XMLTokener.java

package org.json;

/*
Copyright (c) 2002 JSON.org

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 shall be used for Good, not Evil.

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.
*/

import java.io.Reader;

/**
 * The XMLTokener extends the JSONTokener to provide additional methods
 * for the parsing of XML texts.
 * @author JSON.org
 * @version 2015-12-09
 */
public class XMLTokener extends JSONTokener {


   /** The table of entity values. It initially contains Character values for
    * amp, apos, gt, lt, quot.
    */
   public static final java.util.HashMap<String, Character> entity;

   static {
       entity = new java.util.HashMap<String, Character>(8);
       entity.put("amp",  XML.AMP);
       entity.put("apos", XML.APOS);
       entity.put("gt",   XML.GT);
       entity.put("lt",   XML.LT);
       entity.put("quot", XML.QUOT);
   }

    /**
     * Construct an XMLTokener from a Reader.
     * @param r A source reader.
     */
    public XMLTokener(Reader r) {
        super(r);
    }

    /**
     * Construct an XMLTokener from a string.
     * @param s A source string.
     */
    public XMLTokener(String s) {
        super(s);
    }

    /**
     * Get the text in the CDATA block.
     * @return The string up to the <code>]]&gt;</code>.
     * @throws JSONException If the <code>]]&gt;</code> is not found.
     */
    public String nextCDATA() throws JSONException {
        char         c;
        int          i;
        StringBuilder sb = new StringBuilder();
        while (more()) {
            c = next();
            sb.append(c);
            i = sb.length() - 3;
            if (i >= 0 && sb.charAt(i) == ']' &&
                          sb.charAt(i + 1) == ']' && sb.charAt(i + 2) == '>') {
                sb.setLength(i);
                return sb.toString();
            }
        }
        throw syntaxError("Unclosed CDATA");
    }


    /**
     * Get the next XML outer token, trimming whitespace. There are two kinds
     * of tokens: the '<' character which begins a markup tag, and the content
     * text between markup tags.
     *
     * @return  A string, or a '<' Character, or null if there is no more
     * source text.
     * @throws JSONException
     */
    public Object nextContent() throws JSONException {
        char         c;
        StringBuilder sb;
        do {
            c = next();
        } while (Character.isWhitespace(c));
        if (c == 0) {
            return null;
        }
        if (c == '<') {
            return XML.LT;
        }
        sb = new StringBuilder();
        for (;;) {
            if (c == 0) {
                return sb.toString().trim();
            }
            if (c == '<') {
                back();
                return sb.toString().trim();
            }
            if (c == '&') {
                sb.append(nextEntity(c));
            } else {
                sb.append(c);
            }
            c = next();
        }
    }


    /**
     * Return the next entity. These entities are translated to Characters:
     *     <code>&amp;  &apos;  &gt;  &lt;  &quot;</code>.
     * @param ampersand An ampersand character.
     * @return  A Character or an entity String if the entity is not recognized.
     * @throws JSONException If missing ';' in XML entity.
     */
    public Object nextEntity(@SuppressWarnings("unused") char ampersand) throws JSONException {
        StringBuilder sb = new StringBuilder();
        for (;;) {
            char c = next();
            if (Character.isLetterOrDigit(c) || c == '#') {
                sb.append(Character.toLowerCase(c));
            } else if (c == ';') {
                break;
            } else {
                throw syntaxError("Missing ';' in XML entity: &" + sb);
            }
        }
        String string = sb.toString();
        return unescapeEntity(string);
    }
    
    /**
     * Unescapes an XML entity encoding;
     * @param e entity (only the actual entity value, not the preceding & or ending ;
     * @return
     */
    static String unescapeEntity(String e) {
        // validate
        if (e == null || e.isEmpty()) {
            return "";
        }
        // if our entity is an encoded unicode point, parse it.
        if (e.charAt(0) == '#') {
            int cp;
            if (e.charAt(1) == 'x') {
                // hex encoded unicode
                cp = Integer.parseInt(e.substring(2), 16);
            } else {
                // decimal encoded unicode
                cp = Integer.parseInt(e.substring(1));
            }
            return new String(new int[] {cp},0,1);
        } 
        Character knownEntity = entity.get(e);
        if(knownEntity==null) {
            // we don't know the entity so keep it encoded
            return '&' + e + ';';
        }
        return knownEntity.toString();
    }


