com.ninja_squad.core.jsp.JspFunctions.java Source code

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Here is the source code for com.ninja_squad.core.jsp.JspFunctions.java

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/*
 * The MIT License
 *
 * Copyright (c) 2012, Ninja Squad
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

package com.ninja_squad.core.jsp;

import java.io.IOException;
import java.io.StringReader;
import java.util.List;

import javax.annotation.Nullable;

import com.google.common.base.Function;
import com.google.common.base.Joiner;
import com.google.common.collect.Iterables;
import com.google.common.io.CharStreams;
import com.ninja_squad.core.exception.ShouldNeverHappenException;

/**
 * Functions of the ninja core tag library
 * @author JB Nizet
 */
public final class JspFunctions {

    private static final int ESTIMATED_ADDITIONAL_CHARS = 20;
    private static final Function<String, String> ESCAPE_XML = new EscapeXmlFunction();

    private JspFunctions() {
    }

    /**
     * Transforms all the newlines into <code>&lt;br/&gt;</code>, in order for multi-line text
     * to be displayed into an HTML page. Each line of text is also XML-escaped. <br/>
     * If a null string is passed as argument, an empty string is returned.
     * @param input the string to transform
     * @return the transformed string.
     */
    public static String nlToBr(@Nullable String input) {
        if (input == null) {
            return "";
        }

        try {
            List<String> lines = CharStreams.readLines(new StringReader(input));
            return Joiner.on("<br/>").join(Iterables.transform(lines, ESCAPE_XML));
        } catch (IOException e) {
            throw new ShouldNeverHappenException(e);
        }
    }

    /**
     * Escapes all the characters that must be escaped in a JavaScript String literal (i.e.
     * a tab character is transformed into <code>\t</code>, an apostrophe is transformed
     * into <code>\'</code>, etc.<br/>
     * If a null string is passed as argument, an empty string is returned.
     * @param input the string to escape
     * @return the escaped string.
     */
    public static String escapeJs(@Nullable String input) {
        if (input == null) {
            return "";
        }

        StringBuilder out = new StringBuilder(input.length() + ESTIMATED_ADDITIONAL_CHARS);
        for (int i = 0; i < input.length(); i++) {
            char c = input.charAt(i);
            switch (c) {
            case '\b':
                out.append("\\b");
                break;
            case '\n':
                out.append("\\n");
                break;
            case '\f':
                out.append("\\f");
                break;
            case '\r':
                out.append("\\r");
                break;
            case '\t':
                out.append("\\t");
                break;
            case '\'':
                out.append("\\'");
                break;
            case '"':
                out.append("\\\"");
                break;
            case '\\':
                out.append("\\\\");
                break;
            default:
                out.append(c);
                break;
            }
        }
        return out.toString();
    }

    /**
     * Upper-cases the first letter of the given string. This can be useful when dates, for example,
     * must be displayed as (in French) "Lundi 12 mars" instead of the default "lundi 12 mars".<br/>
     * If a null string is passed as argument, an empty string is returned.
     * @param input the string to transform
     * @return the transformed string
     */
    public static String upperFirst(String input) {
        if (input == null || input.isEmpty()) {
            return "";
        }
        return Character.toUpperCase(input.charAt(0)) + input.substring(1);
    }

    /**
     * The function used to escape XML special chars
     * @author JB Nizet
     */
    private static final class EscapeXmlFunction implements Function<String, String> {
        @Override
        public String apply(String input) {
            if (input == null) {
                return "";
            }
            StringBuilder out = new StringBuilder(input.length() + ESTIMATED_ADDITIONAL_CHARS);
            for (int i = 0; i < input.length(); i++) {
                char c = input.charAt(i);
                if (c <= '>') { // optimization
                    switch (c) {
                    case '<':
                        out.append("&lt;");
                        break;
                    case '>':
                        out.append("&gt;");
                        break;
                    case '&':
                        out.append("&amp;");
                        break;
                    case '"':
                        out.append("&#034;");
                        break;
                    case '\'':
                        out.append("&#039;");
                        break;
                    default:
                        out.append(c);
                        break;
                    }
                } else {
                    out.append(c);
                }
            }
            return out.toString();
        }
    }
}