public override Verb Parse()
{
var block = new Block();
var index = position;
prefixOperatorParser = new PrefixOperatorParser();
valueParser = new ValueParser();
postfixOperatorParser = new PostfixOperatorParser(asStatement);
infixOperatorParser = new InfixOperatorParser();
andOrParser = new AndOrParser(Stop.PassAlong(stop, Structures));
ignoreReturnsParser = new IgnoreReturnsParser();
ifExpressionParser = new IfExpressionParser();
IMaybe <int> newIndex;
if (index < source.Length)
{
newIndex = isStopping(index);
if (newIndex.IsSome)
{
return(returnBlock(block, newIndex.Value));
}
newIndex = getTerm(block, index);
if (newIndex.IsNone || newIndex.Value == index)
{
return(null);
}
index = newIndex.Value;
}
while (index < source.Length)
{
newIndex = isStopping(index);
if (newIndex.IsSome)
{
return(returnBlock(block, newIndex.Value));
}
if (infixOperatorParser.Scan(source, index))
{
block.Add(infixOperatorParser.Verb);
index = infixOperatorParser.Position;
}
else
{
break;
}
newIndex = getTerm(block, index);
if (newIndex.IsNone || newIndex.Value == index)
{
return(null);
}
index = newIndex.Value;
}
if (index < source.Length)
{
newIndex = isStopping(index);
if (newIndex.IsSome)
{
return(returnBlock(block, newIndex.Value));
}
if (andOrParser.Scan(source, index))
{
block.Add(andOrParser.Verb);
index = andOrParser.Position;
}
}
return(returnBlock(block, index));
}
public static IMaybe <(Block, Block, int)> GetExpressionThenBlock(string source, int index)
{
return(GetExpression(source, index, Stop.ExpressionThenBlock())
.Map(t => GetOneOrMultipleBlock(source, t.Item2).Map(t2 => (t.Item1, t2.Item1, t2.Item2))));
}
public static IMaybe <(Block, Block, int)> GetComparisand(string source, int index, Stop stop)
{
if (ExpressionParser.GetExpression(source, index, stop).If(out var expression, out var i))
{
(var comparisand, var condition) = GetComparisand(expression);
return((comparisand, condition, i).Some());
}
return(MaybeFunctions.none <(Block, Block, int)>());
}
public static IMaybe <(Block, int)> GetExpression(string source, int index, Stop stop, bool asStatement = false)
{
var parser = new ExpressionParser(stop, asStatement);
return(when(parser.Scan(source, index), () => (parser.Block, parser.Position)));
}
public static Stop PassAlong(Stop stop, EntityType color) => new Stop(stop.Pattern, stop.Consume, color);