public static bool IsSimplePrecedence(this GrammarPrecedence grammarPrecedence)
{
if (grammarPrecedence.Grammar.GetCyclicNonTerminals().Any())
{
return(false);
}
if (!grammarPrecedence.Grammar.IsReversibleGrammar())
{
return(false);
}
foreach (var a in grammarPrecedence.Grammar.Symbols)
{
foreach (var b in grammarPrecedence.Grammar.Symbols)
{
var pair = (a, b);
var isLess = grammarPrecedence.IsLess(pair);
var isEqual = grammarPrecedence.IsEqual(pair);
var isGreater = grammarPrecedence.IsGreater(pair);
if (isLess && isEqual || isEqual && isGreater || isLess && isGreater)
{
return(false);
}
}
}
return(true);
}
public GrammarAnalyzer(GrammarPrecedence grammar)
{
this.grammar = grammar;
IsSimplePrecedence = grammar.IsSimplePrecedence();
IsWeakPrecedence = IsSimplePrecedence || grammar.IsWeakPrecedence();
foreach (var rule in grammar.Grammar.GetRules())
{
rules.Add(rule.Right.Reverse(), rule);
}
}
private static bool HasAmbiguousEndedRules(this GrammarPrecedence grammar)
{
foreach (var sRule in grammar.Grammar.GetRules())
{
foreach (var aRule in grammar.Grammar.GetRules())
{
if (sRule.Right.Count > aRule.Right.Count && aRule.Right.Any() && sRule.Right.EndsWith(aRule.Right))
{
var x = sRule.Right[sRule.Right.Count - aRule.Right.Count - 1];
var a = aRule.Left;
if (grammar.IsEqual((x, a)) || grammar.IsLess((x, a)))
{
return(true);
}
}
}
}
return(false);
}
public static bool IsWeakPrecedence(this GrammarPrecedence grammarPrecedence)
{
if (grammarPrecedence.Grammar.GetCyclicNonTerminals().Any())
{
return(false);
}
if (!grammarPrecedence.Grammar.IsReversibleGrammar())
{
return(false);
}
if (grammarPrecedence.Equal.Any(grammarPrecedence.IsGreater))
{
return(false);
}
if (grammarPrecedence.Less.Any(grammarPrecedence.IsGreater))
{
return(false);
}
if (grammarPrecedence.HasAmbiguousEndedRules())
{
return(false);
}
return(true);
}
