/*
* jumpStatement
* return 语句在第一遍扫描结束之后回填
* break continue 可以在for while语句的时候，直接转换成为jump语句
*/
public override object VisitJumpStatement([NotNull] CMMParser.JumpStatementContext context)
{
IntermediateCode code = null;
switch (context.GetChild(0).GetText())
{
case "break":
code = new IntermediateCode(InstructionType.b, context.Start.Line);
break;
case "continue":
code = new IntermediateCode(InstructionType.cnt, context.Start.Line);
break;
case "return":
if (context.ChildCount == 2)
{
// 向操作栈压入0表示没有返回值
codes.Add(new IntermediateCode(0, InstructionType.push, context.Start.Line));
}
else
{
Visit(context.expression());
// 向操作栈压入1表示有返回值
codes.Add(new IntermediateCode(1, InstructionType.push, context.Start.Line));
}
code = new IntermediateCode(InstructionType.ret, context.Start.Line);
break;
}
codes.Add(code);
return(null);
}
/// <summary>
/// Visit a parse tree produced by <see cref="CMMParser.jumpStatement"/>.
/// <para>
/// The default implementation returns the result of calling <see cref="AbstractParseTreeVisitor{Result}.VisitChildren(IRuleNode)"/>
/// on <paramref name="context"/>.
/// </para>
/// </summary>
/// <param name="context">The parse tree.</param>
/// <return>The visitor result.</return>
public virtual Result VisitJumpStatement([NotNull] CMMParser.JumpStatementContext context)
{
return(VisitChildren(context));
}
/// <summary>
/// Exit a parse tree produced by <see cref="CMMParser.jumpStatement"/>.
/// <para>The default implementation does nothing.</para>
/// </summary>
/// <param name="context">The parse tree.</param>
public virtual void ExitJumpStatement([NotNull] CMMParser.JumpStatementContext context)
{
}
