/*
* Copyright 2010 JBoss, a divison Red Hat, Inc.
*
* 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 org.jboss.errai.bus.server.io;
import org.jboss.errai.common.client.types.DecodingContext;
import org.jboss.errai.common.client.types.UHashMap;
import org.jboss.errai.common.client.types.UnsatisfiedForwardLookup;
import org.mvel2.CompileException;
import org.mvel2.util.StringAppender;
import java.io.*;
import java.nio.CharBuffer;
import java.util.*;
import static org.jboss.errai.bus.server.io.TypeDemarshallHelper.demarshallAll;
import static org.jboss.errai.common.client.protocols.SerializationParts.ENCODED_TYPE;
/**
* High-performance stream JSON parser. Provides the decoding algorithm to interpret the Errai Wire Protcol,
* including serializable types. This parser always assumes the outer payload is a Map. So it probably shouldn't
* be used as a general parser.
*
* @author Mike Brock
* @since 1.1
*/
public class JSONStreamDecoder {
private CharBuffer buffer;
private BufferedReader reader;
private char carry;
private int read;
private boolean initial = true;
private DecodingContext decodingContext = new DecodingContext();
public JSONStreamDecoder(InputStream inStream) {
this.buffer = CharBuffer.allocate(25);
try {
this.reader = new BufferedReader(
new InputStreamReader(inStream, "UTF-8")
);
} catch (UnsupportedEncodingException e) {
throw new Error("UTF-8 is not supported by this JVM?", e);
}
}
public static Object decode(InputStream instream) throws IOException {
return new JSONStreamDecoder(instream).parse();
}
public char read() throws IOException {
if (carry != 0) {
char c = carry;
carry = 0;
return c;
}
if (read <= 0) {
if (!initial) buffer.rewind();
initial = false;
if ((read = reader.read(buffer)) <= 0) {
return 0;
}
buffer.rewind();
}
read--;
return buffer.get();
}
public Object parse() {
try {
Context ctx = new Context();
Object v = _parse(ctx, null, false);
if (decodingContext.isUnsatisfiedDependencies()) {
TypeDemarshallHelper.resolveDependencies(decodingContext);
}
return v;
}
catch (Exception e) {
throw new RuntimeException(e);
}
}
private Object _parse(Context ctx, Object collection, boolean map) throws IOException {
char c;
StringAppender appender;
while ((c = read()) != 0) {
switch (c) {
case '[':
ctx.addValue(_parse(new Context(), new ArrayList(), false));
break;
case '{':
ctx.addValue(_parse(new Context(), new UHashMap(), true));
break;
case ']':
case '}':
if (map && ctx.encodedType) {
ctx.encodedType = false;
try {
return demarshallAll(ctx.record(collection, decodingContext), decodingContext);
}
catch (Exception e) {
throw new RuntimeException("Could not demarshall object", e);
}
} else {
return ctx.record(collection, decodingContext);
}
case ',':
ctx.record(collection, decodingContext);
break;
case '"':
case '\'':
char term = c;
appender = new StringAppender();
StrCapture:
while ((c = read()) != 0) {
switch (c) {
case '\\':
appender.append(handleEscapeSequence());
break;
case '"':
case '\'':
if (c == term) {
ctx.addValue(appender.toString());
term = 0;
break StrCapture;
}
break;
default:
appender.append(c);
}
}
if (term != 0) {
throw new RuntimeException("unterminated string literal");
}
break;
case ':':
continue;
default:
if (isValidNumberPart(c)) {
ctx.addValue(parseNumber(c));
break;
} else if (Character.isJavaIdentifierPart(c)) {
appender = new StringAppender().append(c);
while (((c = read()) != 0) && Character.isJavaIdentifierPart(c)) {
