/// <summary>
/// parse out one symbol expression matcher. leave the enumerator on the character directly following the matched symbol.
/// return the next symbol, and whether or not there is another symbol
/// </summary>
/// <param name="symbols"></param>
/// <param name="validParameters"></param>
/// <param name="currentIndexInStream"></param>
/// <returns></returns>
private static (ReplacementSymbolGenerator, bool) ParseOutSymbolExpression(
Func <char, int> symbolRemapper,
CharEnumerator symbols,
string[] validParameters,
ref int currentIndexInStream)
{
var nextSymbol = symbols.Current;
if (nextSymbol == '(' || nextSymbol == ')')
{
throw new SyntaxException("Cannot use parentheses as a symbol", currentIndexInStream);
}
currentIndexInStream++;
if (!symbols.MoveNext())
{
return(new ReplacementSymbolGenerator(symbolRemapper(nextSymbol)), false);
}
if (symbols.Current != '(')
{
return(new ReplacementSymbolGenerator(symbolRemapper(nextSymbol)), true);
}
var delegates = new List <DynamicExpressionData>();
while (symbols.Current != ')')
{
AttemptMoveNext(symbols, ref currentIndexInStream);
var indentationDepth = 0;
var expressionString = new StringBuilder();
while (symbols.Current != ',')
{
switch (symbols.Current)
{
case '(':
indentationDepth++;
break;
case ')':
indentationDepth--;
break;
default:
break;
}
if (indentationDepth < 0)
{
break;
}
expressionString.Append(symbols.Current);
AttemptMoveNext(symbols, ref currentIndexInStream);
}
var expressionToParse = expressionString.ToString();
try
{
delegates.Add(ExpressionCompiler.CompileExpressionToDelegateWithParameters(
"(" + expressionToParse + ")",
validParameters));
}
catch (SyntaxException e)
{
e.RecontextualizeIndex(currentIndexInStream - expressionToParse.Length - 1);
throw e;
}
}
// reset to next char to stay consistent
currentIndexInStream++;
return(new ReplacementSymbolGenerator(symbolRemapper(nextSymbol), delegates), symbols.MoveNext());
}
