private Rule Select(DiscriminatorInfo discriminator)
{
++this.discriminatorIndex; // eats the current token
var nextToken = this.DiscriminatorPeek();
if (discriminator.SimpleDiscriminations.ContainsKey(nextToken))
{
return(discriminator.SimpleDiscriminations[nextToken]);
}
if (discriminator.ComplexDiscriminations.ContainsKey(nextToken))
{
var nestedDiscriminationInfo = discriminator.ComplexDiscriminations[nextToken];
return(nestedDiscriminationInfo.Item1[this.Select(nestedDiscriminationInfo.Item2)]);
}
throw new InvalidOperationException($"Expected one of the following tokens ({string.Join(", ", discriminator.SimpleDiscriminations.Keys.Concat(discriminator.ComplexDiscriminations.Keys))}), but found {nextToken}");
}
private DiscriminatorInfo GetDiscriminator(Token token, IReadOnlyList <Rule> rules, string name)
{
var prefixDiscriminator = this.discriminatorUsages.FirstOrDefault(
u => u.Token == token &&
rules.All(r => u.Rules.Any(ur => r.Symbols.Take(ur.Symbols.Count).SequenceEqual(ur.Symbols)))
);
if (prefixDiscriminator != null)
{
return(prefixDiscriminator.Discriminator);
}
var discriminators = rules.Select(r => new { r, remainings = this.GetRemainings(r, token) })
.ToArray();
var cacheKey = new DiscriminatorInfoCacheKey(discriminators.Select(t => t.remainings));
DiscriminatorInfo existing;
if (this.discriminatorCache.TryGetValue(cacheKey, out existing))
{
this.discriminatorUsages.Add(new DiscriminatorUsage {
Discriminator = existing, Token = token, Rules = rules
});
return(existing);
}
var discriminatorSymbol = new NonTerminal(name);
var result = new DiscriminatorInfo {
Symbol = discriminatorSymbol
};
this.discriminatorCache.Add(cacheKey, result);
this.discriminatorUsages.Add(new DiscriminatorUsage {
Discriminator = result, Token = token, Rules = rules
});
var discriminatorRules = discriminators.SelectMany(t => t.remainings, (t, remaining) => new { origRule = t.r, newRule = new Rule(discriminatorSymbol, remaining) })
.Select(t => new { t.origRule, t.newRule, next = this.NextOf(new Rule(t.origRule.Produced, t.newRule.Symbols)) })
.ToArray();
var allNexts = discriminatorRules.SelectMany(t => t.next).Distinct().ToArray();
var subDiscriminatorId = 0;
foreach (var next in allNexts)
{
var matchingRules = discriminatorRules.Where(t => t.next.Contains(next)).ToArray();
if (matchingRules.Length == 1)
{
result.SimpleDiscriminations.Add(next, matchingRules.Single().origRule);
}
else
{
//var prefixDiscriminator = this.discriminatorUsages.FirstOrDefault(
// u => u.Token == next
// && matchingRules.All(r => u.Rules.Any(ur => r.newRule.Symbols.Take(ur.Symbols.Count).SequenceEqual(ur.Symbols)))
//);
//if (prefixDiscriminator != null)
//{
// result.ComplexDiscriminations.Add(
// next,
// Tuple.Create(
// matchingRules.ToDictionary(t => t.newRule, t => t.origRule), // wrong
// prefixDiscriminator.Discriminator
// )
// );
// continue;
//}
var subDiscriminator = this.GetDiscriminator(
next,
matchingRules.Select(t => t.newRule).ToArray(),
name: $"{name}/{subDiscriminatorId++}"
);
result.ComplexDiscriminations.Add(
next,
Tuple.Create(
matchingRules.ToDictionary(t => t.newRule, t => t.origRule),
subDiscriminator
)
);
}
}
return(result);
}
