def parse_pri_expr(self):
""" primary-Expression ::= Integer-Literal
| V-name (or identifier)
| Operator primary-Expression
| '(' Expression ')' """
token = self.token_current()
if (token.type == scanner.TK_INTLITERAL):
self.token_accept(scanner.TK_INTLITERAL)
return ast.IntegerExpression(token.val)
if (token.type == scanner.TK_IDENTIFIER):
v = ast.Vname(token.val)
self.token_accept(scanner.TK_IDENTIFIER)
return ast.VnameExpression(v)
if (token.type == scanner.TK_LPAREN):
self.token_accept(scanner.TK_LPAREN)
e1 = self.parse_expr()
self.token_accept(scanner.TK_RPAREN)
return e1
else: #just added
raise ParserError(self.curtoken.pos, self.curtoken.type)
def parse_single_command(self):
"""single-Command ::= Identifier ( ':=' Expression | '(' Expression ')')
| if Expression then single-Command
else single-Command
| while Expression do single-Command
| let Declaration in single-Command
| begin Command end
| return Expression
"""
token = self.token_current()
if token.type == scanner.TK_IDENTIFIER:
self.token_accept_any()
token_next = self.token_current()
if token_next.type == scanner.TK_BECOMES:
self.token_accept_any()
expr = self.parse_expression()
cmd = ast.AssignCommand(ast.Vname(token.val), expr)
elif token_next.type == scanner.TK_LPAREN:
self.token_accept_any()
expr = self.parse_arg_expr()
self.token_accept(scanner.TK_RPAREN)
cmd = ast.CallCommand(token.val, expr)
self.token_accept(scanner.TK_SEMICOLON)
elif token.type == scanner.TK_IF:
self.token_accept_any()
expr = self.parse_expression()
self.token_accept(scanner.TK_THEN)
sc1 = self.parse_single_command()
self.token_accept(scanner.TK_ELSE)
sc2 = self.parse_single_command()
cmd = ast.IfCommand(expr, sc1, sc2)
elif token.type == scanner.TK_WHILE:
self.token_accept_any()
expr = self.parse_expression()
self.token_accept(scanner.TK_DO)
sc1 = self.parse_single_command()
cmd = ast.WhileCommand(expr, sc1)
elif token.type == scanner.TK_LET:
self.token_accept_any()
decl = self.parse_declaration()
self.token_accept(scanner.TK_IN)
sc1 = self.parse_single_command()
cmd = ast.LetCommand(decl, sc1)
elif token.type == scanner.TK_BEGIN:
self.token_accept_any()
cmd = self.parse_command()
self.token_accept(scanner.TK_END)
elif token.type == scanner.TK_RETURN:
self.token_accept_any()
expr = self.parse_expression()
cmd = ast.ReturnCommand(expr)
self.token_accept(scanner.TK_SEMICOLON)
else:
raise ParserError(self.curtoken.pos, self.curtoken.type)
return cmd
def parse_parameter_list(self):
""" Identifier ':' 'Type-denoter' ( ',' Identifier : Type-denoter )*
Returns a list of tuples with the format [(Vname(var_name), TypeDenoter(var_type)),...]
"""
param_list = []
var_name = self.token_current().val
self.token_accept(scanner.TK_IDENTIFIER)
self.token_accept(scanner.TK_COLON)
var_type = self.token_current().val
self.token_accept(scanner.TK_IDENTIFIER)
param_list.append((ast.Vname(var_name), ast.TypeDenoter(var_type)))
while self.curtoken.type == scanner.TK_COMMA:
self.token_accept_any()
var_name = self.token_current().val
self.token_accept(scanner.TK_IDENTIFIER)
self.token_accept(scanner.TK_COLON)
var_type = self.token_current().val
self.token_accept(scanner.TK_IDENTIFIER)
param_list.append((ast.Vname(var_name), ast.TypeDenoter(var_type)))
return param_list
def parse_primary_expression(self):
"""Integer-Literal
| V-name
| Operator primary-Expression
| '(' Expression ')'
| function-call
"""
token = self.token_current()
# Integer-Literal
if token.type == scanner.TK_INTLITERAL:
e1 = ast.IntegerExpression(token.val)
self.token_accept_any()
# Variable name or function call
elif token.type == scanner.TK_IDENTIFIER:
name = self.token_current().val
self.token_accept_any()
# Function call
if self.curtoken.type == scanner.TK_LPAREN:
self.token_accept_any()
param_list = self.parse_argument_list()
self.token_accept(scanner.TK_RPAREN)
e1 = ast.CallCommand(name, param_list)
# Variable name
else:
e1 = ast.VnameExpression(ast.Vname(name))
# Unary Expression
elif token.type == scanner.TK_OPERATOR:
oper = self.token_current()
self.token_accept_any()
e1 = ast.UnaryExpression(oper.val, self.parse_primary_expression())
# ( Expression )
elif token.type == scanner.TK_LPAREN:
self.token_accept_any()
e1 = self.parse_expression()
self.token_accept(scanner.TK_RPAREN)
# Unexpected tokens
else:
raise ParserException(self.curtoken.pos, self.curtoken.type)
return e1
def parse_primary_expression(self):
""" primary-Expression ::= Integer-Literal
| Identifier ( *empty* | '(' Expression ')' )
| Operator primary-Expression
| '(' Expression ')'
"""
token = self.token_current()
if token.type == scanner.TK_INTLITERAL:
self.token_accept_any()
expr = ast.IntegerExpression(token.val)
elif token.type == scanner.TK_IDENTIFIER:
self.token_accept_any()
next = self.token_current()
if next.type == scanner.TK_LPAREN:
ident = token.val
self.token_accept_any()
