/// <summary>
/// Called when the item is a while item.
/// </summary>
/// <param name="target">The object that was passed to IParseItem.Visit.</param>
/// <returns>The passed target or a modification of it.</returns>
/// <exception cref="System.ArgumentNullException">If target is null.</exception>
public IParseItem Visit(WhileItem target)
{
if (target == null)
throw new ArgumentNullException("target");
ILGenerator gen = compiler.CurrentGenerator;
target.Break.UserData = target.Break.UserData ?? gen.DefineLabel();
Label start = gen.DefineLabel();
Label end = (Label)target.Break.UserData;
// start:
gen.MarkLabel(start);
// if (!{Exp}.IsTrue) goto end;
target.Exp.Accept(this);
gen.Emit(OpCodes.Callvirt, typeof(ILuaValue).GetMethod("get_IsTrue"));
gen.Emit(OpCodes.Brfalse, end);
// {Block}
target.Block.Accept(this);
// goto start;
gen.Emit(OpCodes.Br, start);
// end:
gen.MarkLabel(end);
return target;
}
/// <summary>
/// Called when the item is a while item.
/// </summary>
/// <param name="target">The object that was passed to IParseItem.Visit.</param>
/// <returns>The passed target or a modification of it.</returns>
/// <exception cref="System.ArgumentNullException">If target is null.</exception>
public IParseItem Visit(WhileItem target)
{
if (target == null)
throw new ArgumentNullException("target");
target.Exp.Accept(this);
using (tree.Block(true))
{
tree.DefineLabel(target.Break);
target.Block.Accept(this);
}
return target;
}
/// <summary>
/// Reads a while statement from the input.
/// </summary>
/// <param name="input">Where to read input from.</param>
/// <param name="prev">The token to append what is read into.</param>
/// <returns>The object that was read.</returns>
protected virtual IParseStatement ReadWhile(ITokenizer input, ref Token prev)
{
var debug = input.Read(); // read 'while'
WhileItem w = new WhileItem();
if (debug.Value != "while")
throw new InvalidOperationException(string.Format(Resources.MustBeOn, "while", "ReadWhile"));
// read the expression
w.Exp = ReadExp(input, ref debug);
// read 'do'
var name = Read(input, ref debug);
if (name.Value != "do")
throw new SyntaxException(
string.Format(Resources.TokenInvalidExpecting, name.Value, "while", "do"),
input.Name, name);
// read the block
w.Block = ReadBlock(input, ref debug);
// read 'end'
name = Read(input, ref debug);
if (name.Value != "end")
throw new SyntaxException(
string.Format(Resources.TokenInvalidExpecting, name.Value, "while", "end"),
input.Name, name);
prev.Append(debug);
w.Debug = debug;
return w;
}