python-plus-plus/ppp/ppp-whole.ppp

enum Keyword {
	Enum,
	Struct,
	Func,
	If,
	Else,
	While,
	Break,
	Continue,
	Do,
	For,
	To,
	In,
	Match,
	Case,
	Assert,
	Return,
	Lambda
}

enum OptionalKeyword {
	Some(Keyword),
	None
}

func keyword_from_str(keyword: str) -> OptionalKeyword {
	if keyword == "enum" return OptionalKeyword.Some(Keyword.Enum);
	if keyword == "struct" return OptionalKeyword.Some(Keyword.Struct);
	if keyword == "func" return OptionalKeyword.Some(Keyword.Func);
	if keyword == "if" return OptionalKeyword.Some(Keyword.If);
	if keyword == "else" return OptionalKeyword.Some(Keyword.Else);
	if keyword == "while" return OptionalKeyword.Some(Keyword.While);
	if keyword == "break" return OptionalKeyword.Some(Keyword.Break);
	if keyword == "continue" return OptionalKeyword.Some(Keyword.Continue);
	if keyword == "do" return OptionalKeyword.Some(Keyword.Do);
	if keyword == "for" return OptionalKeyword.Some(Keyword.For);
	if keyword == "to" return OptionalKeyword.Some(Keyword.To);
	if keyword == "in" return OptionalKeyword.Some(Keyword.In);
	if keyword == "match" return OptionalKeyword.Some(Keyword.Match);
	if keyword == "case" return OptionalKeyword.Some(Keyword.Case);
	if keyword == "assert" return OptionalKeyword.Some(Keyword.Assert);
	if keyword == "return" return OptionalKeyword.Some(Keyword.Return);
	if keyword == "lambda" return OptionalKeyword.Some(Keyword.Lambda);
	return OptionalKeyword.None;
}

func keyword_to_str(keyword: Keyword) -> str {
	match keyword in {
		case Enum return "enum";
		case Struct return "struct";
		case Func return "func";
		case If return "if";
		case Else return "else";
		case While return "while";
		case Break return "break";
		case Continue return "continue";
		case Do return "do";
		case For return "for";
		case To return "to";
		case In return "in";
		case Match return "match";
		case Case return "case";
		case Assert return "assert";
		case Return return "return";
		case Lambda return "lambda";
	}
	assert false, "Invalid keyword";
}

enum Symbol {
	Open,
	Close,
	OpenCurly,
	CloseCurly,
	Comma,
	OpenSquare,
	CloseSquare,
	Colon,
	Left,
	Right,
	Arrow,
	Semicolon,
	Equal,
	Dequal,
	Exclamation,
	NotEqual,
	Dot,
	Plus,
	Dash,
	Asterisk,
	Dasterisk,
	Slash,
	QuestionMark,
	Ampersand,
	Dampersand,
	Pipe,
	Dpipe,
	Dleft,
	Dright,
	GreaterEqual,
	LesserEqual,
	Percent,
	Tilde,
	Carot
}

enum OptionalSymbol {
	Some(Symbol),
	None
}

func symbol_from_str(symbol: str) -> OptionalSymbol {
	if symbol == "(" return OptionalSymbol.Some(Symbol.Open);
	if symbol == ")" return OptionalSymbol.Some(Symbol.Close);
	if symbol == "{" return OptionalSymbol.Some(Symbol.OpenCurly);
	if symbol == "}" return OptionalSymbol.Some(Symbol.CloseCurly);
	if symbol == "," return OptionalSymbol.Some(Symbol.Comma);
	if symbol == "[" return OptionalSymbol.Some(Symbol.OpenSquare);
	if symbol == "]" return OptionalSymbol.Some(Symbol.CloseSquare);
	if symbol == ":" return OptionalSymbol.Some(Symbol.Colon);
	if symbol == "<" return OptionalSymbol.Some(Symbol.Left);
	if symbol == ">" return OptionalSymbol.Some(Symbol.Right);
	if symbol == "->" return OptionalSymbol.Some(Symbol.Arrow);
	if symbol == ";" return OptionalSymbol.Some(Symbol.Semicolon);
	if symbol == "=" return OptionalSymbol.Some(Symbol.Equal);
	if symbol == "==" return OptionalSymbol.Some(Symbol.Dequal);
	if symbol == "!" return OptionalSymbol.Some(Symbol.Exclamation);
	if symbol == "!=" return OptionalSymbol.Some(Symbol.NotEqual);
	if symbol == "." return OptionalSymbol.Some(Symbol.Dot);
	if symbol == "+" return OptionalSymbol.Some(Symbol.Plus);
	if symbol == "-" return OptionalSymbol.Some(Symbol.Dash);
	if symbol == "*" return OptionalSymbol.Some(Symbol.Asterisk);
	if symbol == "**" return OptionalSymbol.Some(Symbol.Dasterisk);
	if symbol == "/" return OptionalSymbol.Some(Symbol.Slash);
	if symbol == "?" return OptionalSymbol.Some(Symbol.QuestionMark);
	if symbol == "&" return OptionalSymbol.Some(Symbol.Ampersand);
	if symbol == "&&" return OptionalSymbol.Some(Symbol.Dampersand);
	if symbol == "|" return OptionalSymbol.Some(Symbol.Pipe);
	if symbol == "||" return OptionalSymbol.Some(Symbol.Dpipe);
	if symbol == "<<" return OptionalSymbol.Some(Symbol.Dleft);
	if symbol == ">>" return OptionalSymbol.Some(Symbol.Dright);
	if symbol == ">=" return OptionalSymbol.Some(Symbol.GreaterEqual);
	if symbol == "<=" return OptionalSymbol.Some(Symbol.LesserEqual);
	if symbol == "%" return OptionalSymbol.Some(Symbol.Percent);
	if symbol == "~" return OptionalSymbol.Some(Symbol.Tilde);
	if symbol == "^" return OptionalSymbol.Some(Symbol.Carot);
	assert false, "Unimplemented symbol '%s'" % symbol; 
}

