JsonPath/json-path/src/main/java/com/jayway/jsonpath/internal/Utils.java

/*
 * Copyright 2011 the original author or 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 com.jayway.jsonpath.internal;

import com.jayway.jsonpath.JsonPathException;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.Closeable;
import java.io.IOException;
import java.io.InputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.ObjectStreamClass;
import java.io.OutputStream;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;

public final class Utils {

    public static final String CR = System.getProperty("line.separator");

    /**
     * Creates a range of integers from start (inclusive) to end (exclusive)
     *
     * @param start
     * @param end
     * @return
     */
    public static List<Integer> createRange(int start, int end) {
        if (end <= start) {
            throw new IllegalArgumentException("Cannot create range from " + start + " to " + end + ", end must be greater than start.");
        }
        if (start == end-1) {
            return Collections.emptyList();
        }
        List<Integer> range = new ArrayList<Integer>(end-start-1);
        for (int i = start; i < end; i++) {
            range.add(i);
        }
        return range;
    }

    // accept a collection of objects, since all objects have toString()
    public static String join(String delimiter, String wrap, Iterable<? extends Object> objs) {
        Iterator<? extends Object> iter = objs.iterator();
        if (!iter.hasNext()) {
            return "";
        }
        StringBuilder buffer = new StringBuilder();
        buffer.append(wrap).append(iter.next()).append(wrap);
        while (iter.hasNext()) {
            buffer.append(delimiter).append(wrap).append(iter.next()).append(wrap);
        }
        return buffer.toString();
    }

    // accept a collection of objects, since all objects have toString()
    public static String join(String delimiter, Iterable<? extends Object> objs) {
        return join(delimiter, "", objs);
    }

    //---------------------------------------------------------
    //
    // IO
    //
    //---------------------------------------------------------

    public static void closeQuietly(Closeable closeable) {
        try {
            if (closeable != null) {
                closeable.close();
            }
        } catch (IOException ignore) {
        }
    }

    //---------------------------------------------------------
    //
    // Strings
    //
    //---------------------------------------------------------
    public static boolean isInt(String str) {
        if (str == null) {
            return false;
        }
        int sz = str.length();
        for (int i = 0; i < sz; i++) {
            if (Character.isDigit(str.charAt(i)) == false) {
                return false;
            }
        }
        return true;
    }

    public static boolean isNumeric(String str) {
        if (str == null) {
            return false;
        }
        int sz = str.length();
        for (int i = 0; i < sz; i++) {
            if (Character.isDigit(str.charAt(i)) == false && !(str.charAt(i) == '.')) {
                return false;
            }
        }
        return true;
    }

    /**
     * <p>Checks if a CharSequence is empty ("") or null.</p>
     * <p/>
     * <pre>
     * StringUtils.isEmpty(null)      = true
     * StringUtils.isEmpty("")        = true
     * StringUtils.isEmpty(" ")       = false
     * StringUtils.isEmpty("bob")     = false
     * StringUtils.isEmpty("  bob  ") = false
     * </pre>
     * <p/>
     * <p>NOTE: This method changed in Lang version 2.0.
     * It no longer trims the CharSequence.
     * That functionality is available in isBlank().</p>
     *
     * @param cs the CharSequence to check, may be null
     * @return {@code true} if the CharSequence is empty or null
     * @since 3.0 Changed signature from isEmpty(String) to isEmpty(CharSequence)
     */
    public static boolean isEmpty(CharSequence cs) {
        return cs == null || cs.length() == 0;
    }

    /**
     * Used by the indexOf(CharSequence methods) as a green implementation of indexOf.
     *
     * @param cs         the {@code CharSequence} to be processed
     * @param searchChar the {@code CharSequence} to be searched for
     * @param start      the start index
     * @return the index where the search sequence was found
     */
    static int indexOf(CharSequence cs, CharSequence searchChar, int start) {
        return cs.toString().indexOf(searchChar.toString(), start);
    }

