byte)s);
-		return buf[:n];
-
-	case 0: // denormalized
-		exp += 1;
-
-	case:
-		mant |= u64(1) << flt.mantbits;
-	}
-
-	exp += flt.bias;
-
-	d_: Decimal;
-	d := &d_;
-	assign(d, mant);
-	shift(d, exp - int(flt.mantbits));
-	digs: Decimal_Slice;
-	shortest := prec < 0;
-	if shortest {
-		round_shortest(d, mant, exp, flt);
-		digs = Decimal_Slice{digits = d.digits[:], count = d.count, decimal_point = d.decimal_point};
-		switch fmt {
-		case 'e', 'E': prec = digs.count-1;
-		case 'f', 'F': prec = max(digs.count-digs.decimal_point, 0);
-		case 'g', 'G': prec = digs.count;
-		}
-	} else {
-		switch fmt {
-		case 'e', 'E': round(d, prec+1);
-		case 'f', 'F': round(d, d.decimal_point+prec);
-		case 'g', 'G':
-			if prec == 0 {
-				prec = 1;
-			}
-			round(d, prec);
-		}
-
-		digs = Decimal_Slice{digits = d.digits[:], count = d.count, decimal_point = d.decimal_point};
-	}
-	return format_digits(buf, shortest, neg, digs, prec, fmt);
-}
-
-
-
-format_digits :: proc(buf: []byte, shortest: bool, neg: bool, digs: Decimal_Slice, prec: int, fmt: byte) -> []byte {
-	Buffer :: struct {
-		b: []byte,
-		n: int,
-	}
-
-	to_bytes :: proc(b: Buffer) -> []byte do return b.b[:b.n];
-	add_bytes :: proc(buf: ^Buffer, bytes: ..byte) {
-		buf.n += copy(buf.b[buf.n:], bytes);
-	}
-
-	b := Buffer{b = buf};
-
-	switch fmt {
-	case 'f', 'F':
-		add_bytes(&b, neg ? '-' : '+');
-
-		// integer, padded with zeros when needed
-		if digs.decimal_point > 0 {
-			m := min(digs.count, digs.decimal_point);
-			add_bytes(&b, ..digs.digits[0:m]);
-			for ; m < digs.decimal_point; m += 1 {
-				add_bytes(&b, '0');
+		if r < 32 {
+			write_string(buf, &i, "\\x");
+			b: [2]byte;
+			s := append_bits(b[:], u64(r), 16, true, 64, digits, nil);
+			switch len(s) {
+			case 0: write_string(buf, &i, "00");
+			case 1: write_rune(buf, &i, '0');
+			case 2: write_string(buf, &i, s);
 			}
 		} else {
-			add_bytes(&b, '0');
+			write_rune(buf, &i, r);
 		}
-
-
-		// fractional part
-		if prec > 0 {
-			add_bytes(&b, '.');
-			for i in 0..prec-1 {
-				c: byte = '0';
-				if j := digs.decimal_point + i; 0 <= j && j < digs.count {
-					c = digs.digits[j];
-				}
-				add_bytes(&b, c);
-			}
-		}
-		return to_bytes(b);
-
-	case 'e', 'E':
-		add_bytes(&b, neg ? '-' : '+');
-
-		ch := byte('0');
-		if digs.count != 0 {
-			ch = digs.digits[0];
-		}
-		add_bytes(&b, ch);
-
-		if prec > 0 {
-			add_bytes(&b, '.');
-			i := 1;
-			m := min(digs.count, prec+1);
-			if i < m {
-				add_bytes(&b, ..digs.digits[i:m]);
-				i = m;
-			}
-			for ; i <= prec; i += 1 {
-				add_bytes(&b, '0');
-			}
-		}
-
-		add_bytes(&b, fmt);
-		exp := digs.decimal_point-1;
-		if digs.count == 0 {
-			// Zero has exponent of 0
-			exp = 0;
-		}
-
-		ch = '+';
-		if exp < 0 {
-			ch = '-';
-			exp = -exp;
-		}
-		add_bytes(&b, ch);
-
-		switch {
-		case exp < 10:  add_bytes(&b, '0', byte(exp)+'0'); // add prefix 0
-		case exp < 100: add_bytes(&b, byte(exp/10)+'0',  byte(exp%10)+'0');
-		case:           add_bytes(&b, byte(exp/100)+'0', byte(exp/10)%10+'0', byte(exp%10)+'0');
-		}
-
-		return to_bytes(b);
-
-	case 'g', 'G':
-		eprec := prec;
-		if eprec > digs.count && digs.count >= digs.decimal_point {
-			eprec = digs.count;
-		}
-
-		if shortest {
-			eprec = 6;
-		}
-
-		exp := digs.decimal_point - 1;
-		if exp < -4 || exp >= eprec {
-			if prec > digs.count {
-				prec = digs.count;
-			}