func symbol_to_str(symbol: Symbol) -> str {
	match symbol in {
		case Open return "(";
		case Close return ")";
		case OpenCurly return "{";
		case CloseCurly return "}";
		case Comma return ",";
		case OpenSquare return "[";
		case CloseSquare return "]";
		case Colon return ":";
		case Left return "<";
		case Right return ">";
		case Arrow return "->";
		case Semicolon return ";";
		case Equal return "=";
		case Dequal return "==";
		case Exclamation return "!";
		case NotEqual return "!=";
		case Dot return ".";
		case Plus return "+";
		case Dash return "-";
		case Asterisk return "*";
		case Dasterisk return "**";
		case Slash return "/";
		case QuestionMark return "?";
		case Ampersand return "&";
		case Dampersand return "&&";
		case Pipe return "|";
		case Dpipe return "||";
		case Dleft return "<<";
		case Dright return ">>";
		case GreaterEqual return ">=";
		case LesserEqual return "<=";
		case Percent return "%";
		case Tilde return "~";
		case Carot return "^";
	}
	assert false, "Invalid symbol";
}

enum TokenContents {
	Keyword(Keyword),
	Identifier(str),
	Number(int),
	String(str),
	Symbol(Symbol),
	Eof
}

func token_contents_to_str(token: TokenContents) -> str {
	match token in {
		case Keyword(keyword) return "Keyword(%s)" % keyword_to_str(keyword);
		case Identifier(string) return "Identifier(%s)" % string;
		case Number(number) return "Number(%d)" % number;
		case String(string) return "String(\"%s\")" % string;
		case Symbol(symbol) return "Symbol('%s')" % symbol_to_str(symbol);
		case Eof return "Eof";
	}
}

struct Token {
	line: int,
	col: int,
	value: str,
	contents: TokenContents
}

func token_to_str(token: Token) -> str {
	return token_contents_to_str(token.contents)+"{:"+int_to_str(token.line)+":"+int_to_str(token.col)+"}";
}

enum OptionalToken {
	Some(Token),
	None
}

func is_some_token(maybe_token: OptionalToken) -> bool {
	match maybe_token in {
		case Some(_) return true;
		case None return false;
	}
	assert false, "Unreachable";
}

struct Lexer {
	source: str,
	location: int,
	line: int,
	col: int,
	peeked_token: OptionalToken
}

func new_lexer(source: str) -> Lexer {
	return Lexer{
		source = source,
		location = 0,
		line = 1,
		col = 0,
		peeked_token = OptionalToken.None
	};
}

func lexer_from_file(path: str) -> Lexer return new_lexer(read(path));

func is_space(char: str) -> bool {
	return char == " " || char == "\t" || char == "\n";
}

func is_digit(char: str) -> bool {
	return char == "0" || char == "1" || char == "2" || char == "3" || char == "4" || char == "5" || char == "6" || char == "7" || char == "8" || char == "9";
}

func is_alpha(char: str) -> bool {
	return char == "a" || char == "b" || char == "c" || char == "d" || char == "e" || char == "f" || char == "g" || char == "h" || char == "i" || char == "j" || char == "k" || char == "l" || char == "m" || char == "n" || char == "o" || char == "p" || char == "q" || char == "r" || char == "s" || char == "t" || char == "u" || char == "v" || char == "w" || char == "x" || char == "y" || char == "z" || char == "A" || char == "B" || char == "C" || char == "D" || char == "E" || char == "F" || char == "G" || char == "H" || char == "I" || char == "J" || char == "K" || char == "L" || char == "M" || char == "N" || char == "O" || char == "P" || char == "Q" || char == "R" || char == "S" || char == "T" || char == "U" || char == "V" || char == "W" || char == "X" || char == "Y" || char == "Z" || char == "_";
}

func lexer_next_token(lexer: Lexer) -> Token {
	match lexer.peeked_token in {
		case Some(token) do {
			lexer.peeked_token = OptionalToken.None;
			return token;
		}
	}

	while lexer.location < len(lexer.source) && is_space(lexer.source[lexer.location]) do {
		if lexer.source[lexer.location] == "\n" do {
			lexer.line = lexer.line + 1;
			lexer.col = 0;
		}
		lexer.location = lexer.location + 1;
	}

	if lexer.location >= len(lexer.source) return Token{line=lexer.line, col=lexer.col, value="\0", contents=TokenContents.Eof};

