public void TokenTrySuccessIsTransparent()
{
var tryAb = Token.EqualTo('a').Then(_ => Token.EqualTo('b')).Try();
var result = tryAb.TryParse(StringAsCharTokenList.Tokenize("ab"));
Assert.True(result.HasValue);
Assert.True(result.Remainder.IsAtEnd);
}
public void TokenTryFailureBacktracks()
{
var tryAb = Token.EqualTo('a').Then(_ => Token.EqualTo('b')).Try();
var result = tryAb.TryParse(StringAsCharTokenList.Tokenize("ac"));
Assert.False(result.HasValue);
Assert.True(result.Backtrack);
}
public void ApplyOnParsedTokenCallsAppliedParser()
{
var input = StringAsCharTokenList.Tokenize("abcd");
var aAs42 = Token.EqualTo('a').Apply(Character.AnyChar.Value(42));
var result = aAs42(input);
Assert.Equal(42, result.Value);
}
public void AnAppliedParserMustConsumeTheWholeTokenSpan()
{
var input = StringAsCharTokenList.Tokenize("abcd");
var just42 = Token.EqualTo('a').Apply(Parse.Return(42));
var result = just42(input);
Assert.False(result.HasValue);
// The "invalid a" here is the token name, since we're using characters as tokens - in normal use
// this would read more like "invalid URI: unexpected `:`".
Assert.Equal("Syntax error (line 1, column 1): invalid a, unexpected `a`.", result.ToString());
}
public void AFailingAppliedParserDoesNotCauseTokenBacktracking2()
{
var input = StringAsCharTokenList.Tokenize("abcd");
var just42 = Token.EqualTo('a').Apply(Span.EqualTo("b"))
.Or(Token.EqualTo('x').Value(TextSpan.Empty));
var result = just42(input);
Assert.False(result.HasValue);
// The "invalid a" here is the token name, since we're using characters as tokens - in normal use
// this would read more like "invalid URI: expected `:`".
Assert.Equal("Syntax error (line 1, column 1): invalid a, unexpected `a`, expected `b`.", result.ToString());
}
