MergedBinding.java revision a128d1c99ea98bb48c45d648906652e3d618d513 
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.store.SetterStore;
23import android.databinding.tool.util.L;
24import android.databinding.tool.writer.WriterPackage;
25
26import java.lang.reflect.Array;
27import java.util.ArrayList;
28import java.util.Arrays;
29import java.util.List;
30
31/**
32 * Multiple binding expressions can be evaluated using a single adapter. In those cases,
33 * we replace the Binding with a MergedBinding.
34 */
35public class MergedBinding extends Binding {
36    private final SetterStore.MultiAttributeSetter mMultiAttributeSetter;
37    public MergedBinding(ExprModel model, SetterStore.MultiAttributeSetter multiAttributeSetter,
38            BindingTarget target, Iterable<Binding> bindings) {
39        super(target, createMergedName(bindings), createArgListExpr(model, bindings));
40        mMultiAttributeSetter = multiAttributeSetter;
41    }
42
43    private static Expr createArgListExpr(ExprModel model, final Iterable<Binding> bindings) {
44        List<Expr> args = new ArrayList<>();
45        for (Binding binding : bindings) {
46            args.add(binding.getExpr());
47        }
48        Expr expr = model.argListExpr(args);
49        expr.setBindingExpression(true);
50        return expr;
51    }
52
53    private static String createMergedName(Iterable<Binding> bindings) {
54        StringBuilder sb = new StringBuilder();
55        for (Binding binding : bindings) {
56            sb.append(binding.getName());
57        }
58        return sb.toString();
59    }
60
61    public Expr[] getComponentExpressions() {
62        ArgListExpr args = (ArgListExpr) getExpr();
63        return args.getChildren().toArray(new Expr[args.getChildren().size()]);
64    }
65
66    @Override
67    public String getBindingAdapterInstanceClass() {
68        return mMultiAttributeSetter.getBindingAdapterInstanceClass();
69    }
70
71    @Override
72    public boolean requiresOldValue() {
73        return mMultiAttributeSetter.requiresOldValue();
74    }
75
76    @Override
77    public int getMinApi() {
78        return 1;
79    }
80
81    @Override
82    public String toJavaCode(String targetViewName, String bindingComponent) {
83        final ArgListExpr args = (ArgListExpr) getExpr();
84        final List<String> newValues = new ArrayList<>();
85        for (Expr expr : args.getChildren()) {
86            newValues.add(expr.toCode().generate());
87        }
88        final List<String> oldValues;
89        if (requiresOldValue()) {
90            oldValues = new ArrayList<>();
91            for (Expr expr : args.getChildren()) {
92                oldValues.add("this." + WriterPackage.getOldValueName(expr));
93            }
94        } else {
95            oldValues = Arrays.asList(new String[args.getChildren().size()]);
96        }
97        final String[] expressions = concat(oldValues, newValues, String.class);
98        L.d("merged binding arg: %s", args.getUniqueKey());
99        return mMultiAttributeSetter.toJava(bindingComponent, targetViewName, expressions);
100    }
101
102    private static <T> T[] concat(List<T> l1, List<T> l2, Class<T> klass) {
103        List<T> result = new ArrayList<>();
104        result.addAll(l1);
105        result.addAll(l2);
106        return result.toArray((T[]) Array.newInstance(klass, result.size()));
107    }
108}
109