--- /dev/null
+/*
+ * 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 java.io.Closeable;
+import java.io.Flushable;
+import java.io.IOException;
+import java.io.Writer;
+
+import static com.google.gson.stream.JsonScope.DANGLING_NAME;
+import static com.google.gson.stream.JsonScope.EMPTY_ARRAY;
+import static com.google.gson.stream.JsonScope.EMPTY_DOCUMENT;
+import static com.google.gson.stream.JsonScope.EMPTY_OBJECT;
+import static com.google.gson.stream.JsonScope.NONEMPTY_ARRAY;
+import static com.google.gson.stream.JsonScope.NONEMPTY_DOCUMENT;
+import static com.google.gson.stream.JsonScope.NONEMPTY_OBJECT;
+
+/**
+ * Writes a JSON (<a href="http://www.ietf.org/rfc/rfc4627.txt">RFC 4627</a>)
+ * encoded value to a stream, one token at a time. The stream includes both
+ * literal values (strings, numbers, booleans and nulls) as well as the begin
+ * and end delimiters of objects and arrays.
+ *
+ * <h3>Encoding JSON</h3>
+ * To encode your data as JSON, create a new {@code JsonWriter}. Each JSON
+ * document must contain one top-level array or object. Call methods on the
+ * writer as you walk the structure's contents, nesting arrays and objects as
+ * necessary:
+ * <ul>
+ * <li>To write <strong>arrays</strong>, first call {@link #beginArray()}.
+ * Write each of the array's elements with the appropriate {@link #value}
+ * methods or by nesting other arrays and objects. Finally close the array
+ * using {@link #endArray()}.
+ * <li>To write <strong>objects</strong>, first call {@link #beginObject()}.
+ * Write each of the object's properties by alternating calls to
+ * {@link #name} with the property's value. Write property values with the
+ * appropriate {@link #value} method or by nesting other objects or arrays.
+ * Finally close the object using {@link #endObject()}.
+ * </ul>
+ *
+ * <h3>Example</h3>
+ * Suppose we'd like to encode a stream of messages such as the following: <pre> {@code
+ * [
+ * {
+ * "id": 912345678901,
+ * "text": "How do I stream JSON in Java?",
+ * "geo": null,
+ * "user": {
+ * "name": "json_newb",
+ * "followers_count": 41
+ * }
+ * },
+ * {
+ * "id": 912345678902,
+ * "text": "@json_newb just use JsonWriter!",
+ * "geo": [50.454722, -104.606667],
+ * "user": {
+ * "name": "jesse",
+ * "followers_count": 2
+ * }
+ * }
+ * ]}</pre>
+ * This code encodes the above structure: <pre> {@code
+ * public void writeJsonStream(OutputStream out, List<Message> messages) throws IOException {
+ * JsonWriter writer = new JsonWriter(new OutputStreamWriter(out, "UTF-8"));
+ * writer.setIndentSpaces(4);
+ * writeMessagesArray(writer, messages);
+ * writer.close();
+ * }
+ *
+ * public void writeMessagesArray(JsonWriter writer, List<Message> messages) throws IOException {
+ * writer.beginArray();
+ * for (Message message : messages) {
+ * writeMessage(writer, message);
+ * }
+ * writer.endArray();
+ * }
+ *
+ * public void writeMessage(JsonWriter writer, Message message) throws IOException {
+ * writer.beginObject();
+ * writer.name("id").value(message.getId());
+ * writer.name("text").value(message.getText());
+ * if (message.getGeo() != null) {
+ * writer.name("geo");
+ * writeDoublesArray(writer, message.getGeo());
+ * } else {
+ * writer.name("geo").nullValue();
+ * }
+ * writer.name("user");
+ * writeUser(writer, message.getUser());
+ * writer.endObject();
+ * }
+ *
+ * public void writeUser(JsonWriter writer, User user) throws IOException {
+ * writer.beginObject();
+ * writer.name("name").value(user.getName());
+ * writer.name("followers_count").value(user.getFollowersCount());
+ * writer.endObject();
+ * }
+ *
+ * public void writeDoublesArray(JsonWriter writer, List<Double> doubles) throws IOException {
+ * writer.beginArray();
+ * for (Double value : doubles) {
+ * writer.value(value);
+ * }
+ * writer.endArray();
+ * }}</pre>
+ *
+ * <p>Each {@code JsonWriter} may be used to write a single JSON stream.