	if is_digit(lexer.source[lexer.location]) do {
		number_str: str = "";
		while lexer.location < len(lexer.source) && is_digit(lexer.source[lexer.location]) do {
			number_str = number_str + lexer.source[lexer.location];
			lexer.location = lexer.location + 1;
		}
		number: int = str_to_int(number_str);
		return Token{line=lexer.line, col=lexer.col, value=number_str, contents=TokenContents.Number(number)};
	} else if is_alpha(lexer.source[lexer.location]) do {
		word_str: str = "";
		while lexer.location < len(lexer.source) && is_alpha(lexer.source[lexer.location]) do {
			word_str = word_str + lexer.source[lexer.location];
			lexer.location = lexer.location + 1;
		}
		match keyword_from_str(word_str) in {
			case Some(keyword) return Token{line=lexer.line, col=lexer.col, value=word_str, contents=TokenContents.Keyword(keyword)};
			case None return Token{line=lexer.line, col=lexer.col, value=word_str, contents=TokenContents.Identifier(word_str)};
		}
		assert false, "Identifier";
	} else if lexer.source[lexer.location] == "\"" do {
		lexer.location = lexer.location + 1;
		string_str: str = "";
		escaping: bool = false;
		while lexer.location < len(lexer.source) && (lexer.source[lexer.location] != "\"" || escaping) do {
			escaping = escaping? false: lexer.source[lexer.location] == "\\";
			string_str = string_str + lexer.source[lexer.location];
			lexer.location = lexer.location + 1;
		}
		lexer.location = lexer.location + 1;
		return Token{line=lexer.line, col=lexer.col, value="\""+string_str+"\"", contents=TokenContents.String(string_str)};
	} else if lexer.source[lexer.location] == "|" && lexer.location < len(lexer.source)-1 && lexer.source[lexer.location+1] == "|" do {
		lexer.location = lexer.location + 2;
		return Token{line=lexer.line, col=lexer.col, value="||", contents=TokenContents.Symbol(Symbol.Dpipe)};
	} else if lexer.source[lexer.location] == "&" && lexer.location < len(lexer.source)-1 && lexer.source[lexer.location+1] == "&" do {
		lexer.location = lexer.location + 2;
		return Token{line=lexer.line, col=lexer.col, value="&&", contents=TokenContents.Symbol(Symbol.Dampersand)};
	} else if lexer.source[lexer.location] == "*" && lexer.location < len(lexer.source)-1 && lexer.source[lexer.location+1] == "*" do {
		lexer.location = lexer.location + 2;
		return Token{line=lexer.line, col=lexer.col, value="**", contents=TokenContents.Symbol(Symbol.Dasterisk)};
	} else if lexer.source[lexer.location] == "-" && lexer.location < len(lexer.source)-1 && lexer.source[lexer.location+1] == ">" do {
		lexer.location = lexer.location + 2;
		return Token{line=lexer.line, col=lexer.col, value="->", contents=TokenContents.Symbol(Symbol.Arrow)};
	} else if lexer.source[lexer.location] == ">" && lexer.location < len(lexer.source)-1 && lexer.source[lexer.location+1] == "=" do {
		lexer.location = lexer.location + 2;
		return Token{line=lexer.line, col=lexer.col, value=">=", contents=TokenContents.Symbol(Symbol.GreaterEqual)};
	} else if lexer.source[lexer.location] == "<" && lexer.location < len(lexer.source)-1 && lexer.source[lexer.location+1] == "=" do {
		lexer.location = lexer.location + 2;
		return Token{line=lexer.line, col=lexer.col, value="<=", contents=TokenContents.Symbol(Symbol.LesserEqual)};
	} else if lexer.source[lexer.location] == "=" && lexer.location < len(lexer.source)-1 && lexer.source[lexer.location+1] == "=" do {
		lexer.location = lexer.location + 2;
		return Token{line=lexer.line, col=lexer.col, value="==", contents=TokenContents.Symbol(Symbol.Dequal)};
	} else if lexer.source[lexer.location] == "!" && lexer.location < len(lexer.source)-1 && lexer.source[lexer.location+1] == "=" do {
		lexer.location = lexer.location + 2;
		return Token{line=lexer.line, col=lexer.col, value="!=", contents=TokenContents.Symbol(Symbol.NotEqual)};
	} else {
		match symbol_from_str(lexer.source[lexer.location]) in {
			case Some(symbol) do {
				lexer.location = lexer.location + 1;
				return Token{line=lexer.line, col=lexer.col, value=lexer.source[lexer.location-1], contents=TokenContents.Symbol(symbol)};
			}
			case None assert False, "Unimplemented, '%s'" % lexer.source[lexer.location];
		}
		assert false, "Unreachable Symbol";
	}

	assert false, "Unreachable, next_token";
}

func lexer_peek_token(lexer: Lexer) -> Token {
	match lexer.peeked_token in {
		case Some(token) return token;
		case None do {
			token: Token = lexer_next_token(lexer);
			lexer.peeked_token = OptionalToken.Some(token);
			return token;
		}
	}
	assert false, "Unreachable";
}

