| package com.google.polo.json; |
| |
| import java.io.IOException; |
| import java.io.Writer; |
| |
| /* |
| 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. |
| * <p> |
| * A JSONWriter instance provides a <code>value</code> method for appending |
| * values to the |
| * text, and a <code>key</code> |
| * method for adding keys before values in objects. There are <code>array</code> |
| * and <code>endArray</code> methods that make and bound array values, and |
| * <code>object</code> and <code>endObject</code> methods which make and bound |
| * object values. All of these methods return the JSONWriter instance, |
| * permitting a cascade style. For example, <pre> |
| * new JSONWriter(myWriter) |
| * .object() |
| * .key("JSON") |
| * .value("Hello, World!") |
| * .endObject();</pre> which writes <pre> |
| * {"JSON":"Hello, World!"}</pre> |
| * <p> |
| * The first method called must be <code>array</code> or <code>object</code>. |
| * 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. |
| * <p> |
| * This can sometimes be easier than using a JSONObject to build a string. |
| * @author JSON.org |
| * @version 2008-09-18 |
| */ |
| public class JSONWriter { |
| private static final int maxdepth = 20; |
| |
| /** |
| * The comma flag determines if a comma should be output before the next |
| * value. |
| */ |
| private boolean comma; |
| |
| /** |
| * The current mode. Values: |
| * 'a' (array), |
| * 'd' (done), |
| * 'i' (initial), |
| * 'k' (key), |
| * 'o' (object). |
| */ |
| protected char mode; |
| |
| /** |
| * The object/array stack. |
| */ |
| private JSONObject stack[]; |
| |
| /** |
| * The stack top index. A value of 0 indicates that the stack is empty. |
| */ |
| private int top; |
| |
| /** |
| * 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 = 'i'; |
| this.stack = new JSONObject[maxdepth]; |
| this.top = 0; |
| this.writer = w; |
| } |
| |
| /** |
| * Append a value. |
| * @param s A string value. |
| * @return this |
| * @throws JSONException If the value is out of sequence. |
| */ |
| private JSONWriter append(String s) throws JSONException { |
| if (s == null) { |
| throw new JSONException("Null pointer"); |
| } |
| if (this.mode == 'o' || this.mode == 'a') { |
| try { |
| if (this.comma && this.mode == 'a') { |
| this.writer.write(','); |
| } |
| this.writer.write(s); |
| } catch (IOException e) { |
| throw new JSONException(e); |
| } |
| if (this.mode == 'o') { |
| this.mode = 'k'; |
| } |
| this.comma = true; |
| return this; |
| } |
| throw new JSONException("Value out of sequence."); |
| } |
| |
| /** |
| * Begin appending a new array. All values until the balancing |
| * <code>endArray</code> will be appended to this array. The |
| * <code>endArray</code> method must be called to mark the array's end. |
| * @return this |
| * @throws JSONException If the nesting is too deep, or if the object is |
| * started in the wrong place (for example as a key or after the end of the |
| * outermost array or object). |
| */ |
| public JSONWriter array() throws JSONException { |
| if (this.mode == 'i' || this.mode == 'o' || this.mode == 'a') { |
| this.push(null); |
| this.append("["); |
| this.comma = false; |
| return this; |
| } |
| throw new JSONException("Misplaced array."); |
| } |
| |
| /** |
| * End something. |
| * @param m Mode |
| * @param c Closing character |
| * @return this |
| * @throws JSONException If unbalanced. |
| */ |
| private JSONWriter end(char m, char c) throws JSONException { |
| if (this.mode != m) { |
| throw new JSONException(m == 'o' ? "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 |
| * <code>array</code>. |
| * @return this |
| * @throws JSONException If incorrectly nested. |
| */ |
| public JSONWriter endArray() throws JSONException { |
| return this.end('a', ']'); |
| } |
| |
| /** |
