def test_let_statements(self):
input = """
let x = 5;
let y = 10;
let foobar = 838383;
"""
l = lexer.Lexer(input)
p = parser.Parser(l)
program = p.parse_program()
self.check_parse_errors(p)
self.assertIsNotNone(program)
self.assertEqual(len(program.statements), 3)
tests = [
"x",
"y",
"foobar",
]
for i, expected in enumerate(tests):
stmt = program.statements[i]
self.assertEqual(stmt.token_literal(), "let")
self.assertIsInstance(stmt, ast.LetStatement)
let_stmt = stmt
self.assertEqual(let_stmt.name.value, expected)
self.assertEqual(let_stmt.name.token_literal(), expected)
def test_parsing_infix_expression(self):
tests = [
["5 + 5;", 5, "+", 5],
["5 - 5;", 5, "-", 5],
["5 * 5;", 5, "*", 5],
["5 / 5;", 5, "/", 5],
["5 > 5;", 5, ">", 5],
["5 < 5;", 5, "<", 5],
["5 == 5;", 5, "==", 5],
["5 != 5;", 5, "!=", 5],
]
for test in tests:
l = lexer.Lexer(test[0])
p = parser.Parser(l)
program = p.parse_program()
self.check_parse_errors(p)
self.assertEqual(len(program.statements), 1)
stmt = program.statements[0]
self.assertIsInstance(stmt, ast.ExpressionStatement)
exp = stmt.expression
self.assertIsInstance(exp, ast.InfixExpression)
# TODO self._test_integer_literal(exp.left, test[1])
self.assertEqual(exp.operator, test[2])
def test_identifier_expression(self):
input = "foobar;"
l = lexer.Lexer(input)
p = parser.Parser(l)
program = p.parse_program()
self.check_parse_errors(p)
self.assertEqual(len(program.statements), 1)
stmt = program.statements[0]
self.assertIsInstance(stmt, ast.ExpressionStatement)
ident = stmt.expression
self.assertEqual(ident.value, "foobar")
self.assertEqual(ident.token_literal(), "foobar")
def test_integer_literal_expression(self):
input = "5;"
l = lexer.Lexer(input)
p = parser.Parser(l)
program = p.parse_program()
self.check_parse_errors(p)
self.assertEqual(len(program.statements), 1)
stmt = program.statements[0]
self.assertIsInstance(stmt, ast.ExpressionStatement)
literal = stmt.expression
self.assertIsInstance(literal, ast.IntegerLiteral)
self.assertEqual(literal.value, 5)
self.assertEqual(literal.token_literal(), "5")
def test_return_statement(self):
input = """
return 5;
return 10;
return 993322;
"""
l = lexer.Lexer(input)
p = parser.Parser(l)
program = p.parse_program()
self.check_parse_errors(p)
self.assertEqual(len(program.statements), 3)
for stmt in program.statements:
self.assertIsInstance(stmt, ast.ReturnStatement)
self.assertEqual(stmt.token_literal(), "return")
def test_parsing_prefix_expressions(self):
tests = [
["!5;", "!", 5],
["-15;", "-", 15],
]
for test in tests:
l = lexer.Lexer(test[0])
p = parser.Parser(l)
program = p.parse_program()
self.check_parse_errors(p)
self.assertEqual(len(program.statements), 1)
stmt = program.statements[0]
self.assertIsInstance(stmt, ast.ExpressionStatement)
exp = stmt.expression
self.assertIsInstance(exp, ast.PrefixExpression)
self.assertEqual(exp.operator, test[1])
integ = exp.right
self.assertIsInstance(integ, ast.IntegerLiteral)
self.assertEqual(integ.value, test[2])
self.assertEqual(integ.token_literal(), str(test[2]))
def test_next_token(self):
input = """
let five = 5;
let ten = 10;
let add = fn(x, y) {
x + y;
};
let result = add(five, ten);
!-/*5;
5 < 10 > 5;
if (5 < 10) {
return true;
} else {
return false;
}
10 == 10;
10 != 9;
"""
tests = [
(token.LET, "let"),
(token.IDENT, "five"),
(token.ASSIGN, "="),
(token.INT, "5"),
(token.SEMICOLON, ";"),
(token.LET, "let"),
(token.IDENT, "ten"),
(token.ASSIGN, "="),
(token.INT, "10"),
(token.SEMICOLON, ";"),
(token.LET, "let"),
(token.IDENT, "add"),
(token.ASSIGN, "="),
(token.FUNCTION, "fn"),
(token.LPAREN, "("),
(token.IDENT, "x"),
(token.COMMA, ","),
(token.IDENT, "y"),
(token.RPAREN, ")"),
(token.LBRACE, "{"),
(token.IDENT, "x"),
(token.PLUS, "+"),
(token.IDENT, "y"),
(token.SEMICOLON, ";"),
(token.RBRACE, "}"),
(token.SEMICOLON, ";"),
(token.LET, "let"),
(token.IDENT, "result"),
(token.ASSIGN, "="),
(token.IDENT, "add"),
(token.LPAREN, "("),
(token.IDENT, "five"),
(token.COMMA, ","),
(token.IDENT, "ten"),
(token.RPAREN, ")"),
(token.SEMICOLON, ";"),
(token.BANG, "!"),
(token.MINUS, "-"),
(token.SLASH, "/"),
(token.ASTERISK, "*"),
(token.INT, "5"),
(token.SEMICOLON, ";"),
(token.INT, "5"),
(token.LT, "<"),
(token.INT, "10"),
(token.GT, ">"),
(token.INT, "5"),
(token.SEMICOLON, ";"),
(token.IF, "if"),
(token.LPAREN, "("),
(token.INT, "5"),
(token.LT, "<"),
(token.INT, "10"),
(token.RPAREN, ")"),
(token.LBRACE, "{"),
(token.RETURN, "return"),
(token.TRUE, "true"),
(token.SEMICOLON, ";"),
(token.RBRACE, "}"),
(token.ELSE, "else"),
(token.LBRACE, "{"),
(token.RETURN, "return"),
(token.FALSE, "false"),
(token.SEMICOLON, ";"),
(token.RBRACE, "}"),
(token.INT, "10"),
(token.EQ, "=="),
(token.INT, "10"),
(token.SEMICOLON, ";"),
(token.INT, "10"),
(token.NOT_EQ, "!="),
(token.INT, "9"),
(token.SEMICOLON, ";"),
(token.EOF, ""),
]
l = lexer.Lexer(input)
for expected_type, expected_literal in tests:
tok = l.next_token()
self.assertEqual(tok.type, expected_type)
self.assertEqual(tok.literal, expected_literal)