func lexer_check_token(lexer: Lexer, expected: TokenContents) -> bool {
	token: Token = lexer_peek_token(lexer);
	return token.contents == expected;
}

func lexer_take_token(lexer: Lexer, token: TokenContents) -> OptionalToken {
	if lexer_check_token(lexer, token) return OptionalToken.Some(lexer_next_token(lexer));
	return OptionalToken.None;
}

func lexer_take_tokens(lexer: Lexer, tokens: TokenContents[]) -> OptionalToken {
	for token in tokens do {
		if lexer_check_token(lexer, token) return OptionalToken.Some(lexer_next_token(lexer));
	}
	return OptionalToken.None;
}

func lexer_assert_token(lexer: Lexer, expected: TokenContents) -> Token {
	token: Token = lexer_next_token(lexer);
	assert token.contents == expected, "Expected %s but got %s!" % (token_contents_to_str(expected), token_to_str(token));
	return token;
}

func lexer_check_tokens(lexer: Lexer, tokens: TokenContents[]) -> bool {
	for token in tokens if lexer_check_token(lexer, token) return true;
	return false;
}

enum TypeExpression {
	Tuple(TypeExpression[]),
	Union(TypeExpression[]),
	List(TypeExpression),
	Array(TypeExpression, int),
	Name(str),
	Specification(TypeExpression, TypeExpression[]),
	Function(TypeExpression[], TypeExpression)
}

enum OptionalTypeExpression {
	Some(TypeExpression),
	None
}

func parse_type_primary(lexer: Lexer) -> TypeExpression {
	base_type: TypeExpression;
	if is_some_token(lexer_take_token(lexer, TokenContents.Symbol(Symbol.Open))) do {
		if is_some_token(lexer_take_token(lexer, TokenContents.Symbol(Symbol.Close))) return TypeExpression.Tuple([]);

		types: TypeExpression[] = [parse_type(lexer)];
		while is_some_token(lexer_take_token(lexer, TokenContents.Symbol(Symbol.Comma))) types = types + [parse_type(lexer)];
		lexer_assert_token(lexer, TokenContents.Symbol(Symbol.Close));
		base_type = TypeExpression.Tuple(types);
	} else if is_some_token(lexer_take_token(lexer, TokenContents.Symbol(Symbol.OpenSquare))) do {
		assert false, "Unimplemented parse_type_primary array";
	} else {
		base_type = TypeExpression.Name(parse_identifier(lexer));
	}

	closing: Symbol;
	while lexer_check_tokens(lexer, [TokenContents.Symbol(Symbol.OpenSquare), TokenContents.Symbol(Symbol.Left)]) do {
		match lexer_next_token(lexer).contents in {
			case Symbol(symbol) do {
				match symbol in {
					case OpenSquare match lexer_peek_token(lexer).contents in {
						case Number(number) do {
							lexer_assert_token(lexer, TokenContents.Symbol(Symbol.CloseSquare));
							base_type = TypeExpression.Array(base_type, number);
							continue;
						}
					}
				}

				match symbol in {
					case OpenSquare closing = Symbol.CloseSquare;
					case Left closing = Symbol.Right;
					case _ assert false, "Unreachable";
				}

				match symbol in {
					case OpenSquare if is_some_token(lexer_take_token(lexer, TokenContents.Symbol(closing))) do {
						base_type = TypeExpression.List(base_type);
						continue;
					}
				}

				generics: TypeExpression[] = [parse_type(lexer)];
				while is_some_token(lexer_take_token(lexer, TokenContents.Symbol(Symbol.Comma))) generics = generics + [parse_type(lexer)];

				lexer_assert_token(lexer, TokenContents.Symbol(closing));
				match base_type in {
					case Specification assert false, "Cannot specify an already specified type";
				}

				base_type = TypeExpression.Specification(base_type, generics);
			}
			case _ assert false, "Unreachable";
		}
	}

	return base_type;
}

func parse_type(lexer: Lexer) -> TypeExpression {
	base_type: TypeExpression = parse_type_primary(lexer);
	if !is_some_token(lexer_take_token(lexer, TokenContents.Symbol(Symbol.Arrow))) return base_type;
	return_type: TypeExpression = parse_type(lexer);
	match base_type in {
		case Tuple(type_expressions) return TypeExpression.Function(type_expressions, return_type);
	}
	return TypeExpression.Function([base_type], return_type);
}

struct TypeDeclaration {
	name: str,
	type_: TypeExpression
}

func parse_type_declaration(lexer: Lexer) -> TypeDeclaration {
	entry_name: str = parse_identifier(lexer);
	lexer_assert_token(lexer, TokenContents.Symbol(Symbol.Colon));
	entry_type: TypeExpression = parse_type(lexer);
	return TypeDeclaration{name=entry_name, type_=entry_type};
}

enum EnumEntry {
	Const(str),
	Tuple(str, TypeExpression[]),
	Struct(str, TypeDeclaration[])
}