-			return format_digits(buf, shortest, neg, digs, prec-1, fmt+'e'-'g'); // keep the same case
-		}
-
-		if prec > digs.decimal_point {
-			prec = digs.count;
-		}
-
-		return format_digits(buf, shortest, neg, digs, max(prec-digs.decimal_point, 0), 'f');
-
-	case:
-		add_bytes(&b, '%', fmt);
-		return to_bytes(b);
 	}
+	write_byte(buf, &i, '\'');
 
-
+	return string(buf[:i]);
 }
-
-round_shortest :: proc(d: ^Decimal, mant: u64, exp: int, flt: ^Float_Info) {
-	if mant == 0 { // If mantissa is zero, the number is zero
-		d.count = 0;
-		return;
-	}
-
-	/*
-		10^(dp-nd) > 2^(exp-mantbits)
-		log2(10) * (dp-nd) > exp-mantbits
-		log(2) >~ 0.332
-		332*(dp-nd) >= 100*(exp-mantbits)
-	 */
-	minexp := flt.bias+1;
-	if exp > minexp && 332*(d.decimal_point-d.count) >= 100*(exp - int(flt.mantbits)) {
-		// Number is already its shortest
-		return;
-	}
-
-	upper_: Decimal; upper := &upper_;
-	assign(upper, 2*mant - 1);
-	shift(upper, exp - int(flt.mantbits) - 1);
-
-	mantlo: u64;
-	explo:  int;
-	if mant > 1<<flt.mantbits || exp == minexp {
-		mantlo = mant-1;
-		explo = exp;
-	} else {
-		mantlo = 2*mant - 1;
-		explo = exp-1;
-	}
-	lower_: Decimal; lower := &lower_;
-	assign(lower, 2*mantlo + 1);
-	shift(lower, explo - int(flt.mantbits) - 1);
-
-	inclusive := mant%2 == 0;
-
-	for i in 0..d.count-1 {
-		l: byte = '0'; // lower digit
-		if i < lower.count {
-			l = lower.digits[i];
-		}
-		m := d.digits[i];   // middle digit
-		u: byte = '0'; // upper digit
-		if i < upper.count {
-			u = upper.digits[i];
-		}
-
-		ok_round_down := l != m || inclusive && i+1 == lower.count;
-		ok_round_up   := m != u && (inclusive || m+1 < u || i+1 < upper.count);
-
-		if ok_round_down && ok_round_up {
-			round(d, i+1);
-			return;
-		}
-		if ok_round_down {
-			round_down(d, i+1);
-			return;
-		}
-		if ok_round_up {
-			round_up(d, i+1);
-			return;
-		}
-	}
-
-}
-
-MAX_BASE :: 32;
-digits := "0123456789abcdefghijklmnopqrstuvwxyz";
-
-
-is_integer_negative :: proc(u: u64, is_signed: bool, bit_size: int) -> (unsigned: u64, neg: bool) {
-	if is_signed {
-		switch bit_size {
-		case 8:
-			i := i8(u);
-			neg = i < 0;
-			u = u64(abs(i64(i)));
-		case 16:
-			i := i16(u);
-			neg = i < 0;
-			u = u64(abs(i64(i)));
-		case 32:
-			i := i32(u);
-			neg = i < 0;
-			u = u64(abs(i64(i)));
-		case 64:
-			i := i64(u);
-			neg = i < 0;
-			u = u64(abs(i64(i)));
-		case:
-			panic("is_integer_negative: Unknown integer size");
-		}
-	}
-	return u, neg;
-}
-
-append_bits :: proc(buf: []byte, u: u64, base: int, is_signed: bool, bit_size: int, digits: string, flags: Int_Flags) -> string {
-	if base < 2 || base > MAX_BASE {
-		panic("strconv: illegal base passed to append_bits");
-	}
-
-	neg: bool;
-	a: [129]byte;
-	i := len(a);
-	u, neg = is_integer_negative(u, is_signed, bit_size);
-	b := u64(base);
-	for u >= b {
-		i-=1; a[i] = digits[u % b];
-		u /= b;
-	}
-	i-=1; a[i] = digits[u % b];
-
-	if .Prefix in flags {
-		ok := true;
-		switch base {
-		case  2: i-=1; a[i] = 'b';
-		case  8: i-=1; a[i] = 'o';
-		case 10: i-=1; a[i] = 'd';
-		case 12: i-=1; a[i] = 'z';
-		case 16: i-=1; a[i] = 'x';
-		case: ok = false;
-		}
-		if ok {
-			i-=1; a[i] = '0';
-		}
-	}
-
-	switch {
-	case neg:
-		i-=1; a[i] = '-';
-	case .Plus in flags:
-		i-=1; a[i] = '+';
-	case .Space in flags:
-		i-=1; a[i] = ' ';
-	}
-
-	out := a[i:];
-	copy(buf, out);
-	return string(buf[0:len(out)]);
-}
-