public void BeforeEveryTest()
{
var grammar = new ContextFreeGrammar('S');
grammar.Produce("S", "t2");
grammar.Produce("S", "vA", "vT");
grammar.Produce("A", "t0");
grammar.Produce("T", "vS", "vB");
grammar.Produce("B", "t1");
_parser = new TopDownParser(grammar);
}
public void Should_eliminate_all_epsilon_rules_when_converting_grammer_to_chomsky_normal_form()
{
var grammar = new ContextFreeGrammar("S");
grammar.Produce("S", "vA", "vB");
grammar.Produce("A", "t0");
grammar.Produce("B");
grammar.Produce("B", "t1");
var cnf = grammar.ToChomskyNormalForm();
var rules = cnf.GetRules("B");
Assert.That(rules, Has.None.Empty);
}
public void Should_check_grammar_for_chomsky_normal_form()
{
var grammar = new ContextFreeGrammar("S");
grammar.Produce("S", "t1", "t2", "t3");
Assert.That(grammar.IsInChomskyNormalForm, Is.False);
}
public void Should_not_allow_creation_of_topdown_parser_with_invalid_grammar()
{
Assert.That(() =>
{
var grammar = new ContextFreeGrammar("S");
grammar.Produce("S", "A", "B");
new TopDownParser(grammar);
}, Throws.ArgumentException);
}
public void BeforeEveryTest()
{
_grammar = new ContextFreeGrammar("S");
_grammar.Produce("S");
_grammar.Produce("S", "t2");
_grammar.Produce("S", "vA", "vT");
_grammar.Produce("A", "t0");
_grammar.Produce("A", "t1");
_grammar.Produce("T", "vS", "vB");
_grammar.Produce("B", "t1");
}
public void Should_eliminate_all_unit_rules_when_converting_grammer_to_chomsky_normal_form()
{
var grammar = new ContextFreeGrammar("S");
grammar.Produce("S", "vA", "vB");
grammar.Produce("A", "vB");
grammar.Produce("B", "t1");
var cnf = grammar.ToChomskyNormalForm();
var rules = cnf.GetRules("A");
Debug.WriteLine(cnf);
Assert.That(rules.Single().Single(), Is.Not.EqualTo(new Variable("B")));
}
public void Should_transform_all_rules_into_proper_form_when_converting_grammer_to_chomsky_normal_form()
{
var grammar = new ContextFreeGrammar("S");
grammar.Produce("S", "t1", "t2", "t3");
var cnf = grammar.ToChomskyNormalForm();
var rules = cnf.GetRules("S");
Assert.That(rules.Select(r => r.ToList()), Has.All.Count.LessThanOrEqualTo(2));
}
public void Should_not_allow_creation_of_recursive_unit_rules()
{
var grammar = new ContextFreeGrammar("S");
Assert.That(() => grammar.Produce("S", "vS"), Throws.Exception);
}
