path: root/plugins/org.eclipse.tcf.core/src/org/eclipse/tcf/protocol/JSON.java

/*******************************************************************************
 * Copyright (c) 2007, 2013 Wind River Systems, Inc. and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     Wind River Systems - initial API and implementation
 *******************************************************************************/
package org.eclipse.tcf.protocol;

import java.io.IOException;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import org.eclipse.tcf.core.Base64;


/**
 * JSON is TCF preferred marshaling. This class implements generation and parsing of JSON strings.
 * The code is optimized for speed since it is a time-critical part of the framework.
 *
 * Reading of JSON produces data structure that consists of objects of these classes:
 * Boolean, Number, String, Collection, Map.
 *
 * Writing of JSON is supported for:
 * Boolean, Number, String, char[], byte[], Object[], Collection, Map
 *
 * Clients can enable writing support for objects of a other classes by
 * registering ObjectWriter interface implementation.
 *
 * @noinstantiate This class is not intended to be instantiated by clients.
 */
public final class JSON {

    /**
     * Clients implement ObjectWriter interface when they want to enable marshaling of
     * object classes that are not directly supported by JSON library.
     */
    public interface ObjectWriter<V> {
        void write(V o) throws IOException;
    }

    private static final Map<Class<?>,ObjectWriter<?>> object_writers =
        new HashMap<Class<?>,ObjectWriter<?>>();

    /** Wrapper class for binary byte blocs */
    public final static class Binary {
        public final byte[] bytes;
        public final int offs;
        public final int size;

        public Binary(byte[] bytes, int offs, int size) {
            this.bytes = bytes;
            this.offs = offs;
            this.size = size;
        }
    }

    private static char[] tmp_buf = new char[0x1000];
    private static byte[] tmp_bbf = new byte[0x1000];
    private static int tmp_buf_pos;
    private static boolean zero_copy;
    private static Binary[] bin_buf = new Binary[0x10];
    private static int bin_buf_pos;

    private static byte[] inp;
    private static int inp_pos;
    private static int cur_ch;

    // This buffer is used to create nice error reports
    private static final char[] err_buf = new char[100];
    private static int err_buf_pos;
    private static int err_buf_cnt;

    /**
     * Add a handler for converting objects of a particular class into JSON.
     * @param cls - a class
     * @param writer - ObjectWriter implementation that provides generation of JSON for a given class.
     */
    public static <X> void addObjectWriter(Class<X> cls, ObjectWriter<X> writer) {
        object_writers.put(cls, writer);
    }

    /**
     * Write a character into JSON output buffer.
     * Clients should not call this method directly, except from ObjectWriter implementation.
     * @param ch
     */
    public static void write(char ch) {
        if (tmp_buf_pos >= tmp_buf.length) {
            char[] tmp = new char[tmp_buf.length * 2];
            System.arraycopy(tmp_buf, 0, tmp, 0, tmp_buf_pos);
            tmp_buf = tmp;
        }
        tmp_buf[tmp_buf_pos++] = ch;
    }

    /**
     * Write a string into JSON output buffer.
     * The string is written "as-is". Call writeObject() to convert a String into JSON string.
     * Clients should not call this method directly, except from ObjectWriter implementation.
     * @param s - a string
     */
    public static void write(String s) {
        int l = s.length();
        for (int i = 0; i < l; i++) {
            char ch = s.charAt(i);
            if (tmp_buf_pos >= tmp_buf.length) write(ch);
            else tmp_buf[tmp_buf_pos++] = ch;
        }
    }

