private bool TryRecognizeSimpleLiteralExpression(
QualifiedName fullyQualifiedName,
IEbnfLexerRuleExpression ebnfLexerRule,
out LexerRule lexerRule)
{
lexerRule = null;
if (ebnfLexerRule is EbnfLexerRuleExpressionSimple)
{
var term = ebnfLexerRule.Term;
if (term is EbnfLexerRuleTermConcatenation)
{
return(false);
}
var factor = term.Factor;
if (factor is EbnfLexerRuleFactorLiteral literal)
{
lexerRule = new StringLiteralLexerRule(literal.Value, new TokenName(fullyQualifiedName.FullName));
return(true);
}
}
return(false);
}
private Nfa LexerRuleExpression(IEbnfLexerRuleExpression expression)
{
var nfa = LexerRuleTerm(expression.Term);
if (expression is EbnfLexerRuleExpressionAlteration alteration)
{
var alterationNfa = LexerRuleExpression(alteration);
nfa = nfa.Union(alterationNfa);
}
return(nfa);
}
private LexerRule LexerRuleExpression(
QualifiedName fullyQualifiedName,
IEbnfLexerRuleExpression ebnfLexerRule)
{
if (TryRecognizeSimpleLiteralExpression(fullyQualifiedName, ebnfLexerRule, out var lexerRule))
{
return(lexerRule);
}
var nfa = LexerRuleExpression(ebnfLexerRule);
var dfa = this.nfaToDfa.Transform(nfa);
return(new DfaLexerRule(dfa, fullyQualifiedName.FullName));
}
private EbnfBlockLexerRule VisitLexerRuleNode(IInternalTreeNode node)
{
EbnfQualifiedIdentifier identifier = null;
IEbnfLexerRuleExpression expression = null;
foreach (var internalNode in node.Children.OfType <IInternalTreeNode>())
{
if (internalNode.Is(EbnfGrammar.QualifiedIdentifier))
{
identifier = VisitQualifiedIdentifierNode(internalNode);
}
else if (internalNode.Is(EbnfGrammar.LexerRuleExpression))
{
expression = VisitLexerRuleExpressionNode(internalNode);
}
}
return(new EbnfBlockLexerRule(new EbnfLexerRule(identifier, expression)));
}
private IEbnfLexerRuleExpression VisitLexerRuleExpressionNode(IInternalTreeNode node)
{
IEbnfLexerRuleTerm term = null;
IEbnfLexerRuleExpression expression = null;
foreach (var internalNode in node.Children.OfType <IInternalTreeNode>())
{
if (internalNode.Is(EbnfGrammar.LexerRuleTerm))
{
term = VisitLexerRuleTermNode(internalNode);
}
else if (internalNode.Is(EbnfGrammar.LexerRuleExpression))
{
expression = VisitLexerRuleExpressionNode(internalNode);
}
}
if (expression == null)
{
return(new EbnfLexerRuleExpressionSimple(term));
}
return(new EbnfLexerRuleExpressionAlteration(term, expression));
}
public EbnfLexerRule(EbnfQualifiedIdentifier identifier, IEbnfLexerRuleExpression expression)
{
Identifier = identifier;
Expression = expression;
}
public EbnfLexerRuleExpressionAlteration(IEbnfLexerRuleTerm term, IEbnfLexerRuleExpression expression)
{
Term = term;
Expression = expression;
}