func parse_enum_entry(lexer: Lexer) -> EnumEntry {
	entry_name: str = parse_identifier(lexer);
	if is_some_token(lexer_take_token(lexer, TokenContents.Symbol(Symbol.Open))) do {
		entry_types: TypeExpression[] = [parse_type(lexer)];
		while is_some_token(lexer_take_token(lexer, TokenContents.Symbol(Symbol.Comma))) entry_types = entry_types + [parse_type(lexer)];
		lexer_assert_token(lexer, TokenContents.Symbol(Symbol.Close));
		return EnumEntry.Tuple(entry_name, entry_types);
	} else if is_some_token(lexer_take_token(lexer, TokenContents.Symbol(Symbol.OpenCurly))) do {
		if is_some_token(lexer_take_token(lexer, TokenContents.Symbol(Symbol.CloseCurly))) return EnumEntry.Struct(entry_name, []);

		assert false, "Unimplemented parse_enum_entry";
	}

	return EnumEntry.Const(entry_name);
}

enum Expression {
	FunctionCall(Expression, Expression[]),
	Variable(str),
	ArrayAccess(Expression, Expression),
	Array(Expression[]),
	FieldAccess(Expression, str),
	Number(int),
	String(str),
	Tuple(Expression[]),
	StructInstantiation(Expression, (str, Expression)[]),
	LoopComrehension(Expression, str, Expression),
	Return(Expression),
	Ternary(Expression, Expression, Expression),
	Or(Expression, Expression),
	And(Expression, Expression),
	Bor(Expression, Expression),
	Bxor(Expression, Expression),
	Band(Expression, Expression),
	Equal(Expression, Expression),
	NotEqual(Expression, Expression),
	LessThan(Expression, Expression),
	GreaterThan(Expression, Expression),
	LessThanOrEqual(Expression, Expression),
	GreaterThanOrEqual(Expression, Expression),
	ShiftLeft(Expression, Expression),
	ShiftRight(Expression, Expression),
	Addition(Expression, Expression),
	Subtract(Expression, Expression),
	Multiplication(Expression, Expression),
	Division(Expression, Expression),
	Modulo(Expression, Expression),
	Bnot(Expression),
	Not(Expression),
	UnaryPlus(Expression),
	UnaryMinus(Expression)
}

enum OptionalExpression {
	Some(Expression),
	None
}

func parse_struct_argument(lexer: Lexer) -> (str, Expression) {
	parameter: str = parse_identifier(lexer);
	lexer_assert_token(lexer, TokenContents.Symbol(Symbol.Equal));
	return (parameter, parse_expression(lexer));
}

func parse_primary(lexer: Lexer) -> Expression {
	base_expression: Expression;
	if is_some_token(lexer_take_token(lexer, TokenContents.Symbol(Symbol.Open))) do {
		if is_some_token(lexer_take_token(lexer, TokenContents.Symbol(Symbol.Close))) base_expression = Expression.Tuple([]);
		else {
			elements: Expression[] = [parse_expression(lexer)];
			singleton: bool = false;
			while is_some_token(lexer_take_token(lexer, TokenContents.Symbol(Symbol.Comma))) do {
				if lexer_check_token(lexer, TokenContents.Symbol(Symbol.Close)) do {
					singleton = true;
					break;
				}
				elements = elements + [parse_expression(lexer)];
			}
			lexer_assert_token(lexer, TokenContents.Symbol(Symbol.Close));
			base_expression = singleton || len(elements) > 1? Expression.Tuple(elements): elements[0];
		}
	} else if is_some_token(lexer_take_token(lexer, TokenContents.Symbol(Symbol.OpenSquare))) do {
		if is_some_token(lexer_take_token(lexer, TokenContents.Symbol(Symbol.CloseSquare))) base_expression = Expression.Array([]);
		else {
			expressions: Expression[] = [parse_expression(lexer)];
			if is_some_token(lexer_take_token(lexer, TokenContents.Keyword(Keyword.For))) do {
				variable: str = parse_identifier(lexer);
				lexer_assert_token(lexer, TokenContents.Keyword(Keyword.In));
				expression: Expression = parse_expression(lexer);
				lexer_assert_token(lexer, TokenContents.Symbol(Symbol.CloseSquare));
				base_expression = Expression.LoopComrehension(expressions[0], variable, expression);
			} else {
				while is_some_token(lexer_take_token(lexer, TokenContents.Symbol(Symbol.Comma))) expressions = expressions + [parse_expression(lexer)];
				lexer_assert_token(lexer, TokenContents.Symbol(Symbol.CloseSquare));
				base_expression = Expression.Array(expressions);
			}
		}
	} else {
		match lexer_next_token(lexer).contents in {
			case String(string) base_expression = Expression.String(string);
			case Number(number) base_expression = Expression.Number(number);
			case Identifier(string) base_expression = Expression.Variable(string);
			case _token assert false, "Expected identifier, but got %s!" % token_to_str(_token);
		}
	}

	while lexer_check_tokens(lexer, [TokenContents.Symbol(Symbol.Open), TokenContents.Symbol(Symbol.OpenSquare), TokenContents.Symbol(Symbol.Dot), TokenContents.Symbol(Symbol.OpenCurly)]) do {
		match lexer_next_token(lexer).contents in {
			case Symbol(symbol) match symbol in {
				case Dot base_expression = Expression.FieldAccess(base_expression, parse_identifier(lexer));
				case Open do {
					if is_some_token(lexer_take_token(lexer, TokenContents.Symbol(Symbol.Close))) base_expression = Expression.FunctionCall(base_expression, []);
					else {
						arguments: Expression[] = [parse_expression(lexer)];
						while is_some_token(lexer_take_token(lexer, TokenContents.Symbol(Symbol.Comma))) arguments = arguments + [parse_expression(lexer)];

