public static bool TryParseAll <T>(TokenListParser <ExpressionToken, T> parser, string source, out T value, out string error)
{
if (source == null)
{
throw new ArgumentNullException(nameof(source));
}
var tokens = ExpressionTokenizer.TryTokenize(source);
if (!tokens.HasValue)
{
value = default;
error = tokens.ToString();
return(false);
}
var result = parser.AtEnd()(tokens.Value);
if (!result.HasValue)
{
value = default;
error = result.ToString();
return(false);
}
value = result.Value;
error = null;
return(true);
}
static void Main()
{
Console.Write(Prompt);
var line = Console.ReadLine();
while (line != null)
{
if (!string.IsNullOrWhiteSpace(line))
{
try
{
var tokens = ExpressionTokenizer.TryTokenize(line);
if (!tokens.HasValue)
{
WriteSyntaxError(tokens.ToString(), tokens.ErrorPosition);
}
else if (!ExpressionParser.TryParse(tokens.Value, out var expr, out var error, out var errorPosition))
{
WriteSyntaxError(error, errorPosition);
}
else
{
var result = ExpressionEvaluator.Evaluate(expr);
Console.ForegroundColor = ConsoleColor.Cyan;
Console.WriteLine(result);
}
}
public void ValidResultsAreComputed(string source, string result)
{
var tokens = ExpressionTokenizer.TryTokenize(source);
Assert.True(tokens.HasValue, tokens.ToString());
Assert.True(ExpressionParser.TryParse(tokens.Value, out var expr, out var err), err);
var actual = ExpressionEvaluator.Evaluate(expr);
Assert.Equal(result, actual.ToString());
}