    /**
     * Write a non-negative integer number into JSON output buffer.
     * Clients should not call this method directly, except from ObjectWriter implementation.
     * @param n - a number
     */
    public static void writeUInt(int n) {
        assert n >= 0;
        if (n >= 10) writeUInt(n / 10);
        write((char)('0' + n % 10));
    }

    private static int readUTF8Char() {
        if (inp_pos >= inp.length) return -1;
        int ch = inp[inp_pos++];
        if (ch < 0) {
            int n = 0;
            if ((ch & 0xe0) == 0xc0) {
                ch &= 0x1f;
                n = 1;
            }
            else if ((ch & 0xf0) == 0xe0) {
                ch &= 0x0f;
                n = 2;
            }
            else if ((ch & 0xf8) == 0xf0) {
                ch &= 0x07;
                n = 3;
            }
            else if ((ch & 0xfc) == 0xf8) {
                ch &= 0x03;
                n = 4;
            }
            else if ((ch & 0xfe) == 0xfc) {
                ch &= 0x01;
                n = 5;
            }
            while (n > 0) {
                if (inp_pos >= inp.length || (inp[inp_pos] & 0xc0) != 0x80) break;
                ch = (ch << 6) | (inp[inp_pos++] & 0x3f);
                n--;
            }
            while (n > 0) {
                ch = ch << 6;
                n--;
            }
            if (ch < 0) ch = 0;
        }
        return ch;
    }

    private static void read() throws IOException {
        cur_ch = readUTF8Char();
        err_buf[err_buf_pos++] = (char)cur_ch;
        if (err_buf_pos >= err_buf.length) {
            err_buf_pos = 0;
            err_buf_cnt++;
        }
    }

    private static void skipWS() throws IOException {
        while (cur_ch <= ' ') {
            switch (cur_ch) {
            case '\r':
            case '\n':
            case '\t':
            case ' ':
                read();
                break;
            default:
                return;
            }
        }
    }

    private static void error() throws IOException {
        error("syntax error");
    }

    private static void error(String msg) throws IOException {
        StringBuffer bf = new StringBuffer();
        bf.append("JSON " + msg + ":");
        int cnt = 0;
        boolean nl = true;
        for (int i = 0;; i++) {
            char ch = 0;
            if (err_buf_cnt == 0 && i < err_buf_pos) {
                ch = err_buf[i];
            }
            else if (err_buf_cnt > 0 && i < err_buf.length) {
                ch = err_buf[(err_buf_pos + i) % err_buf.length];
            }
            else {
                int n = readUTF8Char();
                if (n < 0) break;
                ch = (char)n;
            }
            if (nl) {
                bf.append("\n ");
                if (err_buf_cnt == 0) bf.append(cnt);
                else bf.append('*');
                bf.append(": ");
                if (cnt == 0 && err_buf_cnt > 0) bf.append("...");
                nl = false;
            }
            if (ch == 0) {
                cnt++;
                nl = true;
                continue;
            }
            bf.append(ch);
        }
        throw new IOException(bf.toString());
    }

    private static int readHexDigit() throws IOException {
        int n = 0;
        if (cur_ch >= '0' && cur_ch <= '9') n = cur_ch - '0';
        else if (cur_ch >= 'A' && cur_ch <= 'F') n = cur_ch - 'A' + 10;
        else if (cur_ch >= 'a' && cur_ch <= 'f') n = cur_ch - 'a' + 10;
        else error();
        read();
        return n;
    }

    private static Object readFloat(boolean sign, BigInteger val) throws IOException {
        int scale = 0;
        int fraction = 0;
        if (cur_ch == '.') {
            read();
            while (cur_ch >= '0' && cur_ch <= '9') {
                val = val.multiply(BigInteger.valueOf(10));
                val = val.add(BigInteger.valueOf(cur_ch - '0'));
                fraction++;
                read();
            }
        }
        if (cur_ch == 'E' || cur_ch == 'e') {
            read();
            boolean neg = cur_ch == '-';
            if (neg || cur_ch == '+') read();
            while (cur_ch >= '0' && cur_ch <= '9') {
                scale = scale * 10 + cur_ch - '0';
                read();
            }
            if (neg) scale = -scale;
        }
        if (sign) val = val.negate();
        return new BigDecimal(val, fraction - scale);
    }

