private bool Literal(InputBuffer buffer, out LiteralAmountToken literal)
{
var seenDecimalPoint = false;
var digits = new StringBuilder();
// TODO: Would be good for this to use rules like the other parts
// of the grammar, but for now let's keep it simple.
while (buffer.HasNext() && (buffer.IsDigit() || buffer.Peek() == '.'))
{
var c = buffer.Next();
if (c == '.' && seenDecimalPoint)
{
// We only accept a single decimal point.
literal = null;
return(false);
}
seenDecimalPoint = c == '.';
digits.Append(c);
}
if (!decimal.TryParse(digits.ToString(), out var amount))
{
literal = null;
return(false);
}
literal = AmountToken.Literal(amount);
return(true);
}
// fraction = literal-literal/literal | literal literal/literal | literal/literal
private ParserRule[] GetFractionRules() => new ParserRule[]
{
// Mixed number fraction rule e.g. 1 1/2
ParserRuleBuilder
.New()
.Token <LiteralAmountToken>(Literal)
.Condition(buffer => buffer.TryConsume(' ') || buffer.TryConsume('-'))
.Token <LiteralAmountToken>(Literal)
.Condition(buffer => buffer.TryConsume('/'))
.Token <LiteralAmountToken>(Literal)
.Map(tokens =>
{
var wholeNumber = tokens[0] as LiteralAmountToken;
var numerator = tokens[1] as LiteralAmountToken;
var denominator = tokens[2] as LiteralAmountToken;
return(ParserRuleResult.Success(AmountToken.Fraction(wholeNumber, numerator, denominator)));
})
.Build(),
// Standard fraction rule e.g. 1/2
ParserRuleBuilder
.New()
.Token <LiteralAmountToken>(Literal)
.Condition(buffer => buffer.TryConsume('/'))
.Token <LiteralAmountToken>(Literal)
.Map(tokens =>
{
var numerator = tokens[0] as LiteralAmountToken;
var denominator = tokens[1] as LiteralAmountToken;
return(ParserRuleResult.Success(AmountToken.Fraction(wholeNumber: null, numerator, denominator)));
})
.Build()
};
IEnumerable <Token> RecognizeAmountRange(IEnumerable <Token> tokens, int start = 0)
{
if (start >= tokens.Count())
{
return(tokens);
}
AmountToken amountFrom = null;
AmountToken amountTo = null;
Token symbol = null;
var first = start;
var i = 0;
for (; i < tokens.Count(); i++)
{
var token = tokens.ElementAt(i);
if (amountFrom == null)
{
if (token.Type == TokenType.Number)
{
first = i;
amountFrom = token as AmountToken ?? new AmountToken(token);
}
continue;
}
if (symbol == null)
{
if (token.Type == TokenType.Symbol && token.Value == "-")
{
symbol = token;
continue;
}
break;
}
if (token.Type == TokenType.Number)
{
amountTo = token as AmountToken ?? new AmountToken(token);
}
break;
}
List <Token> adjusted = null;
if (amountFrom != null &&
symbol != null &&
amountTo != null)
{
adjusted = tokens.Take(first).ToList();
adjusted.Add(new AmountRangeToken(amountFrom, amountTo, amountFrom, symbol, amountTo));
adjusted.AddRange(tokens.Skip(i + 1));
}
return(adjusted == null ? tokens : RecognizeAmountRange(adjusted, first));
}
/// <summary>
/// Attempts to parse <paramref name="rawAmount"/> as an <see cref="AmountToken"/>.
/// </summary>
/// <param name="rawAmount">The raw amount to parse.</param>
/// <param name="token">
/// When this method returns, contains the token that was parsed from the buffer if
/// the parsing succeeded, or <see langword="null"/> if the parsing failed.
/// </param>
/// <returns>
/// <see langword="true"/> when the parsing succeeded; <see langword="false"/> otherwise.
