/*
* 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.smartandroid.sa.json.stream;
import java.io.Closeable;
import java.io.EOFException;
import java.io.IOException;
import java.io.Reader;
import java.util.ArrayList;
import java.util.List;
/**
* 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 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"));
* return readMessagesArray(reader);
* }
*
* 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 final class JsonReader implements Closeable {
/** The only non-execute prefix this parser permits */
private static final char[] NON_EXECUTE_PREFIX = ")]}'\n".toCharArray();
private final StringPool stringPool = new StringPool();
/** 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.
*/
private final char[] buffer = new char[1024];
private int pos = 0;
private int limit = 0;
/*
* The offset of the first character in the buffer.
*/
private int bufferStartLine = 1;
private int bufferStartColumn = 1;
private final List<JsonScope> stack = new ArrayList<JsonScope>();
{
push(JsonScope.EMPTY_DOCUMENT);
}
/**
* True if we've already read the next token. If we have, the string value
* for that token will be assigned to {@code value} if such a string value
* exists. And the token type will be assigned to {@code token} if the token
* type is known. The token type may be null for literals, since we derive
* that lazily.
*/
private boolean hasToken;
/**
* The type of the next token to be returned by {@link #peek} and
* {@link #advance}, or {@code null} if it is unknown and must first be
* derived from {@code value}. This value is undefined if {@code hasToken}
* is false.
*/
private JsonToken token;
/** The text of the next name. */
private String name;
/** The text of the next literal value. */
private String value;
/** True if we're currently handling a skipValue() call. */
private boolean skipping = false;
/**
* 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 void setLenient(boolean lenient) {
this.lenient = lenient;
}
/**
* Returns true if this parser is liberal in what it accepts.
*/
public 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 {
expect(JsonToken.BEGIN_ARRAY);
}
/**
* Consumes the next token from the JSON stream and asserts that it is the
* end of the current array.
*/
public void endArray() throws IOException {
expect(JsonToken.END_ARRAY);
}
/**
* Consumes the next token from the JSON stream and asserts that it is the
* beginning of a new object.
*/
public void beginObject() throws IOException {
expect(JsonToken.BEGIN_OBJECT);
}
/**
* Consumes the next token from the JSON stream and asserts that it is the
* end of the current array.
*/
public void endObject() throws IOException {
expect(JsonToken.END_OBJECT);
}
/**
* Consumes {@code expected}.
*/
private void expect(JsonToken expected) throws IOException {
quickPeek();
if (token != expected) {
throw new IllegalStateException("Expected " + expected
+ " but was " + peek());
}
advance();
}
/**
* Returns true if the current array or object has another element.
*/
public boolean hasNext() throws IOException {
quickPeek();
return token != JsonToken.END_OBJECT && token != JsonToken.END_ARRAY;
}
/**
* Returns the type of the next token without consuming it.
*/
public JsonToken peek() throws IOException {
quickPeek();
if (token == null) {
decodeLiteral();
}
return token;
}
/**
* Ensures that a token is ready. After this call either {@code token} or
* {@code value} will be non-null. To ensure {@code token} has a definitive
* value, use {@link #peek()}
*/
private JsonToken quickPeek() throws IOException {
if (hasToken) {
return token;
}
switch (peekStack()) {
case EMPTY_DOCUMENT:
if (lenient) {
consumeNonExecutePrefix();
}
replaceTop(JsonScope.NONEMPTY_DOCUMENT);
JsonToken firstToken = nextValue();
if (!lenient && firstToken != JsonToken.BEGIN_ARRAY
&& firstToken != JsonToken.BEGIN_OBJECT) {
syntaxError("Expected JSON document to start with '[' or '{'");
}
return firstToken;
case EMPTY_ARRAY:
return nextInArray(true);
case NONEMPTY_ARRAY:
return nextInArray(false);
case EMPTY_OBJECT:
return nextInObject(true);
case DANGLING_NAME:
return objectValue();
case NONEMPTY_OBJECT:
return nextInObject(false);
case NONEMPTY_DOCUMENT:
try {
JsonToken token = nextValue();
if (lenient) {
return token;
}
throw syntaxError("Expected EOF");
} catch (EOFException e) {
hasToken = true; // TODO: avoid throwing here?
return token = JsonToken.END_DOCUMENT;
}
case CLOSED:
throw new IllegalStateException("JsonReader is closed");
default:
throw new AssertionError();
}
}
/**
* Consumes the non-execute prefix if it exists.