    private static Object readNestedObject() throws IOException {
        skipWS();
        switch (cur_ch) {
        case '(':
            read();
            int len = 0;
            while (cur_ch >= '0' && cur_ch <= '9') {
                len = len * 10 + (cur_ch - '0');
                read();
            }
            if (cur_ch != ')') error();
            byte[] res = new byte[len];
            System.arraycopy(inp, inp_pos, res, 0, len);
            inp_pos += len;
            read();
            return res;
        case '"':
            read();
            tmp_buf_pos = 0;
            for (;;) {
                if (cur_ch < 0) error();
                if (cur_ch == '"') break;
                if (cur_ch == '\\') {
                    read();
                    if (cur_ch < 0) error();
                    switch (cur_ch) {
                    case '"':
                    case '\\':
                    case '/':
                        break;
                    case 'b':
                        cur_ch = '\b';
                        break;
                    case 'f':
                        cur_ch = '\f';
                        break;
                    case 'n':
                        cur_ch = '\n';
                        break;
                    case 'r':
                        cur_ch = '\r';
                        break;
                    case 't':
                        cur_ch = '\t';
                        break;
                    case 'u':
                        read();
                        int n = 0;
                        n |= readHexDigit() << 12;
                        n |= readHexDigit() << 8;
                        n |= readHexDigit() << 4;
                        n |= readHexDigit();
                        write((char)n);
                        continue;
                    default:
                        error();
                        break;
                    }
                }
                if (tmp_buf_pos >= tmp_buf.length) {
                    write((char)cur_ch);
                }
                else {
                    tmp_buf[tmp_buf_pos++] = (char)cur_ch;
                }
                if (inp_pos >= inp.length || inp[inp_pos] < 0) {
                    cur_ch = readUTF8Char();
                }
                else {
                    cur_ch = inp[inp_pos++];
                }
                err_buf[err_buf_pos++] = (char)cur_ch;
                if (err_buf_pos >= err_buf.length) {
                    err_buf_pos = 0;
                    err_buf_cnt++;
                }
            }
            read();
            return new String(tmp_buf, 0, tmp_buf_pos);
        case '[':
            read();
            skipWS();
            List<Object> l = new ArrayList<Object>();
            if (cur_ch <= 0) error();
            if (cur_ch != ']') {
                for (;;) {
                    l.add(readNestedObject());
                    skipWS();
                    if (cur_ch == ']') break;
                    if (cur_ch != ',') error();
                    read();
                }
            }
            read();
            return Collections.unmodifiableList(l);
        case '{':
            read();
            skipWS();
            Map<String,Object> m = new HashMap<String,Object>();
            if (cur_ch <= 0) error();
            if (cur_ch != '}') {
                for (;;) {
                    String key = (String)readNestedObject();
                    skipWS();
                    if (cur_ch != ':') error();
                    read();
                    Object val = readNestedObject();
                    m.put(key, val);
                    skipWS();
                    if (cur_ch == '}') break;
                    if (cur_ch != ',') error();
                    read();
                }
            }
            read();
            return Collections.unmodifiableMap(m);
        case 'n':
            read();
            if (cur_ch != 'u') error();
            read();
            if (cur_ch != 'l') error();
            read();
            if (cur_ch != 'l') error();
            read();
            return null;
        case 'f':
            read();
            if (cur_ch != 'a') error();
            read();
            if (cur_ch != 'l') error();
            read();
            if (cur_ch != 's') error();
            read();
            if (cur_ch != 'e') error();
            read();
            return Boolean.FALSE;
        case 't':
            read();
            if (cur_ch != 'r') error();
            read();
            if (cur_ch != 'u') error();
            read();
            if (cur_ch != 'e') error();
            read();
            return Boolean.TRUE;
        case 'N':
            read();
            if (cur_ch != 'a') error();
            read();
            if (cur_ch != 'N') error();
            read();
            return Float.NaN;
        default:
            boolean neg = cur_ch == '-';
            if (neg) read();
            if (cur_ch >= '0' && cur_ch <= '9') {
                int v = 0;
                while (v <= 0x7fffffff / 10 - 1) {
                    v = v * 10 + (cur_ch - '0');
                    read();
                    if (cur_ch < '0' || cur_ch > '9') {
                        if (cur_ch == '.' || cur_ch == 'E' || cur_ch == 'e') {
                            return readFloat(neg, BigInteger.valueOf(v));
                        }
                        if (neg) v = -v;
                        return Integer.valueOf(v);
                    }
                }
                long vl = v;
                while (vl < 0x7fffffffffffffffl / 10 - 1) {
                    vl = vl * 10 + (cur_ch - '0');
                    read();
                    if (cur_ch < '0' || cur_ch > '9') {
                        if (cur_ch == '.' || cur_ch == 'E' || cur_ch == 'e') {
                            return readFloat(neg, BigInteger.valueOf(vl));
                        }
                        if (neg) vl = -vl;
                        return Long.valueOf(vl);
                    }
                }
                StringBuffer sb = new StringBuffer();
                sb.append(vl);
                while (true) {
                    sb.append((char)cur_ch);
                    read();
                    if (cur_ch < '0' || cur_ch > '9') {
                        BigInteger n = new BigInteger(sb.toString());
                        if (cur_ch == '.' || cur_ch == 'E' || cur_ch == 'e') {
                            return readFloat(neg, n);
                        }
                        if (neg) n = n.negate();
                        return n;
                    }
                }
            }
            error();
            return null;
        }
    }

