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/*
* Copyright 2016-2017 UnboundID Corp.
* All Rights Reserved.
*/
/*
* Copyright (C) 2016-2017 UnboundID Corp.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License (GPLv2 only)
* or the terms of the GNU Lesser General Public License (LGPLv2.1 only)
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see .
*/
package com.unboundid.util.json;
import java.io.BufferedInputStream;
import java.io.Closeable;
import java.io.InputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.LinkedHashMap;
import java.util.Map;
import com.unboundid.util.ByteStringBuffer;
import com.unboundid.util.Debug;
import com.unboundid.util.StaticUtils;
import com.unboundid.util.ThreadSafety;
import com.unboundid.util.ThreadSafetyLevel;
import static com.unboundid.util.json.JSONMessages.*;
/**
* This class provides a mechanism for reading JSON objects from an input
* stream. It assumes that any non-ASCII data that may be read from the input
* stream is encoded as UTF-8.
*/
@ThreadSafety(level=ThreadSafetyLevel.NOT_THREADSAFE)
public final class JSONObjectReader
implements Closeable
{
// The buffer used to hold the bytes of the object currently being read.
private final ByteStringBuffer currentObjectBytes;
// A buffer to use to hold strings being decoded.
private final ByteStringBuffer stringBuffer;
// The input stream from which JSON objects will be read.
private final InputStream inputStream;
/**
* Creates a new JSON object reader that will read objects from the provided
* input stream.
*
* @param inputStream The input stream from which the data should be read.
*/
public JSONObjectReader(final InputStream inputStream)
{
this.inputStream = new BufferedInputStream(inputStream);
currentObjectBytes = new ByteStringBuffer();
stringBuffer = new ByteStringBuffer();
}
/**
* Reads the next JSON object from the input stream.
*
* @return The JSON object that was read, or {@code null} if the end of the
* end of the stream has been reached..
*
* @throws IOException If a problem is encountered while reading from the
* input stream.
*
* @throws JSONException If the data read
*/
public JSONObject readObject()
throws IOException, JSONException
{
// Skip over any whitespace before the beginning of the next object.
skipWhitespace();
currentObjectBytes.clear();
// The JSON object must start with an open curly brace.
final Object firstToken = readToken(true);
if (firstToken == null)
{
return null;
}
if (! firstToken.equals('{'))
{
throw new JSONException(ERR_OBJECT_READER_ILLEGAL_START_OF_OBJECT.get(
String.valueOf(firstToken)));
}
final LinkedHashMap m =
new LinkedHashMap(10);
readObject(m);
return new JSONObject(m, currentObjectBytes.toString());
}
/**
* Closes this JSON object reader and the underlying input stream.
*
* @throws IOException If a problem is encountered while closing the
* underlying input stream.
*/
public void close()
throws IOException
{
inputStream.close();
}
/**
* Reads a token from the input stream, skipping over any insignificant
* whitespace that may be before the token. The token that is returned will
* be one of the following:
*
*
A {@code Character} that is an opening curly brace.
*
A {@code Character} that is a closing curly brace.
*
A {@code Character} that is an opening square bracket.
*
A {@code Character} that is a closing square bracket.
*
A {@code Character} that is a colon.
*
A {@code Character} that is a comma.
*
A {@link JSONBoolean}.
*
A {@link JSONNull}.
*
A {@link JSONNumber}.
*
A {@link JSONString}.
*
*
* @param allowEndOfStream Indicates whether it is acceptable to encounter
* the end of the input stream. This should only
* be {@code true} when the token is expected to be
* the open parenthesis of the outermost JSON
* object.
*
* @return The token that was read, or {@code null} if the end of the input
* stream was reached.
*
* @throws IOException If a problem is encountered while reading from the
* input stream.
*
* @throws JSONException If a problem was encountered while reading the
* token.
