def expr(self):
"""
Implements the EXPR grammar for variables.
:return: BinOpNode of all possible TERM objects.
"""
parse_result = ParseResult()
if self.current_token.matches(TP_KEYWORD, 'VAR'):
parse_result.register_advancement()
self.advance()
if self.current_token.type != TP_IDENTIFIER:
return parse_result.failure(
InvalidSyntaxError('Expected identifier',
self.current_token.start_pos,
self.current_token.end_pos))
var_name = self.current_token
self.advance()
if self.current_token.type != TP_EQUALS:
return parse_result.failure(
InvalidSyntaxError('Expected "="',
self.current_token.start_pos,
self.current_token.end_pos))
self.advance()
expression = parse_result.register(self.expr())
if parse_result.error:
return parse_result
return parse_result.success(VarAssignNode(var_name, expression))
node = parse_result.register(
self.binary_operation(self.comparison_expr, [(TP_KEYWORD, 'AND'),
(TP_KEYWORD, 'OR')]))
if parse_result.error:
return parse_result.failure(
InvalidSyntaxError('Expected VAR or mathematical operator',
self.current_token.start_pos,
self.current_token.end_pos))
return parse_result.success(node)
def if_expr_cases(self, case_keyword):
"""
General function for all if-expr grammars.
:param case_keyword: Keyword for the if-case.
:return: Tuple with the primary case and the else case.
"""
cases, else_case = [], None
parse_result = ParseResult()
if not self.current_token.matches(TP_KEYWORD, case_keyword):
return parse_result.failure(
InvalidSyntaxError("Expected '{}'".format(case_keyword),
self.current_token.start_pos,
self.current_token.end_pos))
parse_result.register_advancement()
self.advance()
condition = parse_result.register(self.expr())
if parse_result.error:
return parse_result
if not self.current_token.matches(TP_KEYWORD, 'THEN'):
return parse_result.failure(
InvalidSyntaxError(f"Expected 'THEN'",
self.current_token.start_pos,
self.current_token.end_pos))
parse_result.register_advancement()
self.advance()
if self.current_token.type == TP_NEWLINE:
parse_result.register_advancement()
self.advance()
statements = parse_result.register(self.statements())
if parse_result.error:
return parse_result
cases.append((condition, statements, True))
if self.current_token.matches(TP_KEYWORD, 'END'):
parse_result.register_advancement()
self.advance()
else:
all_cases = parse_result.register(self.if_expr_b_or_c())
if parse_result.error:
return parse_result
new_cases, else_case = all_cases
cases.extend(new_cases)
else:
expr = parse_result.register(self.statement())
if parse_result.error:
return parse_result
cases.append((condition, expr, False))
all_cases = parse_result.register(self.if_expr_b_or_c())
if parse_result.error:
return parse_result
new_cases, else_case = all_cases
cases.extend(new_cases)
return parse_result.success((cases, else_case))
def if_expr_c(self):
"""
Returns cases relating to the ELSE condition.
:return: Cases relating to the ELSE condition.
"""
else_case = None
parse_result = ParseResult()
if self.current_token.matches(TP_KEYWORD, 'ELSE'):
parse_result.register_advancement()
self.advance()
if self.current_token.type == TP_NEWLINE:
parse_result.register_advancement()
self.advance()
statements = parse_result.register(self.statements())
if parse_result.error:
return parse_result
else_case = (statements, True)
if self.current_token.matches(TP_KEYWORD, 'END'):
parse_result.register_advancement()
self.advance()
else:
return parse_result.failure(
InvalidSyntaxError("Expected 'END'",
self.current_token.start_pos,
self.current_token.end_pos))
else:
expr = parse_result.register(self.statement())
if parse_result.error:
return parse_result
else_case = (expr, False)
return parse_result.success(else_case)
def statement(self):
"""
Parses a single statement in the grammar.
:return: An expression in the grammar.
"""
parse_result = ParseResult()
start_pos = self.current_token.start_pos.copy()
if self.current_token.matches(TP_KEYWORD, 'RETURN'):
parse_result.register_advancement()
self.advance()
expr = parse_result.try_register(self.expr())
if not expr:
self.reverse(parse_result.to_reverse_count)
return parse_result.success(
ReturnNode(expr, start_pos,
self.current_token.start_pos.copy()))
if self.current_token.matches(TP_KEYWORD, 'CONTINUE'):
parse_result.register_advancement()
self.advance()
return parse_result.success(
ContinueNode(start_pos, self.current_token.start_pos.copy()))
if self.current_token.matches(TP_KEYWORD, 'BREAK'):
parse_result.register_advancement()
self.advance()
return parse_result.success(
BreakNode(start_pos, self.current_token.start_pos.copy()))
expr = parse_result.register(self.expr())
if parse_result.error:
return parse_result.failure(
InvalidSyntaxError(
"Expected 'RETURN', 'CONTINUE', 'BREAK', 'VAR', 'IF', 'FOR', "
"'WHILE', 'FUN', int, float, identifier, '+', '-', '(', '[' or 'NOT'",
self.current_token.start_pos, self.current_token.end_pos))
return parse_result.success(expr)
def list_expr(self):
"""
Parses a ListNode instance.
