1/* 2 * Copyright (C) 2012 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 com.android.tools.lint.checks; 18 19import com.android.annotations.NonNull; 20import com.android.annotations.Nullable; 21import com.android.tools.lint.detector.api.Category; 22import com.android.tools.lint.detector.api.Context; 23import com.android.tools.lint.detector.api.Detector; 24import com.android.tools.lint.detector.api.Issue; 25import com.android.tools.lint.detector.api.JavaContext; 26import com.android.tools.lint.detector.api.Scope; 27import com.android.tools.lint.detector.api.Severity; 28 29import java.io.File; 30import java.util.Collections; 31import java.util.List; 32 33import lombok.ast.AstVisitor; 34import lombok.ast.ConstructorDeclaration; 35import lombok.ast.Expression; 36import lombok.ast.ForwardingAstVisitor; 37import lombok.ast.IntegralLiteral; 38import lombok.ast.MethodDeclaration; 39import lombok.ast.MethodInvocation; 40import lombok.ast.Node; 41import lombok.ast.Return; 42import lombok.ast.StrictListAccessor; 43 44/** Detector looking for Toast.makeText() without a corresponding show() call */ 45public class ToastDetector extends Detector implements Detector.JavaScanner { 46 /** The main issue discovered by this detector */ 47 public static final Issue ISSUE = Issue.create( 48 "ShowToast", //$NON-NLS-1$ 49 "Looks for code creating a Toast but forgetting to call show() on it", 50 51 "`Toast.makeText()` creates a `Toast` but does *not* show it. You must call " + 52 "`show()` on the resulting object to actually make the `Toast` appear.", 53 54 Category.CORRECTNESS, 55 6, 56 Severity.WARNING, 57 ToastDetector.class, 58 Scope.JAVA_FILE_SCOPE); 59 60 61 /** Constructs a new {@link ToastDetector} check */ 62 public ToastDetector() { 63 } 64 65 @Override 66 public boolean appliesTo(@NonNull Context context, @NonNull File file) { 67 return true; 68 } 69 70 71 // ---- Implements JavaScanner ---- 72 73 @Override 74 public List<String> getApplicableMethodNames() { 75 return Collections.singletonList("makeText"); //$NON-NLS-1$ 76 } 77 78 private Node findSurroundingMethod(Node scope) { 79 while (scope != null) { 80 Class<? extends Node> type = scope.getClass(); 81 // The Lombok AST uses a flat hierarchy of node type implementation classes 82 // so no need to do instanceof stuff here. 83 if (type == MethodDeclaration.class || type == ConstructorDeclaration.class) { 84 return scope; 85 } 86 87 scope = scope.getParent(); 88 } 89 90 return null; 91 } 92 93 @Override 94 public void visitMethod(@NonNull JavaContext context, @Nullable AstVisitor visitor, 95 @NonNull MethodInvocation node) { 96 assert node.astName().astValue().equals("makeText"); 97 if (node.astOperand() == null) { 98 // "makeText()" in the code with no operand 99 return; 100 } 101 102 String operand = node.astOperand().toString(); 103 if (!(operand.equals("Toast") || operand.endsWith(".Toast"))) { 104 return; 105 } 106 107 // Make sure you pass the right kind of duration: it's not a delay, it's 108 // LENGTH_SHORT or LENGTH_LONG 109 // (see http://code.google.com/p/android/issues/detail?id=3655) 110 StrictListAccessor<Expression, MethodInvocation> args = node.astArguments(); 111 if (args.size() == 3) { 112 Expression duration = args.last(); 113 if (duration instanceof IntegralLiteral) { 114 context.report(ISSUE, context.getLocation(duration), 115 "Expected duration Toast.LENGTH_SHORT or Toast.LENGTH_LONG, a custom " + 116 "duration value is not supported", 117 null); 118 } 119 } 120 121 Node method = findSurroundingMethod(node.getParent()); 122 if (method == null) { 123 return; 124 } 125 126 ShowFinder finder = new ShowFinder(node); 127 method.accept(finder); 128 if (!finder.isShowCalled()) { 129 context.report(ISSUE, method, context.getLocation(node), 130 "Toast created but not shown: did you forget to call show() ?", null); 131 } 132 } 133 134 private class ShowFinder extends ForwardingAstVisitor { 135 /** Whether we've found the show method */ 136 private boolean mFound; 137 /** The target makeText call */ 138 private MethodInvocation mTarget; 139 /** Whether we've seen the target makeText node yet */ 140 private boolean mSeenTarget; 141 142 private ShowFinder(MethodInvocation target) { 143 mTarget = target; 144 } 145 146 @Override 147 public boolean visitMethodInvocation(MethodInvocation node) { 148 if (node == mTarget) { 149 mSeenTarget = true; 150 } else if ((mSeenTarget || node.astOperand() == mTarget) 151 && "show".equals(node.astName().astValue())) { //$NON-NLS-1$ 152 // TODO: Do more flow analysis to see whether we're really calling show 153 // on the right type of object? 154 mFound = true; 155 } 156 157 return true; 158 } 159 160 @Override 161 public boolean visitReturn(Return node) { 162 if (node.astValue() == mTarget) { 163 // If you just do "return Toast.makeText(...) don't warn 164 mFound = true; 165 } 166 return super.visitReturn(node); 167 } 168 169 boolean isShowCalled() { 170 return mFound; 171 } 172 } 173} 174