						lexer_assert_token(lexer, TokenContents.Symbol(Symbol.Close));
						base_expression = Expression.FunctionCall(base_expression, arguments);
					}
				}
				case OpenSquare do {
					index: Expression = parse_expression(lexer);
					lexer_assert_token(lexer, TokenContents.Symbol(Symbol.CloseSquare));
					base_expression = Expression.ArrayAccess(base_expression, index);
				}
				case OpenCurly do {
					if is_some_token(lexer_take_token(lexer, TokenContents.Symbol(Symbol.CloseCurly))) base_expression = Expression.StructInstantiation(base_expression, []);
					else {
						struct_arguments: (str, Expression)[] = [parse_struct_argument(lexer)];
						while is_some_token(lexer_take_token(lexer, TokenContents.Symbol(Symbol.Comma))) struct_arguments = struct_arguments + [parse_struct_argument(lexer)];
						
						lexer_assert_token(lexer, TokenContents.Symbol(Symbol.CloseCurly));
						base_expression = Expression.StructInstantiation(base_expression, struct_arguments);
					}
				}
				case _ assert false, "Unimplemented parse_primary symbol %s" % symbol_to_str(symbol);
			}
			case _ assert false, "Unimplemented parse_primary %s" % token_to_str(lexer_next_token(lexer));
		}
	}

	return base_expression;
}

func parse_unary(lexer: Lexer) -> Expression {
	if is_some_token(lexer_take_token(lexer, TokenContents.Symbol(Symbol.Tilde))) return Expression.Bnot(parse_unary(lexer));
	if is_some_token(lexer_take_token(lexer, TokenContents.Symbol(Symbol.Exclamation))) return Expression.Not(parse_unary(lexer));
	if is_some_token(lexer_take_token(lexer, TokenContents.Symbol(Symbol.Plus))) return Expression.UnaryPlus(parse_unary(lexer));
	if is_some_token(lexer_take_token(lexer, TokenContents.Symbol(Symbol.Dash))) return Expression.UnaryMinus(parse_unary(lexer));
	if is_some_token(lexer_take_token(lexer, TokenContents.Keyword(Keyword.Return))) return Expression.Return(parse_unary(lexer));
	return parse_primary(lexer);
}

precedences: (Symbol, (Expression, Expression) -> Expression)[][] = [
	[(Symbol.Dpipe, Expression.Or)],
	[(Symbol.Dampersand, Expression.And)],
	[(Symbol.Pipe, Expression.Bor)],
	[(Symbol.Carot, Expression.Bxor)],
	[(Symbol.Ampersand, Expression.Band)],
	[(Symbol.Dequal, Expression.Equal), (Symbol.NotEqual, Expression.NotEqual)],
	[(Symbol.Left, Expression.LessThan), (Symbol.Right, Expression.GreaterThan), (Symbol.LesserEqual, Expression.LessThanOrEqual), (Symbol.GreaterEqual, Expression.GreaterThanOrEqual)],
	[(Symbol.Dleft, Expression.ShiftLeft), (Symbol.Dright, Expression.ShiftRight)],
	[(Symbol.Plus, Expression.Addition), (Symbol.Dash, Expression.Subtract)],
	[(Symbol.Asterisk, Expression.Multiplication), (Symbol.Slash, Expression.Division), (Symbol.Percent, Expression.Modulo)]
];

func parse_expression_at_level(lexer: Lexer, level: int) -> Expression {
	if level >= len(precedences) return parse_unary(lexer);
	left: Expression = parse_expression_at_level(lexer, level+1);
	tokens: TokenContents[] = [TokenContents.Symbol(symbol_expressor[0]) for symbol_expressor in precedences[level]];
	expressor: (Expression, Expression) -> Expression;
	while lexer_check_tokens(lexer, tokens) do {
		match lexer_next_token(lexer).contents in {
			case Symbol(symbol) do {
				for symbol_expressor in precedences[level] if symbol_expressor[0] == symbol expressor = symbol_expressor[1];
				left = expressor(left, parse_expression_at_level(lexer, level+1));
			}
			case _ assert false, "Unreachable";
		}
	}
	return left;
}

func parse_ternary(lexer: Lexer) -> Expression {
	expression: Expression = parse_expression_at_level(lexer, 0);
	if !is_some_token(lexer_take_token(lexer, TokenContents.Symbol(Symbol.QuestionMark))) return expression;
	if_true: Expression = parse_expression_at_level(lexer, 0);
	lexer_assert_token(lexer, TokenContents.Symbol(Symbol.Colon));
	if_false: Expression = parse_ternary(lexer);
	return Expression.Ternary(expression, if_true, if_false);
}

