/*
* Copyright (C) 2010 Google 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 com.google.gson.stream;
import com.google.gson.internal.JsonReaderInternalAccess;
import com.google.gson.internal.bind.JsonTreeReader;
import java.io.Closeable;
import java.io.EOFException;
import java.io.IOException;
import java.io.Reader;
/**
* Reads a JSON (<a href="http://www.ietf.org/rfc/rfc4627.txt">RFC 4627</a>) encoded value as a
* stream of tokens. This stream includes both literal values (strings, numbers, booleans, and
* nulls) as well as the begin and end delimiters of objects and arrays. The tokens are traversed in
* depth-first order, the same order that they appear in the JSON document. Within JSON objects,
* name/value pairs are represented by a single token.
*
* <h3>Parsing JSON</h3>
* To create a recursive descent parser for your own JSON streams, first create an entry point
* method that creates a {@code JsonReader}.
*
* <p>
* Next, create handler methods for each structure in your JSON text. You'll need a method for each
* object type and for each array type.
* <ul>
* <li>Within <strong>array handling</strong> methods, first call {@link
* #beginArray} to consume the array's opening bracket. Then create a while loop that accumulates
* values, terminating when {@link #hasNext} is false. Finally, read the array's closing bracket by
* calling {@link
* #endArray}.
* <li>Within <strong>object handling</strong> methods, first call {@link
* #beginObject} to consume the object's opening brace. Then create a while loop that assigns values
* to local variables based on their name. This loop should terminate when {@link #hasNext} is
* false. Finally, read the object's closing brace by calling {@link #endObject}.
* </ul>
* <p>
* When a nested object or array is encountered, delegate to the corresponding handler method.
*
* <p>
* When an unknown name is encountered, strict parsers should fail with an exception. Lenient
* parsers should call {@link #skipValue()} to recursively skip the value's nested tokens, which may
* otherwise conflict.
*
* <p>
* If a value may be null, you should first check using {@link #peek()}. Null literals can be
* consumed using either {@link #nextNull()} or {@link
* #skipValue()}.
*
* <h3>Example</h3>
* Suppose we'd like to parse a stream of messages such as the following:
* <pre> {@code
* [
* {
* "id": 912345678901,
* "text": "How do I read a JSON stream in Java?",
* "geo": null,
* "user": {
* "name": "json_newb",
* "followers_count": 41
* }
* },
* {
* "id": 912345678902,
* "text": "@json_newb just use JsonReader!",
* "geo": [50.454722, -104.606667],
* "user": {
* "name": "jesse",
* "followers_count": 2
* }
* }
* ]}</pre> This code implements the parser for the above structure:
* <pre> {@code
*
* public List<Message> readJsonStream(InputStream in) throws IOException {
* JsonReader reader = new JsonReader(new InputStreamReader(in, "UTF-8"));
* try {
* return readMessagesArray(reader);
* } finally {
* reader.close();
* }
* }
*
* public List<Message> readMessagesArray(JsonReader reader) throws IOException {
* List<Message> messages = new ArrayList<Message>();
*
* reader.beginArray();
* while (reader.hasNext()) {
* messages.add(readMessage(reader));
* }
* reader.endArray();
* return messages;
* }
*
* public Message readMessage(JsonReader reader) throws IOException {
* long id = -1;
* String text = null;
* User user = null;
* List<Double> geo = null;
*
* reader.beginObject();
* while (reader.hasNext()) {
* String name = reader.nextName();
* if (name.equals("id")) {
* id = reader.nextLong();
* } else if (name.equals("text")) {
* text = reader.nextString();
* } else if (name.equals("geo") && reader.peek() != JsonToken.NULL) {
* geo = readDoublesArray(reader);
* } else if (name.equals("user")) {
* user = readUser(reader);
* } else {
* reader.skipValue();
* }
* }
* reader.endObject();
* return new Message(id, text, user, geo);
* }
*
* public List<Double> readDoublesArray(JsonReader reader) throws IOException {
* List<Double> doubles = new ArrayList<Double>();
*
* reader.beginArray();
* while (reader.hasNext()) {
* doubles.add(reader.nextDouble());
* }
* reader.endArray();
* return doubles;
* }
*
* public User readUser(JsonReader reader) throws IOException {
* String username = null;
* int followersCount = -1;
*
* reader.beginObject();
* while (reader.hasNext()) {
* String name = reader.nextName();
* if (name.equals("name")) {
* username = reader.nextString();
* } else if (name.equals("followers_count")) {
* followersCount = reader.nextInt();
* } else {
* reader.skipValue();
* }
* }
* reader.endObject();
* return new User(username, followersCount);
* }}</pre>
*
* <h3>Number Handling</h3>
* This reader permits numeric values to be read as strings and string values to be read as numbers.
* For example, both elements of the JSON array {@code
* [1, "1"]} may be read using either {@link #nextInt} or {@link #nextString}. This behavior is
* intended to prevent lossy numeric conversions: double is JavaScript's only numeric type and very
* large values like {@code
* 9007199254740993} cannot be represented exactly on that platform. To minimize precision loss,
* extremely large values should be written and read as strings in JSON.
*
* <a name="nonexecuteprefix"/><h3>Non-Execute Prefix</h3>
* Web servers that serve private data using JSON may be vulnerable to <a
* href="http://en.wikipedia.org/wiki/JSON#Cross-site_request_forgery">Cross-site request
* forgery</a> attacks. In such an attack, a malicious site gains access to a private JSON file by
* executing it with an HTML {@code <script>} tag.
*
* <p>
* Prefixing JSON files with <code>")]}'\n"</code> makes them non-executable by {@code <script>}
* tags, disarming the attack. Since the prefix is malformed JSON, strict parsing fails when it is
* encountered. This class permits the non-execute prefix when
* {@link #setLenient(boolean) lenient parsing} is enabled.
