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      1 /*
      2  * Copyright (C) 2007 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 com.android.dx.ssa;
     18 
     19 import com.android.dx.rop.code.RegisterSpec;
     20 import com.android.dx.rop.code.RegisterSpecList;
     21 import com.android.dx.rop.code.RegisterSpecSet;
     22 
     23 /**
     24  * Represents a mapping between two register numbering schemes.
     25  * Subclasses of this may be mutable, and as such the mapping provided
     26  * is only valid for the lifetime of the method call in which
     27  * instances of this class are passed.
     28  */
     29 public abstract class RegisterMapper {
     30     /**
     31      * Gets the count of registers (really, the total register width, since
     32      * category width is counted) in the new namespace.
     33      * @return ≥ 0 width of new namespace.
     34      */
     35     public abstract int getNewRegisterCount();
     36 
     37     /**
     38      * @param registerSpec old register
     39      * @return register in new space
     40      */
     41     public abstract RegisterSpec map(RegisterSpec registerSpec);
     42 
     43     /**
     44      *
     45      * @param sources old register list
     46      * @return new mapped register list, or old if nothing has changed.
     47      */
     48     public final RegisterSpecList map(RegisterSpecList sources) {
     49         int sz = sources.size();
     50         RegisterSpecList newSources = new RegisterSpecList(sz);
     51 
     52         for (int i = 0; i < sz; i++) {
     53             newSources.set(i, map(sources.get(i)));
     54         }
     55 
     56         newSources.setImmutable();
     57 
     58         // Return the old sources if nothing has changed.
     59         return newSources.equals(sources) ? sources : newSources;
     60     }
     61 
     62     /**
     63      *
     64      * @param sources old register set
     65      * @return new mapped register set, or old if nothing has changed.
     66      */
     67     public final RegisterSpecSet map(RegisterSpecSet sources) {
     68         int sz = sources.getMaxSize();
     69         RegisterSpecSet newSources = new RegisterSpecSet(getNewRegisterCount());
     70 
     71         for (int i = 0; i < sz; i++) {
     72             RegisterSpec registerSpec = sources.get(i);
     73             if (registerSpec != null) {
     74                 newSources.put(map(registerSpec));
     75             }
     76         }
     77 
     78         newSources.setImmutable();
     79 
     80         // Return the old sources if nothing has changed.
     81         return newSources.equals(sources) ? sources : newSources;
     82     }
     83 }
     84