+ * Instances of this class are not thread safe. Calls that would result in a
+ * malformed JSON string will fail with an {@link IllegalStateException}.
+ *
+ * @author Jesse Wilson
+ * @since 1.6
+ */
+public class JsonWriter implements Closeable, Flushable {
+
+ /*
+ * From RFC 4627, "All Unicode characters may be placed within the
+ * quotation marks except for the characters that must be escaped:
+ * quotation mark, reverse solidus, and the control characters
+ * (U+0000 through U+001F)."
+ *
+ * We also escape '\u2028' and '\u2029', which JavaScript interprets as
+ * newline characters. This prevents eval() from failing with a syntax
+ * error. http://code.google.com/p/google-gson/issues/detail?id=341
+ */
+ private static final String[] REPLACEMENT_CHARS;
+ private static final String[] HTML_SAFE_REPLACEMENT_CHARS;
+ static {
+ REPLACEMENT_CHARS = new String[128];
+ for (int i = 0; i <= 0x1f; i++) {
+ REPLACEMENT_CHARS[i] = String.format("\\u%04x", (int) i);
+ }
+ REPLACEMENT_CHARS['"'] = "\\\"";
+ REPLACEMENT_CHARS['\\'] = "\\\\";
+ REPLACEMENT_CHARS['\t'] = "\\t";
+ REPLACEMENT_CHARS['\b'] = "\\b";
+ REPLACEMENT_CHARS['\n'] = "\\n";
+ REPLACEMENT_CHARS['\r'] = "\\r";
+ REPLACEMENT_CHARS['\f'] = "\\f";
+ HTML_SAFE_REPLACEMENT_CHARS = REPLACEMENT_CHARS.clone();
+ HTML_SAFE_REPLACEMENT_CHARS['<'] = "\\u003c";
+ HTML_SAFE_REPLACEMENT_CHARS['>'] = "\\u003e";
+ HTML_SAFE_REPLACEMENT_CHARS['&'] = "\\u0026";
+ HTML_SAFE_REPLACEMENT_CHARS['='] = "\\u003d";
+ HTML_SAFE_REPLACEMENT_CHARS['\''] = "\\u0027";
+ }
+
+ /** The output data, containing at most one top-level array or object. */
+ private final Writer out;
+
+ private int[] stack = new int[32];
+ private int stackSize = 0;
+ {
+ push(EMPTY_DOCUMENT);
+ }
+
+ /**
+ * A string containing a full set of spaces for a single level of
+ * indentation, or null for no pretty printing.
+ */
+ private String indent;
+
+ /**
+ * The name/value separator; either ":" or ": ".
+ */
+ private String separator = ":";
+
+ private boolean lenient;
+
+ private boolean htmlSafe;
+
+ private String deferredName;
+
+ private boolean serializeNulls = true;
+
+ /**
+ * Creates a new instance that writes a JSON-encoded stream to {@code out}.
+ * For best performance, ensure {@link Writer} is buffered; wrapping in
+ * {@link java.io.BufferedWriter BufferedWriter} if necessary.
+ */
+ public JsonWriter(Writer out) {
+ if (out == null) {
+ throw new NullPointerException("out == null");
+ }
+ this.out = out;
+ }
+
+ /**
+ * Sets the indentation string to be repeated for each level of indentation
+ * in the encoded document. If {@code indent.isEmpty()} the encoded document
+ * will be compact. Otherwise the encoded document will be more
+ * human-readable.