:return: A ListNode instance.
"""
element_nodes = []
parse_result = ParseResult()
start_pos = self.current_token.start_pos.copy()
if self.current_token.type != TP_LSQUARE:
return parse_result.failure(
InvalidSyntaxError('Expected "["',
self.current_token.start_pos,
self.current_token.end_pos))
parse_result.register_advancement()
self.advance()
if self.current_token.type == TP_RSQUARE:
parse_result.register_advancement()
self.advance()
else: # Non-empty list detected
element_nodes.append(parse_result.register(self.expr()))
if parse_result.error:
return parse_result.failure(
InvalidSyntaxError(
'Expected "]", "VAR", "IF", "FOR", "WHILE", "FUNC", int, float, or identifier',
self.current_token.start_pos,
self.current_token.end_pos))
while self.current_token.type == TP_COMMA:
parse_result.register_advancement()
self.advance()
element_nodes.append(parse_result.register(self.expr()))
if parse_result.error:
return parse_result
if self.current_token.type != TP_RSQUARE:
return parse_result.failure(
InvalidSyntaxError('Expected ",", or "]"',
self.current_token.start_pos,
self.current_token.end_pos))
parse_result.register_advancement()
self.advance()
return parse_result.success(
ListNode(element_nodes, start_pos,
self.current_token.end_pos.copy()))
def while_expr(self):
"""
Parses a while-loop expression in the grammar.
:return: WhileNode with all conditions of the while-loop.
"""
parse_result = ParseResult()
if not self.current_token.matches(TP_KEYWORD, 'WHILE'):
return parse_result.failure(
InvalidSyntaxError("Expected 'WHILE'",
self.current_token.start_pos,
self.current_token.end_pos))
parse_result.register_advancement()
self.advance()
condition = parse_result.register(self.expr())
if parse_result.error:
return parse_result
if not self.current_token.matches(TP_KEYWORD, 'THEN'):
return parse_result.failure(
InvalidSyntaxError("Expected 'THEN'",
self.current_token.start_pos,
self.current_token.end_pos))
parse_result.register_advancement()
self.advance()
if self.current_token.type == TP_NEWLINE:
parse_result.register_advancement()
self.advance()
body = parse_result.register(self.statements())
if parse_result.error:
return parse_result
if not self.current_token.matches(TP_KEYWORD, 'END'):
return parse_result.failure(
InvalidSyntaxError("Expected 'END'",
self.current_token.start_pos,
self.current_token.end_pos))
parse_result.register_advancement()
self.advance()
return parse_result.success(WhileNode(condition, body, True))
body = parse_result.register(self.statement())
if parse_result.error:
return parse_result
return parse_result.success(WhileNode(condition, body, False))
def parse(self):
"""
Triggers the parsing of the input stream.
:return: Parser instance.
"""
parser = self.statements()
if not parser.error and self.current_token.type != TP_EOF:
return parser.failure(
InvalidSyntaxError(self.current_token.start_pos,
self.current_token.end_pos,
'Expected "+", "-", "*", or "/"'))
return parser
def call(self):
"""
Returns a CallNode for calling functions. Also returns
the pure atom if there are no arguments in parenthesis.
:return: CallNode for calling functions or the pure atom..
"""
parse_result = ParseResult()
atom = parse_result.register(self.atom())
if parse_result.error:
return parse_result
if self.current_token.type == TP_LPAREN:
parse_result.register_advancement()
self.advance()
arg_nodes = []
if self.current_token.type == TP_RPAREN:
parse_result.register_advancement()
self.advance()
else: # At least one argument being passed
arg_nodes.append(parse_result.register(self.expr()))
if parse_result.error:
return parse_result.failure(
InvalidSyntaxError(
'Expected ")", "VAR", "IF", "FOR", "WHILE", "FUNC", int, float, or identifier',
self.current_token.start_pos,
self.current_token.end_pos))
while self.current_token.type == TP_COMMA:
parse_result.register_advancement()
self.advance()
arg_nodes.append(parse_result.register(self.expr()))
if parse_result.error:
return parse_result
if self.current_token.type != TP_RPAREN:
return parse_result.failure(
InvalidSyntaxError('Expected "," or ")"',
self.current_token.start_pos,
self.current_token.end_pos))
parse_result.register_advancement()
self.advance()
return parse_result.success(CallNode(atom, arg_nodes))
return parse_result.success(atom)
def comparison_expr(self):
"""
Implements the comparison expression grammar.
