class Assign:
def __init__(self):
self.id = None
self.expr = None
#Simple parsing for Assign
def parse(self):
self.id = Id()
self.id.parse(TokList.getIdOrConst())
TokList.nextToken()
TokList.match('ASSIGN', 'assign')
self.expr = Expr()
self.expr.parse()
TokList.match('SEMICOLON', 'assign')
#Simple printing for Assign
def print(self):
TokList.printIndent()
self.id.print()
print(':=', end='')
self.expr.print()
print(';')
#Executor that determines value of an expression and then sets that value to the respective Id
def exec(self):
val = self.expr.exec()
self.id.setValue(val)
class IdList:
def __init__(self):
self.id = None
self.id_list = None
#Simple parsing to check for further ids
def parse(self):
self.id = Id()
#Passing in name of id to the parse function
self.id.parse(TokList.getIdOrConst())
TokList.nextToken()
if TokList.checkTok('COMMA'):
TokList.match('COMMA', 'id list')
self.id_list = IdList()
self.id_list.parse()
#Simple printing
def print(self):
self.id.print()
if (self.id_list is not None):
print(',', end='')
self.id_list.print()
def exec(self):
pass
#Used to set the values of all variables in an Id List, init determines whether it is initialization or not
def setIdValues(self, init):
if init == 1:
if TokList.getIdValue(self.id.name) == 'null':
print('ERROR: value ' + self.id.name +
' is already initialized')
exit()
#Initialized to 'null' as None is the previous assignment, 'null' is used later to check for initialization
TokList.setIdValue(self.id.name, 'null')
if self.id_list is not None:
self.id_list.setIdValues(1)
else:
self.id.setValue(TokList.currentData())
TokList.nextData()
if self.id_list is not None:
self.id_list.setIdValues(0)
class Case:
def __init__(self):
self.case_line = None
self.expr = None
self.id = None
#Simple parse of the case statement
def parse(self):
TokList.match('CASE','case')
self.id = Id()
self.id.parse(TokList.getIdOrConst())
TokList.nextToken()
TokList.match('OF','case')
self.case_line = CaseLine()
self.case_line.parse()
TokList.match('ELSE','case')
self.expr = Expr()
self.expr.parse()
TokList.match('END','case')
TokList.match('SEMICOLON','case')
#Printing with proper indentation manipulation and new line printings
def print(self):
TokList.printIndent()
print('case ', end='')
self.id.print()
print(' of')
TokList.increaseIndent()
TokList.printIndent()
self.case_line.print()
#Necessary for new line printings
print()
TokList.printIndent()
print('else ', end='')
self.expr.print()
print()
TokList.decreaseIndent()
TokList.printIndent()
print('end;')
#Recursive execution based on values in the case line. Id value is passed in to all versions of case
def exec(self):
if not (self.case_line.exec(self.id)):
self.id.setValue(self.expr.exec())
class Factor:
def __init__(self):
self.const = None
self.id = None
self.expr = None
#Simple parsing that checks for constant, Id, or paranthesis
def parse(self):
if TokList.checkTok('CONST'):
self.const = Const()
self.const.parse(TokList.getIdOrConst())
TokList.nextToken()
elif TokList.checkTok('ID'):
self.id = Id()
self.id.parse(TokList.getIdOrConst())
TokList.nextToken()
elif TokList.match('LEFTPARAN', 'factor'):
self.expr = Expr.Expr()
self.expr.parse()
TokList.match('RIGHTPARAN', 'factor')
#Simple print statement
def print(self):
if self.const is not None:
self.const.print()
elif self.id is not None:
self.id.print()
elif self.expr is not None:
print('(', end='')
self.expr.print()
print(')', end='')
#Simple execution statement that returns a value based on parsing
def exec(self):
if self.const is not None:
return self.const.exec()
elif self.id is not None:
return self.id.exec()
elif self.expr is not None:
return self.expr.exec()