*/
private void consumeNonExecutePrefix() throws IOException {
// fast forward through the leading whitespace
nextNonWhitespace();
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;
}
/**
* Advances the cursor in the JSON stream to the next token.
*/
private JsonToken advance() throws IOException {
quickPeek();
JsonToken result = token;
hasToken = false;
token = null;
value = null;
name = null;
return result;
}
/**
* Returns the next token, a {@link JsonToken#NAME property name}, and
* consumes it.
*
* @throws IOException
* if the next token in the stream is not a property name.
*/
public String nextName() throws IOException {
quickPeek();
if (token != JsonToken.NAME) {
throw new IllegalStateException("Expected a name but was " + peek());
}
String result = name;
advance();
return result;
}
/**
* Returns the {@link 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 {
peek();
if (value == null
|| (token != JsonToken.STRING && token != JsonToken.NUMBER)) {
throw new IllegalStateException("Expected a string but was "
+ peek());
}
String result = value;
advance();
return result;
}
/**
* Returns the {@link 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 {
quickPeek();
if (value == null || token == JsonToken.STRING) {
throw new IllegalStateException("Expected a boolean but was "
+ peek());
}
boolean result;
if (value.equalsIgnoreCase("true")) {
result = true;
} else if (value.equalsIgnoreCase("false")) {
result = false;
} else {
throw new IllegalStateException("Not a boolean: " + value);
}
advance();
return result;
}
/**
* 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 {
quickPeek();
if (value == null || token == JsonToken.STRING) {
throw new IllegalStateException("Expected null but was " + peek());
}
if (!value.equalsIgnoreCase("null")) {
throw new IllegalStateException("Not a null: " + value);
}
advance();
}
/**
* Returns the {@link 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.
*
* @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 {
quickPeek();
if (value == null) {
throw new IllegalStateException("Expected a double but was "
+ peek());
}
double result = Double.parseDouble(value);
if ((result >= 1.0d && value.startsWith("0"))) {
throw new NumberFormatException("JSON forbids octal prefixes: "
+ value);
}
if (!lenient && (Double.isNaN(result) || Double.isInfinite(result))) {
throw new NumberFormatException("JSON forbids NaN and infinities: "
+ value);
}
advance();
return result;
}
/**
* Returns the {@link 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 {
quickPeek();
if (value == null) {
throw new IllegalStateException("Expected a long but was " + peek());
}
long result;
try {
result = Long.parseLong(value);
} catch (NumberFormatException ignored) {
double asDouble = Double.parseDouble(value); // don't catch this
// NumberFormatException
result = (long) asDouble;
if (result != asDouble) {
throw new NumberFormatException(value);
}
}
if (result >= 1L && value.startsWith("0")) {
throw new NumberFormatException("JSON forbids octal prefixes: "
+ value);
}
advance();
return result;
}
/**
* Returns the {@link 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 {
quickPeek();
if (value == null) {
throw new IllegalStateException("Expected an int but was " + peek());
}
int result;
try {
result = Integer.parseInt(value);
} catch (NumberFormatException ignored) {
double asDouble = Double.parseDouble(value); // don't catch this
// NumberFormatException
result = (int) asDouble;
if (result != asDouble) {
throw new NumberFormatException(value);
}
}
if (result >= 1L && value.startsWith("0")) {
throw new NumberFormatException("JSON forbids octal prefixes: "
+ value);
}
advance();
return result;
}
/**
* Closes this JSON reader and the underlying {@link Reader}.
*/
public void close() throws IOException {
hasToken = false;
value = null;
token = null;
stack.clear();
stack.add(JsonScope.CLOSED);
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 {
skipping = true;
try {
int count = 0;
do {
JsonToken token = advance();
if (token == JsonToken.BEGIN_ARRAY
|| token == JsonToken.BEGIN_OBJECT) {
count++;
} else if (token == JsonToken.END_ARRAY
|| token == JsonToken.END_OBJECT) {
count--;
}
} while (count != 0);
} finally {
skipping = false;
}
}
private JsonScope peekStack() {
return stack.get(stack.size() - 1);
}
private JsonScope pop() {
return stack.remove(stack.size() - 1);
}
private void push(JsonScope newTop) {
stack.add(newTop);
}
/**
* Replace the value on the top of the stack with the given value.