*/
private Object readToken(final boolean allowEndOfStream)
throws IOException, JSONException
{
skipWhitespace();
final Byte byteRead = readByte(allowEndOfStream);
if (byteRead == null)
{
return null;
}
switch (byteRead)
{
case '{':
return '{';
case '}':
return '}';
case '[':
return '[';
case ']':
return ']';
case ':':
return ':';
case ',':
return ',';
case '"':
// This is the start of a JSON string.
return readString();
case 't':
case 'f':
// This is the start of a JSON true or false value.
return readBoolean();
case 'n':
// This is the start of a JSON null value.
return readNull();
case '-':
case '0':
case '1':
case '2':
case '3':
case '4':
case '5':
case '6':
case '7':
case '8':
case '9':
// This is the start of a JSON number value.
return readNumber();
default:
throw new JSONException(
ERR_OBJECT_READER_ILLEGAL_FIRST_CHAR_FOR_JSON_TOKEN.get(
currentObjectBytes.length(), byteToCharString(byteRead)));
}
}
/**
* Skips over any valid JSON whitespace at the current position in the input
* stream.
*
* @throws IOException If a problem is encountered while reading from the
* input stream.
*
* @throws JSONException If a problem is encountered while skipping
* whitespace.
*/
private void skipWhitespace()
throws IOException, JSONException
{
while (true)
{
inputStream.mark(1);
final Byte byteRead = readByte(true);
if (byteRead == null)
{
// We've reached the end of the input stream.
return;
}
switch (byteRead)
{
case ' ':
case '\t':
case '\n':
case '\r':
// Spaces, tabs, newlines, and carriage returns are valid JSON
// whitespace.
break;
// Technically, JSON does not provide support for comments. But this
// implementation will accept three types of comments:
// - Comments that start with /* and end with */ (potentially spanning
// multiple lines).
// - Comments that start with // and continue until the end of the line.
// - Comments that start with # and continue until the end of the line.
// All comments will be ignored by the parser.
case '/':
// This probably starts a comment. If so, then the next byte must be
// either another forward slash or an asterisk.
final byte nextByte = readByte(false);
if (nextByte == '/')
{
// Keep reading until we encounter a newline, a carriage return, or
// the end of the input stream.
while (true)
{
final Byte commentByte = readByte(true);
if (commentByte == null)
{
return;
}
if ((commentByte == '\n') || (commentByte == '\r'))
{
break;
}
}
}
else if (nextByte == '*')
{
// Keep reading until we encounter an asterisk followed by a slash.
// If we hit the end of the input stream before that, then that's an
// error.
while (true)
{
final Byte commentByte = readByte(false);
if (commentByte == '*')
{
final Byte possibleSlashByte = readByte(false);
if (possibleSlashByte == '/')
{
break;
}
}
}
}
else
{
throw new JSONException(
ERR_OBJECT_READER_ILLEGAL_SLASH_SKIPPING_WHITESPACE.get(
currentObjectBytes.length()));
}
break;
case '#':
// Keep reading until we encounter a newline, a carriage return, or
// the end of the input stream.
while (true)
{
final Byte commentByte = readByte(true);
if (commentByte == null)
{
return;
}
if ((commentByte == '\n') || (commentByte == '\r'))
{
break;
}
}
break;
default:
// We read a byte that isn't whitespace, so we'll need to reset the
// stream so it will be read again, and we'll also need to remove the
// that byte from the currentObjectBytes buffer.
inputStream.reset();
currentObjectBytes.setLength(currentObjectBytes.length() - 1);
return;
}
}
}
/**
* Reads the next byte from the input stream.
*
* @param allowEndOfStream Indicates whether it is acceptable to encounter
* the end of the input stream. This should only
* be {@code true} when the token is expected to be
* the open parenthesis of the outermost JSON
* object.
*
* @return The next byte read from the input stream, or {@code null} if the
* end of the input stream has been reached and that is acceptable.
*
* @throws IOException If a problem is encountered while reading from the
* input stream.
*
* @throws JSONException If the end of the input stream is reached when that
* is not acceptable.
*/
private Byte readByte(final boolean allowEndOfStream)
throws IOException, JSONException
{
final int byteRead = inputStream.read();
if (byteRead < 0)
{
if (allowEndOfStream)
{
return null;
}
else
{
throw new JSONException(ERR_OBJECT_READER_UNEXPECTED_END_OF_STREAM.get(
currentObjectBytes.length()));
}
}
final byte b = (byte) (byteRead & 0xFF);
currentObjectBytes.append(b);
return b;
}
/**
* Reads a string from the input stream. The open quotation must have already
* been read.
*
* @return The JSON string that was read.
