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Grace Framework : Grace Web Common
package org.grails.web.json;
import static org.grails.web.json.JSONWriter.Mode.*;
import groovy.lang.Writable;
import java.io.IOException;
import java.io.Writer;
import java.util.Stack;
/*
Copyright (c) 2006 JSON.org
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
The Software shall be used for Good, not Evil.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
*/
/**
* JSONWriter provides a quick and convenient way of producing JSON text.
* The texts produced strictly conform to JSON syntax rules. No whitespace is
* added, so the results are ready for transmission or storage. Each instance of
* JSONWriter can produce one JSON text.
*
* A JSONWriter instance provides a value method for appending
* values to the
* text, and a key
* method for adding keys before values in objects. There are array
* and endArray methods that make and bound array values, and
* object and endObject methods which make and bound
* object values. All of these methods return the JSONWriter instance,
* permitting a cascade style. For example,
* new JSONWriter(myWriter)
* .object()
* .key("JSON")
* .value("Hello, World!")
* .endObject(); which writes
* {"JSON":"Hello, World!"}
*
* The first method called must be array or object.
* There are no methods for adding commas or colons. JSONWriter adds them for
* you. Objects and arrays can be nested up to 20 levels deep.
*
* This can sometimes be easier than using a JSONObject to build a string.
*
* @author JSON.org
* @version 2
*/
public class JSONWriter {
/**
* The comma flag determines if a comma should be output before the next
* value.
*/
protected boolean comma;
/**
* The current mode. Values:
*/
protected Mode mode;
/**
* The Mode stack.
*/
private Stack stack = new Stack<>();
/**
* The writer that will receive the output.
*/
protected Writer writer;
/**
* Make a fresh JSONWriter. It can be used to build one JSON text.
*/
public JSONWriter(Writer w) {
this.comma = false;
this.mode = INIT;
this.writer = w;
}
private static class WritableString implements Writable {
private String string;
WritableString(String string) {
this.string = string;
}
@Override
public Writer writeTo(Writer out) throws IOException {
out.write(string);
return out;
}
public String toString() {
return string;
}
}
/**
* Append a value.
* @param s A string value.
* @return this
*/
protected JSONWriter append(String s) {
if (s == null) {
throw new JSONException("Null pointer");
}
return append(new WritableString(s));
}
protected JSONWriter append(Writable writableValue) {
if (this.mode == OBJECT || this.mode == ARRAY) {
try {
if (this.comma && this.mode == ARRAY) {
this.comma();
}
writableValue.writeTo(writer);
} catch (IOException e) {
throw new JSONException(e);
}
if (this.mode == OBJECT) {
this.mode = KEY;
}
this.comma = true;
return this;
}
throw new JSONException("Value out of sequence: expected mode to be OBJECT or ARRAY when writing '" + writableValue + "' but was " + this.mode);
}
protected void comma() {
try {
this.writer.write(',');
} catch (IOException e) {
throw new JSONException(e);
}
}
/**
* Begin appending a new array. All values until the balancing
* endArray will be appended to this array. The
* endArray method must be called to mark the array's end.
*
* @return this
*/
public JSONWriter array() {
if (this.mode == INIT || this.mode == OBJECT || this.mode == ARRAY) {
this.push(ARRAY);
this.append("[");
this.comma = false;
return this;
}
throw new JSONException("Misplaced array: expected mode of INIT, OBJECT or ARRAY but was " + this.mode);
}
/**
* End something.
*
* @param m Mode
* @param c Closing character
* @return this
*/
protected JSONWriter end(Mode m, char c) {
if (this.mode != m) {
throw new JSONException(m == OBJECT ? "Misplaced endObject." :
"Misplaced endArray.");
}
this.pop(m);
try {
this.writer.write(c);
} catch (IOException e) {
throw new JSONException(e);
}
this.comma = true;
return this;
}
/**
* End an array. This method most be called to balance calls to
* array.
*
* @return this
*/
public JSONWriter endArray() {
return end(ARRAY, ']');
}
/**
* End an object. This method most be called to balance calls to
* object.
*
* @return this
*/
public JSONWriter endObject() {
return end(KEY, '}');
}
/**
* Append a key. The key will be associated with the next value. In an
* object, every value must be preceded by a key.
*
* @param s A key string.
* @return this
*/
public JSONWriter key(String s) {
if (s == null) {
throw new JSONException("Null key.");
}
if (this.mode == KEY) {
try {
if (this.comma) {
this.comma();
}
JSONObject.writeQuoted(this.writer, s);
this.writer.write(':');
this.comma = false;
this.mode = OBJECT;
return this;
} catch (IOException e) {
throw new JSONException(e);
}
}
throw new JSONException("Misplaced key: expected mode of KEY but was " + this.mode);
}
/**
* Begin appending a new object. All keys and values until the balancing
* endObject will be appended to this object. The
* endObject method must be called to mark the object's end.
*
* @return this
*/
public JSONWriter object() {
if (this.mode == INIT) {
this.mode = OBJECT;
}
if (this.mode == OBJECT || this.mode == ARRAY) {
this.append("{");
this.push(KEY);
this.comma = false;
return this;
}
throw new JSONException("Misplaced object: expected mode of INIT, OBJECT or ARRAY but was " + this.mode);
}
/**
* Pop an array or object scope.
*
* @param c The scope to close.
*/
protected void pop(Mode c) {
if (this.stack.size() == 0 || this.stack.pop() != c) {
throw new JSONException("Nesting error.");
}
if (this.stack.size() > 0)
this.mode = this.stack.peek();
else
this.mode = DONE;
}
/**
* Push an array or object scope.
*
* @param c The scope to open.
*/
protected void push(Mode c) {
this.stack.push(c);
this.mode = c;
}
/**
* Append either the value true or the value
* false.
*
* @param b A boolean.
* @return this
*/
public JSONWriter value(boolean b) {
return append(b ? "true" : "false");
}
/**
* Append a double value.
*
* @param d A double.
* @return this
*/
public JSONWriter value(double d) {
return value(Double.valueOf(d));
}
/**
* Append a long value.
*
* @param l A long.
* @return this
*/
public JSONWriter value(long l) {
return append(Long.toString(l));
}
/**
* Append a number value
*
* @param number
* @return
*/
public JSONWriter value(Number number) {
return number != null ? append(number.toString()) : valueNull();
}
public JSONWriter valueNull() {
return append(nullWritable);
}
static Writable nullWritable = new NullWritable();
private static class NullWritable implements Writable {
@Override
public Writer writeTo(Writer out) throws IOException {
out.write("null");
return out;
}
}
/**
* Append an object value.
*
* @param o The object to append. It can be null, or a Boolean, Number,
* String, JSONObject, or JSONArray.
* @return this
*/
public JSONWriter value(Object o) {
return o != null ? append(new QuotedWritable(o)) : valueNull();
}
private static class QuotedWritable implements Writable {
Object o;
QuotedWritable(Object o) {
this.o = o;
}
@Override
public Writer writeTo(Writer out) throws IOException {
JSONObject.writeValue(out, o);
return out;
}
public String toString() {
return String.valueOf(o);
}
}
/**
* Enumeration of the possible modes of the JSONWriter
*/
protected enum Mode {
INIT,
OBJECT,
ARRAY,
KEY,
DONE
}
}