public static bool HasSameReturnValue(AstReturn returnA, AstReturn returnB)
{
// Both return undefined
if (returnA.Value == null && returnB.Value == null)
{
return(true);
}
// Only one of them is undefined
if (returnA.Value == null || returnB.Value == null)
{
return(false);
}
// Both is SymbolRef
if (returnA.Value is AstSymbolRef symbolA && returnB.Value is AstSymbolRef symbolB)
{
return(IsSameReference(symbolA, symbolB));
}
// Both is Call
if (returnA.Value is AstCall callA && returnB.Value is AstCall callB)
{
return(IsSameCall(callA, callB));
}
// Both is constants with same value
var constReturnA = returnA.Value.ConstValue();
var constReturnB = returnB.Value.ConstValue();
return(constReturnA != null && constReturnB != null && constReturnA.Equals(constReturnB));
}
private static EvalValue CalcReturn(IEnvironment env, AstReturn ast)
{
var ret = ast.result.Eval(env);
env.Set("return@" + env.GetScopeName(), ret);
// 中断执行
throw new ReturnException(ast);
}
/// <summary>
/// 解析语句state
/// </summary>
/// <returns></returns>
private AstStatement DoStatement()
{
// state ::== <while><expr><do>{<expr>|<state>}<end>';'
// | <if><expr><do>{<expr>|<state>}<end>';'
// | <return><expr>';'
if (Is("while", TokenType.KEYWORD))
{
// while语句
Pass("while", TokenType.KEYWORD);
AstExpression condition = DoExpression();
Pass("do", TokenType.KEYWORD);
List <AstNode> list = DoBlock();
Pass("end", TokenType.KEYWORD);
Pass(";", TokenType.SEPERATOR);
var ret = new AstWhile(list, condition);
Utils.LogDebug("[P] while语句: {0}", ret.ToString());
return(ret);
}
if (Is("if", TokenType.KEYWORD))
{
// if语句
Pass("if", TokenType.KEYWORD);
AstExpression condition = DoExpression();
Pass("do", TokenType.KEYWORD);
List <AstNode> list = DoBlock();
List <AstNode> elseList = null;
if (Is("else", TokenType.KEYWORD))
{
// 有else块
Pass("else", TokenType.KEYWORD);
elseList = DoBlock();
}
Pass("end", TokenType.KEYWORD);
Pass(";", TokenType.SEPERATOR);
var ret = new AstIf(list, condition, elseList);
Utils.LogDebug("[P] if语句: {0}", ret.ToString());
return(ret);
}
if (Is("return", TokenType.KEYWORD))
{
// return语句
Pass("return", TokenType.KEYWORD);
AstExpression expr = DoExpression();
var ret = new AstReturn(new List <AstNode>(), expr);
Utils.LogDebug("[P] return语句: {0}", ret.ToString());
return(ret);
}
throw new ParseException(m_scanner.Peek(0), "未知语句");
}
public ReturnInfo(AstReturn returnStatement, AstBlock parentBlock, AstIf?ifStatement)
{
ReturnStatement = returnStatement;
ParentBlock = parentBlock;
IfStatement = ifStatement;
}
private void CompileReturn(AstReturn node, Syt syt, StringBuilder sb)
{
var nodeFnc = node.NodeAncestor<AstSubroutine>();
if (nodeFnc.Type.Ktype == Ktype.Void)
{
if (node.expr != null)
throw new Erparse(node, "void method cannot return value");
sb.AppendLine("push constant 0");
}
else
{
if (node.expr == null)
throw new Erparse(node, "void method must return value");
CompileRecursive(node.expr, syt, sb);
}
sb.AppendLine("return");
}