*/
private void replaceTop(JsonScope newTop) {
stack.set(stack.size() - 1, newTop);
}
@SuppressWarnings("fallthrough")
private JsonToken nextInArray(boolean firstElement) throws IOException {
if (firstElement) {
replaceTop(JsonScope.NONEMPTY_ARRAY);
} else {
/* Look for a comma before each element after the first element. */
switch (nextNonWhitespace()) {
case ']':
pop();
hasToken = true;
return token = JsonToken.END_ARRAY;
case ';':
checkLenient(); // fall-through
case ',':
break;
default:
throw syntaxError("Unterminated array");
}
}
switch (nextNonWhitespace()) {
case ']':
if (firstElement) {
pop();
hasToken = true;
return token = JsonToken.END_ARRAY;
}
// fall-through to handle ",]"
case ';':
case ',':
/* In lenient mode, a 0-length literal means 'null' */
checkLenient();
pos--;
hasToken = true;
value = "null";
return token = JsonToken.NULL;
default:
pos--;
return nextValue();
}
}
@SuppressWarnings("fallthrough")
private JsonToken nextInObject(boolean firstElement) throws IOException {
/*
* Read delimiters. Either a comma/semicolon separating this and the
* previous name-value pair, or a close brace to denote the end of the
* object.
*/
if (firstElement) {
/* Peek to see if this is the empty object. */
switch (nextNonWhitespace()) {
case '}':
pop();
hasToken = true;
return token = JsonToken.END_OBJECT;
default:
pos--;
}
} else {
switch (nextNonWhitespace()) {
case '}':
pop();
hasToken = true;
return token = JsonToken.END_OBJECT;
case ';':
case ',':
break;
default:
throw syntaxError("Unterminated object");
}
}
/* Read the name. */
int quote = nextNonWhitespace();
switch (quote) {
case '\'':
checkLenient(); // fall-through
case '"':
name = nextString((char) quote);
break;
default:
checkLenient();
pos--;
name = nextLiteral();
if (name.length() == 0) {
throw syntaxError("Expected name");
}
}
replaceTop(JsonScope.DANGLING_NAME);
hasToken = true;
return token = JsonToken.NAME;
}
private JsonToken objectValue() throws IOException {
/*
* Read the name/value separator. Usually a colon ':'. In lenient mode
* we also accept an equals sign '=', or an arrow "=>".
*/
switch (nextNonWhitespace()) {
case ':':
break;
case '=':
checkLenient();
if ((pos < limit || fillBuffer(1)) && buffer[pos] == '>') {
pos++;
}
break;
default:
throw syntaxError("Expected ':'");
}
replaceTop(JsonScope.NONEMPTY_OBJECT);
return nextValue();
}
@SuppressWarnings("fallthrough")
private JsonToken nextValue() throws IOException {
int c = nextNonWhitespace();
switch (c) {
case '{':
push(JsonScope.EMPTY_OBJECT);
hasToken = true;
return token = JsonToken.BEGIN_OBJECT;
case '[':
push(JsonScope.EMPTY_ARRAY);
hasToken = true;
return token = JsonToken.BEGIN_ARRAY;
case '\'':
checkLenient(); // fall-through
case '"':
value = nextString((char) c);
hasToken = true;
return token = JsonToken.STRING;
default:
pos--;
return readLiteral();
}
}
/**
* 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 {
// Before clobbering the old characters, update where buffer starts
for (int i = 0; i < pos; i++) {
if (buffer[i] == '\n') {
bufferStartLine++;
bufferStartColumn = 1;
} else {
bufferStartColumn++;
}
}
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 (bufferStartLine == 1 && bufferStartColumn == 1 && limit > 0
&& buffer[0] == '\ufeff') {
pos++;
bufferStartColumn--;
}
if (limit >= minimum) {
return true;
}
}
return false;
}
private int getLineNumber() {
int result = bufferStartLine;
for (int i = 0; i < pos; i++) {
if (buffer[i] == '\n') {
result++;
}
}
return result;
}
private int getColumnNumber() {
int result = bufferStartColumn;
for (int i = 0; i < pos; i++) {
if (buffer[i] == '\n') {
result = 1;
} else {
result++;
}
}
return result;
}
private int nextNonWhitespace() throws IOException {
while (pos < limit || fillBuffer(1)) {
int c = buffer[pos++];
switch (c) {
case '\t':
case ' ':
case '\n':
case '\r':
continue;
case '/':
if (pos == limit && !fillBuffer(1)) {
return c;
}
checkLenient();
char peek = buffer[pos];
switch (peek) {
case '*':
// skip a /* c-style comment */