func parse_expression(lexer: Lexer) -> Expression {
	if is_some_token(lexer_take_token(lexer, TokenContents.Keyword(Keyword.Return))) return Expression.Return(parse_expression(lexer));
	if is_some_token(lexer_take_token(lexer, TokenContents.Keyword(Keyword.Lambda))) do {
		parameters: TypeDeclaration[];
		if is_some_token(lexer_take_token(lexer, TokenContents.Symbol(Symbol.EqualArrow))) parameters = [];
		else do {
			parameters = [parse_type_declaration(lexer)];
			while is_some_token(lexer_take_token(lexer, TokenContents.Symbol(Symbol.Comma))) parameters = parameters + [parse_type_declaration(lexer)];
			lexer_assert_token(lexer, TokenContents.Symbol(Symbol.EqualArrow));
		}
		return Expression.Lambda(parameters, parse_expression(lexer));
	}
	return parse_ternary(lexer);
}

enum Statement {
	Statements(Statement[]),
	EnumDefinition(str, EnumEntry[]),
	StructDefinition(str, TypeDeclaration[]),
	FunctionDefinition(str, TypeDeclaration[], OptionalTypeExpression, Statement),
	Expression(Expression),
	Assignment(Expression, Expression, OptionalTypeExpression),
	TypeDeclaration(TypeDeclaration),
	If(Expression, Statement, OptionalStatement),
	While(Expression, Statement),
	DoWhile(Statement, OptionalExpression),
	Break,
	Continue,
	Match(Expression, (Expression, Statement)[]),
	Assert(Expression, OptionalExpression),
	ForLoop(str, Expression, Statement)
}

func statement_to_str(statement: Statement) -> str {
	match statement in {
		case EnumDefinition(name, entries) return "Enum %s" % name;
	}
	assert false, "Unimplemented statement_to_str";
}

enum OptionalStatement {
	Some(Statement),
	None
}

func parse_identifier(lexer: Lexer) -> str {
	identifier_token: Token = lexer_next_token(lexer);
	match identifier_token.contents in {
		case Identifier(identifier) return identifier;
		case _ assert false, "Expected identifier, but got %s!" % token_to_str(identifier_token);
	}
}

func parse_number(lexer: Lexer) -> int {
	number_token: Token = lexer_next_token(lexer);
	match number_token.contents in {
		case Number(number) return number;
		case _ assert false, "Expected number!";
	}
}

func parse_string(lexer: Lexer) -> str {
	string_token: Token = lexer_next_token(lexer);
	match string_token.contents in {
		case String(string) return string;
		case _ assert false, "Expected string!";
	}
}

func is_valid_target(expression: Expression) -> bool {
	match expression in {
		case FieldAccess(subexpression, _) return is_valid_target(subexpression);
		case Variable(_) return true;
		case _ assert false, "Unimplemented is_valid_target %s" % expression;
	}
}

func parse_statement(lexer: Lexer) -> Statement {
	if is_some_token(lexer_take_token(lexer, TokenContents.Keyword(Keyword.Enum))) do {
		enum_name: str = parse_identifier(lexer);

		lexer_assert_token(lexer, TokenContents.Symbol(Symbol.OpenCurly));
		if is_some_token(lexer_take_token(lexer, TokenContents.Symbol(Symbol.CloseCurly))) return Statement.EnumDefinition(enum_name, []);
		
		enum_entries: EnumEntry[] = [parse_enum_entry(lexer)];
		
		while is_some_token(lexer_take_token(lexer, TokenContents.Symbol(Symbol.Comma))) enum_entries = enum_entries + [parse_enum_entry(lexer)];
		lexer_assert_token(lexer, TokenContents.Symbol(Symbol.CloseCurly));
		return Statement.EnumDefinition(enum_name, enum_entries);
	} else if is_some_token(lexer_take_token(lexer, TokenContents.Keyword(Keyword.Struct))) do {
		struct_name: str = parse_identifier(lexer);
		lexer_assert_token(lexer, TokenContents.Symbol(Symbol.OpenCurly));
		if is_some_token(lexer_take_token(lexer, TokenContents.Symbol(Symbol.CloseCurly))) return Statement.StructDefinition(struct_name, []);

		struct_entries: TypeDeclaration[] = [parse_type_declaration(lexer)];
		while is_some_token(lexer_take_token(lexer, TokenContents.Symbol(Symbol.Comma))) struct_entries = struct_entries + [parse_type_declaration(lexer)];

		lexer_assert_token(lexer, TokenContents.Symbol(Symbol.CloseCurly));
		return Statement.StructDefinition(struct_name, struct_entries);
	} else if is_some_token(lexer_take_token(lexer, TokenContents.Keyword(Keyword.Func))) do {
		function_name: str = parse_identifier(lexer);
		lexer_assert_token(lexer, TokenContents.Symbol(Symbol.Open));
		function_arguments: TypeDeclaration[] = [];
		if !is_some_token(lexer_take_token(lexer, TokenContents.Symbol(Symbol.Close))) do {
			function_arguments = function_arguments + [parse_type_declaration(lexer)];
			while is_some_token(lexer_take_token(lexer, TokenContents.Symbol(Symbol.Comma))) function_arguments = function_arguments + [parse_type_declaration(lexer)];
		}

