xtext

Question

我有以下语法：

Model: prog+=Program*;

Program: g=Greeting  de+=DataEntry* s+=Statement*;

Greeting: 'Hello' t=ProgPara '!';

ProgPara: 'PROGRAM'  pname=Progname ';';

Progname : name=ID;

DataEntry:  a=INT v=Varname ';';   

Varname : name = ID;

Statement: (c=CopyStmt|m=MoveStmt) ';';

CopyStmt: 'COPY' 'TO' qname=[IndexVarname|ID] ;

IndexVarname : (Indexname|Varname);   

Indexname : '(' name = ID ')';

MoveStmt: 'MOVE' 'TO' p=[PrVarName|ID];

PrVarName : (Varname|Progname);

但它抛出错误：

PrVarName : (Varname|Progname);

所以我修改了语法如下：

PrVarName : (v=Varname|Progname);

我更新了 Scope provider 如下：

override getScope(EObject context, EReference reference) {
    if (context instanceof CopyStmt) {
        if (reference.featureID == TestDslPackage.COPY_STMT__QNAME) {
            val rootElement = EcoreUtil2.getRootContainer(context);
            val candidates1 = EcoreUtil2.getAllContentsOfType(rootElement, Indexname);
            val candidates2 = EcoreUtil2.getAllContentsOfType(rootElement, Varname);
            val candidates = candidates1 + candidates2;

            return Scopes.scopeFor(candidates);
        }
    } else if (context instanceof MoveStmt) {
        if (reference.featureID == TestDslPackage.MOVE_STMT__P) {
            val rootElement = EcoreUtil2.getRootContainer(context);
            val candidates1 = EcoreUtil2.getAllContentsOfType(rootElement, Progname);
            val candidates2 = EcoreUtil2.getAllContentsOfType(rootElement, Varname);
            val candidates = candidates1 + candidates2;

            return Scopes.scopeFor(candidates);
        }
    }       
}

一旦构建了语法并且我运行下面的测试用例，它就会在 MOVE 语句中抛出错误 "Couldn't resolve reference to PrVarName 'test1'."

Hello PROGRAM test;!

1 test1;
2 test2;
3 test3;

COPY TO test2;
MOVE TO test1;

看来我不能在两个不同的交叉引用中使用 Varname。但是有一个非常合理的需要。我该如何实现？

提前致谢。

Answer 1

PrVarName : p=(Progname|Varname);

不好，因为它更改了类型层次结构。 Progname 和 Varname 不再是 PrVarName 的子类型。通过还原更改并引入通用的命名超类型，您可以解决此问题

Model:
    prog+=Program*;

Program:
    g=Greeting de+=DataEntry* s+=Statement*;

Greeting:
    'Hello' t=ProgPara '!';

ProgPara:
    'PROGRAM' pname=Progname ';';

DataEntry:
    a=INT (v=Varname | in=Indexname) ';';

Statement:
    (c=CopyStmt | m=MoveStmt) ';';

CopyStmt:
    'COPY' 'TO' qname=[IndexVarname|ID];

MoveStmt:
    'MOVE' 'TO' p=[PrVarName|ID];

PrVarName:
    Progname | Varname;

IndexVarname:
    (Indexname | Varname);

Named:Progname|Indexname|Varname;   

Progname:
    {Progname} name=ID; 

Indexname:
    {Indexname}'(' name=ID ')';

Varname:
    {Varame}name=ID;

xtext - 无法解析对的引用

xtext - Couldn't resolve reference to

cross-reference