def procedure_definition(self):
# eating procedure keyword
self.must_next(Type.Reserved.Procedure)
self.next_token()
# eating name of procedure
self.must_next(Type.Word)
procedure_name = self.token.value
self.next_token()
#eating procedure params if have
procedure_params = self.procedure_or_function_params()
# eating ;
self.must_next(Type.Lang.Semi)
self.next_token()
vars_declarations = self.declarations()
main_function = self.compound_statement()
self.must_next(Type.Lang.Semi)
self.next_token()
self.must_next(Type.Reserved.End)
self.next_token()
self.must_next(Type.Lang.Semi)
self.next_token()
return Node.Procedure(procedure_name, procedure_params,
vars_declarations, main_function)
def function_definition(self):
# eating procedure keyword
self.must_next(Type.Reserved.Function)
self.next_token()
# eating name of procedure
self.must_next(Type.Word)
function_name = self.token.value
self.next_token()
# eating procedure params if have
function_params = self.procedure_or_function_params()
# eating return type
self.must_next(Type.Lang.Colon)
self.next_token()
function_return_type = self.type_spec()
# eating ;
self.must_next(Type.Lang.Semi)
self.next_token()
vars_declarations = self.declarations()
main_function = self.compound_statement()
self.must_next(Type.Lang.Semi)
self.next_token()
self.must_next(Type.Reserved.End)
self.next_token()
self.must_next(Type.Lang.Semi)
self.next_token()
return Node.Function(function_name, function_params,
function_return_type, vars_declarations,
main_function)
def expr(self):
node = self.term()
if self.is_next(Type.BinaryOperation.Or):
while self.token.type in (Type.BinaryOperation.Or):
operation_token = self.token
self.next_token()
new_node = self.term()
node = Node.BinaryOperation(node, new_node, operation_token)
else:
while self.token.type in (Type.BinaryOperation.Plus,
Type.BinaryOperation.Minus):
operation_token = self.token
self.next_token()
new_node = self.term()
node = Node.BinaryOperation(node, new_node, operation_token)
return node
def compound_statement(self):
self.must_next(Type.Reserved.Begin)
self.next_token()
node = Node.Compound(self.statement_list())
self.must_next(Type.Reserved.End)
self.next_token()
return node
def var_declarations(self):
vars = self.vars_names()
self.must_next(Type.Lang.Colon)
self.next_token()
cur_type = self.type_spec()
self.must_next(Type.Lang.Semi)
self.next_token()
return Node.VarsDeclatrations(vars, cur_type)
def while_statement(self):
self.must_next(Type.Reserved.While)
self.next_token()
expression = self.comparing_expr()
self.must_next(Type.Reserved.Do)
self.next_token()
code = self.statement()
return Node.WhileBlock(expression, code)
def assign_statement(self):
node = self.variable()
while self.token.type == Type.BinaryOperation.Assign:
operation_token = self.token
self.next_token()
new_node = self.comparing_expr()
node = Node.AssignOperation(node.value, new_node)
return node
def program(self):
program_name = self.program_init()
procedures = self.procedures_and_functions()
vars_declarations = self.declarations()
main_function = self.compound_statement()
self.must_next(Type.Lang.Dot)
return Node.Program(program_name, procedures, vars_declarations,
main_function)
def term(self):
node = self.factor()
if self.is_next(Type.BinaryOperation.And):
while self.token.type in (Type.BinaryOperation.And):
operation_token = self.token
self.next_token()
new_node = self.factor()
node = Node.BinaryOperation(node, new_node, operation_token)
else:
while self.token.type in (Type.BinaryOperation.Mul,
Type.BinaryOperation.Div,
Type.BinaryOperation.Mod,
Type.BinaryOperation.DivInt):
operation_token = self.token
self.next_token()
new_node = self.factor()
node = Node.BinaryOperation(node, new_node, operation_token)
return node
def if_statement(self):
self.must_next(Type.Reserved.If)
self.next_token()
if_expression = self.comparing_expr()
self.must_next(Type.Reserved.Then)
self.next_token()
if_code = self.statement()
else_code = None
if self.is_next(Type.Reserved.Else):
self.next_token()
else_code = self.statement()
return Node.IfBlock(if_expression, if_code, else_code)
def factor(self):
result = None
if self.is_next([
Type.BinaryOperation.Plus, Type.BinaryOperation.Minus,
Type.UnaryOperation.Not
]):
op_token = self.token
self.next_token()
result = Node.UnaryOperation(self.factor(), op_token)
return result
elif self.is_next(available_var_types):
result = Node.Number(self.token)
self.next_token()
return result
elif self.is_next(Type.Lang.LeftBracket):
self.next_token()
result = self.comparing_expr()
self.must_next(Type.Lang.RightBracket)
self.next_token()
return result
elif self.is_next(Type.Word) and self.is_nth(Type.Lang.LeftBracket, 1):
return self.procedure_or_function_call()
elif self.is_next(Type.Word):
return self.variable()
def comparing_expr(self):
handle_operations = [
Type.BinaryOperation.Equal,
Type.BinaryOperation.NotEqual,
Type.BinaryOperation.Less,
Type.BinaryOperation.LessEqual,
Type.BinaryOperation.Bigger,
Type.BinaryOperation.BiggerEqual,
]
node = self.expr()
if self.is_next(handle_operations):
operation_token = self.token
self.next_token()
new_node = self.expr()
node = Node.BinaryOperation(node, new_node, operation_token)
return node
def procedure_params_vars(self):
referenced = False
# check if params are passed by reference
if self.is_next(Type.Reserved.Var):
referenced = True
self.next_token()
vars = [self.variable()]
while self.token.type == Type.Lang.Comma:
self.next_token()
vars.append(self.variable())
self.must_next(Type.Lang.Colon)
self.next_token()
cur_type = self.type_spec()
return Node.ProcedureOrFunctionVarsDeclatrations(
vars, cur_type, referenced)
def for_statement(self):
self.must_next(Type.Reserved.For)
self.next_token()
assign_statement = self.assign_statement()
plus = True
if self.is_next(Type.Reserved.To):
self.must_next(Type.Reserved.To)
self.next_token()
plus = True
else:
self.must_next(Type.Reserved.DownTo)
self.next_token()
plus = False
to_value = self.comparing_expr()
self.must_next(Type.Reserved.Do)
self.next_token()
code = self.statement()
return Node.ForBlock(assign_statement, plus, to_value, code)
def statement(self):
# assign_statement or compound_statement or empty
if self.is_next(Type.Reserved.Begin):
return self.compound_statement()
if self.is_next(Type.Word) and self.is_nth(Type.BinaryOperation.Assign,
1):
return self.assign_statement()
if self.is_next(Type.Word) and (self.is_nth(Type.Lang.Semi, 1) or
self.is_nth(Type.Lang.LeftBracket, 1)):
return self.procedure_or_function_call()
if self.is_next(Type.Reserved.If):
return self.if_statement()
if self.is_next(Type.Reserved.While):
return self.while_statement()
if self.is_next(Type.Reserved.For):
return self.for_statement()
return Node.NoOperation()
def variable(self):
self.must_next(Type.Word)
result = Node.Var(self.token)
self.next_token()
return result
def procedure_or_function_call(self):
self.must_next(Type.Word)
name_of_proc = self.token.value
self.next_token()
passed_params = self.procedure_or_function_passed_params()
return Node.ProcedureOrFunctionCall(name_of_proc, passed_params)