io.primeval.common.base.Preconditions Maven / Gradle / Ivy
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/*
* Copyright (C) 2007 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.
*/
package io.primeval.common.base;
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
* @throws IllegalArgumentException
* if {@code expression} is false
*/
public static void checkArgument(boolean expression) {
if (!expression) {
throw new IllegalArgumentException();
}
}
/**
* Ensures the truth of an expression involving one or more 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 IllegalArgumentException
* if {@code expression} is false
*/
public static void checkArgument(
boolean expression, Object errorMessage) {
if (!expression) {
throw new IllegalArgumentException(String.valueOf(errorMessage));
}
}
/**
* 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
* @throws NullPointerException
* if the check fails and either {@code
* errorMessageTemplate} or {@code errorMessageArgs} is null (don't let this happen)
*/
public static void checkArgument(boolean expression,
String errorMessageTemplate,
Object... errorMessageArgs) {
if (!expression) {
throw new IllegalArgumentException(
format(errorMessageTemplate, errorMessageArgs));
}
}
/**
* 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
* @throws IllegalStateException
* if {@code expression} is false
*/
public static void checkState(boolean expression) {
if (!expression) {
throw new IllegalStateException();
}
}
/**
* 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));
}
}
/**
* 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 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 IllegalStateException
* if {@code expression} is false
* @throws NullPointerException
* if the check fails and either {@code
* errorMessageTemplate} or {@code errorMessageArgs} is null (don't let this happen)
*/
public static void checkState(boolean expression,
String errorMessageTemplate,
Object... errorMessageArgs) {
if (!expression) {
throw new IllegalStateException(
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 that an object reference passed as a parameter to the calling method is not null.
*
* @param reference
* an object reference
* @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)}.
* @return the non-null reference that was validated
* @throws NullPointerException
* if {@code reference} is null
*/
public static T checkNotNull(T reference,
String errorMessageTemplate,
Object... errorMessageArgs) {
if (reference == null) {
// If either of these parameters is null, the right thing happens anyway
throw new NullPointerException(
format(errorMessageTemplate, errorMessageArgs));
}
return reference;
}
/*
* All recent hotspots (as of 2009) *really* like to have the natural code
*
* if (guardExpression) { throw new BadException(messageExpression); }
*
* refactored so that messageExpression is moved to a separate String-returning method.
*
* if (guardExpression) { throw new BadException(badMsg(...)); }
*
* The alternative natural refactorings into void or Exception-returning methods are much slower. This is a big deal
* - we're talking factors of 2-8 in microbenchmarks, not just 10-20%. (This is a hotspot optimizer bug, which
* should be fixed, but that's a separate, big project).
*
* The coding pattern above is heavily used in java.util, e.g. in ArrayList. There is a RangeCheckMicroBenchmark in
* the JDK that was used to test this.
*
* But the methods in this class want to throw different exceptions, depending on the args, so it appears that this
* pattern is not directly applicable. But we can use the ridiculous, devious trick of throwing an exception in the
* middle of the construction of another exception. Hotspot is fine with that.
*/
/**
* Ensures that {@code index} specifies a valid element in an array, list or string of size {@code size}. An
* element index may range from zero, inclusive, to {@code size}, exclusive.
*
* @param index
* a user-supplied index identifying an element of an array, list or string
* @param size
* the size of that array, list or string
* @return the value of {@code index}
* @throws IndexOutOfBoundsException
* if {@code index} is negative or is not less than {@code size}
* @throws IllegalArgumentException
* if {@code size} is negative
*/
public static int checkElementIndex(int index, int size) {
return checkElementIndex(index, size, "index");
}
/**
* Ensures that {@code index} specifies a valid element in an array, list or string of size {@code size}. An
* element index may range from zero, inclusive, to {@code size}, exclusive.
