def test_empty_expression():
from stilus.nodes.null import null
from stilus.nodes.boolean import false
expression = Expression()
assert len(expression) == 0
assert expression.is_empty()
assert expression.first() is null
assert expression.to_boolean() is false
def test_expression_string_first_boolean():
from stilus.nodes.boolean import true
from stilus.nodes.boolean import false
from stilus.nodes.null import null
expression = Expression()
expression.append(true)
expression.append(false)
expression.append(null)
assert str(expression) == "(true false null)"
expression.is_list = True
assert str(expression) == "(true, false, null)"
assert expression.first() is true
assert expression.to_boolean().value is True
def castable(self, expr: Expression):
return (len(expr.nodes) == 2 and expr.first().node_name == "unit"
and expr.nodes[1] and hasattr(expr.nodes[1], "name")
and expr.nodes[1].name in units)
def cast(self, expr: Expression):
return Unit(expr.first().value, expr.nodes[1].name)