expr = self.parse_arg_expr()
self.token_accept(scanner.TK_RPAREN)
expr = ast.CallExpression(ident, expr)
else:
expr = ast.VnameExpression(ast.Vname(token.val))
elif token.type == scanner.TK_OPERATOR:
oper = token.val
self.token_accept_any()
expr = self.parse_primary_expression()
expr = ast.UnaryExpression(oper, expr)
elif token.type == scanner.TK_LPAREN:
self.token_accept_any()
expr = self.parse_expression()
self.token_accept(scanner.TK_RPAREN)
return expr
else:
raise ParserError(self.curtoken.pos, self.curtoken.type)
return expr
def parse_single_command(self):
""" single-Command ::= V-name ':=' Expression
| Identifier '(' Expression ')'
| if Expression then single-Command
else single-Command
| while Expression do single-Command
| let Declaration in single-Command
| begin Command end """
token = self.token_current()
if token.type == scanner.TK_IDENTIFIER:
temp = token.val
self.token_accept(scanner.TK_IDENTIFIER)
token = self.token_current()
if token.type == scanner.TK_BECOMES:
self.token_accept(scanner.TK_BECOMES)
vname = ast.Vname(temp)
e1 = self.parse_expr()
token = self.token_current()
return ast.AssignCommand(vname, e1)
if token.type == scanner.TK_LPAREN:
self.token_accept(scanner.TK_LPAREN)
e1 = self.parse_expr()
self.token_accept(scanner.TK_RPAREN)
return ast.CallCommand(temp, e1)
else: #just added
raise ParserError(self.curtoken.pos, self.curtoken.type)
if token.type == scanner.TK_IF:
self.token_accept(scanner.TK_IF)
e1 = self.parse_expr()
token = self.token_current()
if token.type == scanner.TK_THEN:
self.token_accept(scanner.TK_THEN)
e2 = self.parse_single_command()
token = self.token_current()
if token.type == scanner.TK_ELSE:
self.token_accept(scanner.TK_ELSE)
e3 = self.parse_single_command()
token = self.token_current()
return ast.IfCommand(e1, e2, e3)
else:
raise ParserError(self.curtoken.pos, self.curtoken.type)
else:
raise ParserError(self.curtoken.pos, self.curtoken.type)
if token.type == scanner.TK_WHILE:
self.token_accept_any()
e1 = self.parse_expr()
token = self.token_current()
if token.type == scanner.TK_DO:
self.token_accept_any()
e2 = self.parse_single_command()
token = self.token_current()
return ast.WhileCommand(e1, e2)
else:
raise ParserError(self.curtoken.pos, self.curtoken.type)
if token.type == scanner.TK_BEGIN:
self.token_accept(scanner.TK_BEGIN)
while token.type != scanner.TK_END:
e1 = self.parse_command()
token = self.token_current()
if token.type == scanner.TK_END:
self.token_accept_any()
token = self.token_current()
return e1
if token.type == scanner.TK_LET:
e1 = self.parse_let_command()
return e1
else: #just added
raise ParserError(self.curtoken.pos, self.curtoken.type)
def parse_single_command(self):
"""V-name ':=' Expression ';'
| call-command ';'
| if Expression then single-Command else single-Command
| while Expression do single-Command
| let Declaration in single-Command
| begin Command end
"""
# Assignment or Function Call
if self.curtoken.type == scanner.TK_IDENTIFIER:
name = self.token_current().val
self.token_accept_any()
# Variable Assignment
if self.curtoken.type == scanner.TK_BECOMES:
self.token_accept_any()
expr = self.parse_expression()
self.token_accept(scanner.TK_SEMICOLON)
return ast.AssignCommand(ast.Vname(name), expr)
# Function call
elif self.curtoken.type == scanner.TK_LPAREN:
self.token_accept_any()
param_list = self.parse_argument_list()
self.token_accept(scanner.TK_RPAREN)
self.token_accept(scanner.TK_SEMICOLON)
return ast.CallCommand(name, param_list)
# Unexpected tokens
else:
raise ParserException(self.curtoken.pos, self.curtoken.type)
# While Loop
elif self.curtoken.type == scanner.TK_WHILE:
self.token_accept_any()
expr = self.parse_expression()
self.token_accept(scanner.TK_DO)
com = self.parse_single_command()
return ast.WhileCommand(expr, com)
# If Statement
elif self.curtoken.type == scanner.TK_IF:
self.token_accept_any()
expr = self.parse_expression()
self.token_accept(scanner.TK_THEN)
com1 = self.parse_single_command()
self.token_accept(scanner.TK_ELSE)
com2 = self.parse_single_command()
return ast.IfCommand(expr, com1, com2)
# Let-In Statement
elif self.curtoken.type == scanner.TK_LET:
self.token_accept_any()
dec = self.parse_declaration()
self.token_accept(scanner.TK_IN)
com = self.parse_single_command()
return ast.LetCommand(dec, com)
# Begin-End Statement
elif self.curtoken.type == scanner.TK_BEGIN:
self.token_accept_any()
com = self.parse_command()
self.token_accept(scanner.TK_END)
return com
elif self.curtoken.type == scanner.TK_RETURN:
self.token_accept_any()
expr = self.parse_expression()
self.token_accept(scanner.TK_SEMICOLON)
return ast.ReturnCommand(expr)
# Unexpected tokens
else:
raise ParserException(self.curtoken.pos, self.curtoken.type)
def parse_ident(self):
""" V-name ::= Identifier """
token = self.token_current()
v = ast.Vname(token.val)
self.token_accept_any()
return v