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.expr;
18
19import android.databinding.tool.reflection.ModelAnalyzer;
20import android.databinding.tool.reflection.ModelClass;
21import android.databinding.tool.writer.KCode;
22
23import java.util.ArrayList;
24import java.util.BitSet;
25import java.util.List;
26
27public class TernaryExpr extends Expr {
28    TernaryExpr(Expr pred, Expr ifTrue, Expr ifFalse) {
29        super(pred, ifTrue, ifFalse);
30    }
31
32    public Expr getPred() {
33        return getChildren().get(0);
34    }
35
36    public Expr getIfTrue() {
37        return getChildren().get(1);
38    }
39
40    public Expr getIfFalse() {
41        return getChildren().get(2);
42    }
43
44    @Override
45    protected String computeUniqueKey() {
46        return "?:" + super.computeUniqueKey();
47    }
48
49    @Override
50    public String getInvertibleError() {
51        if (getPred().isDynamic()) {
52            return "The condition of a ternary operator must be constant: " +
53                    getPred().toFullCode();
54        }
55        final String trueInvertible = getIfTrue().getInvertibleError();
56        if (trueInvertible != null) {
57            return trueInvertible;
58        } else {
59            return getIfFalse().getInvertibleError();
60        }
61    }
62
63    @Override
64    protected ModelClass resolveType(ModelAnalyzer modelAnalyzer) {
65        final Expr ifTrue = getIfTrue();
66        final Expr ifFalse = getIfFalse();
67        if (isNullLiteral(ifTrue)) {
68            return ifFalse.getResolvedType();
69        } else if (isNullLiteral(ifFalse)) {
70            return ifTrue.getResolvedType();
71        }
72        return modelAnalyzer.findCommonParentOf(getIfTrue().getResolvedType(),
73                getIfFalse().getResolvedType());
74    }
75
76    private static boolean isNullLiteral(Expr expr) {
77        final ModelClass type = expr.getResolvedType();
78        return (type.isObject() && (expr instanceof SymbolExpr) &&
79                "null".equals(((SymbolExpr)expr).getText()));
80    }
81
82    @Override
83    protected List<Dependency> constructDependencies() {
84        List<Dependency> deps = new ArrayList<Dependency>();
85        Expr predExpr = getPred();
86        final Dependency pred = new Dependency(this, predExpr);
87        pred.setMandatory(true);
88        deps.add(pred);
89
90        Expr ifTrueExpr = getIfTrue();
91        if (ifTrueExpr.isDynamic()) {
92            deps.add(new Dependency(this, ifTrueExpr, predExpr, true));
93        }
94        Expr ifFalseExpr = getIfFalse();
95        if (ifFalseExpr.isDynamic()) {
96            deps.add(new Dependency(this, ifFalseExpr, predExpr, false));
97        }
98        return deps;
99    }
100
101    @Override
102    protected BitSet getPredicateInvalidFlags() {
103        return getPred().getInvalidFlags();
104    }
105
106    @Override
107    protected KCode generateCode(boolean expand) {
108        return new KCode()
109                .app("", getPred().toCode(expand))
110                .app(" ? ", getIfTrue().toCode(expand))
111                .app(" : ", getIfFalse().toCode(expand));
112
113    }
114
115    @Override
116    public KCode toInverseCode(KCode variable) {
117        return new KCode()
118                .app("if (", getPred().toCode(true))
119                .app(") {")
120                .tab(getIfTrue().toInverseCode(variable))
121                .nl(new KCode("} else {"))
122                .tab(getIfFalse().toInverseCode(variable))
123                .nl(new KCode("}"));
124    }
125
126    @Override
127    public boolean isConditional() {
128        return true;
129    }
130}
131