		lexer_assert_token(lexer, TokenContents.Symbol(Symbol.Close));
		function_return_type: OptionalTypeExpression = OptionalTypeExpression.None;
		if is_some_token(lexer_take_token(lexer, TokenContents.Symbol(Symbol.Arrow))) function_return_type = OptionalTypeExpression.Some(parse_type(lexer));

		function_body: Statement = parse_statement(lexer);
		return Statement.FunctionDefinition(function_name, function_arguments, function_return_type, function_body);
	} else if is_some_token(lexer_take_token(lexer, TokenContents.Keyword(Keyword.If))) do {
		return Statement.If(parse_expression(lexer), parse_statement(lexer), is_some_token(lexer_take_token(lexer, TokenContents.Keyword(Keyword.Else)))? OptionalStatement.Some(parse_statement(lexer)): OptionalStatement.None);
	} else if is_some_token(lexer_take_token(lexer, TokenContents.Keyword(Keyword.Match))) do {
		value: Expression = parse_expression(lexer);
		lexer_assert_token(lexer, TokenContents.Keyword(Keyword.In));
		lexer_assert_token(lexer, TokenContents.Symbol(Symbol.OpenCurly));
		
		cases: (Expression, Statement)[] = [];
		while is_some_token(lexer_take_token(lexer, TokenContents.Keyword(Keyword.Case))) cases = cases + [(parse_expression(lexer), parse_statement(lexer))];
		lexer_assert_token(lexer, TokenContents.Symbol(Symbol.CloseCurly));
		return Statement.Match(value, cases);
	} else if is_some_token(lexer_take_token(lexer, TokenContents.Keyword(Keyword.Assert))) do {
		condition: Expression = parse_expression(lexer);
		message: OptionalExpression = is_some_token(lexer_take_token(lexer, TokenContents.Symbol(Symbol.Comma)))? OptionalExpression.Some(parse_expression(lexer)): OptionalExpression.None;
		lexer_assert_token(lexer, TokenContents.Symbol(Symbol.Semicolon));
		return Statement.Assert(condition, message);
	} else if is_some_token(lexer_take_token(lexer, TokenContents.Keyword(Keyword.Do))) do {
		body: Statement = parse_statement(lexer);
		condition: OptionalExpression = OptionalExpression.None;
		if is_some_token(lexer_take_token(lexer, TokenContents.Keyword(Keyword.While))) do {
			condition = parse_expression(lexer);
			lexer_assert_token(lexer, TokenContents.Symbol(Symbol.Semicolon));
		}
		return Statement.DoWhile(body, condition);
	} else if is_some_token(lexer_take_token(lexer, TokenContents.Keyword(Keyword.While))) do {
		return Statement.While(parse_expression(lexer), parse_statement(lexer));
	} else if is_some_token(lexer_take_token(lexer, TokenContents.Keyword(Keyword.For))) do {
		variable: str = parse_identifier(lexer);
		lexer_assert_token(lexer, TokenContents.Keyword(Keyword.In));
		expression: Expression = parse_expression(lexer);
		body: Statement = parse_statement(lexer);
		return Statement.ForLoop(variable, expression, body);
	} else if is_some_token(lexer_take_token(lexer, TokenContents.Keyword(Keyword.Continue))) do {
		lexer_assert_token(lexer, TokenContents.Symbol(Symbol.Semicolon));
		return Statement.Continue;
	} else if is_some_token(lexer_take_token(lexer, TokenContents.Keyword(Keyword.Break))) do {
		lexer_assert_token(lexer, TokenContents.Symbol(Symbol.Semicolon));
		return Statement.Break;
	}

	else if is_some_token(lexer_take_token(lexer, TokenContents.Symbol(Symbol.OpenCurly))) do {
		statements = [];
		while !is_some_token(lexer_take_token(lexer, TokenContents.Symbol(Symbol.CloseCurly))) statements = statements + [parse_statement(lexer)];
		return Statement.Statements(statements);
	} else {
		expression: Expression = parse_expression(lexer);
		type_: OptionalTypeExpression = OptionalTypeExpression.None;
		if is_some_token(lexer_take_token(lexer, TokenContents.Symbol(Symbol.Colon))) do {
			match expression in {
				case Variable(_) type_ = OptionalTypeExpression.Some(parse_type(lexer));
				case _ assert false, "Invalid target";
			}
		}

		if is_some_token(lexer_take_token(lexer, TokenContents.Symbol(Symbol.Equal))) do {
			assert is_valid_target(expression), "Invalid target!";
			right_expression: Expression = parse_expression(lexer);
			lexer_assert_token(lexer, TokenContents.Symbol(Symbol.Semicolon));
			return Statement.Assignment(expression, right_expression, type_);
		}

		lexer_assert_token(lexer, TokenContents.Symbol(Symbol.Semicolon));
		match expression in {
			case Variable(name) match type_ in {
				case Some(type_expression) return Statement.TypeDeclaration(TypeDeclaration{name=name, type_=type_expression});
			}
		}
		return Statement.Expression(expression);
	} 
}

print("Parsing...\n");
lexer: Lexer = lexer_from_file("test.pyc");
statements: Statement[] = [];
while !is_some_token(lexer_take_token(lexer, TokenContents.Eof)) statements = statements + [parse_statement(lexer)];