    /**
     * <p>Counts how many times the substring appears in the larger string.</p>
     * <p/>
     * <p>A {@code null} or empty ("") String input returns {@code 0}.</p>
     * <p/>
     * <pre>
     * StringUtils.countMatches(null, *)       = 0
     * StringUtils.countMatches("", *)         = 0
     * StringUtils.countMatches("abba", null)  = 0
     * StringUtils.countMatches("abba", "")    = 0
     * StringUtils.countMatches("abba", "a")   = 2
     * StringUtils.countMatches("abba", "ab")  = 1
     * StringUtils.countMatches("abba", "xxx") = 0
     * </pre>
     *
     * @param str the CharSequence to check, may be null
     * @param sub the substring to count, may be null
     * @return the number of occurrences, 0 if either CharSequence is {@code null}
     * @since 3.0 Changed signature from countMatches(String, String) to countMatches(CharSequence, CharSequence)
     */
    public static int countMatches(CharSequence str, CharSequence sub) {
        if (isEmpty(str) || isEmpty(sub)) {
            return 0;
        }
        int count = 0;
        int idx = 0;
        while ((idx = indexOf(str, sub, idx)) != -1) {
            count++;
            idx += sub.length();
        }
        return count;
    }

    //---------------------------------------------------------
    //
    // Validators
    //
    //---------------------------------------------------------

    /**
     * <p>Validate that the specified argument is not {@code null};
     * otherwise throwing an exception with the specified message.
     * <p/>
     * <pre>Validate.notNull(myObject, "The object must not be null");</pre>
     *
     * @param <T>     the object type
     * @param object  the object to check
     * @param message the {@link String#format(String, Object...)} exception message if invalid, not null
     * @param values  the optional values for the formatted exception message
     * @return the validated object (never {@code null} for method chaining)
     * @throws NullPointerException if the object is {@code null}
     */
    public static <T> T notNull(T object, String message, Object... values) {
        if (object == null) {
            throw new IllegalArgumentException(String.format(message, values));
        }
        return object;
    }

    /**
     * <p>Validate that the argument condition is {@code true}; otherwise
     * throwing an exception with the specified message. This method is useful when
     * validating according to an arbitrary boolean expression, such as validating a
     * primitive number or using your own custom validation expression.</p>
     * <p/>
     * <pre>Validate.isTrue(i > 0.0, "The value must be greater than zero: %d", i);</pre>
     * <p/>
     * <p>For performance reasons, the long value is passed as a separate parameter and
     * appended to the exception message only in the case of an error.</p>
     *
     * @param expression the boolean expression to check
     * @param message
     * @throws IllegalArgumentException if expression is {@code false}
     */
    public static void isTrue(boolean expression, String message) {
        if (expression == false) {
            throw new IllegalArgumentException(message);
        }
    }

    /**
     * <p>Validate that the specified argument character sequence is
     * neither {@code null} nor a length of zero (no characters);
     * otherwise throwing an exception with the specified message.
     * <p/>
     * <pre>Validate.notEmpty(myString, "The string must not be empty");</pre>
     *
     * @param <T>     the character sequence type
     * @param chars   the character sequence to check, validated not null by this method
     * @param message the {@link String#format(String, Object...)} exception message if invalid, not null
     * @param values  the optional values for the formatted exception message, null array not recommended
     * @return the validated character sequence (never {@code null} method for chaining)
     * @throws NullPointerException     if the character sequence is {@code null}
     * @throws IllegalArgumentException if the character sequence is empty
     */
    public static <T extends CharSequence> T notEmpty(T chars, String message, Object... values) {
        if (chars == null) {
            throw new IllegalArgumentException(String.format(message, values));
        }
        if (chars.length() == 0) {
            throw new IllegalArgumentException(String.format(message, values));
        }
        return chars;
    }


    //---------------------------------------------------------
    //
    // Converters
    //
    //---------------------------------------------------------
    public static String toString(Object o) {
        if (null == o) {
            return null;
        }

        return o.toString();
    }

    //---------------------------------------------------------
    //
    // Serialization
    //
    //---------------------------------------------------------


    /**
     * <p>Serializes an {@code Object} to the specified stream.</p>
     * <p/>
     * <p>The stream will be closed once the object is written.
     * This avoids the need for a finally clause, and maybe also exception
     * handling, in the application code.</p>
     * <p/>
     * <p>The stream passed in is not buffered internally within this method.
     * This is the responsibility of your application if desired.</p>
     *
     * @param obj          the object to serialize to bytes, may be null
     * @param outputStream the stream to write to, must not be null
     * @throws IllegalArgumentException if {@code outputStream} is {@code null}
     * @throws RuntimeException         (runtime) if the serialization fails
     */
    public static void serialize(Serializable obj, OutputStream outputStream) {
        if (outputStream == null) {
            throw new IllegalArgumentException("The OutputStream must not be null");
        }
        ObjectOutputStream out = null;
        try {
            // stream closed in the finally
            out = new ObjectOutputStream(outputStream);
            out.writeObject(obj);