    /**
     * Write an object into JSON output buffer.
     * Clients should not call this method directly, except from ObjectWriter implementation.
     * @param o - an object to write
     */
    @SuppressWarnings({ "rawtypes", "unchecked" })
    public static void writeObject(Object o) throws IOException {
        if (o == null) {
            write("null");
        }
        else if (o instanceof Boolean) {
            write(o.toString());
        }
        else if (o instanceof Number) {
            write(o.toString());
        }
        else if (o instanceof String) {
            String s = (String)o;
            char[] arr = new char[s.length()];
            s.getChars(0, arr.length, arr, 0);
            writeObject(arr);
        }
        else if (o instanceof char[]) {
            char[] s = (char[])o;
            write('"');
            int l = s.length;
            for (int i = 0; i < l; i++) {
                char ch = s[i];
                switch (ch) {
                case 0:
                    write("\\u0000");
                    break;
                case 1:
                    write("\\u0001");
                    break;
                case '\r':
                    write("\\r");
                    break;
                case '\n':
                    write("\\n");
                    break;
                case '\t':
                    write("\\t");
                    break;
                case '\b':
                    write("\\b");
                    break;
                case '\f':
                    write("\\f");
                    break;
                case '"':
                case '\\':
                    write('\\');
                default:
                    if (tmp_buf_pos >= tmp_buf.length) write(ch);
                    else tmp_buf[tmp_buf_pos++] = ch;
                }
            }
            write('"');
        }
        else if (o instanceof Binary) {
            Binary b = (Binary)o;
            if (zero_copy) {
                write('(');
                write(Integer.toString(b.size));
                write(')');
                write((char)1);
                bin_buf[bin_buf_pos++] = b;
            }
            else {
                writeObject(Base64.toBase64(b.bytes, b.offs, b.size));
            }
        }
        else if (o instanceof byte[]) {
            write('[');
            byte[] arr = (byte[])o;
            boolean comma = false;
            for (int i = 0; i < arr.length; i++) {
                if (comma) write(',');
                writeUInt(arr[i] & 0xff);
                comma = true;
            }
            write(']');
        }
        else if (o instanceof Object[]) {
            write('[');
            Object[] arr = (Object[])o;
            boolean comma = false;
            for (int i = 0; i < arr.length; i++) {
                if (comma) write(',');
                writeObject(arr[i]);
                comma = true;
            }
            write(']');
        }
        else if (o instanceof Collection) {
            write('[');
            boolean comma = false;
            for (Iterator<Object> i = ((Collection<Object>)o).iterator(); i.hasNext();) {
                if (comma) write(',');
                writeObject(i.next());
                comma = true;
            }
            write(']');
        }
        else if (o instanceof Map) {
            Map<String,Object> map = (Map<String,Object>)o;
            write('{');
            boolean comma = false;
            for (Iterator<Map.Entry<String,Object>> i = map.entrySet().iterator(); i.hasNext();) {
                if (comma) write(',');
                Map.Entry<String,Object> e = i.next();
                writeObject(e.getKey());
                write(':');
                writeObject(e.getValue());
                comma = true;
            }
            write('}');
        }
        else {
            ObjectWriter writer = object_writers.get(o.getClass());
            if (writer == null) {
                for (Class<?> c : object_writers.keySet()) {
                    if (c.isInstance(o)) {
                        writer = object_writers.get(c);
                        break;
                    }
                }
            }
            if (writer != null) {
                writer.write(o);
            }
            else {
                throw new IOException("JSON: unsupported object type:" + o.getClass());
            }
        }
    }

