/// <summary>
/// Represents BNF operator of "*".
/// </summary>
/// <param name="charset">Character set to be accepted.</param>
/// <returns>Always true.</returns>
protected bool Repeat(CharsetValidator charset)
{
while (charset(Text, P))
{
P++;
}
return(true);
}
/// <summary>
/// Represents BNF operator "?".
/// </summary>
/// <param name="charset">Character set to be accepted.</param>
/// <returns>Always true.</returns>
protected bool Optional(CharsetValidator charset) // ?
{
if (!charset(Text, P))
{
return(true);
}
P++;
return(true);
}
/// <summary>
/// Represents <code>n</code> times repetition of characters.
/// </summary>
/// <param name="charset">Character set to be accepted.</param>
/// <param name="n">Repetition count.</param>
/// <returns>true if the rule matches; otherwise false.</returns>
protected bool Repeat(CharsetValidator charset, int n)
{
for (int i = 0; i < n; i++)
{
if (!charset(Text, P + i))
{
return(false);
}
}
P += n;
return(true);
}
/// <summary>
/// Represents BNF operator of "+".
/// </summary>
/// <param name="charset">Character set to be accepted.</param>
/// <returns>true if the rule matches; otherwise false.</returns>
protected bool OneAndRepeat(CharsetValidator charset)
{
if (!charset(Text, P))
{
return(false);
}
while (charset(Text, ++P))
{
;
}
return(true);
}
/// <summary>
/// Represents at least <code>min</code> times, at most <code>max</code> times
/// repetition of characters.
/// </summary>
/// <param name="charset">Character set to be accepted.</param>
/// <param name="min">Minimum repetition count. Negative value is treated as 0.</param>
/// <param name="max">Maximum repetition count. Negative value is treated as positive infinity.</param>
/// <returns>true if the rule matches; otherwise false.</returns>
protected bool Repeat(CharsetValidator charset, int min, int max)
{
for (int i = 0; i < min; i++)
{
if (!charset(Text, P + i))
{
return(false);
}
}
for (int i = 0; i < max; i++)
{
if (!charset(Text, P + min + i))
{
P += min + i;
return(true);
}
}
P += min + max;
return(true);
}