*
* @throws IOException If a problem is encountered while reading from the
* input stream.
*
* @throws JSONException If a problem was encountered while reading the JSON
* string.
*/
private JSONString readString()
throws IOException, JSONException
{
// Use a buffer to hold the string being decoded. Also mark the current
// position in the bytes that comprise the string representation so that
// the JSON string representation (including the opening quote) will be
// exactly as it was provided.
stringBuffer.clear();
final int jsonStringStartPos = currentObjectBytes.length() - 1;
while (true)
{
final Byte byteRead = readByte(false);
// See if it's a non-ASCII byte. If so, then assume that it's UTF-8 and
// read the appropriate number of remaining bytes. We need to handle this
// specially to avoid incorrectly detecting the end of the string because
// a subsequent byte in a multi-byte character happens to be the same as
// the ASCII quotation mark byte.
if ((byteRead & 0x80) == 0x80)
{
final byte[] charBytes;
if ((byteRead & 0xE0) == 0xC0)
{
// It's a two-byte character.
charBytes = new byte[]
{
byteRead,
readByte(false)
};
}
else if ((byteRead & 0xF0) == 0xE0)
{
// It's a three-byte character.
charBytes = new byte[]
{
byteRead,
readByte(false),
readByte(false)
};
}
else if ((byteRead & 0xF8) == 0xF0)
{
// It's a four-byte character.
charBytes = new byte[]
{
byteRead,
readByte(false),
readByte(false),
readByte(false)
};
}
else
{
// This isn't a valid UTF-8 sequence.
throw new JSONException(
ERR_OBJECT_READER_INVALID_UTF_8_BYTE_IN_STREAM.get(
currentObjectBytes.length(),
"0x" + StaticUtils.toHex(byteRead)));
}
stringBuffer.append(new String(charBytes, "UTF-8"));
continue;
}
// If the byte that we read was an escape, then we know that whatever
// immediately follows it shouldn't be allowed to signal the end of the
// string.
if (byteRead == '\\')
{
final byte nextByte = readByte(false);
switch (nextByte)
{
case '"':
case '\\':
case '/':
stringBuffer.append(nextByte);
break;
case 'b':
stringBuffer.append('\b');
break;
case 'f':
stringBuffer.append('\f');
break;
case 'n':
stringBuffer.append('\n');
break;
case 'r':
stringBuffer.append('\r');
break;
case 't':
stringBuffer.append('\t');
break;
case 'u':
final char[] hexChars =
{
(char) (readByte(false) & 0xFF),
(char) (readByte(false) & 0xFF),
(char) (readByte(false) & 0xFF),
(char) (readByte(false) & 0xFF)
};
try
{
stringBuffer.append(
(char) Integer.parseInt(new String(hexChars), 16));
}
catch (final Exception e)
{
Debug.debugException(e);
throw new JSONException(
ERR_OBJECT_READER_INVALID_UNICODE_ESCAPE.get(
currentObjectBytes.length()),
e);
}
break;
default:
throw new JSONException(
ERR_OBJECT_READER_INVALID_ESCAPED_CHAR.get(
currentObjectBytes.length(), byteToCharString(nextByte)));
}
continue;
}
if (byteRead == '"')
{
// It's an unescaped quote, so it marks the end of the string.
return new JSONString(stringBuffer.toString(),
new String(currentObjectBytes.getBackingArray(),
jsonStringStartPos,
(currentObjectBytes.length() - jsonStringStartPos),
"UTF-8"));
}
final int byteReadInt = (byteRead & 0xFF);
if ((byteRead & 0xFF) <= 0x1F)
{
throw new JSONException(ERR_OBJECT_UNESCAPED_CONTROL_CHAR.get(
currentObjectBytes.length(), byteToCharString(byteRead)));
}
else
{
stringBuffer.append((char) byteReadInt);
}
}
}
/**
* Reads a JSON Boolean from the input stream. The first byte of either 't'
* or 'f' will have already been read.
*
* @return The JSON Boolean that was read.
*
* @throws IOException If a problem is encountered while reading from the
* input stream.
*
* @throws JSONException If a problem was encountered while reading the JSON
* Boolean.
