/// <summary>
/// Tries parsing a term in the given text.
/// </summary>
public static bool AcceptTerm(Dictionary<string, Expression> Variables, string Text, ref int Index, ref Expression Term, out int ErrorIndex)
{
if (AcceptLiteral(Text, ref Index, ref Term, out ErrorIndex))
return true;
int cur = Index;
if (AcceptString("-", Text, ref cur))
{
if (AcceptTerm(Variables, Text, ref cur, ref Term, out ErrorIndex))
{
Term = new UnaryExpression(Term, UnaryOperation.Negate);
Index = cur;
return true;
}
}
if (AcceptString("~", Text, ref cur))
{
if (AcceptTerm(Variables, Text, ref cur, ref Term, out ErrorIndex))
{
Term = new UnaryExpression(Term, UnaryOperation.Complement);
Index = cur;
return true;
}
}
int wordend = 0;
string word = null;
if (AcceptWord(Text, ref cur, ref word))
{
wordend = cur;
if (Variables.TryGetValue(word, out Term))
{
Index = cur;
return true;
}
AcceptExtendedWhitespace(Text, ref cur);
}
if (AcceptString("(", Text, ref cur))
{
AcceptExtendedWhitespace(Text, ref cur);
if (AcceptExpression(Variables, Text, ref cur, ref Term, out ErrorIndex))
{
AcceptExtendedWhitespace(Text, ref cur);
if (AcceptString(")", Text, ref cur))
{
if (word != null)
{
switch (word)
{
case "saw":
Term = new UnaryExpression(Term, UnaryOperation.Saw);
break;
case "sin":
Term = new UnaryExpression(Term, UnaryOperation.Sine);
break;
case "square":
Term = new UnaryExpression(Term, UnaryOperation.Square);
break;
case "tri":
Term = new UnaryExpression(Term, UnaryOperation.Triangle);
break;
default:
ErrorIndex = wordend;
return false;
}
}
Index = cur;
return true;
}
ErrorIndex = cur;
return false;
}
return false;
}
// Sequencer
if (AcceptString("[", Text, ref cur))
{
List<Expression> items = new List<Expression>();
ErrorIndex = cur;
while (true)
{
AcceptExtendedWhitespace(Text, ref cur);
if (AcceptExpression(Variables, Text, ref cur, ref Term, out ErrorIndex))
{
items.Add(Term);
if (AcceptString(",", Text, ref cur))
{
continue;
}
}
break;
}
if (AcceptString("]", Text, ref cur) && items.Count > 0)
{
if (AcceptTerm(Variables, Text, ref cur, ref Term, out ErrorIndex))
{
Term = new SequencerExpression(items, Term);
Index = cur;
return true;
}
}
else
{
ErrorIndex = cur;
return false;
}
}
return false;
}