    /**
     * Returns the next XML meta token. This is used for skipping over <!...>
     * and <?...?> structures.
     * @return Syntax characters (<code>< > / = ! ?</code>) are returned as
     *  Character, and strings and names are returned as Boolean. We don't care
     *  what the values actually are.
     * @throws JSONException If a string is not properly closed or if the XML
     *  is badly structured.
     */
    public Object nextMeta() throws JSONException {
        char c;
        char q;
        do {
            c = next();
        } while (Character.isWhitespace(c));
        switch (c) {
        case 0:
            throw syntaxError("Misshaped meta tag");
        case '<':
            return XML.LT;
        case '>':
            return XML.GT;
        case '/':
            return XML.SLASH;
        case '=':
            return XML.EQ;
        case '!':
            return XML.BANG;
        case '?':
            return XML.QUEST;
        case '"':
        case '\'':
            q = c;
            for (;;) {
                c = next();
                if (c == 0) {
                    throw syntaxError("Unterminated string");
                }
                if (c == q) {
                    return Boolean.TRUE;
                }
            }
        default:
            for (;;) {
                c = next();
                if (Character.isWhitespace(c)) {
                    return Boolean.TRUE;
                }
                switch (c) {
                case 0:
                case '<':
                case '>':
                case '/':
                case '=':
                case '!':
                case '?':
                case '"':
                case '\'':
                    back();
                    return Boolean.TRUE;
                }
            }
        }
    }


    /**
     * Get the next XML Token. These tokens are found inside of angle
     * brackets. It may be one of these characters: <code>/ > = ! ?</code> or it
     * may be a string wrapped in single quotes or double quotes, or it may be a
     * name.
     * @return a String or a Character.
     * @throws JSONException If the XML is not well formed.
     */
    public Object nextToken() throws JSONException {
        char c;
        char q;
        StringBuilder sb;
        do {
            c = next();
        } while (Character.isWhitespace(c));
        switch (c) {
        case 0:
            throw syntaxError("Misshaped element");
        case '<':
            throw syntaxError("Misplaced '<'");
        case '>':
            return XML.GT;
        case '/':
            return XML.SLASH;
        case '=':
            return XML.EQ;
        case '!':
            return XML.BANG;
        case '?':
            return XML.QUEST;

// Quoted string

        case '"':
        case '\'':
            q = c;
            sb = new StringBuilder();
            for (;;) {
                c = next();
                if (c == 0) {
                    throw syntaxError("Unterminated string");
                }
                if (c == q) {
                    return sb.toString();
                }
                if (c == '&') {
                    sb.append(nextEntity(c));
                } else {
                    sb.append(c);
                }
            }
        default:

// Name

            sb = new StringBuilder();
            for (;;) {
                sb.append(c);
                c = next();
                if (Character.isWhitespace(c)) {
                    return sb.toString();
                }
                switch (c) {
                case 0:
                    return sb.toString();
                case '>':
                case '/':
                case '=':
                case '!':
                case '?':
                case '[':
                case ']':
                    back();
                    return sb.toString();
                case '<':
                case '"':
                case '\'':
                    throw syntaxError("Bad character in a name");
                }
            }
        }
    }


    /**
     * Skip characters until past the requested string.
     * If it is not found, we are left at the end of the source with a result of false.
     * @param to A string to skip past.
     */
    // The Android implementation of JSONTokener has a public method of public void skipPast(String to)
    // even though ours does not have that method, to have API compatibility, our method in the subclass
    // should match.
    public void skipPast(String to) {
        boolean b;
        char c;
        int i;
        int j;
        int offset = 0;
        int length = to.length();
        char[] circle = new char[length];

        /*
         * First fill the circle buffer with as many characters as are in the
         * to string. If we reach an early end, bail.
         */

        for (i = 0; i < length; i += 1) {
            c = next();
            if (c == 0) {
                return;
            }
            circle[i] = c;
        }

        /* We will loop, possibly for all of the remaining characters. */

        for (;;) {
            j = offset;
            b = true;

            /* Compare the circle buffer with the to string. */

            for (i = 0; i < length; i += 1) {
                if (circle[j] != to.charAt(i)) {
                    b = false;
                    break;
                }
                j += 1;
                if (j >= length) {
                    j -= length;
                }
            }

            /* If we exit the loop with b intact, then victory is ours. */

            if (b) {
                return;
            }

            /* Get the next character. If there isn't one, then defeat is ours. */

            c = next();
            if (c == 0) {
                return;
            }
            /*
             * Shove the character in the circle buffer and advance the
             * circle offset. The offset is mod n.
             */
            circle[offset] = c;
            offset += 1;
            if (offset >= length) {
                offset -= length;
            }
        }
    }
}