*
* <p>
* Each {@code JsonReader} may be used to read a single JSON stream. Instances of this class are not
* thread safe.
*
* @author Jesse Wilson
* @since 1.6
*/
public class JsonReader implements Closeable {
/**
* The only non-execute prefix this parser permits
*/
private static final char[] NON_EXECUTE_PREFIX = ")]}'\n".toCharArray();
private static final long MIN_INCOMPLETE_INTEGER = Long.MIN_VALUE / 10;
private static final int PEEKED_NONE = 0;
private static final int PEEKED_BEGIN_OBJECT = 1;
private static final int PEEKED_END_OBJECT = 2;
private static final int PEEKED_BEGIN_ARRAY = 3;
private static final int PEEKED_END_ARRAY = 4;
private static final int PEEKED_TRUE = 5;
private static final int PEEKED_FALSE = 6;
private static final int PEEKED_NULL = 7;
private static final int PEEKED_SINGLE_QUOTED = 8;
private static final int PEEKED_DOUBLE_QUOTED = 9;
private static final int PEEKED_UNQUOTED = 10;
/**
* When this is returned, the string value is stored in peekedString.
*/
private static final int PEEKED_BUFFERED = 11;
private static final int PEEKED_SINGLE_QUOTED_NAME = 12;
private static final int PEEKED_DOUBLE_QUOTED_NAME = 13;
private static final int PEEKED_UNQUOTED_NAME = 14;
/**
* When this is returned, the integer value is stored in peekedLong.
*/
private static final int PEEKED_LONG = 15;
private static final int PEEKED_NUMBER = 16;
private static final int PEEKED_EOF = 17;
/* State machine when parsing numbers */
private static final int NUMBER_CHAR_NONE = 0;
private static final int NUMBER_CHAR_SIGN = 1;
private static final int NUMBER_CHAR_DIGIT = 2;
private static final int NUMBER_CHAR_DECIMAL = 3;
private static final int NUMBER_CHAR_FRACTION_DIGIT = 4;
private static final int NUMBER_CHAR_EXP_E = 5;
private static final int NUMBER_CHAR_EXP_SIGN = 6;
private static final int NUMBER_CHAR_EXP_DIGIT = 7;
/**
* The input JSON.
*/
private final Reader in;
/**
* True to accept non-spec compliant JSON
*/
private boolean lenient = false;
/**
* Use a manual buffer to easily read and unread upcoming characters, and also so we can
* create strings without an intermediate StringBuilder. We decode literals directly out of
* this buffer, so it must be at least as long as the longest token that can be reported as a
* number.
*/
private final char[] buffer = new char[1024];
private int pos = 0;
private int limit = 0;
private int lineNumber = 0;
private int lineStart = 0;
private int peeked = PEEKED_NONE;
/**
* A peeked value that was composed entirely of digits with an optional leading dash. Positive
* values may not have a leading 0.
*/
private long peekedLong;
/**
* The number of characters in a peeked number literal. Increment 'pos' by this after reading
* a number.
*/
private int peekedNumberLength;
/**
* A peeked string that should be parsed on the next double, long or string. This is populated
* before a numeric value is parsed and used if that parsing fails.
*/
private String peekedString;
/*
* The nesting stack. Using a manual array rather than an ArrayList saves 20%.
*/
private int[] stack = new int[32];
private int stackSize = 0;
{
stack[stackSize++] = JsonScope.EMPTY_DOCUMENT;
}
/**
* Creates a new instance that reads a JSON-encoded stream from {@code in}.
*/
public JsonReader(Reader in) {
if (in == null) {
throw new NullPointerException("in == null");
}
this.in = in;
}
/**
* Configure this parser to be be liberal in what it accepts. By default, this parser is
* strict and only accepts JSON as specified by <a
* href="http://www.ietf.org/rfc/rfc4627.txt">RFC 4627</a>. Setting the parser to lenient
* causes it to ignore the following syntax errors:
*
* <ul>
* <li>Streams that start with the <a href="#nonexecuteprefix">non-execute prefix</a>,
* <code>")]}'\n"</code>.
* <li>Streams that include multiple top-level values. With strict parsing, each stream must
* contain exactly one top-level value.
* <li>Top-level values of any type. With strict parsing, the top-level value must be an
* object or an array.
* <li>Numbers may be {@link Double#isNaN() NaNs} or {@link
* Double#isInfinite() infinities}.
* <li>End of line comments starting with {@code //} or {@code #} and ending with a newline
* character.
* <li>C-style comments starting with {@code /*} and ending with {@code *}{@code /}. Such
* comments may not be nested.
* <li>Names that are unquoted or {@code 'single quoted'}.
* <li>Strings that are unquoted or {@code 'single quoted'}.
* <li>Array elements separated by {@code ;} instead of {@code ,}.
* <li>Unnecessary array separators. These are interpreted as if null was the omitted value.
* <li>Names and values separated by {@code =} or {@code =>} instead of {@code :}.
* <li>Name/value pairs separated by {@code ;} instead of {@code ,}.
* </ul>
*/
public final void setLenient(boolean lenient) {
this.lenient = lenient;
}
/**
* Returns true if this parser is liberal in what it accepts.
*/
public final boolean isLenient() {
return lenient;
}
/**
* Consumes the next token from the JSON stream and asserts that it is the beginning of a new
* array.
*/
public void beginArray() throws IOException {
int p = peeked;
if (p == PEEKED_NONE) {
p = doPeek();
}
if (p == PEEKED_BEGIN_ARRAY) {
push(JsonScope.EMPTY_ARRAY);
peeked = PEEKED_NONE;
} else {
throw new IllegalStateException("Expected BEGIN_ARRAY but was " + peek()
+ " at line " + getLineNumber() + " column " + getColumnNumber());
}
}
/**
* Consumes the next token from the JSON stream and asserts that it is the end of the current
* array.
