com.google.maps.internal.ratelimiter.Preconditions Maven / Gradle / Ivy
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/*
* Copyright (C) 2012 The Guava Authors
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
* in compliance with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software distributed under the License
* is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
* or implied. See the License for the specific language governing permissions and limitations under
* the License.
*/
/*
* Copyright 2017 Google Inc. All rights reserved.
*
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not use this
* file except in compliance with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software distributed under
* the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF
* ANY KIND, either express or implied. See the License for the specific language governing
* permissions and limitations under the License.
*/
package com.google.maps.internal.ratelimiter;
/**
* Static convenience methods that help a method or constructor check whether it was invoked
* correctly (that is, whether its preconditions were met).
*
* This is a minimal port of Google Guava's com.google.common.base.Preconditions necessary to
* implement the ratelimiter classes.
*/
public final class Preconditions {
private Preconditions() {}
/**
* Ensures the truth of an expression involving one or more parameters to the calling method.
*
* @param expression a boolean expression
* @param errorMessageTemplate a template for the exception message should the check fail. The
* message is formed by replacing each {@code %s} placeholder in the template with an
* argument. These are matched by position - the first {@code %s} gets {@code
* errorMessageArgs[0]}, etc. Unmatched arguments will be appended to the formatted message in
* square braces. Unmatched placeholders will be left as-is.
* @param errorMessageArgs the arguments to be substituted into the message template. Arguments
* are converted to strings using {@link String#valueOf(Object)}.
* @throws IllegalArgumentException if {@code expression} is false
*/
public static void checkArgument(
boolean expression, String errorMessageTemplate, Object... errorMessageArgs) {
if (!expression) {
throw new IllegalArgumentException(format(errorMessageTemplate, errorMessageArgs));
}
}
/**
* Ensures that an object reference passed as a parameter to the calling method is not null.
*
* @param reference an object reference
* @return the non-null reference that was validated
* @throws NullPointerException if {@code reference} is null
*/
public static T checkNotNull(T reference) {
if (reference == null) {
throw new NullPointerException();
}
return reference;
}
/**
* Ensures that an object reference passed as a parameter to the calling method is not null.
*
* @param reference an object reference
* @param errorMessage the exception message to use if the check fails; will be converted to a
* string using {@link String#valueOf(Object)}
* @return the non-null reference that was validated
* @throws NullPointerException if {@code reference} is null
*/
public static T checkNotNull(T reference, Object errorMessage) {
if (reference == null) {
throw new NullPointerException(String.valueOf(errorMessage));
}
return reference;
}
/**
* Ensures the truth of an expression involving the state of the calling instance, but not
* involving any parameters to the calling method.
*
* @param expression a boolean expression
* @param errorMessage the exception message to use if the check fails; will be converted to a
* string using {@link String#valueOf(Object)}
* @throws IllegalStateException if {@code expression} is false
*/
public static void checkState(boolean expression, Object errorMessage) {
if (!expression) {
throw new IllegalStateException(String.valueOf(errorMessage));
}
}
/**
* Substitutes each {@code %s} in {@code template} with an argument. These are matched by
* position: the first {@code %s} gets {@code args[0]}, etc. If there are more arguments than
* placeholders, the unmatched arguments will be appended to the end of the formatted message in
* square braces.
*
* @param template a string containing 0 or more {@code %s} placeholders. null is treated as
* "null".
* @param args the arguments to be substituted into the message template. Arguments are converted
* to strings using {@link String#valueOf(Object)}. Arguments can be null.
*/
static String format(String template, Object... args) {
template = String.valueOf(template); // null -> "null"
args = args == null ? new Object[] {"(Object[])null"} : args;
// start substituting the arguments into the '%s' placeholders
StringBuilder builder = new StringBuilder(template.length() + 16 * args.length);
int templateStart = 0;
int i = 0;
while (i < args.length) {
int placeholderStart = template.indexOf("%s", templateStart);
if (placeholderStart == -1) {
break;
}
builder.append(template, templateStart, placeholderStart);
builder.append(args[i++]);
templateStart = placeholderStart + 2;
}
builder.append(template, templateStart, template.length());
// if we run out of placeholders, append the extra args in square braces
if (i < args.length) {
builder.append(" [");
builder.append(args[i++]);
while (i < args.length) {
builder.append(", ");
builder.append(args[i++]);
}
builder.append(']');
}
return builder.toString();
}
}