    private static byte[] toBytes() {
        int inp_pos = 0;
        int out_pos = 0;
        int blc_pos = 0;
        while (inp_pos < tmp_buf_pos) {
            if (out_pos > tmp_bbf.length - 4) {
                byte[] tmp = new byte[tmp_bbf.length * 2];
                System.arraycopy(tmp_bbf, 0, tmp, 0, out_pos);
                tmp_bbf = tmp;
            }
            int ch = tmp_buf[inp_pos++];
            if (ch == 1) {
                Binary b = bin_buf[blc_pos++];
                while (out_pos > tmp_bbf.length - b.size) {
                    byte[] tmp = new byte[tmp_bbf.length * 2];
                    System.arraycopy(tmp_bbf, 0, tmp, 0, out_pos);
                    tmp_bbf = tmp;
                }
                System.arraycopy(b.bytes, b.offs, tmp_bbf, out_pos, b.size);
                out_pos += b.size;
            }
            else if (ch < 0x80) {
                tmp_bbf[out_pos++] = (byte)ch;
            }
            else if (ch < 0x800) {
                tmp_bbf[out_pos++] = (byte)((ch >> 6) | 0xc0);
                tmp_bbf[out_pos++] = (byte)(ch & 0x3f | 0x80);
            }
            else if (ch < 0x10000) {
                tmp_bbf[out_pos++] = (byte)((ch >> 12) | 0xe0);
                tmp_bbf[out_pos++] = (byte)((ch >> 6) & 0x3f | 0x80);
                tmp_bbf[out_pos++] = (byte)(ch & 0x3f | 0x80);
            }
            else {
                tmp_bbf[out_pos++] = (byte)((ch >> 18) | 0xf0);
                tmp_bbf[out_pos++] = (byte)((ch >> 12) & 0x3f | 0x80);
                tmp_bbf[out_pos++] = (byte)((ch >> 6) & 0x3f | 0x80);
                tmp_bbf[out_pos++] = (byte)(ch & 0x3f | 0x80);
            }
        }
        byte[] res = new byte[out_pos];
        System.arraycopy(tmp_bbf, 0, res, 0, out_pos);
        return res;
    }

    /**
     * Convert Java object to JSON string.
     * @param o - a Java object
     * @return JASON string
     * @throws IOException
     */
    public static String toJSON(Object o) throws IOException {
        assert Protocol.isDispatchThread();
        tmp_buf_pos = 0;
        bin_buf_pos = 0;
        zero_copy = false;
        writeObject(o);
        return new String(tmp_buf, 0, tmp_buf_pos);
    }

    /**
     * Convert Java object to array of bytes that contains UTF-8 encoded JSON string.
     * @param o - a Java object
     * @return array of bytes
     * @throws IOException
     */
    public static byte[] toJASONBytes(Object o) throws IOException {
        assert Protocol.isDispatchThread();
        tmp_buf_pos = 0;
        bin_buf_pos = 0;
        zero_copy = false;
        writeObject(o);
        return toBytes();
    }

    /**
     * Convert multiple Java object to array of bytes that contains
     * a sequence of zero terminate UTF-8 encoded JSON strings.
     * @param o - array of Java objects
     * @return array of bytes
     * @throws IOException
     */
    public static byte[] toJSONSequence(Object[] o) throws IOException {
        assert Protocol.isDispatchThread();
        if (o == null || o.length == 0) return null;
        tmp_buf_pos = 0;
        bin_buf_pos = 0;
        zero_copy = false;
        for (int i = 0; i < o.length; i++) {
            writeObject(o[i]);
            write((char)0);
        }
        return toBytes();
    }

