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      1 /*
      2  * Copyright (C) 2016 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.processing.ErrorMessages;
     20 import android.databinding.tool.processing.Scope;
     21 import android.databinding.tool.store.Location;
     22 import android.databinding.tool.util.L;
     23 import android.databinding.tool.util.Preconditions;
     24 
     25 import java.util.ArrayList;
     26 import java.util.List;
     27 import java.util.Map;
     28 
     29 /**
     30  * Callbacks are evaluated when event happens, not when execute pending is run. To separate their
     31  * expressions, we provide a separate model for them that extends the main model. This allows them
     32  * to introduce their own variables etc. without mixing them with other expressions.
     33  */
     34 public class CallbackExprModel extends ExprModel {
     35     // used for imports and other stuff.
     36     final ExprModel mOriginal;
     37     final List<CallbackArgExpr> mArguments = new ArrayList<CallbackArgExpr>();
     38     public CallbackExprModel(ExprModel original) {
     39         mOriginal = original;
     40     }
     41 
     42     @Override
     43     public Map<String, String> getImports() {
     44         return mOriginal.getImports();
     45     }
     46 
     47     @Override
     48     public StaticIdentifierExpr addImport(String alias, String type, Location location) {
     49         return mOriginal.addImport(alias, type, location);
     50     }
     51 
     52     @Override
     53     public <T extends Expr> T register(T expr) {
     54         // locations are only synced to main model so we need to sync overselves here.
     55         setCurrentLocationInFile(mOriginal.getCurrentLocationInFile());
     56         setCurrentParserContext(mOriginal.getCurrentParserContext());
     57         return super.register(expr);
     58     }
     59 
     60     @Override
     61     public void seal() {
     62         // ensure all types are calculated
     63         for (Expr expr : mExprMap.values()) {
     64             expr.getResolvedType();
     65             expr.markAsUsedInCallback();
     66         }
     67         markSealed();
     68         // we do not resolve dependencies for these expression because they are resolved via
     69         // ExecutionPath and should not interfere with the main expr model's dependency graph.
     70     }
     71 
     72     @Override
     73     public IdentifierExpr identifier(String name) {
     74         CallbackArgExpr arg = findArgByName(name);
     75         if (arg != null) {
     76             return arg;
     77         }
     78         IdentifierExpr id = new IdentifierExpr(name);
     79         final Expr existing = mExprMap.get(id.getUniqueKey());
     80         if (existing == null) {
     81              // this is not a method variable reference. register it in the main model
     82             final IdentifierExpr identifier = mOriginal.identifier(name);
     83             mExprMap.put(identifier.getUniqueKey(), identifier);
     84             identifier.markAsUsedInCallback();
     85             return identifier;
     86         }
     87         return (IdentifierExpr) existing;
     88     }
     89 
     90     private CallbackArgExpr findArgByName(String name) {
     91         for (CallbackArgExpr arg : mArguments) {
     92             if (name.equals(arg.getName())) {
     93                 return arg;
     94             }
     95         }
     96         return null;
     97     }
     98 
     99     public CallbackArgExpr callbackArg(String name) {
    100         Preconditions.checkNull(findArgByName(name),
    101                 ErrorMessages.DUPLICATE_CALLBACK_ARGUMENT, name);
    102         final CallbackArgExpr id = new CallbackArgExpr(mArguments.size(), name);
    103         final CallbackArgExpr added = register(id);
    104         mArguments.add(added);
    105 
    106         try {
    107             Scope.enter(added);
    108             IdentifierExpr identifierWithSameName = mOriginal.findIdentifier(name);
    109             if (identifierWithSameName != null) {
    110                 L.w(ErrorMessages.CALLBACK_VARIABLE_NAME_CLASH, name, name,
    111                         identifierWithSameName.getUserDefinedType());
    112             }
    113         } finally {
    114             Scope.exit();
    115         }
    116         return added;
    117     }
    118 
    119     public int getArgCount() {
    120         return mArguments.size();
    121     }
    122 
    123     public List<CallbackArgExpr> getArguments() {
    124         return mArguments;
    125     }
    126 }
    127