def unary_operator(tokens, precedences):
if tokens.current.value not in ('-', '!', '?', '#'):
raise ParserException('未知或未实现操作符 {0}'.format(tokens.current.value),
tokens.current.line_no)
token = tokens.consume('OPERATOR')
right = expression(tokens, precedences.get(token.value, 0))
if right is not None:
return ast.UnaryOperator(token.line_no, token.value, right)
raise ParserException('操作符 {0} 右侧表达式缺失'.format(token.value), token.line_no)
def binary_operator(tokens, left, precedences):
if tokens.current.value not in ('+', '-', '*', '/', '^', '%', '>', '>=',
'<', '<=', '==', '!=', 'and', 'or'):
raise ParserException('未知或未实现操作符 {0}'.format(tokens.current.value),
tokens.current.line_no)
token = tokens.consume('OPERATOR')
right = expression(tokens, precedences.get(token.value, 0))
if right is not None:
return ast.BinaryOperator(token.line_no, token.value, left, right)
raise ParserException('操作符 {0} 右侧表达式缺失'.format(token.value), token.line_no)
def swap_statement(tokens, left):
'''交换语句'''
line_no = tokens.current.line_no
tokens.consume('SWAP')
right = expression(tokens)
if isinstance(left, ast.Readonly) or isinstance(right, ast.Readonly):
raise ParserException('不可将值赋予只读的关键词', tokens.current.line_no)
tokens.consume('SEMICOLON')
if right is not None:
return ast.Swap(line_no, left, right)
raise ParserException('交换语句右侧表达式缺失', token.line_no)
def assignment_statement(tokens, left):
'''赋值语句'''
line_no = tokens.current.line_no
if isinstance(left, ast.Readonly):
raise ParserException('不可将值赋予只读的关键词', tokens.current.line_no)
tokens.consume('ASSIGN')
right = expression(tokens)
tokens.consume('SEMICOLON')
if right is not None:
return ast.Assignment(line_no, left, right)
raise ParserException('赋值语句右侧表达式缺失', token.line_no)
def call_block_statement(tokens):
token = tokens.consume('CALL')
right = expression(tokens)
tokens.consume('SEMICOLON')
if right is not None:
return ast.CallBlock(token.line_no, right)
raise ParserException('操作符 {0} 右侧表达式缺失'.format(token.value), token.line_no)
def call(tokens, left, precedences):
token = tokens.consume('CALL')
right = expression(tokens, precedences.get(token.value, 0))
if right is None:
raise ParserException('右侧调用函数 {0} 缺失'.format(token.value),
token.line_no)
return ast.Call(token.line_no, left, right)
def reload(tokens, left, precedences):
token = tokens.consume('RELOAD')
right = expression(tokens, precedences.get(token.value, 0))
if right is None:
raise ParserException('重装符 {0} 右侧表达式缺失'.format(token.value),
token.line_no)
return ast.Reload(token.line_no, left, right)
def unfold_statement(tokens):
'''展开语句'''
token = tokens.consume('UNFOLD')
right = expression(tokens)
tokens.consume('SEMICOLON')
if right is not None:
return ast.Unfold(token.line_no, right)
raise ParserException('操作符 {0} 右侧表达式缺失'.format(token.value), token.line_no)
def return_statement(tokens):
'''返回语句'''
if ParserScope.get_node_with('fun'):
token = tokens.consume('RETURN')
right = expression(tokens)
if right is None:
right = ast.Nothing(tokens.current.line_no)
tokens.consume('SEMICOLON')
return ast.Return(tokens.current.line_no, right)
else:
raise ParserException('在函数外使用return', tokens.current.line_no)
def subscript(tokens, left, precedences):
token = tokens.consume('LBRACK')
if tokens.current.name == 'ALWAYS':
token = tokens.consume('ALWAYS')
right = ast.Always(token.line_no)
else:
# 优先级永远低于括号内的
right = expression(tokens)
tokens.consume('RBRACK')
if right is None:
raise ParserException('下标不能为空', token.line_no)
return ast.Subscript(token.line_no, left, right)
def table(tokens, precedences):
start_token = tokens.consume('LBRACK')
items = []
while not tokens.is_end():
if tokens.current.name == 'ALWAYS':
token = tokens.consume('ALWAYS')
tokens.consume('COLON')
item = expression(tokens)
if item is None:
raise ParserException(
'映射右侧值表达式缺失'.format(tokens.current.value),
tokens.current.line_no)
items.append(ast.AlwaysItem(token.line_no, item))
elif tokens.current.name == 'UNFOLD':
tokens.consume('UNFOLD')
right = expression(tokens)
if right is not None:
items.append(ast.Unfold(right.line_no, right))
else:
raise ParserException(
'展开操作符 {0} 右侧表达式缺失'.format(tokens.current.value),
tokens.current.line_no)
else:
left = expression(tokens)
if left is None:
break
if tokens.current.name == 'COLON':
token = tokens.consume('COLON')
right = expression(tokens)
if right is None:
raise ParserException('映射右侧值表达式缺失', left.line_no)
items.append(ast.DictItem(token.line_no, left, right))
else:
items.append(ast.ListItem(left.line_no, left))
if tokens.current.name == 'COMMA':
tokens.consume('COMMA')
else:
break
tokens.consume('RBRACK')
return ast.TableStatementNode(start_token.line_no, items)
def statements(tokens, scope):
stmts = []
while not tokens.is_end():
parser, container = statement.get(
tokens.current.name, [expression_statement, ('fun', 'program')])
if scope not in container:
raise ParserException(
'{} 不能在 {} 中使用'.format(tokens.current.name, scope),
tokens.current.line_no)
stmt = parser(tokens)
if stmt:
stmts.append(stmt)
else:
break
return stmts
def reduce(tokens, left, precedences):
token = tokens.consume('REDUCE')
right = expression(tokens, precedences.get(token.value, 0))
if right is not None:
return ast.Reduce(token.line_no, left, right)
raise ParserException('操作符 {0} 右侧表达式缺失'.format(token.value), token.line_no)
def index(tokens, _):
if ParserScope.get_node_with('loop'):
token = tokens.consume('INDEX')
return ast.Index(token.line_no)
else:
raise ParserException('在循环外使用index', tokens.current.line_no)
def variable(tokens, precedences):
token = tokens.consume('AT')
right = expression(tokens, precedences.get(token.value, 0))
if right is not None:
return ast.Variable(token.line_no, right)
raise ParserException('{0} 右侧表达式缺失'.format(token.value), token.line_no)
def incorrect_always(tokens, _):
raise ParserException('always只能用于Table声明或下标', tokens.current.line_no)