Preconditions.java

/*
 * Copyright 2013 Andriy Vityuk
 *
 * 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.vityuk.ginger.util;

/**
 * Do the same that Guava code without 6MB jar ...
 */
public class Preconditions {

    public static void checkArgument(boolean expression) {
        if (!expression) {
            throw new IllegalArgumentException();
        }
    }

    public static void checkArgument(boolean expression, Object errorMessage) {
        if (!expression) {
            throw new IllegalArgumentException(String.valueOf(errorMessage));
        }
    }

    public static void checkArgument(boolean expression, String errorMessageTemplate, Object... errorMessageArgs) {
        if (!expression) {
            throw new IllegalArgumentException(format(errorMessageTemplate, errorMessageArgs));
        }
    }

    public static <T> T checkNotNull(T reference) {
        if (reference == null) {
            throw new NullPointerException();
        } else {
            return reference;
        }
    }

    public static <T> T checkNotNull(T reference, Object errorMessage) {
        if (reference == null) {
            throw new NullPointerException(String.valueOf(errorMessage));
        } else {
            return reference;
        }
    }

    public static <T> T checkNotNull(T reference, String errorMessageTemplate, Object... errorMessageArgs) {
        if (reference == null) {
            throw new NullPointerException(format(errorMessageTemplate, errorMessageArgs));
        } else {
            return reference;
        }
    }

    public static void checkState(boolean expression) {
        if (!expression) {
            throw new IllegalStateException();
        }
    }

    public static void checkState(
            boolean expression, Object errorMessage) {
        if (!expression) {
            throw new IllegalStateException(String.valueOf(errorMessage));
        }
    }

    public static void checkState(boolean expression,
                                  String errorMessageTemplate,
                                  Object... errorMessageArgs) {
        if (!expression) {
            throw new IllegalStateException(
                    format(errorMessageTemplate, errorMessageArgs));
        }
    }

    static String format(String template, Object... args) {
        template = String.valueOf(template);
        StringBuilder builder = new StringBuilder(template.length() + 16 * args.length);
        int templateStart = 0;

        int i;
        int placeholderStart;
        for (i = 0; i < args.length; templateStart = placeholderStart + 2) {
            placeholderStart = template.indexOf("%s", templateStart);
            if (placeholderStart == -1) {
                break;
            }

            builder.append(template.substring(templateStart, placeholderStart));
            builder.append(args[i++]);
        }

        builder.append(template.substring(templateStart));
        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();
    }
}