/// <summary>
/// Scans the current parse engine for a matrix expression.
/// </summary>
/// <param name="engine">The parse engine to use.</param>
/// <returns>The found expression or NULL.</returns>
public override Expression Scan(ParseEngine engine)
{
var column = engine.CurrentColumn;
var line = engine.CurrentLine;
var chars = engine.Characters;
var start = engine.Pointer;
if (chars[start] == '[')
{
engine.Advance();
var terminated = false;
var statement = new Statement();
var ws = false;
var nl = false;
while (engine.Pointer < chars.Length && engine.IsParsing)
{
if (ParseEngine.IsWhiteSpace(chars[engine.Pointer]))
{
ws = true;
engine.Advance();
}
else if (ParseEngine.IsNewLine(chars[engine.Pointer]))
{
nl = true;
engine.Advance();
}
else if (chars[engine.Pointer] == ']')
{
terminated = true;
engine.Advance();
break;
}
else if (chars[engine.Pointer] == ',')
{
ws = false;
nl = false;
statement.Push(engine, new ColumnOperator(engine));
engine.Advance();
}
else if (chars[engine.Pointer] == ';')
{
ws = false;
nl = false;
statement.Push(engine, new RowOperator(engine));
engine.Advance();
}
else if (engine.Pointer < chars.Length - 1 && ParseEngine.IsComment(chars[engine.Pointer], chars[engine.Pointer + 1]))
{
if (ParseEngine.IsLineComment(chars[engine.Pointer], chars[engine.Pointer + 1]))
{
engine.AdvanceToNextLine();
}
else
{
engine.AdvanceTo("*/");
}
}
else
{
engine.ParseBlock(statement, nl ? (Operator) new RowOperator(engine) : (ws ? new ColumnOperator(engine) : null));
ws = false;
nl = false;
}
}
if (!terminated)
{
var err = new YAMPMatrixNotClosedError(line, column);
engine.AddError(err);
}
var container = statement.Finalize(engine).Container;
return(new MatrixExpression(line, column, engine.Pointer - start, engine.Query, container ?? new ContainerExpression()));
}
return(null);
}