/// <summary>
///
/// </summary>
/// <param name="scanner"></param>
/// <exception cref="ArgumentNullException"></exception>
/// <returns></returns>
public override ReadResult <Alternative> Read(ITextScanner scanner)
{
if (scanner == null)
{
throw new ArgumentNullException(nameof(scanner));
}
var context = scanner.GetContext();
IList <SyntaxError> errors = new List <SyntaxError>(lexers.Length);
SyntaxError partialMatch = null;
// ReSharper disable once ForCanBeConvertedToForeach
for (var i = 0; i < lexers.Length; i++)
{
var result = lexers[i].ReadElement(scanner);
if (result.Success)
{
return(ReadResult <Alternative> .FromResult(new Alternative(result.Text, result.Element, context, i + 1)));
}
errors.Add(result.Error);
if (partialMatch == null || result.Text.Length > partialMatch.Text.Length)
{
partialMatch = result.Error;
}
}
Debug.Assert(partialMatch != null, "partialMatch != null");
return(ReadResult <Alternative> .FromSyntaxError(partialMatch));
}
public override ReadResult <Terminal> Read(ITextScanner scanner)
{
if (scanner == null)
{
throw new ArgumentNullException(nameof(scanner));
}
var context = scanner.GetContext();
MatchResult result = null;
// ReSharper disable once ForCanBeConvertedToForeach
for (var i = 0; i < valueRange.Length; i++)
{
var c = valueRange[i];
result = scanner.TryMatch(c);
if (result.EndOfInput)
{
return(ReadResult <Terminal> .FromSyntaxError(SyntaxError.FromMatchResult(result, context)));
}
if (result.Success)
{
return(ReadResult <Terminal> .FromResult(new Terminal(result.Text, context)));
}
}
Debug.Assert(result != null, "result != null");
return(ReadResult <Terminal> .FromSyntaxError(SyntaxError.FromMatchResult(result, context)));
}
public override ReadResult <Alternative> Read(ITextScanner scanner)
{
if (scanner == null)
{
throw new ArgumentNullException(nameof(scanner));
}
var context = scanner.GetContext();
ILexer bestCandidate = null;
var bestCandidateLength = -1;
var ordinal = 0;
IList <SyntaxError> errors = new List <SyntaxError>(lexers.Length);
SyntaxError partialMatch = null;
// ReSharper disable once ForCanBeConvertedToForeach
for (var i = 0; i < lexers.Length; i++)
{
var lexer = lexers[i];
var candidate = lexer.ReadElement(scanner);
if (candidate.Success)
{
var alternative = candidate.Element;
var length = alternative.Text.Length;
if (length > bestCandidateLength)
{
bestCandidate = lexer;
bestCandidateLength = length;
ordinal = i + 1;
}
if (length != 0)
{
scanner.Unread(alternative.Text);
}
}
else
{
errors.Add(candidate.Error);
if (partialMatch == null || candidate.Text.Length > partialMatch.Text.Length)
{
partialMatch = candidate.Error;
}
}
}
if (bestCandidate == null)
{
Debug.Assert(partialMatch != null, "partialMatch != null");
return(ReadResult <Alternative> .FromSyntaxError(partialMatch));
}
var readResult = bestCandidate.ReadElement(scanner);
Debug.Assert(readResult.Success, "readResult.Success");
return(ReadResult <Alternative> .FromResult(new Alternative(readResult.Text, readResult.Element, context, ordinal)));
}
public override ReadResult <Sign> Read(ITextScanner scanner)
{
var result = innerLexer.Read(scanner);
if (result.Success)
{
var sign = new Sign(result.Element);
return(ReadResult <Sign> .FromResult(sign));
}
var syntaxError = SyntaxError.FromReadResult(result, scanner.GetContext());
return(ReadResult <Sign> .FromSyntaxError(syntaxError));
}
public override ReadResult <Integer> Read(ITextScanner scanner)
{
var result = innerLexer.Read(scanner);
if (result.Success)
{
var integer = new Integer(result.Element);
return(ReadResult <Integer> .FromResult(integer));
}
var syntaxError = SyntaxError.FromReadResult(result, scanner.GetContext());
return(ReadResult <Integer> .FromSyntaxError(syntaxError));
}
public override ReadResult <Alpha> Read(ITextScanner scanner)
{
if (scanner == null)
{
throw new ArgumentNullException(nameof(scanner));
}
var context = scanner.GetContext();
var result = innerLexer.Read(scanner);
if (result.Success)
{
return(ReadResult <Alpha> .FromResult(new Alpha(result.Element)));
}
return(ReadResult <Alpha> .FromSyntaxError(SyntaxError.FromReadResult(result, context)));
}
public override ReadResult <Terminal> Read(ITextScanner scanner)
{
if (scanner == null)
{
throw new ArgumentNullException(nameof(scanner));
}
var context = scanner.GetContext();
var result = scanner.TryMatch(terminal, comparer);
if (result.Success)
{
return(ReadResult <Terminal> .FromResult(new Terminal(result.Text, context)));
}
return(ReadResult <Terminal> .FromSyntaxError(SyntaxError.FromMatchResult(result, context)));
}
public override ReadResult <Repetition> Read(ITextScanner scanner)
{
if (scanner == null)
{
throw new ArgumentNullException(nameof(scanner));
}
var context = scanner.GetContext();
var stringBuilder = new StringBuilder();
IList <Element> elements = new List <Element>(lowerBound);
// ReSharper disable once ForCanBeConvertedToForeach
for (var i = 0; i < upperBound; i++)
{
var readResult = lexer.ReadElement(scanner);
if (readResult.Success)
{
elements.Add(readResult.Element);
stringBuilder.Append(readResult.Text);
}
else
{
if (elements.Count >= lowerBound)
{
return
(ReadResult <Repetition> .FromResult(
new Repetition(stringBuilder.ToString(), elements, context)));
}
var partialMatch = stringBuilder.ToString();
if (partialMatch.Length != 0)
{
scanner.Unread(partialMatch);
}
return
(ReadResult <Repetition> .FromSyntaxError(
new SyntaxError(
readResult.EndOfInput,
partialMatch,
readResult.ErrorText,
context,
readResult.Error)));
}
}
return(ReadResult <Repetition> .FromResult(new Repetition(stringBuilder.ToString(), elements, context)));
}
public static TElement Read <TElement>([NotNull] this ILexer <TElement> instance, [NotNull] ITextScanner scanner) where TElement : Element
{
if (instance == null)
{
throw new ArgumentNullException(nameof(instance));
}
if (scanner == null)
{
throw new ArgumentNullException(nameof(scanner));
}
var offset = scanner.Offset;
scanner.StartRecording();
TElement candidate = null;
try
{
var context = scanner.GetContext();
foreach (var element in instance.Read(scanner, context))
{
if (candidate == null)
{
candidate = element;
}
else if (element.Text.Length > candidate.Text.Length)
{
candidate = element;
}
}
if (candidate == null)
{
return(null);
}
scanner.Seek(offset + candidate.Text.Length);
}
finally
{
scanner.StopRecording();
}
return(candidate);
}
public override ReadResult <HexadecimalDigit> Read(ITextScanner scanner)
{
if (scanner == null)
{
throw new ArgumentNullException(nameof(scanner));
}
var result = innerLexer.Read(scanner);
if (result.Success)
{
return(ReadResult <HexadecimalDigit> .FromResult(new HexadecimalDigit(result.Element)));
}
return(ReadResult <HexadecimalDigit> .FromSyntaxError(SyntaxError.FromReadResult(result, scanner.GetContext())));
}