    /**
     * Convert multiple Java object to array of bytes that contains
     * a sequence of zero terminate UTF-8 encoded JSON strings.
     * @param o - array of Java objects
     * @param zero_copy - true to enable "zero copy" JSON extension.
     * "zero copy" extension allows insertion of binary data arrays into JSON string.
     * The extension allows more efficient transfer of large binary blocs.
     * @return array of bytes
     * @throws IOException
     */
    public static byte[] toJSONSequence(Object[] o, boolean zero_copy) throws IOException {
        assert Protocol.isDispatchThread();
        if (o == null || o.length == 0) return null;
        tmp_buf_pos = 0;
        bin_buf_pos = 0;
        JSON.zero_copy = zero_copy;
        for (int i = 0; i < o.length; i++) {
            writeObject(o[i]);
            write((char)0);
        }
        return toBytes();
    }

    /**
     * Convert byte array that contains UTF-8 encoded JSON string to Java object.
     * @param b - array of bytes with UTF-8 encoded JSON string
     * @return Java object that represents data in the JSON string
     * @throws IOException
     */
    public static Object parseOne(byte[] b) throws IOException {
        assert Protocol.isDispatchThread();
        if (b.length == 0) return null;
        inp = b;
        inp_pos = 0;
        err_buf_pos = 0;
        err_buf_cnt = 0;
        read();
        Object o = readNestedObject();
        if (cur_ch >= 0) error();
        return o;
    }

    /**
     * Convert byte array that contains sequence of zero terminated UTF-8 encoded JSON string
     * to array of Java objects.
     * @param b - array of bytes with sequence of zero terminated UTF-8 encoded JSON string
     * @return array of Java objects that represents data in the sequence of JSON strings
     * @throws IOException
     */
    public static Object[] parseSequence(byte[] b) throws IOException {
        assert Protocol.isDispatchThread();
        inp = b;
        inp_pos = 0;
        err_buf_pos = 0;
        err_buf_cnt = 0;
        read();
        List<Object> l = new ArrayList<Object>();
        while (cur_ch >= 0) {
            if (cur_ch == 0) l.add(null);
            else l.add(readNestedObject());
            if (cur_ch != 0) error("missing \\0 terminator");
            read();
        }
        return l.toArray();
    }

    /**
     * Converts a Java object to array of bytes.
     * The object is expected to be created from a JSON string by using one of methods in this class.
     * If the object is not one of supported representations of binary data, the method throws Error.
     * @param o - a Java object representing JSON binary data
     * @return array of bytes
     */
    public static byte[] toByteArray(Object o) {
        if (o == null) return null;
        if (o instanceof byte[]) return (byte[])o;
        if (o instanceof char[]) return Base64.toByteArray((char[])o);
        if (o instanceof String) return Base64.toByteArray(((String)o).toCharArray());
        throw new Error();
    }

    /**
     * Converts a Java object to bytes in a given array of bytes.
     * The object is expected to be created from a JSON string by using one of methods in this class.
     * If the object is not one of supported representations of binary data, the method throws Error.
     * @param buf - destination array of bytes
     * @param offs - starting position in the destination array
     * @param size - the number of bytes to be copied into the destination array
     * @param o - a Java object representing JSON binary data
     */
    public static void toByteArray(byte[] buf, int offs, int size, Object o) {
        if (o instanceof char[]) Base64.toByteArray(buf, offs, size, (char[])o);
        else if (o instanceof String) Base64.toByteArray(buf, offs, size, ((String)o).toCharArray());
        else if (o != null) System.arraycopy(toByteArray(o), 0, buf, offs, size);
    }

    /**
     * Converts a JSON number to BigInteger.
     * @param n - a Number.
     * @return BigInteger.
     */
    public static BigInteger toBigInteger(Number n) {
        if (n == null) return null;
        if (n instanceof BigInteger) return (BigInteger)n;
        return BigInteger.valueOf(n.longValue());
    }
}