1 /* 2 * Copyright (C) 2016 The Dagger Authors. 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 17 package dagger.internal; 18 19 import org.jspecify.annotations.Nullable; 20 21 /** 22 * An adaptation of Guava's {@code com.google.common.base.Preconditions} that is specially tailored 23 * to support checks applied in Dagger's generated code. 24 */ 25 public final class Preconditions { 26 /** 27 * Ensures that an object reference passed as a parameter to the calling method is not null. 28 * 29 * @param reference an object reference 30 * @return the non-null reference that was validated 31 * @throws NullPointerException if {@code reference} is null 32 */ checkNotNull(@ullable T reference)33 public static <T> T checkNotNull(@Nullable T reference) { 34 if (reference == null) { 35 throw new NullPointerException(); 36 } 37 return reference; 38 } 39 40 /** 41 * Ensures that an object reference passed as a parameter to the calling method is not null. 42 * 43 * @param reference an object reference 44 * @param errorMessage the exception message to use if the check fails 45 * @return the non-null reference that was validated 46 * @throws NullPointerException if {@code reference} is null 47 */ checkNotNull(T reference, String errorMessage)48 public static <T> T checkNotNull(T reference, String errorMessage) { 49 if (reference == null) { 50 throw new NullPointerException(errorMessage); 51 } 52 return reference; 53 } 54 55 /** 56 * Ensures that an object reference returned from a provides method is not null. 57 * 58 * @param reference an object reference 59 * @return the non-null reference that was validated 60 * @throws NullPointerException if {@code reference} is null 61 */ checkNotNullFromProvides(T reference)62 public static <T> T checkNotNullFromProvides(T reference) { 63 if (reference == null) { 64 throw new NullPointerException("Cannot return null from a non-@Nullable @Provides method"); 65 } 66 return reference; 67 } 68 69 /** 70 * Ensures that an object reference returned from a component method is not null. 71 * 72 * @param reference an object reference 73 * @return the non-null reference that was validated 74 * @throws NullPointerException if {@code reference} is null 75 */ checkNotNullFromComponent(T reference)76 public static <T> T checkNotNullFromComponent(T reference) { 77 if (reference == null) { 78 throw new NullPointerException("Cannot return null from a non-@Nullable component method"); 79 } 80 return reference; 81 } 82 83 /** 84 * Ensures that an object reference passed as a parameter to the calling method is not null. 85 * 86 * @param reference an object reference 87 * @param errorMessageTemplate a template for the exception message should the check fail. The 88 * message is formed by replacing the single {@code %s} placeholder in the template with 89 * {@code errorMessageArg}. 90 * @param errorMessageArg the argument to be substituted into the message template. Converted to a 91 * string using {@link String#valueOf(Object)}, except for {@link Class} objects, which use 92 * {@link Class#getCanonicalName()}. 93 * @return the non-null reference that was validated 94 * @throws NullPointerException if {@code reference} is null 95 * @throws IllegalArgumentException if {@code errorMessageTemplate} doesn't contain exactly one 96 * "%s" 97 */ checkNotNull( T reference, String errorMessageTemplate, Object errorMessageArg)98 public static <T> T checkNotNull( 99 T reference, String errorMessageTemplate, Object errorMessageArg) { 100 if (reference == null) { 101 // Simple implementation of String.format, which is not GWT-compatible 102 if (!errorMessageTemplate.contains("%s")) { 103 throw new IllegalArgumentException("errorMessageTemplate has no format specifiers"); 104 } 105 if (errorMessageTemplate.indexOf("%s") != errorMessageTemplate.lastIndexOf("%s")) { 106 throw new IllegalArgumentException( 107 "errorMessageTemplate has more than one format specifier"); 108 } 109 String argString = 110 String.valueOf( 111 errorMessageArg instanceof Class 112 ? ((Class) errorMessageArg).getCanonicalName() 113 : errorMessageArg); 114 throw new NullPointerException(errorMessageTemplate.replace("%s", argString)); 115 } 116 return reference; 117 } 118 119 /** 120 * Checks that the component builder field {@code requirement} has been initialized. 121 * 122 * @throws IllegalStateException if {@code requirement is null} 123 */ checkBuilderRequirement(T requirement, Class<T> clazz)124 public static <T> void checkBuilderRequirement(T requirement, Class<T> clazz) { 125 if (requirement == null) { 126 throw new IllegalStateException(clazz.getCanonicalName() + " must be set"); 127 } 128 } 129 Preconditions()130 private Preconditions() {} 131 } 132