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      1 /*
      2  * Copyright (C) 2015 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package android.databinding.tool.expr;
     18 
     19 import android.databinding.tool.reflection.ModelAnalyzer;
     20 import android.databinding.tool.reflection.ModelClass;
     21 import android.databinding.tool.writer.KCode;
     22 
     23 import java.util.List;
     24 
     25 /**
     26  * This is a special expression that is created when we have an adapter that has multiple
     27  * parameters.
     28  * <p>
     29  * When it is detected, we create a new binding with this argument list expression and merge N
     30  * bindings into a new one so that rest of the code generation logic works as expected.
     31  */
     32 public class ArgListExpr extends Expr {
     33     private int mId;
     34     public ArgListExpr(int id, Iterable<Expr> children) {
     35         super(children);
     36         mId = id;
     37     }
     38 
     39     @Override
     40     protected String computeUniqueKey() {
     41         return "ArgList[" + mId + "]" + super.computeUniqueKey();
     42     }
     43 
     44     @Override
     45     protected KCode generateCode() {
     46         throw new IllegalStateException("should never try to convert an argument expressions"
     47                 + " into code");
     48     }
     49 
     50     @Override
     51     public Expr cloneToModel(ExprModel model) {
     52         return model.argListExpr(cloneToModel(model, getChildren()));
     53     }
     54 
     55     @Override
     56     protected ModelClass resolveType(ModelAnalyzer modelAnalyzer) {
     57         return modelAnalyzer.findClass(Void.class);
     58     }
     59 
     60     @Override
     61     protected List<Dependency> constructDependencies() {
     62         return super.constructDynamicChildrenDependencies();
     63     }
     64 
     65     @Override
     66     public boolean canBeEvaluatedToAVariable() {
     67         return false;
     68     }
     69 
     70     @Override
     71     public String getInvertibleError() {
     72         return "Merged bindings are not invertible.";
     73     }
     74 }
     75