MergedBinding.java revision 975c05c00dae9193a636c4775df81d8665fc6749 
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.WriterPackage;
26
27import java.lang.reflect.Array;
28import java.util.ArrayList;
29import java.util.Arrays;
30import java.util.List;
31
32/**
33 * Multiple binding expressions can be evaluated using a single adapter. In those cases,
34 * we replace the Binding with a MergedBinding.
35 */
36public class MergedBinding extends Binding {
37    private final SetterStore.MultiAttributeSetter mMultiAttributeSetter;
38    public MergedBinding(ExprModel model, SetterStore.MultiAttributeSetter multiAttributeSetter,
39            BindingTarget target, Iterable<Binding> bindings) {
40        super(target, createMergedName(bindings), createArgListExpr(model, bindings));
41        mMultiAttributeSetter = multiAttributeSetter;
42    }
43
44    @Override
45    public void resolveListeners() {
46        ModelClass[] parameters = mMultiAttributeSetter.getParameterTypes();
47        List<Expr> children = getExpr().getChildren();
48        final Expr expr = getExpr();
49        for (int i = 0; i < children.size(); i++) {
50            final Expr child = children.get(i);
51            child.resolveListeners(parameters[i], expr);
52        }
53    }
54
55    private static Expr createArgListExpr(ExprModel model, final Iterable<Binding> bindings) {
56        List<Expr> args = new ArrayList<>();
57        for (Binding binding : bindings) {
58            args.add(binding.getExpr());
59        }
60        Expr expr = model.argListExpr(args);
61        expr.setBindingExpression(true);
62        return expr;
63    }
64
65    private static String createMergedName(Iterable<Binding> bindings) {
66        StringBuilder sb = new StringBuilder();
67        for (Binding binding : bindings) {
68            sb.append(binding.getName());
69        }
70        return sb.toString();
71    }
72
73    public Expr[] getComponentExpressions() {
74        ArgListExpr args = (ArgListExpr) getExpr();
75        return args.getChildren().toArray(new Expr[args.getChildren().size()]);
76    }
77
78    @Override
79    public String getBindingAdapterInstanceClass() {
80        return mMultiAttributeSetter.getBindingAdapterInstanceClass();
81    }
82
83    @Override
84    public boolean requiresOldValue() {
85        return mMultiAttributeSetter.requiresOldValue();
86    }
87
88    @Override
89    public int getMinApi() {
90        return 1;
91    }
92
93    @Override
94    public String toJavaCode(String targetViewName, String bindingComponent) {
95        final ArgListExpr args = (ArgListExpr) getExpr();
96        final List<String> newValues = new ArrayList<>();
97        for (Expr expr : args.getChildren()) {
98            newValues.add(expr.toCode().generate());
99        }
100        final List<String> oldValues;
101        if (requiresOldValue()) {
102            oldValues = new ArrayList<>();
103            for (Expr expr : args.getChildren()) {
104                oldValues.add("this." + WriterPackage.getOldValueName(expr));
105            }
106        } else {
107            oldValues = Arrays.asList(new String[args.getChildren().size()]);
108        }
109        final String[] expressions = concat(oldValues, newValues, String.class);
110        L.d("merged binding arg: %s", args.getUniqueKey());
111        return mMultiAttributeSetter.toJava(bindingComponent, targetViewName, expressions);
112    }
113
114    private static <T> T[] concat(List<T> l1, List<T> l2, Class<T> klass) {
115        List<T> result = new ArrayList<>();
116        result.addAll(l1);
117        result.addAll(l2);
118        return result.toArray((T[]) Array.newInstance(klass, result.size()));
119    }
120}
121