def factor(self):
if self.currtok[0] == 'MINUS' or self.currtok[0] == "NOT":
self.currtok = next(self.tokens)
tree = self.primary()
return ast.UnaryExpr(tree)
else:
return self.primary()
def factor(self):
"""
Factor → [UnaryOp] Primary
:return:
"""
# Check if the token is either a minus or a "not" aka an UnaryOp
if self.currtok[0] in [lexer.Lexer.MINUS, lexer.Lexer.NOT]:
tmp = self.currtok[1]
self.currtok = next(self.tokens)
tree = self.primary()
return ast.UnaryExpr(tmp, tree)
# If not, call primary method
else:
return self.primary()
def factor(self):
"""
Factor ⇒ [ UnaryOp ] Primary
"""
# Check for optional UnaryOp operator.
if self.currToken[0] in (lexer.Lexer.SUBTRACT, lexer.Lexer.NOT):
# Capture the operator to create a UnaryExpr object.
op = self.currToken[0]
# Move to the next token.
self.currToken = next(self.tokens)
# Check for a factor expression and capture it to create a Unary object. There could be more than one '-'.
expr = self.factor()
# Return a UnaryExpr object.
return ast.UnaryExpr(expr, op)
# There is no UnaryOp.
else:
# Check for a primary expression and return it.
return self.primary()
def p_expr_unop_not(p):
'expr : NOT expr'
p[0] = ast.UnaryExpr('neg', p[2], p.lineno(1))
def p_expr_unop_minus(p):
'expr : MINUS expr %prec UMINUS'
p[0] = ast.UnaryExpr('uminus', p[2], p.lineno(1))
def p_num_expr_unary(p):
'''num_expr : MINUS expr %prec UMINUS'''
p[0] = ast.UnaryExpr(p[2])