MergedBinding.java revision 2611838bffef5a009ca71e3e9e59a93f29b098ed 
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
17package android.databinding.tool;
18
19import android.databinding.tool.expr.ArgListExpr;
20import android.databinding.tool.expr.Expr;
21import android.databinding.tool.expr.ExprModel;
22import android.databinding.tool.reflection.ModelClass;
23import android.databinding.tool.store.SetterStore;
24import android.databinding.tool.util.L;
25import android.databinding.tool.writer.CodeGenUtil;
26import android.databinding.tool.writer.WriterPackage;
27
28import java.lang.reflect.Array;
29import java.util.ArrayList;
30import java.util.Arrays;
31import java.util.List;
32
33/**
34 * Multiple binding expressions can be evaluated using a single adapter. In those cases,
35 * we replace the Binding with a MergedBinding.
36 */
37public class MergedBinding extends Binding {
38    private final SetterStore.MultiAttributeSetter mMultiAttributeSetter;
39    public MergedBinding(ExprModel model, SetterStore.MultiAttributeSetter multiAttributeSetter,
40            BindingTarget target, Iterable<Binding> bindings) {
41        super(target, createMergedName(bindings), createArgListExpr(model, bindings));
42        mMultiAttributeSetter = multiAttributeSetter;
43    }
44
45    private static Expr createArgListExpr(ExprModel model, final Iterable<Binding> bindings) {
46        List<Expr> args = new ArrayList<>();
47        for (Binding binding : bindings) {
48            args.add(binding.getExpr());
49        }
50        Expr expr = model.argListExpr(args);
51        expr.setBindingExpression(true);
52        return expr;
53    }
54
55    private static String createMergedName(Iterable<Binding> bindings) {
56        StringBuilder sb = new StringBuilder();
57        for (Binding binding : bindings) {
58            sb.append(binding.getName());
59        }
60        return sb.toString();
61    }
62
63    @Override
64    public void resolveListeners() {
65        ModelClass[] params = mMultiAttributeSetter.getParameterTypes();
66        List<Expr> expressions = getExpr().getChildren();
67        for (int i = 0; i < params.length; i++) {
68            expressions.get(i).resolveListeners(params[i]);
69        }
70    }
71
72    public Expr[] getComponentExpressions() {
73        ArgListExpr args = (ArgListExpr) getExpr();
74        return args.getChildren().toArray(new Expr[args.getChildren().size()]);
75    }
76
77    @Override
78    public boolean requiresOldValue() {
79        return mMultiAttributeSetter.requiresOldValue();
80    }
81
82    @Override
83    public int getMinApi() {
84        return 1;
85    }
86
87    @Override
88    public String toJavaCode(String targetViewName) {
89        final ArgListExpr args = (ArgListExpr) getExpr();
90        final List<String> newValues = new ArrayList<>();
91        for (Expr expr : args.getChildren()) {
92            newValues.add(CodeGenUtil.Companion.toCode(expr, false).generate());
93        }
94        final List<String> oldValues;
95        if (requiresOldValue()) {
96            oldValues = new ArrayList<>();
97            for (Expr expr : args.getChildren()) {
98                oldValues.add("this." + WriterPackage.getOldValueName(expr));
99            }
100        } else {
101            oldValues = Arrays.asList(new String[args.getChildren().size()]);
102        }
103        final String[] expressions = concat(oldValues, newValues, String.class);
104        L.d("merged binding arg: %s", args.getUniqueKey());
105        return mMultiAttributeSetter.toJava(targetViewName, expressions);
106    }
107
108    private static <T> T[] concat(List<T> l1, List<T> l2, Class<T> klass) {
109        List<T> result = new ArrayList<>();
110        result.addAll(l1);
111        result.addAll(l2);
112        return result.toArray((T[]) Array.newInstance(klass, result.size()));
113    }
114}
115