*/
public void endArray() throws IOException {
int p = peeked;
if (p == PEEKED_NONE) {
p = doPeek();
}
if (p == PEEKED_END_ARRAY) {
stackSize--;
peeked = PEEKED_NONE;
} else {
throw new IllegalStateException("Expected END_ARRAY but was " + peek()
+ " at line " + getLineNumber() + " column " + getColumnNumber());
}
}
/**
* Consumes the next token from the JSON stream and asserts that it is the beginning of a new
* object.
*/
public void beginObject() throws IOException {
int p = peeked;
if (p == PEEKED_NONE) {
p = doPeek();
}
if (p == PEEKED_BEGIN_OBJECT) {
push(JsonScope.EMPTY_OBJECT);
peeked = PEEKED_NONE;
} else {
throw new IllegalStateException("Expected BEGIN_OBJECT but was " + peek()
+ " at line " + getLineNumber() + " column " + getColumnNumber());
}
}
/**
* Consumes the next token from the JSON stream and asserts that it is the end of the current
* object.
*/
public void endObject() throws IOException {
int p = peeked;
if (p == PEEKED_NONE) {
p = doPeek();
}
if (p == PEEKED_END_OBJECT) {
stackSize--;
peeked = PEEKED_NONE;
} else {
throw new IllegalStateException("Expected END_OBJECT but was " + peek()
+ " at line " + getLineNumber() + " column " + getColumnNumber());
}
}
/**
* Returns true if the current array or object has another element.
*/
public boolean hasNext() throws IOException {
int p = peeked;
if (p == PEEKED_NONE) {
p = doPeek();
}
return p != PEEKED_END_OBJECT && p != PEEKED_END_ARRAY;
}
/**
* Returns the type of the next token without consuming it.
*/
public JsonToken peek() throws IOException {
int p = peeked;
if (p == PEEKED_NONE) {
p = doPeek();
}
switch (p) {
case PEEKED_BEGIN_OBJECT:
return JsonToken.BEGIN_OBJECT;
case PEEKED_END_OBJECT:
return JsonToken.END_OBJECT;
case PEEKED_BEGIN_ARRAY:
return JsonToken.BEGIN_ARRAY;
case PEEKED_END_ARRAY:
return JsonToken.END_ARRAY;
case PEEKED_SINGLE_QUOTED_NAME:
case PEEKED_DOUBLE_QUOTED_NAME:
case PEEKED_UNQUOTED_NAME:
return JsonToken.NAME;
case PEEKED_TRUE:
case PEEKED_FALSE:
return JsonToken.BOOLEAN;
case PEEKED_NULL:
return JsonToken.NULL;
case PEEKED_SINGLE_QUOTED:
case PEEKED_DOUBLE_QUOTED:
case PEEKED_UNQUOTED:
case PEEKED_BUFFERED:
return JsonToken.STRING;
case PEEKED_LONG:
case PEEKED_NUMBER:
return JsonToken.NUMBER;
case PEEKED_EOF:
return JsonToken.END_DOCUMENT;
default:
throw new AssertionError();
}
}
private int doPeek() throws IOException {
int peekStack = stack[stackSize - 1];
if (peekStack == JsonScope.EMPTY_ARRAY) {
stack[stackSize - 1] = JsonScope.NONEMPTY_ARRAY;
} else if (peekStack == JsonScope.NONEMPTY_ARRAY) {
// Look for a comma before the next element.
int c = nextNonWhitespace(true);
switch (c) {
case ']':
return peeked = PEEKED_END_ARRAY;
case ';':
checkLenient(); // fall-through
case ',':
break;
default:
throw syntaxError("Unterminated array");
}
} else if (peekStack == JsonScope.EMPTY_OBJECT || peekStack == JsonScope.NONEMPTY_OBJECT) {
stack[stackSize - 1] = JsonScope.DANGLING_NAME;
// Look for a comma before the next element.
if (peekStack == JsonScope.NONEMPTY_OBJECT) {
int c = nextNonWhitespace(true);
switch (c) {
case '}':
return peeked = PEEKED_END_OBJECT;
case ';':
checkLenient(); // fall-through
case ',':
break;
default:
throw syntaxError("Unterminated object");
}
}
int c = nextNonWhitespace(true);
switch (c) {
case '"':
return peeked = PEEKED_DOUBLE_QUOTED_NAME;
case '\'':
checkLenient();
return peeked = PEEKED_SINGLE_QUOTED_NAME;
case '}':
if (peekStack != JsonScope.NONEMPTY_OBJECT) {
return peeked = PEEKED_END_OBJECT;
} else {
throw syntaxError("Expected name");
}
default:
checkLenient();
pos--; // Don't consume the first character in an unquoted string.
if (isLiteral((char) c)) {
return peeked = PEEKED_UNQUOTED_NAME;
} else {
throw syntaxError("Expected name");
}
}
} else if (peekStack == JsonScope.DANGLING_NAME) {
stack[stackSize - 1] = JsonScope.NONEMPTY_OBJECT;
// Look for a colon before the value.
