/// <summary>
/// Called when the item is an if 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(IfItem target)
{
if (target == null)
throw new ArgumentNullException("target");
ILGenerator gen = compiler.CurrentGenerator;
Label next = gen.DefineLabel(), end = gen.DefineLabel();
// if (!{Exp}.IsTrue) goto next;
target.Exp.Accept(this);
gen.Emit(OpCodes.Callvirt, typeof(ILuaValue).GetMethod("get_IsTrue"));
gen.Emit(OpCodes.Brfalse, next);
// {Block}
target.Block.Accept(this);
// goto end;
gen.Emit(OpCodes.Br, end);
// next:
gen.MarkLabel(next);
foreach (var item in target.Elses)
{
// if (!{item.Item1}.IsTrue) goto next;
next = gen.DefineLabel();
item.Expression.Accept(this);
gen.Emit(OpCodes.Callvirt, typeof(ILuaValue).GetMethod("get_IsTrue"));
gen.Emit(OpCodes.Brfalse, next);
// {item.Item2}
item.Block.Accept(this);
// goto end;
gen.Emit(OpCodes.Br, end);
// next:
gen.MarkLabel(next);
}
if (target.ElseBlock != null)
target.ElseBlock.Accept(this);
// end:
gen.MarkLabel(end);
return target;
}
/// <summary>
/// Called when the item is an if 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(IfItem target)
{
if (target == null)
throw new ArgumentNullException("target");
target.Exp.Accept(this);
using (tree.Block(true))
target.Block.Accept(this);
for (int i = 0; i < target.Elses.Count; i++)
{
using (tree.Block(true))
{
target.Elses[i].Expression.Accept(this);
target.Elses[i].Block.Accept(this);
}
}
if (target.ElseBlock != null)
{
using (tree.Block(true))
target.ElseBlock.Accept(this);
}
return target;
}
/// <summary>
/// Reads an if 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 ReadIf(ITokenizer input, ref Token prev)
{
var debug = input.Read(); // read 'if'
IfItem i = new IfItem();
if (debug.Value != "if")
throw new InvalidOperationException(string.Format(Resources.MustBeOn, "if", "ReadIf"));
// read the initial expression
i.Exp = ReadExp(input, ref debug);
// read 'then'
var name = Read(input, ref debug);
if (name.Value != "then")
throw new SyntaxException(
string.Format(Resources.TokenInvalid, name.Value, "if"),
input.Name, debug);
// read the block
var readBlock = ReadBlock(input, ref debug);
i.Block = readBlock;
// handle elseif(s)
while ((name = input.Peek()).Value == "elseif")
{
Read(input, ref debug); // read 'elseif'
// read the expression
var readExp = ReadExp(input, ref debug);
// read 'then'
name = Read(input, ref debug);
if (name.Value != "then")
throw new SyntaxException(
string.Format(Resources.TokenInvalid, name.Value, "elseif"),
input.Name, debug);
// read the block
readBlock = ReadBlock(input, ref debug);
i.AddElse(readExp, readBlock);
}
// handle else
if (name.Value != "else" && name.Value != "end")
throw new SyntaxException(
string.Format(Resources.TokenInvalid, name.Value, "if"),
input.Name, debug);
if (name.Value == "else")
{
Read(input, ref debug); // read 'else'
// read the block
readBlock = ReadBlock(input, ref debug);
i.ElseBlock = readBlock;
}
// read 'end'
name = Read(input, ref debug);
if (name.Value != "end")
throw new SyntaxException(
string.Format(Resources.TokenInvalid, name.Value, "if"),
input.Name, debug);
prev.Append(debug);
i.Debug = debug;
return i;
}