pos++;
if (!skipTo("*/")) {
throw syntaxError("Unterminated comment");
}
pos += 2;
continue;
case '/':
// skip a // end-of-line comment
pos++;
skipToEndOfLine();
continue;
default:
return c;
}
case '#':
/*
* 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();
continue;
default:
return c;
}
}
throw new EOFException("End of input");
}
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 == '\r' || c == '\n') {
break;
}
}
}
private boolean skipTo(String toFind) throws IOException {
outer: for (; pos + toFind.length() <= limit
|| fillBuffer(toFind.length()); pos++) {
for (int c = 0; c < toFind.length(); c++) {
if (buffer[pos + c] != toFind.charAt(c)) {
continue outer;
}
}
return true;
}
return false;
}
/**
* 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 nextString(char quote) throws IOException {
StringBuilder builder = null;
do {
/* the index of the first character not yet appended to the builder. */
int start = pos;
while (pos < limit) {
int c = buffer[pos++];
if (c == quote) {
if (skipping) {
return "skipped!";
} else if (builder == null) {
return stringPool.get(buffer, start, pos - start - 1);
} else {
builder.append(buffer, start, pos - start - 1);
return builder.toString();
}
} else if (c == '\\') {
if (builder == null) {
builder = new StringBuilder();
}
builder.append(buffer, start, pos - start - 1);
builder.append(readEscapeCharacter());
start = pos;
}
}
if (builder == null) {
builder = new StringBuilder();
}
builder.append(buffer, start, pos - start);
} while (fillBuffer(1));
throw syntaxError("Unterminated string");
}
/**
* Returns the string up to but not including any delimiter characters. This
* does not consume the delimiter character.
*/
@SuppressWarnings("fallthrough")
private String nextLiteral() throws IOException {
StringBuilder builder = null;
do {
/* the index of the first character not yet appended to the builder. */
int start = pos;
while (pos < limit) {
int c = buffer[pos++];
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':
pos--;
if (skipping) {
return "skipped!";
} else if (builder == null) {
return stringPool.get(buffer, start, pos - start);
} else {
builder.append(buffer, start, pos - start);
return builder.toString();
}
}
}
if (builder == null) {
builder = new StringBuilder();
}
builder.append(buffer, start, pos - start);
} while (fillBuffer(1));
return builder.toString();
}
@Override
public String toString() {
return getClass().getSimpleName() + " near " + getSnippet();
}
/**
* 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");
}
String hex = stringPool.get(buffer, pos, 4);
pos += 4;
return (char) Integer.parseInt(hex, 16);
case 't':
return '\t';
case 'b':
return '\b';
case 'n':
return '\n';
case 'r':
return '\r';
case 'f':
return '\f';
case '\'':
case '"':
case '\\':
default:
return escaped;
}
}
/**
* Reads a null, boolean, numeric or unquoted string literal value.
*/
private JsonToken readLiteral() throws IOException {
String literal = nextLiteral();
if (literal.length() == 0) {
throw syntaxError("Expected literal value");
}
value = literal;
hasToken = true;
return token = null; // use decodeLiteral() to get the token type
}
/**
* Assigns {@code nextToken} based on the value of {@code nextValue}.
*/
private void decodeLiteral() throws IOException {
if (value.equalsIgnoreCase("null")) {
token = JsonToken.NULL;
} else if (value.equalsIgnoreCase("true")
|| value.equalsIgnoreCase("false")) {
token = JsonToken.BOOLEAN;
} else {
try {
Double.parseDouble(value); // this work could potentially be
// cached
token = JsonToken.NUMBER;
} catch (NumberFormatException ignored) {
// this must be an unquoted string
checkLenient();
token = JsonToken.STRING;
}
}
}
/**
* 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());
}
private CharSequence getSnippet() {
StringBuilder snippet = new StringBuilder();
int beforePos = Math.min(pos, 20);
snippet.append(buffer, pos - beforePos, beforePos);
int afterPos = Math.min(limit - pos, 20);
snippet.append(buffer, pos, afterPos);
return snippet;
}
}