int c = nextNonWhitespace(true);
switch (c) {
case ':':
break;
case '=':
checkLenient();
if ((pos < limit || fillBuffer(1)) && buffer[pos] == '>') {
pos++;
}
break;
default:
throw syntaxError("Expected ':'");
}
} else if (peekStack == JsonScope.EMPTY_DOCUMENT) {
if (lenient) {
consumeNonExecutePrefix();
}
stack[stackSize - 1] = JsonScope.NONEMPTY_DOCUMENT;
} else if (peekStack == JsonScope.NONEMPTY_DOCUMENT) {
int c = nextNonWhitespace(false);
if (c == -1) {
return peeked = PEEKED_EOF;
} else {
checkLenient();
pos--;
}
} else if (peekStack == JsonScope.CLOSED) {
throw new IllegalStateException("JsonReader is closed");
}
int c = nextNonWhitespace(true);
switch (c) {
case ']':
if (peekStack == JsonScope.EMPTY_ARRAY) {
return peeked = PEEKED_END_ARRAY;
}
// fall-through to handle ",]"
case ';':
case ',':
// In lenient mode, a 0-length literal in an array means 'null'.
if (peekStack == JsonScope.EMPTY_ARRAY || peekStack == JsonScope.NONEMPTY_ARRAY) {
checkLenient();
pos--;
return peeked = PEEKED_NULL;
} else {
throw syntaxError("Unexpected value");
}
case '\'':
checkLenient();
return peeked = PEEKED_SINGLE_QUOTED;
case '"':
if (stackSize == 1) {
checkLenient();
}
return peeked = PEEKED_DOUBLE_QUOTED;
case '[':
return peeked = PEEKED_BEGIN_ARRAY;
case '{':
return peeked = PEEKED_BEGIN_OBJECT;
default:
pos--; // Don't consume the first character in a literal value.
}
if (stackSize == 1) {
checkLenient(); // Top-level value isn't an array or an object.
}
int result = peekKeyword();
if (result != PEEKED_NONE) {
return result;
}
result = peekNumber();
if (result != PEEKED_NONE) {
return result;
}
if (!isLiteral(buffer[pos])) {
throw syntaxError("Expected value");
}
checkLenient();
return peeked = PEEKED_UNQUOTED;
}
private int peekKeyword() throws IOException {
// Figure out which keyword we're matching against by its first character.
char c = buffer[pos];
String keyword;
String keywordUpper;
int peeking;
if (c == 't' || c == 'T') {
keyword = "true";
keywordUpper = "TRUE";
peeking = PEEKED_TRUE;
} else if (c == 'f' || c == 'F') {
keyword = "false";
keywordUpper = "FALSE";
peeking = PEEKED_FALSE;
} else if (c == 'n' || c == 'N') {
keyword = "null";
keywordUpper = "NULL";
peeking = PEEKED_NULL;
} else {
return PEEKED_NONE;
}
// Confirm that chars [1..length) match the keyword.
int length = keyword.length();
for (int i = 1; i < length; i++) {
if (pos + i >= limit && !fillBuffer(i + 1)) {
return PEEKED_NONE;
}
c = buffer[pos + i];
if (c != keyword.charAt(i) && c != keywordUpper.charAt(i)) {
return PEEKED_NONE;
}
}
if ((pos + length < limit || fillBuffer(length + 1))
&& isLiteral(buffer[pos + length])) {
return PEEKED_NONE; // Don't match trues, falsey or nullsoft!
}
// We've found the keyword followed either by EOF or by a non-literal character.
pos += length;
return peeked = peeking;
}
private int peekNumber() throws IOException {
// Like nextNonWhitespace, this uses locals 'p' and 'l' to save inner-loop field access.
char[] buffer = this.buffer;
int p = pos;
int l = limit;
long value = 0; // Negative to accommodate Long.MIN_VALUE more easily.
boolean negative = false;
boolean fitsInLong = true;
int last = NUMBER_CHAR_NONE;
int i = 0;
charactersOfNumber:
for (; true; i++) {
if (p + i == l) {
if (i == buffer.length) {
// Though this looks like a well-formed number, it's too long to continue reading. Give up
// and let the application handle this as an unquoted literal.
return PEEKED_NONE;
}
if (!fillBuffer(i + 1)) {
break;
}
p = pos;
l = limit;
}
char c = buffer[p + i];
switch (c) {
case '-':
if (last == NUMBER_CHAR_NONE) {
negative = true;
last = NUMBER_CHAR_SIGN;
continue;
} else if (last == NUMBER_CHAR_EXP_E) {
last = NUMBER_CHAR_EXP_SIGN;
continue;
}
return PEEKED_NONE;
case '+':
if (last == NUMBER_CHAR_EXP_E) {
last = NUMBER_CHAR_EXP_SIGN;
continue;
}
return PEEKED_NONE;
case 'e':
case 'E':
if (last == NUMBER_CHAR_DIGIT || last == NUMBER_CHAR_FRACTION_DIGIT) {
last = NUMBER_CHAR_EXP_E;
continue;
}
return PEEKED_NONE;
case '.':
if (last == NUMBER_CHAR_DIGIT) {
last = NUMBER_CHAR_DECIMAL;
continue;
}
return PEEKED_NONE;
default:
if (c < '0' || c > '9') {
if (!isLiteral(c)) {
break charactersOfNumber;
}
return PEEKED_NONE;
}
if (last == NUMBER_CHAR_SIGN || last == NUMBER_CHAR_NONE) {
value = -(c - '0');
last = NUMBER_CHAR_DIGIT;
} else if (last == NUMBER_CHAR_DIGIT) {
if (value == 0) {
return PEEKED_NONE; // Leading '0' prefix is not allowed (since it could be octal).