+ *
+ * @param indent a string containing only whitespace.
+ */
+ public final void setIndent(String indent) {
+ if (indent.length() == 0) {
+ this.indent = null;
+ this.separator = ":";
+ } else {
+ this.indent = indent;
+ this.separator = ": ";
+ }
+ }
+
+ /**
+ * Configure this writer to relax its syntax rules. By default, this writer
+ * only emits well-formed JSON as specified by <a
+ * href="http://www.ietf.org/rfc/rfc4627.txt">RFC 4627</a>. Setting the writer
+ * to lenient permits the following:
+ * <ul>
+ * <li>Top-level values of any type. With strict writing, the top-level
+ * value must be an object or an array.
+ * <li>Numbers may be {@link Double#isNaN() NaNs} or {@link
+ * Double#isInfinite() infinities}.
+ * </ul>
+ */
+ public final void setLenient(boolean lenient) {
+ this.lenient = lenient;
+ }
+
+ /**
+ * Returns true if this writer has relaxed syntax rules.
+ */
+ public boolean isLenient() {
+ return lenient;
+ }
+
+ /**
+ * Configure this writer to emit JSON that's safe for direct inclusion in HTML
+ * and XML documents. This escapes the HTML characters {@code <}, {@code >},
+ * {@code &} and {@code =} before writing them to the stream. Without this
+ * setting, your XML/HTML encoder should replace these characters with the
+ * corresponding escape sequences.
+ */
+ public final void setHtmlSafe(boolean htmlSafe) {
+ this.htmlSafe = htmlSafe;
+ }
+
+ /**
+ * Returns true if this writer writes JSON that's safe for inclusion in HTML
+ * and XML documents.
+ */
+ public final boolean isHtmlSafe() {
+ return htmlSafe;
+ }
+
+ /**
+ * Sets whether object members are serialized when their value is null.
+ * This has no impact on array elements. The default is true.
+ */
+ public final void setSerializeNulls(boolean serializeNulls) {
+ this.serializeNulls = serializeNulls;
+ }
+
+ /**
+ * Returns true if object members are serialized when their value is null.
+ * This has no impact on array elements. The default is true.
+ */
+ public final boolean getSerializeNulls() {
+ return serializeNulls;
+ }
+
+ /**
+ * Begins encoding a new array. Each call to this method must be paired with
+ * a call to {@link #endArray}.
+ *
+ * @return this writer.
+ */
+ public JsonWriter beginArray() throws IOException {
+ writeDeferredName();
+ return open(EMPTY_ARRAY, "[");
+ }
+
+ /**
+ * Ends encoding the current array.
+ *
+ * @return this writer.
+ */
+ public JsonWriter endArray() throws IOException {
+ return close(EMPTY_ARRAY, NONEMPTY_ARRAY, "]");
+ }
+
+ /**
+ * Begins encoding a new object. Each call to this method must be paired
+ * with a call to {@link #endObject}.
+ *
+ * @return this writer.
+ */
+ public JsonWriter beginObject() throws IOException {
+ writeDeferredName();
+ return open(EMPTY_OBJECT, "{");
+ }
+
+ /**
+ * Ends encoding the current object.
+ *
+ * @return this writer.
+ */
+ public JsonWriter endObject() throws IOException {
+ return close(EMPTY_OBJECT, NONEMPTY_OBJECT, "}");
+ }
+
+ /**
+ * Enters a new scope by appending any necessary whitespace and the given
+ * bracket.
+ */
+ private JsonWriter open(int empty, String openBracket) throws IOException {
+ beforeValue(true);
+ push(empty);
+ out.write(openBracket);
+ return this;
+ }
+
+ /**
+ * Closes the current scope by appending any necessary whitespace and the
+ * given bracket.