appender.append(c);
}
String s = appender.toString();
if (s.length() > 4) ctx.addValue(s);
else if ("null".equals(s)) {
ctx.addValue(null);
} else if ("true".equals(s)) {
ctx.addValue(Boolean.TRUE);
} else if ("false".equals(s)) {
ctx.addValue(Boolean.FALSE);
} else {
ctx.addValue(s);
}
if (c != 0) carry = c;
}
}
}
return ctx.record(collection, decodingContext);
}
public char handleEscapeSequence() throws IOException {
char c;
switch (c = read()) {
case '\\':
return '\\';
case 'b':
return '\b';
case 'f':
return '\f';
case 't':
return '\t';
case 'r':
return '\r';
case 'n':
return '\n';
case '\'':
return '\'';
case '"':
return '\"';
default:
throw new CompileException("illegal escape sequence: " + c);
}
}
public Number parseNumber(char c) throws IOException {
long val = 0;
double dVal = 0;
double factor = 1;
boolean dbl = false;
char[] buf = new char[21];
int len = 0;
do {
buf[len++] = c;
} while ((c = read()) != 0 && isValidNumberPart(c));
if (c != 0) {
carry = c;
}
if (len == 1 && buf[0] == '-') return null;
for (int i = len - 1; i != -1; i--) {
switch (buf[i]) {
case '.':
dVal = ((double) val) / factor;
val = 0;
factor = 1;
dbl = true;
continue;
case '-':
if (i != 0) {
throw new NumberFormatException(new String(buf));
}
val = -val;
break;
case '1':
val += factor;
break;
case '2':
val += 2 * factor;
break;
case '3':
val += 3 * factor;
break;
case '4':
val += 4 * factor;
break;
case '5':
val += 5 * factor;
break;
case '6':
val += 6 * factor;
break;
case '7':
val += 7 * factor;
break;
case '8':
val += 8 * factor;
break;
case '9':
val += 9 * factor;
break;
}
factor *= 10;
}
if (dbl) {
return dVal + val;
} else {
return val;
}
}
private static boolean isValidNumberPart(char c) {
switch (c) {
case '.':
case '-':
case '0':
case '1':
case '2':
case '3':
case '4':
case '5':
case '6':
case '7':
case '8':
case '9':
return true;
default:
return false;
}
}
private static class Context {
Object lhs;
Object rhs;
boolean encodedType = false;
private Context() {
}
private Object addValue(Object val) {
if (lhs == null) {
return lhs = val;
} else {
return rhs = val;
}
}
private Object getValue() {
if (rhs != null) {
return rhs;
} else {
return lhs;
}
}
private void removeValue() {
if (rhs != null) {
rhs = null;
} else {
lhs = null;
}
}
private Object record(Object collection, DecodingContext ctx) {
try {
if (lhs != null) {
if (collection instanceof Map) {
if (!encodedType) encodedType = ENCODED_TYPE.equals(lhs);
boolean rec = true;
if (lhs instanceof UnsatisfiedForwardLookup) {
ctx.addUnsatisfiedDependency(collection, (UnsatisfiedForwardLookup) lhs);
if (!(rhs instanceof UnsatisfiedForwardLookup)) {
((UnsatisfiedForwardLookup) lhs).setVal(rhs);
((UnsatisfiedForwardLookup) lhs).setPath("{}");
}
rec = false;
}
if (rhs instanceof UnsatisfiedForwardLookup) {
ctx.addUnsatisfiedDependency(collection, (UnsatisfiedForwardLookup) rhs);
((UnsatisfiedForwardLookup) rhs).setKey(lhs);
((UnsatisfiedForwardLookup) rhs).setPath(String.valueOf(lhs));
rec = false;
}
//noinspection unchecked
if (rec)
((Map) collection).put(lhs, rhs);
} else {
if (collection == null) return lhs;
if (lhs instanceof UnsatisfiedForwardLookup) {
ctx.addUnsatisfiedDependency(collection, (UnsatisfiedForwardLookup) lhs);
} else {
//noinspection unchecked
((Collection) collection).add(lhs);
}
}
}
return collection;
}
catch (ClassCastException e) {
throw new RuntimeException("error building collection", e);
}
finally {
lhs = rhs = null;
}
}
}
}