}
long newValue = value * 10 - (c - '0');
fitsInLong &= value > MIN_INCOMPLETE_INTEGER
|| (value == MIN_INCOMPLETE_INTEGER && newValue < value);
value = newValue;
} else if (last == NUMBER_CHAR_DECIMAL) {
last = NUMBER_CHAR_FRACTION_DIGIT;
} else if (last == NUMBER_CHAR_EXP_E || last == NUMBER_CHAR_EXP_SIGN) {
last = NUMBER_CHAR_EXP_DIGIT;
}
}
}
// We've read a complete number. Decide if it's a PEEKED_LONG or a PEEKED_NUMBER.
if (last == NUMBER_CHAR_DIGIT && fitsInLong && (value != Long.MIN_VALUE || negative)) {
peekedLong = negative ? value : -value;
pos += i;
return peeked = PEEKED_LONG;
} else if (last == NUMBER_CHAR_DIGIT || last == NUMBER_CHAR_FRACTION_DIGIT
|| last == NUMBER_CHAR_EXP_DIGIT) {
peekedNumberLength = i;
return peeked = PEEKED_NUMBER;
} else {
return PEEKED_NONE;
}
}
private boolean isLiteral(char c) throws IOException {
switch (c) {
case '/':
case '\\':
case ';':
case '#':
case '=':
checkLenient(); // fall-through
case '{':
case '}':
case '[':
case ']':
case ':':
case ',':
case ' ':
case '\t':
case '\f':
case '\r':
case '\n':
return false;
default:
return true;
}
}
/**
* Returns the next token, a {@link com.google.gson.stream.JsonToken#NAME property name}, and
* consumes it.
*
* @throws java.io.IOException if the next token in the stream is not a property name.
*/
public String nextName() throws IOException {
int p = peeked;
if (p == PEEKED_NONE) {
p = doPeek();
}
String result;
if (p == PEEKED_UNQUOTED_NAME) {
result = nextUnquotedValue();
} else if (p == PEEKED_SINGLE_QUOTED_NAME) {
result = nextQuotedValue('\'');
} else if (p == PEEKED_DOUBLE_QUOTED_NAME) {
result = nextQuotedValue('"');
} else {
throw new IllegalStateException("Expected a name but was " + peek()
+ " at line " + getLineNumber() + " column " + getColumnNumber());
}
peeked = PEEKED_NONE;
return result;
}
/**
* Returns the {@link com.google.gson.stream.JsonToken#STRING string} value of the next token,
* consuming it. If the next token is a number, this method will return its string form.
*
* @throws IllegalStateException if the next token is not a string or if this reader is
* closed.
*/
public String nextString() throws IOException {
int p = peeked;
if (p == PEEKED_NONE) {
p = doPeek();
}
String result;
if (p == PEEKED_UNQUOTED) {
result = nextUnquotedValue();
} else if (p == PEEKED_SINGLE_QUOTED) {
result = nextQuotedValue('\'');
} else if (p == PEEKED_DOUBLE_QUOTED) {
result = nextQuotedValue('"');
} else if (p == PEEKED_BUFFERED) {
result = peekedString;
peekedString = null;
} else if (p == PEEKED_LONG) {
result = Long.toString(peekedLong);
} else if (p == PEEKED_NUMBER) {
result = new String(buffer, pos, peekedNumberLength);
pos += peekedNumberLength;
} else {
throw new IllegalStateException("Expected a string but was " + peek()
+ " at line " + getLineNumber() + " column " + getColumnNumber());
}
peeked = PEEKED_NONE;
return result;
}
/**
* Returns the {@link com.google.gson.stream.JsonToken#BOOLEAN boolean} value of the next
* token, consuming it.
*
* @throws IllegalStateException if the next token is not a boolean or if this reader is
* closed.
*/
public boolean nextBoolean() throws IOException {
int p = peeked;
if (p == PEEKED_NONE) {
p = doPeek();
}
if (p == PEEKED_TRUE) {
peeked = PEEKED_NONE;
return true;
} else if (p == PEEKED_FALSE) {
peeked = PEEKED_NONE;
return false;
}
throw new IllegalStateException("Expected a boolean but was " + peek()
+ " at line " + getLineNumber() + " column " + getColumnNumber());
}
/**
* Consumes the next token from the JSON stream and asserts that it is a literal null.
*
* @throws IllegalStateException if the next token is not null or if this reader is closed.
*/
public void nextNull() throws IOException {
int p = peeked;
if (p == PEEKED_NONE) {
p = doPeek();
}
if (p == PEEKED_NULL) {
peeked = PEEKED_NONE;
} else {
throw new IllegalStateException("Expected null but was " + peek()
+ " at line " + getLineNumber() + " column " + getColumnNumber());
}
}
/**
* Returns the {@link com.google.gson.stream.JsonToken#NUMBER double} value of the next token,
* consuming it. If the next token is a string, this method will attempt to parse it as a
* double using {@link Double#parseDouble(String)}.
*
* @throws IllegalStateException if the next token is not a literal value.
* @throws NumberFormatException if the next literal value cannot be parsed as a double, or is
* non-finite.
*/
public double nextDouble() throws IOException {
int p = peeked;
if (p == PEEKED_NONE) {
p = doPeek();
}
if (p == PEEKED_LONG) {
peeked = PEEKED_NONE;
return (double) peekedLong;
}
if (p == PEEKED_NUMBER) {
peekedString = new String(buffer, pos, peekedNumberLength);
pos += peekedNumberLength;
} else if (p == PEEKED_SINGLE_QUOTED || p == PEEKED_DOUBLE_QUOTED) {
peekedString = nextQuotedValue(p == PEEKED_SINGLE_QUOTED ? '\'' : '"');
} else if (p == PEEKED_UNQUOTED) {
peekedString = nextUnquotedValue();
} else if (p != PEEKED_BUFFERED) {
throw new IllegalStateException("Expected a double but was " + peek()
+ " at line " + getLineNumber() + " column " + getColumnNumber());
}
peeked = PEEKED_BUFFERED;
double result = Double.parseDouble(peekedString); // don't catch this NumberFormatException.
if (!lenient && (Double.isNaN(result) || Double.isInfinite(result))) {
throw new MalformedJsonException("JSON forbids NaN and infinities: " + result
+ " at line " + getLineNumber() + " column " + getColumnNumber());
}
peekedString = null;
peeked = PEEKED_NONE;
return result;
}
/**
* Returns the {@link com.google.gson.stream.JsonToken#NUMBER long} value of the next token,
* consuming it. If the next token is a string, this method will attempt to parse it as a
* long. If the next token's numeric value cannot be exactly represented by a Java
* {@code long}, this method throws.
