using System;
using System.Collections.Generic;

namespace AspClassic.Parser;

/// <summary>
/// A parse tree for an argument to a call or index.
/// </summary>
public sealed class Argument : Tree
{
	private readonly SimpleName _Name;

	private readonly Location _ColonEqualsLocation;

	private readonly Expression _Expression;

	/// <summary>
	/// The name of the argument, if any.
	/// </summary>
	public SimpleName Name => _Name;

	/// <summary>
	/// The location of the ':=', if any.
	/// </summary>
	public Location ColonEqualsLocation => _ColonEqualsLocation;

	/// <summary>
	/// The argument, if any.
	/// </summary>
	public Expression Expression => _Expression;

	/// <summary>
	/// Constructs a new parse tree for an argument.
	/// </summary>
	/// <param name="name">The name of the argument, if any.</param>
	/// <param name="colonEqualsLocation">The location of the ':=', if any.</param>
	/// <param name="expression">The expression, if any.</param>
	/// <param name="span">The location of the parse tree.</param>
	public Argument(SimpleName name, Location colonEqualsLocation, Expression expression, Span span)
		: base(TreeType.Argument, span)
	{
		if (expression == null)
		{
			throw new ArgumentNullException("expression");
		}
		SetParent(name);
		SetParent(expression);
		_Name = name;
		_ColonEqualsLocation = colonEqualsLocation;
		_Expression = expression;
	}

	private Argument()
		: base(TreeType.Argument, default(Span))
	{
	}

	protected override void GetChildTrees(IList<Tree> childList)
	{
		Tree.AddChild(childList, Name);
		Tree.AddChild(childList, Expression);
	}
}