:return: Node with the result of the comparison operation.
"""
parse_result = ParseResult()
if self.current_token.matches(TP_KEYWORD, 'NOT'):
op_token = self.current_token
parse_result.register_advancement()
self.advance()
node = parse_result.register(self.comparison_expr())
if parse_result.error:
return parse_result
return parse_result.success(UnaryOpNode(op_token, node))
node = parse_result.register(
self.binary_operation(
self.arithmetic_expr,
[TP_EE, TP_NE, TP_LT, TP_GT, TP_LTE, TP_GTE]))
if parse_result.error:
return parse_result.failure(
InvalidSyntaxError(
"Expected int, float, identifier, '+', '-', '(', or 'NOT'",
self.current_token.start_pos, self.current_token.end_pos))
return parse_result.success(node)
def for_expr(self):
"""
Parses the for-loop expression of the grammar.
:return: ForNode with the for-loop expression.
"""
parse_result = ParseResult()
if not self.current_token.matches(TP_KEYWORD, 'FOR'):
return parse_result.failure(
InvalidSyntaxError("Expected 'FOR'",
self.current_token.start_pos,
self.current_token.end_pos))
parse_result.register_advancement()
self.advance()
if self.current_token.type != TP_IDENTIFIER:
return parse_result.failure(
InvalidSyntaxError("Expected identifier",
self.current_token.start_pos,
self.current_token.end_pos))
var_name = self.current_token
parse_result.register_advancement()
self.advance()
if self.current_token.type != TP_EQUALS:
return parse_result.failure(
InvalidSyntaxError("Expected '='",
self.current_token.start_pos,
self.current_token.end_pos))
parse_result.register_advancement()
self.advance()
start_value = parse_result.register(self.expr())
if parse_result.error:
return parse_result
if not self.current_token.matches(TP_KEYWORD, 'TO'):
return parse_result.failure(
InvalidSyntaxError("Expected 'TO'",
self.current_token.start_pos,
self.current_token.end_pos))
parse_result.register_advancement()
self.advance()
end_value = parse_result.register(self.expr())
if parse_result.error:
return parse_result
if self.current_token.matches(TP_KEYWORD, 'STEP'):
parse_result.register_advancement()
self.advance()
step_value = parse_result.register(self.expr())
if parse_result.error:
return parse_result
else:
step_value = None
if not self.current_token.matches(TP_KEYWORD, 'THEN'):
return parse_result.failure(
InvalidSyntaxError("Expected 'THEN'",
self.current_token.start_pos,
self.current_token.end_pos))
parse_result.register_advancement()
self.advance()
if self.current_token.type == TP_NEWLINE:
parse_result.register_advancement()
self.advance()
body = parse_result.register(self.statements())
if parse_result.error:
return parse_result
if not self.current_token.matches(TP_KEYWORD, 'END'):
return parse_result.failure(
InvalidSyntaxError("Expected 'END'",
self.current_token.start_pos,
self.current_token.end_pos))
parse_result.register_advancement()
self.advance()
return parse_result.success(
ForNode(var_name, start_value, end_value, step_value, body,
True))
body = parse_result.register(self.statement())
if parse_result.error:
return parse_result
return parse_result.success(
ForNode(var_name, start_value, end_value, step_value, body, False))
def func_def(self):
"""
Parses Tokens of a function definition.
:return: FuncDefNode with the function definition.
