X-Git-Url: http://git.ieval.ro/?a=blobdiff_plain;f=src%2Fcom%2Fgoogle%2Fgson%2Fstream%2FJsonWriter.java;fp=src%2Fcom%2Fgoogle%2Fgson%2Fstream%2FJsonWriter.java;h=6a935ddbbe0cdfe52bead7c4d6bf44b5f4ea2bef;hb=cfd903b6b5113fa28991db19bf98d0340ae709a4;hp=0000000000000000000000000000000000000000;hpb=819197b2305a94ab4924c5ae37a3fad762078448;p=unical.git

diff --git a/src/com/google/gson/stream/JsonWriter.java b/src/com/google/gson/stream/JsonWriter.java
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+++ b/src/com/google/gson/stream/JsonWriter.java
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+/*
+ * 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.");
+    }
+  }
+}