*/
private JSONBoolean readBoolean()
throws IOException, JSONException
{
final byte firstByte =
currentObjectBytes.getBackingArray()[currentObjectBytes.length() - 1];
if (firstByte == 't')
{
if ((readByte(false) == 'r') &&
(readByte(false) == 'u') &&
(readByte(false) == 'e'))
{
return JSONBoolean.TRUE;
}
throw new JSONException(ERR_OBJECT_READER_INVALID_BOOLEAN_TRUE.get(
currentObjectBytes.length()));
}
else
{
if ((readByte(false) == 'a') &&
(readByte(false) == 'l') &&
(readByte(false) == 's') &&
(readByte(false) == 'e'))
{
return JSONBoolean.FALSE;
}
throw new JSONException(ERR_OBJECT_READER_INVALID_BOOLEAN_FALSE.get(
currentObjectBytes.length()));
}
}
/**
* Reads a JSON Boolean from the input stream. The first byte of 'n' will
* have already been read.
*
* @return The JSON null that was read.
*
* @throws IOException If a problem is encountered while reading from the
* input stream.
*
* @throws JSONException If a problem was encountered while reading the JSON
* null.
*/
private JSONNull readNull()
throws IOException, JSONException
{
if ((readByte(false) == 'u') &&
(readByte(false) == 'l') &&
(readByte(false) == 'l'))
{
return JSONNull.NULL;
}
throw new JSONException(ERR_OBJECT_READER_INVALID_NULL.get(
currentObjectBytes.length()));
}
/**
* Reads a JSON number from the input stream. The first byte of the number
* will have already been read.
*
* @throws IOException If a problem is encountered while reading from the
* input stream.
*
* @return The JSON number that was read.
*
* @throws IOException If a problem is encountered while reading from the
* input stream.
*
* @throws JSONException If a problem was encountered while reading the JSON
* number.
*/
private JSONNumber readNumber()
throws IOException, JSONException
{
// Use a buffer to hold the string representation of the number being
// decoded. Since the first byte of the number has already been read, we'll
// need to add it into the buffer.
stringBuffer.clear();
stringBuffer.append(
currentObjectBytes.getBackingArray()[currentObjectBytes.length() - 1]);
// Read until we encounter whitespace, a comma, a closing square bracket, or
// a closing curly brace. Then try to parse what we read as a number.
while (true)
{
// Mark the stream so that if we read a byte that isn't part of the
// number, we'll be able to rewind the stream so that byte will be read
// again by something else.
inputStream.mark(1);
final Byte b = readByte(false);
switch (b)
{
case ' ':
case '\t':
case '\n':
case '\r':
case ',':
case ']':
case '}':
// This tell us we're at the end of the number. Rewind the stream so
// that we can read this last byte again whatever tries to get the
// next token. Also remove it from the end of currentObjectBytes
// since it will be re-added when it's read again.
inputStream.reset();
currentObjectBytes.setLength(currentObjectBytes.length() - 1);
return new JSONNumber(stringBuffer.toString());
default:
stringBuffer.append(b);
}
}
}
/**
* Reads a JSON array from the input stream. The opening square bracket will
* have already been read.
*
* @return The JSON array that was read.
*
* @throws IOException If a problem is encountered while reading from the
* input stream.
*
* @throws JSONException If a problem was encountered while reading the JSON
* array.
*/
private JSONArray readArray()
throws IOException, JSONException
{
// The opening square bracket will have already been consumed, so read
// JSON values until we hit a closing square bracket.
final ArrayList values = new ArrayList(10);
boolean firstToken = true;
while (true)
{
// If this is the first time through, it is acceptable to find a closing
// square bracket. Otherwise, we expect to find a JSON value, an opening
// square bracket to denote the start of an embedded array, or an opening
// curly brace to denote the start of an embedded JSON object.
final Object token = readToken(false);
if (token instanceof JSONValue)
{
values.add((JSONValue) token);
}
else if (token.equals('['))
{
values.add(readArray());
}
else if (token.equals('{'))
{
final LinkedHashMap fieldMap =
new LinkedHashMap(10);
values.add(readObject(fieldMap));
}
else if (token.equals(']') && firstToken)
{
// It's an empty array.