        } catch (IOException ex) {
            throw new JsonPathException(ex);
        } finally {
            try {
                if (out != null) {
                    out.close();
                }
            } catch (IOException ex) { // NOPMD
                // ignore close exception
            }
        }
    }

    /**
     * <p>Serializes an {@code Object} to a byte array for
     * storage/serialization.</p>
     *
     * @param obj the object to serialize to bytes
     * @return a byte[] with the converted Serializable
     * @throws RuntimeException (runtime) if the serialization fails
     */
    public static byte[] serialize(Serializable obj) {
        ByteArrayOutputStream baos = new ByteArrayOutputStream(512);
        serialize(obj, baos);
        return baos.toByteArray();
    }

    // Deserialize
    //-----------------------------------------------------------------------

    /**
     * <p>Deserializes an {@code Object} from the specified stream.</p>
     * <p/>
     * <p>The stream will be closed once the object is written. This
     * avoids the need for a finally clause, and maybe also exception
     * handling, in the application code.</p>
     * <p/>
     * <p>The stream passed in is not buffered internally within this method.
     * This is the responsibility of your application if desired.</p>
     *
     * @param inputStream the serialized object input stream, must not be null
     * @return the deserialized object
     * @throws IllegalArgumentException if {@code inputStream} is {@code null}
     * @throws RuntimeException         (runtime) if the serialization fails
     */
    public static Object deserialize(InputStream inputStream) {
        if (inputStream == null) {
            throw new IllegalArgumentException("The InputStream must not be null");
        }
        ObjectInputStream in = null;
        try {
            // stream closed in the finally
            in = new ObjectInputStream(inputStream);
            return in.readObject();

        } catch (ClassNotFoundException ex) {
            throw new JsonPathException(ex);
        } catch (IOException ex) {
            throw new JsonPathException(ex);
        } finally {
            try {
                if (in != null) {
                    in.close();
                }
            } catch (IOException ex) { // NOPMD
                // ignore close exception
            }
        }
    }

    /**
     * <p>Deserializes a single {@code Object} from an array of bytes.</p>
     *
     * @param objectData the serialized object, must not be null
     * @return the deserialized object
     * @throws IllegalArgumentException if {@code objectData} is {@code null}
     * @throws RuntimeException         (runtime) if the serialization fails
     */
    public static Object deserialize(byte[] objectData) {
        if (objectData == null) {
            throw new IllegalArgumentException("The byte[] must not be null");
        }
        ByteArrayInputStream bais = new ByteArrayInputStream(objectData);
        return deserialize(bais);
    }

    /**
     * <p>Custom specialization of the standard JDK {@link java.io.ObjectInputStream}
     * that uses a custom  <code>ClassLoader</code> to resolve a class.
     * If the specified <code>ClassLoader</code> is not able to resolve the class,
     * the context classloader of the current thread will be used.
     * This way, the standard deserialization work also in web-application
     * containers and application servers, no matter in which of the
     * <code>ClassLoader</code> the particular class that encapsulates
     * serialization/deserialization lives. </p>
     * <p/>
     * <p>For more in-depth information about the problem for which this
     * class here is a workaround, see the JIRA issue LANG-626. </p>
     */
    static class ClassLoaderAwareObjectInputStream extends ObjectInputStream {
        private ClassLoader classLoader;

        /**
         * Constructor.
         *
         * @param in          The <code>InputStream</code>.
         * @param classLoader classloader to use
         * @throws IOException if an I/O error occurs while reading stream header.
         * @see java.io.ObjectInputStream
         */
        public ClassLoaderAwareObjectInputStream(InputStream in, ClassLoader classLoader) throws IOException {
            super(in);
            this.classLoader = classLoader;
        }

        /**
         * Overriden version that uses the parametrized <code>ClassLoader</code> or the <code>ClassLoader</code>
         * of the current <code>Thread</code> to resolve the class.
         *
         * @param desc An instance of class <code>ObjectStreamClass</code>.
         * @return A <code>Class</code> object corresponding to <code>desc</code>.
         * @throws IOException            Any of the usual Input/Output exceptions.
         * @throws ClassNotFoundException If class of a serialized object cannot be found.
         */
        @Override
        protected Class<?> resolveClass(ObjectStreamClass desc) throws IOException, ClassNotFoundException {
            String name = desc.getName();
            try {
                return Class.forName(name, false, classLoader);
            } catch (ClassNotFoundException ex) {
                return Class.forName(name, false, Thread.currentThread().getContextClassLoader());
            }
        }

    }

    private Utils () {}
}