*
* @throws IllegalStateException if the next token is not a literal value.
* @throws NumberFormatException if the next literal value cannot be parsed as a number, or
* exactly represented as a long.
*/
public long nextLong() throws IOException {
int p = peeked;
if (p == PEEKED_NONE) {
p = doPeek();
}
if (p == PEEKED_LONG) {
peeked = PEEKED_NONE;
return peekedLong;
}
if (p == PEEKED_NUMBER) {
peekedString = new String(buffer, pos, peekedNumberLength);
pos += peekedNumberLength;
} else if (p == PEEKED_SINGLE_QUOTED || p == PEEKED_DOUBLE_QUOTED) {
peekedString = nextQuotedValue(p == PEEKED_SINGLE_QUOTED ? '\'' : '"');
try {
long result = Long.parseLong(peekedString);
peeked = PEEKED_NONE;
return result;
} catch (NumberFormatException ignored) {
// Fall back to parse as a double below.
}
} else {
throw new IllegalStateException("Expected a long but was " + peek()
+ " at line " + getLineNumber() + " column " + getColumnNumber());
}
peeked = PEEKED_BUFFERED;
double asDouble = Double.parseDouble(peekedString); // don't catch this NumberFormatException.
long result = (long) asDouble;
if (result != asDouble) { // Make sure no precision was lost casting to 'long'.
throw new NumberFormatException("Expected a long but was " + peekedString
+ " at line " + getLineNumber() + " column " + getColumnNumber());
}
peekedString = null;
peeked = PEEKED_NONE;
return result;
}
/**
* Returns the string up to but not including {@code quote}, unescaping any character escape
* sequences encountered along the way. The opening quote should have already been read. This
* consumes the closing quote, but does not include it in the returned string.
*
* @param quote either ' or ".
* @throws NumberFormatException if any unicode escape sequences are malformed.
*/
private String nextQuotedValue(char quote) throws IOException {
// Like nextNonWhitespace, this uses locals 'p' and 'l' to save inner-loop field access.
char[] buffer = this.buffer;
StringBuilder builder = new StringBuilder();
while (true) {
int p = pos;
int l = limit;
/* the index of the first character not yet appended to the builder. */
int start = p;
while (p < l) {
int c = buffer[p++];
if (c == quote) {
pos = p;
builder.append(buffer, start, p - start - 1);
return builder.toString();
} else if (c == '\\') {
pos = p;
builder.append(buffer, start, p - start - 1);
builder.append(readEscapeCharacter());
p = pos;
l = limit;
start = p;
} else if (c == '\n') {
lineNumber++;
lineStart = p;
}
}
builder.append(buffer, start, p - start);
pos = p;
if (!fillBuffer(1)) {
throw syntaxError("Unterminated string");
}
}
}
/**
* Returns an unquoted value as a string.
*/
@SuppressWarnings("fallthrough")
private String nextUnquotedValue() throws IOException {
StringBuilder builder = null;
int i = 0;
findNonLiteralCharacter:
while (true) {
for (; pos + i < limit; i++) {
switch (buffer[pos + i]) {
case '/':
case '\\':
case ';':
case '#':
case '=':
checkLenient(); // fall-through
case '{':
case '}':
case '[':
case ']':
case ':':
case ',':
case ' ':
case '\t':
case '\f':
case '\r':
case '\n':
break findNonLiteralCharacter;
}
}
// Attempt to load the entire literal into the buffer at once.
if (i < buffer.length) {
if (fillBuffer(i + 1)) {
continue;
} else {
break;
}
}
// use a StringBuilder when the value is too long. This is too long to be a number!
if (builder == null) {
builder = new StringBuilder();
}
builder.append(buffer, pos, i);
pos += i;
i = 0;
if (!fillBuffer(1)) {
break;
}
}
String result;
if (builder == null) {
result = new String(buffer, pos, i);
} else {
builder.append(buffer, pos, i);
result = builder.toString();
}
pos += i;
return result;
}
private void skipQuotedValue(char quote) throws IOException {
// Like nextNonWhitespace, this uses locals 'p' and 'l' to save inner-loop field access.
char[] buffer = this.buffer;
do {
int p = pos;
int l = limit;
/* the index of the first character not yet appended to the builder. */
while (p < l) {
int c = buffer[p++];
if (c == quote) {
pos = p;
return;
} else if (c == '\\') {
pos = p;
readEscapeCharacter();
p = pos;
l = limit;
} else if (c == '\n') {
lineNumber++;
lineStart = p;
}
}
pos = p;
} while (fillBuffer(1));
throw syntaxError("Unterminated string");
}
private void skipUnquotedValue() throws IOException {
do {
int i = 0;
for (; pos + i < limit; i++) {
switch (buffer[pos + i]) {
case '/':
case '\\':
case ';':
case '#':
case '=':
checkLenient(); // fall-through
case '{':
case '}':
case '[':
case ']':
case ':':
case ',':
case ' ':
case '\t':
case '\f':
case '\r':
case '\n':
pos += i;
return;
}
}
pos += i;
} while (fillBuffer(1));
}
/**
* Returns the {@link com.google.gson.stream.JsonToken#NUMBER int} value of the next token,
* consuming it. If the next token is a string, this method will attempt to parse it as an
* int. If the next token's numeric value cannot be exactly represented by a Java {@code int},
* this method throws.
