TernaryExpr.java revision 6047998943beebd81e0ae1068df39c0cbee38628 
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.solver.ExecutionPath;
22import android.databinding.tool.writer.KCode;
23
24import java.util.ArrayList;
25import java.util.BitSet;
26import java.util.List;
27
28public class TernaryExpr extends Expr {
29
30    TernaryExpr(Expr pred, Expr ifTrue, Expr ifFalse) {
31        super(pred, ifTrue, ifFalse);
32    }
33
34    public Expr getPred() {
35        return getChildren().get(0);
36    }
37
38    public Expr getIfTrue() {
39        return getChildren().get(1);
40    }
41
42    public Expr getIfFalse() {
43        return getChildren().get(2);
44    }
45
46    @Override
47    protected String computeUniqueKey() {
48        return "?:" + super.computeUniqueKey();
49    }
50
51    @Override
52    public String getInvertibleError() {
53        if (getPred().isDynamic()) {
54            return "The condition of a ternary operator must be constant: " +
55                    getPred().toFullCode();
56        }
57        final String trueInvertible = getIfTrue().getInvertibleError();
58        if (trueInvertible != null) {
59            return trueInvertible;
60        } else {
61            return getIfFalse().getInvertibleError();
62        }
63    }
64
65    @Override
66    protected ModelClass resolveType(ModelAnalyzer modelAnalyzer) {
67        final Expr ifTrue = getIfTrue();
68        final Expr ifFalse = getIfFalse();
69        if (isNullLiteral(ifTrue)) {
70            return ifFalse.getResolvedType();
71        } else if (isNullLiteral(ifFalse)) {
72            return ifTrue.getResolvedType();
73        }
74        return modelAnalyzer.findCommonParentOf(getIfTrue().getResolvedType(),
75                getIfFalse().getResolvedType());
76    }
77
78    private static boolean isNullLiteral(Expr expr) {
79        final ModelClass type = expr.getResolvedType();
80        return (type.isObject() && (expr instanceof SymbolExpr) &&
81                "null".equals(((SymbolExpr) expr).getText()));
82    }
83
84    @Override
85    protected List<Dependency> constructDependencies() {
86        List<Dependency> deps = new ArrayList<Dependency>();
87        Expr predExpr = getPred();
88        final Dependency pred = new Dependency(this, predExpr);
89        pred.setMandatory(true);
90        deps.add(pred);
91
92        Expr ifTrueExpr = getIfTrue();
93        if (ifTrueExpr.isDynamic()) {
94            deps.add(new Dependency(this, ifTrueExpr, predExpr, true));
95        }
96        Expr ifFalseExpr = getIfFalse();
97        if (ifFalseExpr.isDynamic()) {
98            deps.add(new Dependency(this, ifFalseExpr, predExpr, false));
99        }
100        return deps;
101    }
102
103    @Override
104    public List<ExecutionPath> toExecutionPath(List<ExecutionPath> paths) {
105        List<ExecutionPath> executionPaths = getPred().toExecutionPath(paths);
106        // now optionally add others
107        List<ExecutionPath> result = new ArrayList<ExecutionPath>();
108        for (ExecutionPath path : executionPaths) {
109            ExecutionPath ifTrue = path.addBranch(getPred(), true);
110            if (ifTrue != null) {
111                result.addAll(getIfTrue().toExecutionPath(ifTrue));
112            }
113            ExecutionPath ifFalse = path.addBranch(getPred(), false);
114            if (ifFalse != null) {
115                result.addAll(getIfFalse().toExecutionPath(ifFalse));
116            }
117        }
118        return addJustMeToExecutionPath(result);
119    }
120
121    @Override
122    protected BitSet getPredicateInvalidFlags() {
123        return getPred().getInvalidFlags();
124    }
125
126    @Override
127    protected KCode generateCode(boolean expand) {
128        return new KCode()
129                .app("", getPred().toCode(expand))
130                .app(" ? ", getIfTrue().toCode(expand))
131                .app(" : ", getIfFalse().toCode(expand));
132    }
133
134    @Override
135    public KCode toInverseCode(KCode variable) {
136        return new KCode()
137                .app("if (", getPred().toCode(true))
138                .app(") {")
139                .tab(getIfTrue().toInverseCode(variable))
140                .nl(new KCode("} else {"))
141                .tab(getIfFalse().toInverseCode(variable))
142                .nl(new KCode("}"));
143    }
144
145    @Override
146    public boolean isConditional() {
147        return true;
148    }
149}
150