return JSONArray.EMPTY_ARRAY;
}
else
{
throw new JSONException(ERR_OBJECT_READER_INVALID_TOKEN_IN_ARRAY.get(
currentObjectBytes.length(), String.valueOf(token)));
}
firstToken = false;
// If we've gotten here, then we found a JSON value. It must be followed
// by either a comma (to indicate that there's at least one more value) or
// a closing square bracket (to denote the end of the array).
final Object nextToken = readToken(false);
if (nextToken.equals(']'))
{
return new JSONArray(values);
}
else if (! nextToken.equals(','))
{
throw new JSONException(
ERR_OBJECT_READER_INVALID_TOKEN_AFTER_ARRAY_VALUE.get(
currentObjectBytes.length(), String.valueOf(nextToken)));
}
}
}
/**
* Reads a JSON object from the input stream. The opening curly brace will
* have already been read.
*
* @param fields The map into which to place the fields that are read. The
* returned object will include an unmodifiable view of this
* map, but the caller may use the map directly if desired.
*
* @return The JSON object that was read.
*
* @throws IOException If a problem is encountered while reading from the
* input stream.
*
* @throws JSONException If a problem was encountered while reading the JSON
* object.
*/
private JSONObject readObject(final Map fields)
throws IOException, JSONException
{
boolean firstField = true;
while (true)
{
// Read the next token. It must be a JSONString, unless we haven't read
// any fields yet in which case it can be a closing curly brace to
// indicate that it's an empty object.
final String fieldName;
final Object fieldNameToken = readToken(false);
if (fieldNameToken instanceof JSONString)
{
fieldName = ((JSONString) fieldNameToken).stringValue();
if (fields.containsKey(fieldName))
{
throw new JSONException(ERR_OBJECT_READER_DUPLICATE_FIELD.get(
currentObjectBytes.length(), fieldName));
}
}
else if (firstField && fieldNameToken.equals('}'))
{
return new JSONObject(fields);
}
else
{
throw new JSONException(ERR_OBJECT_READER_INVALID_TOKEN_IN_OBJECT.get(
currentObjectBytes.length(), String.valueOf(fieldNameToken)));
}
firstField = false;
// Read the next token. It must be a colon.
final Object colonToken = readToken(false);
if (! colonToken.equals(':'))
{
throw new JSONException(ERR_OBJECT_READER_TOKEN_NOT_COLON.get(
currentObjectBytes.length(), String.valueOf(colonToken),
String.valueOf(fieldNameToken)));
}
// Read the next token. It must be one of the following:
// - A JSONValue
// - An opening square bracket, designating the start of an array.
// - An opening curly brace, designating the start of an object.
final Object valueToken = readToken(false);
if (valueToken instanceof JSONValue)
{
fields.put(fieldName, (JSONValue) valueToken);
}
else if (valueToken.equals('['))
{
final JSONArray a = readArray();
fields.put(fieldName, a);
}
else if (valueToken.equals('{'))
{
final LinkedHashMap m =
new LinkedHashMap(10);
final JSONObject o = readObject(m);
fields.put(fieldName, o);
}
else
{
throw new JSONException(ERR_OBJECT_READER_TOKEN_NOT_VALUE.get(
currentObjectBytes.length(), String.valueOf(valueToken),
String.valueOf(fieldNameToken)));
}
// Read the next token. It must be either a comma (to indicate that
// there will be another field) or a closing curly brace (to indicate
// that the end of the object has been reached).
final Object separatorToken = readToken(false);
if (separatorToken.equals('}'))
{
return new JSONObject(fields);
}
else if (! separatorToken.equals(','))
{
throw new JSONException(
ERR_OBJECT_READER_INVALID_TOKEN_AFTER_OBJECT_VALUE.get(
currentObjectBytes.length(), String.valueOf(separatorToken),
String.valueOf(fieldNameToken)));
}
}
}
/**
* Retrieves a string representation of the provided byte that is intended to
* represent a character. If the provided byte is a printable ASCII
* character, then that character will be used. Otherwise, the string
* representation will be "0x" followed by the hexadecimal representation of
* the byte.
*
* @param b The byte for which to obtain the string representation.
*
* @return A string representation of the provided byte.
*/
private static String byteToCharString(final byte b)
{
if ((b >= ' ') && (b <= '~'))
{
return String.valueOf((char) (b & 0xFF));
}
else
{
return "0x" + StaticUtils.toHex(b);
}
}
}