*
* @throws IllegalStateException if the next token is not a literal value.
* @throws NumberFormatException if the next literal value cannot be parsed as a number, or
* exactly represented as an int.
*/
public int nextInt() throws IOException {
int p = peeked;
if (p == PEEKED_NONE) {
p = doPeek();
}
int result;
if (p == PEEKED_LONG) {
result = (int) peekedLong;
if (peekedLong != result) { // Make sure no precision was lost casting to 'int'.
throw new NumberFormatException("Expected an int but was " + peekedLong
+ " at line " + getLineNumber() + " column " + getColumnNumber());
}
peeked = PEEKED_NONE;
return result;
}
if (p == PEEKED_NUMBER) {
peekedString = new String(buffer, pos, peekedNumberLength);
pos += peekedNumberLength;
} else if (p == PEEKED_SINGLE_QUOTED || p == PEEKED_DOUBLE_QUOTED) {
peekedString = nextQuotedValue(p == PEEKED_SINGLE_QUOTED ? '\'' : '"');
try {
result = Integer.parseInt(peekedString);
peeked = PEEKED_NONE;
return result;
} catch (NumberFormatException ignored) {
// Fall back to parse as a double below.
}
} else {
throw new IllegalStateException("Expected an int but was " + peek()
+ " at line " + getLineNumber() + " column " + getColumnNumber());
}
peeked = PEEKED_BUFFERED;
double asDouble = Double.parseDouble(peekedString); // don't catch this NumberFormatException.
result = (int) asDouble;
if (result != asDouble) { // Make sure no precision was lost casting to 'int'.
throw new NumberFormatException("Expected an int but was " + peekedString
+ " at line " + getLineNumber() + " column " + getColumnNumber());
}
peekedString = null;
peeked = PEEKED_NONE;
return result;
}
/**
* Closes this JSON reader and the underlying {@link java.io.Reader}.
*/
public void close() throws IOException {
peeked = PEEKED_NONE;
stack[0] = JsonScope.CLOSED;
stackSize = 1;
in.close();
}
/**
* Skips the next value recursively. If it is an object or array, all nested elements are
* skipped. This method is intended for use when the JSON token stream contains unrecognized
* or unhandled values.
*/
public void skipValue() throws IOException {
int count = 0;
do {
int p = peeked;
if (p == PEEKED_NONE) {
p = doPeek();
}
if (p == PEEKED_BEGIN_ARRAY) {
push(JsonScope.EMPTY_ARRAY);
count++;
} else if (p == PEEKED_BEGIN_OBJECT) {
push(JsonScope.EMPTY_OBJECT);
count++;
} else if (p == PEEKED_END_ARRAY) {
stackSize--;
count--;
} else if (p == PEEKED_END_OBJECT) {
stackSize--;
count--;
} else if (p == PEEKED_UNQUOTED_NAME || p == PEEKED_UNQUOTED) {
skipUnquotedValue();
} else if (p == PEEKED_SINGLE_QUOTED || p == PEEKED_SINGLE_QUOTED_NAME) {
skipQuotedValue('\'');
} else if (p == PEEKED_DOUBLE_QUOTED || p == PEEKED_DOUBLE_QUOTED_NAME) {
skipQuotedValue('"');
} else if (p == PEEKED_NUMBER) {
pos += peekedNumberLength;
}
peeked = PEEKED_NONE;
} while (count != 0);
}
private void push(int newTop) {
if (stackSize == stack.length) {
int[] newStack = new int[stackSize * 2];
System.arraycopy(stack, 0, newStack, 0, stackSize);
stack = newStack;
}
stack[stackSize++] = newTop;
}
/**
* Returns true once {@code limit - pos >= minimum}. If the data is exhausted before that many
* characters are available, this returns false.
*/
private boolean fillBuffer(int minimum) throws IOException {
char[] buffer = this.buffer;
lineStart -= pos;
if (limit != pos) {
limit -= pos;
System.arraycopy(buffer, pos, buffer, 0, limit);
} else {
limit = 0;
}
pos = 0;
int total;
while ((total = in.read(buffer, limit, buffer.length - limit)) != -1) {
limit += total;
// if this is the first read, consume an optional byte order mark (BOM) if it exists
if (lineNumber == 0 && lineStart == 0 && limit > 0 && buffer[0] == '\ufeff') {
pos++;
lineStart++;
minimum++;
}
if (limit >= minimum) {
return true;
}
}
return false;
}
private int getLineNumber() {
return lineNumber + 1;
}
private int getColumnNumber() {
return pos - lineStart + 1;
}
/**
* Returns the next character in the stream that is neither whitespace nor a part of a
* comment. When this returns, the returned character is always at {@code buffer[pos-1]}; this
* means the caller can always push back the returned character by decrementing {@code pos}.
*/
private int nextNonWhitespace(boolean throwOnEof) throws IOException {
/*
* This code uses ugly local variables 'p' and 'l' representing the 'pos'
* and 'limit' fields respectively. Using locals rather than fields saves
* a few field reads for each whitespace character in a pretty-printed
* document, resulting in a 5% speedup. We need to flush 'p' to its field
* before any (potentially indirect) call to fillBuffer() and reread both
* 'p' and 'l' after any (potentially indirect) call to the same method.