+ */
+ private JsonWriter close(int empty, int nonempty, String closeBracket)
+ throws IOException {
+ int context = peek();
+ if (context != nonempty && context != empty) {
+ throw new IllegalStateException("Nesting problem.");
+ }
+ if (deferredName != null) {
+ throw new IllegalStateException("Dangling name: " + deferredName);
+ }
+
+ stackSize--;
+ if (context == nonempty) {
+ newline();
+ }
+ out.write(closeBracket);
+ return this;
+ }
+
+ 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 the value on the top of the stack.
+ */
+ private int peek() {
+ if (stackSize == 0) {
+ throw new IllegalStateException("JsonWriter is closed.");
+ }
+ return stack[stackSize - 1];
+ }
+
+ /**
+ * Replace the value on the top of the stack with the given value.
+ */
+ private void replaceTop(int topOfStack) {
+ stack[stackSize - 1] = topOfStack;
+ }
+
+ /**
+ * Encodes the property name.
+ *
+ * @param name the name of the forthcoming value. May not be null.
+ * @return this writer.
+ */
+ public JsonWriter name(String name) throws IOException {
+ if (name == null) {
+ throw new NullPointerException("name == null");
+ }
+ if (deferredName != null) {
+ throw new IllegalStateException();
+ }
+ if (stackSize == 0) {
+ throw new IllegalStateException("JsonWriter is closed.");
+ }
+ deferredName = name;
+ return this;
+ }
+
+ private void writeDeferredName() throws IOException {
+ if (deferredName != null) {
+ beforeName();
+ string(deferredName);
+ deferredName = null;
+ }
+ }
+
+ /**
+ * Encodes {@code value}.
+ *
+ * @param value the literal string value, or null to encode a null literal.
+ * @return this writer.
+ */
+ public JsonWriter value(String value) throws IOException {
+ if (value == null) {
+ return nullValue();
+ }
+ writeDeferredName();
+ beforeValue(false);
+ string(value);
+ return this;
+ }
+
+ /**
+ * Encodes {@code null}.
+ *
+ * @return this writer.
+ */
+ public JsonWriter nullValue() throws IOException {
+ if (deferredName != null) {
+ if (serializeNulls) {
+ writeDeferredName();
+ } else {
+ deferredName = null;
+ return this; // skip the name and the value
+ }
+ }
+ beforeValue(false);
+ out.write("null");
+ return this;
+ }
+
+ /**
+ * Encodes {@code value}.
+ *
+ * @return this writer.
+ */
+ public JsonWriter value(boolean value) throws IOException {
+ writeDeferredName();
+ beforeValue(false);
+ out.write(value ? "true" : "false");
+ return this;
+ }
+
+ /**
+ * Encodes {@code value}.
+ *
+ * @param value a finite value. May not be {@link Double#isNaN() NaNs} or
+ * {@link Double#isInfinite() infinities}.
+ * @return this writer.
+ */
+ public JsonWriter value(double value) throws IOException {
+ if (Double.isNaN(value) || Double.isInfinite(value)) {
+ throw new IllegalArgumentException("Numeric values must be finite, but was " + value);
+ }
+ writeDeferredName();
+ beforeValue(false);
+ out.append(Double.toString(value));
+ return this;
+ }
+
+ /**
+ * Encodes {@code value}.
+ *
+ * @return this writer.
+ */
+ public JsonWriter value(long value) throws IOException {
+ writeDeferredName();
+ beforeValue(false);
+ out.write(Long.toString(value));
+ return this;
+ }
+
+ /**
+ * Encodes {@code value}.
+ *
+ * @param value a finite value. May not be {@link Double#isNaN() NaNs} or
+ * {@link Double#isInfinite() infinities}.
+ * @return this writer.
+ */
+ public JsonWriter value(Number value) throws IOException {
+ if (value == null) {
+ return nullValue();
+ }
+
+ writeDeferredName();
+ String string = value.toString();
+ if (!lenient
+ && (string.equals("-Infinity") || string.equals("Infinity") || string.equals("NaN"))) {
+ throw new IllegalArgumentException("Numeric values must be finite, but was " + value);
+ }
+ beforeValue(false);
+ out.append(string);
+ return this;
+ }
+
+ /**
+ * Ensures all buffered data is written to the underlying {@link Writer}
+ * and flushes that writer.
