/*
*
* 用于initializer的编译，分成两种情况。
* 一种情况是直接对已经定义的普通变量进行赋值，另外一种情况是对数组的操作，没看出来。a[1]=[1],[1]
* 前提：Expression Visit的结果已经被push到操作栈中
*/
public override object VisitInitializer([NotNull] CMMParser.InitializerContext context)
{
if (context.ChildCount == 3)
{
// 直接对已经定义的普通变量进行赋值
if (curLocalVariablesTable.ContainsKey(context.GetChild(0).GetText()))
{
throw new VariableRedefinedException(context.GetChild(0).GetText(), context);
}
curLocalVariablesTable.Add(context.GetChild(0).GetText(), curLocalVariablesTableLength);
curLocalVariablesTableLength++;
Visit(context.GetChild(2));
curLocalVariablesTable.TryGetValue(context.GetChild(0).GetText(), out int index);
IntermediateCode code = new IntermediateCode(index, InstructionType.pop, context.Start.Line);
codes.Add(code);
}
else
{
// 定义数组
// 首先visit a[exp] exp的值被压到当前stack上
// expStack.Clear();
// Visit(context.GetChild(2));
// Double expValue = (Double)expStack.Pop();
// if (Math.Ceiling(expValue) != expValue) {
// throw new CompileException("数组元素个数必须为整数！");
// }
// 支支持常量定义
int size = Convert.ToInt32(context.GetChild(2).GetText());
curLocalVariablesTable.Add(context.GetChild(0).GetText(), curLocalVariablesTableLength);
int initialExpCount = context.expression().Length - 1;
for (int i = 1; i < context.expression().Length; i++)
{
// 求出所有子表达式的值 放在栈上
Visit(context.expression()[i]);
}
for (int i = 0; i < size - initialExpCount; i++)
{
// 剩下的元素全部赋值为0
codes.Add(new IntermediateCode(0, InstructionType.push, context.Start.Line));
}
for (int i = size - 1; i >= 0; i--)
{
// 从后往前给数组赋值
codes.Add(new IntermediateCode(curLocalVariablesTableLength + i, InstructionType.pop, context.Start.Line));
}
// 更新局部变量表大小
curLocalVariablesTableLength += size;
}
return(null);
}
/// <summary>
/// Visit a parse tree produced by <see cref="CMMParser.initializer"/>.
/// <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 VisitInitializer([NotNull] CMMParser.InitializerContext context)
{
return(VisitChildren(context));
}
public VariableRedefinedException(string v, CMMParser.InitializerContext context)
{
this.v = v;
this.context = context;
errorInfo = new ErrorInfo(context.Start.Line, context.Start.Column, "列变量" + v + "多次定义");
}
/// <summary>
/// Exit a parse tree produced by <see cref="CMMParser.initializer"/>.
/// <para>The default implementation does nothing.</para>
/// </summary>
/// <param name="context">The parse tree.</param>
public virtual void ExitInitializer([NotNull] CMMParser.InitializerContext context)
{
}