"""
parse_result = ParseResult()
if not self.current_token.matches(TP_KEYWORD, 'FUNC'):
return parse_result.failure(
InvalidSyntaxError("Expected 'FUNC'",
self.current_token.start_pos,
self.current_token.end_pos))
parse_result.register_advancement()
self.advance()
if self.current_token.type == TP_IDENTIFIER:
var_name_tok = self.current_token
parse_result.register_advancement()
self.advance()
if self.current_token.type != TP_LPAREN:
return parse_result.failure(
InvalidSyntaxError("Expected '('",
self.current_token.start_pos,
self.current_token.end_pos))
else:
var_name_tok = None
if self.current_token.type != TP_LPAREN:
return parse_result.failure(
InvalidSyntaxError("Expected identifier or '('",
self.current_token.start_pos,
self.current_token.end_pos))
parse_result.register_advancement()
self.advance()
arg_name_tokens = []
if self.current_token.type == TP_IDENTIFIER:
arg_name_tokens.append(self.current_token)
parse_result.register_advancement()
self.advance()
while self.current_token.type == TP_COMMA:
parse_result.register_advancement()
self.advance()
if self.current_token.type != TP_IDENTIFIER:
return parse_result.failure(
InvalidSyntaxError("Expected identifier",
self.current_token.start_pos,
self.current_token.end_pos))
arg_name_tokens.append(self.current_token)
parse_result.register_advancement()
self.advance()
if self.current_token.type != TP_RPAREN:
return parse_result.failure(
InvalidSyntaxError("Expected ',' or ')'",
self.current_token.start_pos,
self.current_token.end_pos))
else:
if self.current_token.type != TP_RPAREN:
return parse_result.failure(
InvalidSyntaxError("Expected identifier or ')'",
self.current_token.start_pos,
self.current_token.end_pos))
parse_result.register_advancement()
self.advance()
if self.current_token.type == TP_ARROW:
parse_result.register_advancement()
self.advance()
body = parse_result.register(self.expr())
if parse_result.error:
return parse_result
return parse_result.success(
FuncDefNode(var_name_tok, arg_name_tokens, body, True))
if self.current_token.type != TP_NEWLINE:
return parse_result.failure(
InvalidSyntaxError("Expected '->' or NEWLINE",
self.current_token.start_pos,
self.current_token.end_pos))
parse_result.register_advancement()
parse_result.register_advancement()
self.advance()
body = parse_result.register(self.statements())
if parse_result.error:
return parse_result
if not self.current_token.matches(TP_KEYWORD, 'END'):
return parse_result.failure(
InvalidSyntaxError("Expected 'END'",
self.current_token.start_pos,
self.current_token.end_pos))
parse_result.register_advancement()
self.advance()
return parse_result.success(
FuncDefNode(var_name_tok, arg_name_tokens, body, False))
def atom(self):
"""
Parses individual atoms in the stream.
:return: The ParseResult instance.
"""
parse_result = ParseResult()
token = self.current_token
# Parse integers and floating values
if token.type in (TP_INT, TP_FLOAT):
parse_result.register_advancement()
self.advance()
return parse_result.success(NumberNode(token))
# Parse all strings
elif token.type == TP_STRING:
parse_result.register_advancement()
self.advance()
return parse_result.success(StringNode(token))
# Parse all possible identifiers
elif token.type == TP_IDENTIFIER:
parse_result.register_advancement()
self.advance()
return parse_result.success(VarAccessNode(token))
# Parse all grouped expressions
elif token.type == TP_LPAREN:
parse_result.register_advancement()
self.advance()
expression = parse_result.register(self.expr())
if parse_result.error:
return parse_result
if self.current_token.type == TP_RPAREN:
parse_result.register_advancement()
self.advance()
return parse_result.success(expression)
else:
return parse_result.failure(
InvalidSyntaxError('Expected ")"',
self.current_token.start_pos,
self.current_token.end_pos))
# Parse all list statements
if token.type == TP_LSQUARE:
list_expr = parse_result.register(self.list_expr())
if parse_result.error:
return parse_result
return parse_result.success(list_expr)
# Parse all if-statements
elif token.matches(TP_KEYWORD, 'IF'):
if_expr = parse_result.register(self.if_expr())
if parse_result.error:
return parse_result
return parse_result.success(if_expr)
# Parse for- and while-loops
elif token.matches(TP_KEYWORD, 'FOR'):
for_expr = parse_result.register(self.for_expr())
if parse_result.error:
return parse_result
return parse_result.success(for_expr)
elif token.matches(TP_KEYWORD, 'WHILE'):
while_expr = parse_result.register(self.while_expr())
if parse_result.error:
return parse_result
return parse_result.success(while_expr)
# Parse all function definitions
elif token.matches(TP_KEYWORD, 'FUNC'):
func_def = parse_result.register(self.func_def())
if parse_result.error:
return parse_result
return parse_result.success(func_def)
# Defaults to raising an error
# The InvalidSyntaxError will be raised if the Parser is
# unable to properly parse the Token stream you provide
return parse_result.failure(
InvalidSyntaxError(
"Expected int, float, identifier, 'IF', 'FOR', 'WHILE', 'FUNC', '[', '+', '-' or '('",
token.start_pos,
token.end_pos,
))