+ */
+ public void flush() throws IOException {
+ if (stackSize == 0) {
+ throw new IllegalStateException("JsonWriter is closed.");
+ }
+ out.flush();
+ }
+
+ /**
+ * Flushes and closes this writer and the underlying {@link Writer}.
+ *
+ * @throws IOException if the JSON document is incomplete.
+ */
+ public void close() throws IOException {
+ out.close();
+
+ int size = stackSize;
+ if (size > 1 || size == 1 && stack[size - 1] != NONEMPTY_DOCUMENT) {
+ throw new IOException("Incomplete document");
+ }
+ stackSize = 0;
+ }
+
+ private void string(String value) throws IOException {
+ String[] replacements = htmlSafe ? HTML_SAFE_REPLACEMENT_CHARS : REPLACEMENT_CHARS;
+ out.write("\"");
+ int last = 0;
+ int length = value.length();
+ for (int i = 0; i < length; i++) {
+ char c = value.charAt(i);
+ String replacement;
+ if (c < 128) {
+ replacement = replacements[c];
+ if (replacement == null) {
+ continue;
+ }
+ } else if (c == '\u2028') {
+ replacement = "\\u2028";
+ } else if (c == '\u2029') {
+ replacement = "\\u2029";
+ } else {
+ continue;
+ }
+ if (last < i) {
+ out.write(value, last, i - last);
+ }
+ out.write(replacement);
+ last = i + 1;
+ }
+ if (last < length) {
+ out.write(value, last, length - last);
+ }
+ out.write("\"");
+ }
+
+ private void newline() throws IOException {
+ if (indent == null) {
+ return;
+ }
+
+ out.write("\n");
+ for (int i = 1, size = stackSize; i < size; i++) {
+ out.write(indent);
+ }
+ }
+
+ /**
+ * Inserts any necessary separators and whitespace before a name. Also
+ * adjusts the stack to expect the name's value.
+ */
+ private void beforeName() throws IOException {
+ int context = peek();
+ if (context == NONEMPTY_OBJECT) { // first in object
+ out.write(',');
+ } else if (context != EMPTY_OBJECT) { // not in an object!
+ throw new IllegalStateException("Nesting problem.");
+ }
+ newline();
+ replaceTop(DANGLING_NAME);
+ }
+
+ /**
+ * Inserts any necessary separators and whitespace before a literal value,
+ * inline array, or inline object. Also adjusts the stack to expect either a
+ * closing bracket or another element.
+ *
+ * @param root true if the value is a new array or object, the two values
+ * permitted as top-level elements.
+ */
+ @SuppressWarnings("fallthrough")
+ private void beforeValue(boolean root) throws IOException {
+ switch (peek()) {
+ case NONEMPTY_DOCUMENT:
+ if (!lenient) {
+ throw new IllegalStateException(
+ "JSON must have only one top-level value.");
+ }
+ // fall-through
+ case EMPTY_DOCUMENT: // first in document
+ if (!lenient && !root) {
+ throw new IllegalStateException(
+ "JSON must start with an array or an object.");
+ }
+ replaceTop(NONEMPTY_DOCUMENT);
+ break;
+
+ case EMPTY_ARRAY: // first in array
+ replaceTop(NONEMPTY_ARRAY);
+ newline();
+ break;
+
+ case NONEMPTY_ARRAY: // another in array
+ out.append(',');
+ newline();
+ break;
+
+ case DANGLING_NAME: // value for name
+ out.append(separator);
+ replaceTop(NONEMPTY_OBJECT);
+ break;
+
+ default:
+ throw new IllegalStateException("Nesting problem.");
+ }
+ }
+}
projects / unical.git / blobdiff