public void Or_FirstError_ReturnsSecondResult()
{
var parser = Combine.Or(Parse.Fail <int>("test"), Parse.Succeed(42));
var result = parser.Parse("");
ParseAssert.ValueEquals(42, result);
}
public void Label_Error_ReturnsErrorWithMessage()
{
var parser = Parse.Fail <int>("Oh noes").Label(() => "Test");
var result = parser.Parse("");
ParseAssert.ErrorEquals("Test", result);
}
public void Fail_ReturnsParseError()
{
var parser = Parse.Fail <int>("test");
var result = parser.Parse("");
ParseAssert.ErrorEquals("test", result);
}
public void Aggregate_NoMatch_ReturnsSeed()
{
var parser = Parse.Fail <char>("error")
.Aggregate(() => "test", (acc, c) => acc + c);
var result = parser.Parse("zz");
ParseAssert.ValueEquals("test", result);
}
public void Select_Error_ReturnsError()
{
var parser = from i in Parse.Fail <int>("test")
select i * 2;
var result = parser.Parse("");
ParseAssert.ErrorEquals("test", result);
}
public void Where_Error_ReturnsError()
{
var parser = from x in Parse.Fail <int>("test")
where x == 42
select x;
var result = parser.Parse("");
ParseAssert.ErrorEquals("test", result);
}
public void SelectMany_SuccessThenError_ReturnsErrorValue()
{
var parser = from x in Parse.Succeed(21)
from y in Parse.Fail <int>("test")
select x *y;
var result = parser.Parse("");
ParseAssert.ErrorEquals("test", result);
}
public void Label_Error_SetsInnerError()
{
var parser = Parse.Fail <int>("Oh noes").Label(() => "Test");
var result = parser.Parse("");
ParseError error = result.FromError();
Assert.IsNotNull(error.InnerError);
Assert.AreEqual(error.InnerError.Message, "Oh noes");
}
public void Or_FirstErrorConsumesInput_ReturnsFirstError()
{
var parserA = from x in Chars.Any()
from y in Parse.Fail <char>("test")
select y;
var parserB = Chars.Any();
var parser = Combine.Or(parserA, parserB);
var result = parser.Parse("abc");
ParseAssert.ErrorEquals("test", result);
}
public void Try_Error_ReturnsErrorAndResetsPosition()
{
var parser = Parse.Try(from x in Chars.Any()
from y in Chars.Any()
from f in Parse.Fail <char>("test")
select x);
IInputReader input = InputReader.Create("abc");
Position expectedPosition = input.GetPosition();
var result = parser.Parse(input);
ParseAssert.IsError(result);
Assert.AreEqual(expectedPosition, input.GetPosition());
}
/// <summary>
/// Tries to apply the given parsers in order, until one of them succeeds.
/// Returns the value of the succeeding parser.
/// </summary>
public static IParser <T> Choose <T>(IEnumerable <IParser <T> > parsers)
{
return(parsers.Aggregate(Parse.Fail <T>("Empty choose sequence")
, (acc, p) => acc.Or(p)));
}