def while_statement(self, level):
"""
WhileStatement -> while '(' Expression ')' Statement
:param level: indicates level of statements; type(level) - int
:return: ast.WhileStatement object
:raise CliteSyntaxError if an unexpected token is seen
"""
# Consume the keyword if identifying the start of a while statement
self.curr_tok = self.lex.__next__()
# Match left parenthesis
if self.curr_tok[self.CODE] != tokens.SINGLE_TOKENS[tokens.LPAREN][0]:
raise errors.CliteSyntaxError("'(' expected!", self.curr_tok[self.LINE])
# Consume left parenthesis
self.curr_tok = self.lex.__next__()
expression = self.expression()
# Match right parenthesis
if self.curr_tok[self.CODE] != tokens.SINGLE_TOKENS[tokens.RPAREN][0]:
raise errors.CliteSyntaxError("')' expected!", self.curr_tok[self.LINE])
# Consume right parenthesis
self.curr_tok = self.lex.__next__()
statement = self.statement(level + 1)
return ast.WhileStatement(expression, statement, level)
def whilestatement(self):
"""
WhileStatement ⇒ while ( Expression ) Statement
:return:
"""
# Check if the current token is a keyword While
if self.currtok[0] == lexer.Lexer.KWDWHILE:
self.currtok = next(self.tokens)
# Check for an open parenthesis
if self.currtok[0] == lexer.Lexer.OPENP:
self.currtok = next(self.tokens)
left_tree = self.expression()
# Check for a closed parenthesis
if self.currtok[0] == lexer.Lexer.CLOSEDP:
self.currtok = next(self.tokens)
right_tree = self.statement()
left_tree = ast.WhileStatement(left_tree, right_tree)
return left_tree
# If there is no closed parenthesis, throw syntax error
elif self.currtok[0] != lexer.Lexer.CLOSEDP:
raise CliteSyntaxError("Parenthesis expected on line " + str(self.currtok[2]))
# If there is no opening parenthesis, throw syntax error
elif self.currtok[0] != lexer.Lexer.OPENP:
raise CliteSyntaxError("Parenthesis expected on line " + str(self.currtok[2]))
def whileStatement(self):
'''
WhileStatement --> while "(" Expression ")" Statement
:return: ast.whileStatement
'''
# need keyword 'while'
if self.curr_tok[0] != lexer.Lexer.WHILE:
print("Error: 'while' expected found:", self.curr_tok[1],
"on line", self.curr_tok[2])
sys.exit(1)
self.curr_tok = next(self.lex)
# need '('
if self.curr_tok[0] != lexer.Lexer.LPAREN:
print("Error: '(' expected found:", self.curr_tok[1], "on line",
self.curr_tok[2])
sys.exit(1)
self.curr_tok = next(self.lex)
# need Expression
expr = self.expr()
# need ')'
if self.curr_tok[0] != lexer.Lexer.RPAREN:
print("Error: ')' expected found:", self.curr_tok[1], "on line",
self.curr_tok[2])
sys.exit(1)
self.curr_tok = next(self.lex)
# need Statement
stmt = self.statement()
return ast.WhileStatement(expr, stmt)
def loop(p):
return ast.WhileStatement(p[1], p[3])
def p_while_statement_02(t):
'''while_statement : WHILE LPAR lor_expression RPAR SEMI'''
t[0] = ast.WhileStatement(t[3], ast.NullNode())
def p_while_statement_01(t):
'''while_statement : WHILE LPAR lor_expression RPAR statement'''
t[0] = ast.WhileStatement(t[3], t[5])
t[5].isStatement = True
def statement_while(s):
return ast.WhileStatement(s[2], s[5])
cond = self.expression()
t = self.block_stmt()
e : typing.Union[None, ast.Block, ast.IfElseStatement] = None
if toks.add(self.match(token.ELSE)):
if self.peek().type == token.IF:
e = self.if_stmt()
else:
e = self.block_stmt()
return ast.IfElseStatement(toks, cond, t, e)
def while_stmt(self) -> ast.WhileStatement:
if not (tok := self.match(token.WHILE)):
raise Exception("Expected while.")
cond = self.expression()
t = self.block_stmt()
return ast.WhileStatement([tok], cond, t)
def print_stmt(self) -> ast.Print:
toks = TokenList()
if not toks.add(self.match(token.PRINT)):
raise Exception("Expected print statement.")
expr = self.expression()
toks.add(self.match(token.SEMICOLON))
return ast.Print(toks, expr)
def block_stmt(self) -> ast.Block:
self.check_eof("Expected { for block statement.")
toks = TokenList()
if not toks.add(self.match(token.LBRACE)):
raise ParseException("Expected { for block statement.")
# Snapshot the current scope (before block)