| * End an object. This method most be called to balance calls to |
| * <code>object</code>. |
| * @return this |
| * @throws JSONException If incorrectly nested. |
| */ |
| public JSONWriter endObject() throws JSONException { |
| return this.end('k', '}'); |
| } |
| |
| /** |
| * 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 |
| * @throws JSONException If the key is out of place. For example, keys |
| * do not belong in arrays or if the key is null. |
| */ |
| public JSONWriter key(String s) throws JSONException { |
| if (s == null) { |
| throw new JSONException("Null key."); |
| } |
| if (this.mode == 'k') { |
| try { |
| if (this.comma) { |
| this.writer.write(','); |
| } |
| stack[top - 1].putOnce(s, Boolean.TRUE); |
| this.writer.write(JSONObject.quote(s)); |
| this.writer.write(':'); |
| this.comma = false; |
| this.mode = 'o'; |
| return this; |
| } catch (IOException e) { |
| throw new JSONException(e); |
| } |
| } |
| throw new JSONException("Misplaced key."); |
| } |
| |
| |
| /** |
| * Begin appending a new object. All keys and values until the balancing |
| * <code>endObject</code> will be appended to this object. The |
| * <code>endObject</code> method must be called to mark the object's end. |
| * @return this |
| * @throws JSONException If the nesting is too deep, or if the object is |
| * started in the wrong place (for example as a key or after the end of the |
| * outermost array or object). |
| */ |
| public JSONWriter object() throws JSONException { |
| if (this.mode == 'i') { |
| this.mode = 'o'; |
| } |
| if (this.mode == 'o' || this.mode == 'a') { |
| this.append("{"); |
| this.push(new JSONObject()); |
| this.comma = false; |
| return this; |
| } |
| throw new JSONException("Misplaced object."); |
| |
| } |
| |
| |
| /** |
| * Pop an array or object scope. |
| * @param c The scope to close. |
| * @throws JSONException If nesting is wrong. |
| */ |
| private void pop(char c) throws JSONException { |
| if (this.top <= 0) { |
| throw new JSONException("Nesting error."); |
| } |
| char m = this.stack[this.top - 1] == null ? 'a' : 'k'; |
| if (m != c) { |
| throw new JSONException("Nesting error."); |
| } |
| this.top -= 1; |
| this.mode = this.top == 0 ? 'd' : this.stack[this.top - 1] == null ? 'a' : 'k'; |
| } |
| |
| /** |
| * Push an array or object scope. |
| * @param c The scope to open. |
| * @throws JSONException If nesting is too deep. |
| */ |
| private void push(JSONObject jo) throws JSONException { |
| if (this.top >= maxdepth) { |
| throw new JSONException("Nesting too deep."); |
| } |
| this.stack[this.top] = jo; |
| this.mode = jo == null ? 'a' : 'k'; |
| this.top += 1; |
| } |
| |
| |
| /** |
| * Append either the value <code>true</code> or the value |
| * <code>false</code>. |
| * @param b A boolean. |
| * @return this |
| * @throws JSONException |
| */ |
| public JSONWriter value(boolean b) throws JSONException { |
| return this.append(b ? "true" : "false"); |
| } |
| |
| /** |
| * Append a double value. |
| * @param d A double. |
| * @return this |
| * @throws JSONException If the number is not finite. |
| */ |
| public JSONWriter value(double d) throws JSONException { |
| return this.value(new Double(d)); |
| } |
| |
| /** |
| * Append a long value. |
| * @param l A long. |
| * @return this |
| * @throws JSONException |
| */ |
| public JSONWriter value(long l) throws JSONException { |
| return this.append(Long.toString(l)); |
| } |
| |
| |
| /** |
| * Append an object value. |
| * @param o The object to append. It can be null, or a Boolean, Number, |
| * String, JSONObject, or JSONArray, or an object with a toJSONString() |
| * method. |
| * @return this |
| * @throws JSONException If the value is out of sequence. |
| */ |
| public JSONWriter value(Object o) throws JSONException { |
| return this.append(JSONObject.valueToString(o)); |
| } |
| } |