public static PsiExpression getOrCreatePisExpression(GrExpression expr) {
if (expr == null) return null;
final SoftReference<PsiExpression> ref = expr.getUserData(PSI_EXPRESSION);
final PsiExpression element = ref == null ? null : ref.get();
if (element != null) return element;
final GrSyntheticExpression newExpr = new GrSyntheticExpression(expr);
expr.putUserData(PSI_EXPRESSION, new SoftReference<PsiExpression>(newExpr));
return newExpr;
}