*
* @param index
* a user-supplied index identifying an element of an array, list or string
* @param size
* the size of that array, list or string
* @param desc
* the text to use to describe this index in an error message
* @return the value of {@code index}
* @throws IndexOutOfBoundsException
* if {@code index} is negative or is not less than {@code size}
* @throws IllegalArgumentException
* if {@code size} is negative
*/
public static int checkElementIndex(
int index, int size, String desc) {
// Carefully optimized for execution by hotspot (explanatory comment above)
if (index < 0 || index >= size) {
throw new IndexOutOfBoundsException(badElementIndex(index, size, desc));
}
return index;
}
private static String badElementIndex(int index, int size, String desc) {
if (index < 0) {
return format("%s (%s) must not be negative", desc, index);
} else if (size < 0) {
throw new IllegalArgumentException("negative size: " + size);
} else { // index >= size
return format("%s (%s) must be less than size (%s)", desc, index, size);
}
}
/**
* Ensures that {@code index} specifies a valid position in an array, list or string of size {@code size}. A
* position index may range from zero to {@code size}, inclusive.
*
* @param index
* a user-supplied index identifying a position in an array, list or string
* @param size
* the size of that array, list or string
* @return the value of {@code index}
* @throws IndexOutOfBoundsException
* if {@code index} is negative or is greater than {@code size}
* @throws IllegalArgumentException
* if {@code size} is negative
*/
public static int checkPositionIndex(int index, int size) {
return checkPositionIndex(index, size, "index");
}
/**
* Ensures that {@code index} specifies a valid position in an array, list or string of size {@code size}. A
* position index may range from zero to {@code size}, inclusive.
*
* @param index
* a user-supplied index identifying a position in an array, list or string
* @param size
* the size of that array, list or string
* @param desc
* the text to use to describe this index in an error message
* @return the value of {@code index}
* @throws IndexOutOfBoundsException
* if {@code index} is negative or is greater than {@code size}
* @throws IllegalArgumentException
* if {@code size} is negative
*/
public static int checkPositionIndex(
int index, int size, String desc) {
// Carefully optimized for execution by hotspot (explanatory comment above)
if (index < 0 || index > size) {
throw new IndexOutOfBoundsException(badPositionIndex(index, size, desc));
}
return index;
}
private static String badPositionIndex(int index, int size, String desc) {
if (index < 0) {
return format("%s (%s) must not be negative", desc, index);
} else if (size < 0) {
throw new IllegalArgumentException("negative size: " + size);
} else { // index > size
return format("%s (%s) must not be greater than size (%s)",
desc, index, size);
}
}
/**
* Ensures that {@code start} and {@code end} specify a valid positions in an array, list or string of size
* {@code size}, and are in order. A position index may range from zero to {@code size}, inclusive.
*
* @param start
* a user-supplied index identifying a starting position in an array, list or string
* @param end
* a user-supplied index identifying a ending position in an array, list or string
* @param size
* the size of that array, list or string
* @throws IndexOutOfBoundsException
* if either index is negative or is greater than {@code size}, or if {@code end} is less than
* {@code start}
* @throws IllegalArgumentException
* if {@code size} is negative
*/
public static void checkPositionIndexes(int start, int end, int size) {
// Carefully optimized for execution by hotspot (explanatory comment above)
if (start < 0 || end < start || end > size) {
throw new IndexOutOfBoundsException(badPositionIndexes(start, end, size));
}
}
private static String badPositionIndexes(int start, int end, int size) {
if (start < 0 || start > size) {
return badPositionIndex(start, size, "start index");
}
if (end < 0 || end > size) {
return badPositionIndex(end, size, "end index");
}
// end < start
return format("end index (%s) must not be less than start index (%s)",
end, start);
}
/**
* 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 non-null string containing 0 or more {@code %s} placeholders.
* @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"
// 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.substring(templateStart, placeholderStart));
builder.append(args[i++]);
templateStart = placeholderStart + 2;
}
builder.append(template.substring(templateStart));
// 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();
}
}
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