Add `strconv.unquote_string` and `strconv.unquote_char`

core/strconv/strconv.odin

@@ -488,3 +488,157 @@ quote_rune :: proc(buf: []byte, r: rune) -> string {
 
 	return string(buf[:i]);
 }
+
+
+
+
+unquote_char :: proc(str: string, quote: byte) -> (r: rune, multiple_bytes: bool, tail_string: string, success: bool) {
+	hex_to_int :: proc(c: byte) -> int {
+		switch c {
+		case '0'..'9': return int(c-'0');
+		case 'a'..'f': return int(c-'a')+10;
+		case 'A'..'F': return int(c-'A')+10;
+		}
+		return -1;
+	}
+	w: int;
+
+	if str[0] == quote && quote == '"' {
+		return;
+	} else if str[0] >= 0x80 {
+		r, w = utf8.decode_rune_in_string(str);
+		return r, true, str[w:], true;
+	} else if str[0] != '\\' {
+		return rune(str[0]), false, str[1:], true;
+	}
+
+	if len(str) <= 1 {
+		return;
+	}
+	s := str;
+	c := s[1];
+	s = s[2:];
+
+	switch c {
+	case:
+		return;
+
+	case 'a':  r = '\a';
+	case 'b':  r = '\b';
+	case 'f':  r = '\f';
+	case 'n':  r = '\n';
+	case 'r':  r = '\r';
+	case 't':  r = '\t';
+	case 'v':  r = '\v';
+	case '\\': r = '\\';
+
+	case '"':  r = '"';
+	case '\'': r = '\'';
+
+	case '0'..'7':
+		v := int(c-'0');
+		if len(s) < 2 {
+			return;
+		}
+		for i in 0..<len(s) {
+			d := int(s[i]-'0');
+			if d < 0 || d > 7 {
+				return;
+			}
+			v = (v<<3) | d;
+		}
+		s = s[2:];
+		if v > 0xff {
+			return;
+		}
+		r = rune(v);
+
+	case 'x', 'u', 'U':
+		count: int;
+		switch c {
+		case 'x': count = 2;
+		case 'u': count = 4;
+		case 'U': count = 8;
+		}
+
+		if len(s) < count {
+			return;
+		}
+
+		for i in 0..<count {
+			d := hex_to_int(s[i]);
+			if d < 0 {
+				return;
+			}
+			r = (r<<4) | rune(d);
+		}
+		s = s[count:];
+		if c == 'x' {
+			break;
+		}
+		if r > utf8.MAX_RUNE {
+			return;
+		}
+		multiple_bytes = true;
+	}
+
+	success = true;
+	tail_string = s;
+	return;
+}
+
+unquote_string :: proc(lit: string, allocator := context.allocator) -> (res: string, allocated, success: bool) {
+	contains_rune :: proc(s: string, r: rune) -> int {
+		for c, offset in s {
+			if c == r do return offset;
+		}
+		return -1;
+	}
+
+	assert(len(lit) >= 2);
+	if lit[0] == '`' {
+		return lit[1:len(lit)-1], false, true;
+	}
+
+	s := lit;
+	quote := '"';
+
+	if s == `""` {
+		return "", false, true;
+	}
+
+	if contains_rune(s, '\n') >= 0 {
+		return s, false, false;
+	}
+
+	if contains_rune(s, '\\') < 0 && contains_rune(s, quote) < 0 {
+		if quote == '"' {
+			return s, false, true;
+		}
+	}
+
+
+	buf_len := 3*len(s) / 2;
+	buf := make([]byte, buf_len, allocator);
+	offset := 0;
+	for len(s) > 0 {
+		r, multiple_bytes, tail_string, ok := unquote_char(s, byte(quote));
+		if !ok {
+			delete(buf);
+			return s, false, false;
+		}
+		s = tail_string;
+		if r < 0x80 || !multiple_bytes {
+			buf[offset] = byte(r);
+			offset += 1;
+		} else {
+			b, w := utf8.encode_rune(r);
+			copy(buf[offset:], b[:w]);
+			offset += w;
+		}
+	}
+
+	new_string := string(buf[:offset]);
+
+	return new_string, true, true;
+}