*/
char[] buffer = this.buffer;
int p = pos;
int l = limit;
while (true) {
if (p == l) {
pos = p;
if (!fillBuffer(1)) {
break;
}
p = pos;
l = limit;
}
int c = buffer[p++];
if (c == '\n') {
lineNumber++;
lineStart = p;
continue;
} else if (c == ' ' || c == '\r' || c == '\t') {
continue;
}
if (c == '/') {
pos = p;
if (p == l) {
pos--; // push back '/' so it's still in the buffer when this method returns
boolean charsLoaded = fillBuffer(2);
pos++; // consume the '/' again
if (!charsLoaded) {
return c;
}
}
checkLenient();
char peek = buffer[pos];
switch (peek) {
case '*':
// skip a /* c-style comment */
pos++;
if (!skipTo("*/")) {
throw syntaxError("Unterminated comment");
}
p = pos + 2;
l = limit;
continue;
case '/':
// skip a // end-of-line comment
pos++;
skipToEndOfLine();
p = pos;
l = limit;
continue;
default:
return c;
}
} else if (c == '#') {
pos = p;
/*
* Skip a # hash end-of-line comment. The JSON RFC doesn't
* specify this behaviour, but it's required to parse
* existing documents. See http://b/2571423.
*/
checkLenient();
skipToEndOfLine();
p = pos;
l = limit;
} else {
pos = p;
return c;
}
}
if (throwOnEof) {
throw new EOFException("End of input"
+ " at line " + getLineNumber() + " column " + getColumnNumber());
} else {
return -1;
}
}
private void checkLenient() throws IOException {
if (!lenient) {
throw syntaxError("Use JsonReader.setLenient(true) to accept malformed JSON");
}
}
/**
* Advances the position until after the next newline character. If the line is terminated by
* "\r\n", the '\n' must be consumed as whitespace by the caller.
*/
private void skipToEndOfLine() throws IOException {
while (pos < limit || fillBuffer(1)) {
char c = buffer[pos++];
if (c == '\n') {
lineNumber++;
lineStart = pos;
break;
} else if (c == '\r') {
break;
}
}
}
/**
* @param toFind a string to search for. Must not contain a newline.
*/
private boolean skipTo(String toFind) throws IOException {
outer:
for (; pos + toFind.length() <= limit || fillBuffer(toFind.length()); pos++) {
if (buffer[pos] == '\n') {
lineNumber++;
lineStart = pos + 1;
continue;
}
for (int c = 0; c < toFind.length(); c++) {
if (buffer[pos + c] != toFind.charAt(c)) {
continue outer;
}
}
return true;
}
return false;
}
@Override
public String toString() {
return getClass().getSimpleName()
+ " at line " + getLineNumber() + " column " + getColumnNumber();
}
/**
* Unescapes the character identified by the character or characters that immediately follow a
* backslash. The backslash '\' should have already been read. This supports both unicode
* escapes "u000A" and two-character escapes "\n".
*
* @throws NumberFormatException if any unicode escape sequences are malformed.
*/
private char readEscapeCharacter() throws IOException {
if (pos == limit && !fillBuffer(1)) {
throw syntaxError("Unterminated escape sequence");
}
char escaped = buffer[pos++];
switch (escaped) {
case 'u':
if (pos + 4 > limit && !fillBuffer(4)) {
throw syntaxError("Unterminated escape sequence");
}
// Equivalent to Integer.parseInt(stringPool.get(buffer, pos, 4), 16);
char result = 0;
for (int i = pos, end = i + 4; i < end; i++) {
char c = buffer[i];
result <<= 4;
if (c >= '0' && c <= '9') {
result += (c - '0');
} else if (c >= 'a' && c <= 'f') {
result += (c - 'a' + 10);
} else if (c >= 'A' && c <= 'F') {
result += (c - 'A' + 10);
} else {
throw new NumberFormatException("\\u" + new String(buffer, pos, 4));
}
}
pos += 4;
return result;
case 't':
return '\t';
case 'b':
return '\b';
case 'n':
return '\n';
case 'r':
return '\r';
case 'f':
return '\f';
case '\n':
lineNumber++;
lineStart = pos;
// fall-through
case '\'':
case '"':
case '\\':
default:
return escaped;
}
}
/**
* Throws a new IO exception with the given message and a context snippet with this reader's
* content.
*/
private IOException syntaxError(String message) throws IOException {
throw new MalformedJsonException(message
+ " at line " + getLineNumber() + " column " + getColumnNumber());
}
/**
* Consumes the non-execute prefix if it exists.
*/
private void consumeNonExecutePrefix() throws IOException {
// fast forward through the leading whitespace
nextNonWhitespace(true);
pos--;
if (pos + NON_EXECUTE_PREFIX.length > limit && !fillBuffer(NON_EXECUTE_PREFIX.length)) {
return;
}
for (int i = 0; i < NON_EXECUTE_PREFIX.length; i++) {
if (buffer[pos + i] != NON_EXECUTE_PREFIX[i]) {
return; // not a security token!
}
}
// we consumed a security token!
pos += NON_EXECUTE_PREFIX.length;
}
static {
JsonReaderInternalAccess.INSTANCE = new JsonReaderInternalAccess() {
@Override
public void promoteNameToValue(JsonReader reader) throws IOException {
if (reader instanceof JsonTreeReader) {
((JsonTreeReader) reader).promoteNameToValue();
return;
}
int p = reader.peeked;
if (p == PEEKED_NONE) {
p = reader.doPeek();
}
if (p == PEEKED_DOUBLE_QUOTED_NAME) {
reader.peeked = PEEKED_DOUBLE_QUOTED;
} else if (p == PEEKED_SINGLE_QUOTED_NAME) {
reader.peeked = PEEKED_SINGLE_QUOTED;
} else if (p == PEEKED_UNQUOTED_NAME) {
reader.peeked = PEEKED_UNQUOTED;
} else {
throw new IllegalStateException("Expected a name but was " + reader.peek() + " "
+ " at line " + reader.getLineNumber() + " column " + reader.getColumnNumber());
}
}
};
}
}