/// </returns>
public bool TryParse(string rawAmount, out AmountToken token)
{
if (string.IsNullOrEmpty(rawAmount))
{
token = null;
return(false);
}
var buffer = new InputBuffer(rawAmount);
return(Amount(buffer, out token));
}
// range = fraction-fraction | literal-literal
private ParserRule[] GetRangeRules() => new ParserRule[]
{
// Fractional range e.g. 1/4-1/3
ParserRuleBuilder
.New()
.Token <FractionalAmountToken>(Fraction)
.Condition(buffer => buffer.OptionallyConsume(' '))
.Condition(buffer => buffer.TryConsume('-'))
.Condition(buffer => buffer.OptionallyConsume(' '))
.Token <FractionalAmountToken>(Fraction)
.Map(tokens =>
{
var lowerBound = tokens[0] as FractionalAmountToken;
var upperBound = tokens[1] as FractionalAmountToken;
return(ParserRuleResult.Success(AmountToken.Range(lowerBound, upperBound)));
})
.Build(),
// Literal range e.g. 1-2
ParserRuleBuilder
.New()
.Token <LiteralAmountToken>(Literal)
.Condition(buffer => buffer.OptionallyConsume(' '))
.Condition(buffer => buffer.TryConsume('-'))
.Condition(buffer => buffer.OptionallyConsume(' '))
.Token <LiteralAmountToken>(Literal)
.Map(tokens =>
{
var lowerBound = tokens[0] as LiteralAmountToken;
var upperBound = tokens[1] as LiteralAmountToken;
return(ParserRuleResult.Success(AmountToken.Range(lowerBound, upperBound)));
})
.Build()
};
/// <summary>
/// Initializes a new instance of the <see cref="RangeAmountToken"/> class.
/// </summary>
/// <param name="lowerBound">
/// A <see cref="FractionalAmountToken"/> instance representing the lower bound of the range.
/// </param>
/// <param name="upperBound">
/// A <see cref="FractionalAmountToken"/> instance representing the upper bound of the range.
/// </param>
internal RangeAmountToken(FractionalAmountToken lowerBound, FractionalAmountToken upperBound)
{
LowerBound = lowerBound;
UpperBound = upperBound;
}
/// <summary>
/// Initializes a new instance of the <see cref="RangeAmountToken"/> class.
/// </summary>
/// <param name="lowerBound">
/// A <see cref="LiteralAmountToken"/> instance representing the lower bound of the range.
/// </param>
/// <param name="upperBound">
/// A <see cref="LiteralAmountToken"/> instance representing the upper bound of the range.
/// </param>
internal RangeAmountToken(LiteralAmountToken lowerBound, LiteralAmountToken upperBound)
{
LowerBound = lowerBound;
UpperBound = upperBound;
}
private bool Amount(InputBuffer buffer, out AmountToken amount) => ExecuteRules(GetAmountRules, buffer, out amount);
private IEnumerable <Token> RecognizeAmountUnitTokens(IEnumerable <Token> tokens, int start = 0)
{
if (start >= tokens.Count())
{
return(tokens);
}
AmountToken amount = null;
UnitToken unit = null;
var first = tokens.Count() - 1;
var i = start;
for (; i < tokens.Count(); i++)
{
var token = tokens.ElementAt(i);
if (amount == null)
{
if (token.Type == TokenType.Number && !(token is AmountUnitToken))
{
first = i;
if (token is AmountToken)
{
amount = (AmountToken)token;
}
else
{
amount = new AmountToken(token);
}
}
}
else
{
if (token.Type == TokenType.Symbol && token.Value == "-")
{
continue;
}
if (token.Type == TokenType.Unit)
{
unit = (UnitToken)token;
}
break;
}
if (token.Type == TokenType.Unit)
{
if (amount == null)
{
first = i;
}
unit = (UnitToken)token;
break;
}
}
List <Token> adjusted = null;
if (amount != null)
{
adjusted = tokens.Take(first).ToList();
adjusted.Add(new AmountUnitToken(
amount.Amount,
unit,
(unit == null ? new Token[] { amount } : new Token[] { amount, unit })));
adjusted.AddRange(tokens.Skip(first + 1 + (unit == null ? 0 : i - first)));
}
else if (unit != null)
{
adjusted = tokens.Take(first).ToList();
adjusted.Add(new AmountUnitToken(
1f,
unit,
new Token[] { unit }));
adjusted.AddRange(tokens.Skip(first + 1));
}
return(RecognizeAmountUnitTokens(adjusted ?? tokens, first + 1));
}
public AmountRangeToken(AmountToken amountFrom, AmountToken amountTo, params Token[] tokens)
: base(amountTo.Amount, tokens)
{
AmountFrom = amountFrom;
AmountTo = amountTo;
}