Move gson to its own folder

[unical.git] / gson / com / google / gson / JsonStreamParser.java

diff --git a/gson/com/google/gson/JsonStreamParser.java b/gson/com/google/gson/JsonStreamParser.java
new file mode 100644 (file)
index 0000000..f0438db
--- /dev/null
+++ b/gson/com/google/gson/JsonStreamParser.java
@@ -0,0 +1,122 @@
+/*
+ * Copyright (C) 2009 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;
+
+import java.io.EOFException;
+import java.io.IOException;
+import java.io.Reader;
+import java.io.StringReader;
+import java.util.Iterator;
+import java.util.NoSuchElementException;
+
+import com.google.gson.internal.Streams;
+import com.google.gson.stream.JsonReader;
+import com.google.gson.stream.JsonToken;
+import com.google.gson.stream.MalformedJsonException;
+
+/**
+ * A streaming parser that allows reading of multiple {@link JsonElement}s from the specified reader
+ * asynchronously.
+ * 
+ * <p>This class is conditionally thread-safe (see Item 70, Effective Java second edition). To
+ * properly use this class across multiple threads, you will need to add some external
+ * synchronization.  For example:
+ * 
+ * <pre>
+ * JsonStreamParser parser = new JsonStreamParser("['first'] {'second':10} 'third'");
+ * JsonElement element;
+ * synchronized (parser) {  // synchronize on an object shared by threads
+ *   if (parser.hasNext()) {
+ *     element = parser.next();
+ *   }
+ * }
+ * </pre>
+ *
+ * @author Inderjeet Singh
+ * @author Joel Leitch
+ * @since 1.4
+ */
+public final class JsonStreamParser implements Iterator<JsonElement> {
+  private final JsonReader parser;
+  private final Object lock;
+
+  /**
+   * @param json The string containing JSON elements concatenated to each other.
+   * @since 1.4
+   */
+  public JsonStreamParser(String json) {
+    this(new StringReader(json));      
+  }
+  
+  /**
+   * @param reader The data stream containing JSON elements concatenated to each other.
+   * @since 1.4
+   */
+  public JsonStreamParser(Reader reader) {
+    parser = new JsonReader(reader);
+    parser.setLenient(true);
+    lock = new Object();
+  }
+  
+  /**
+   * Returns the next available {@link JsonElement} on the reader. Null if none available.
+   * 
+   * @return the next available {@link JsonElement} on the reader. Null if none available.
+   * @throws JsonParseException if the incoming stream is malformed JSON.
+   * @since 1.4
+   */
+  public JsonElement next() throws JsonParseException {
+    if (!hasNext()) {
+      throw new NoSuchElementException();
+    }
+    
+    try {
+      return Streams.parse(parser);
+    } catch (StackOverflowError e) {
+      throw new JsonParseException("Failed parsing JSON source to Json", e);
+    } catch (OutOfMemoryError e) {
+      throw new JsonParseException("Failed parsing JSON source to Json", e);
+    } catch (JsonParseException e) {
+      throw e.getCause() instanceof EOFException ? new NoSuchElementException() : e;
+    }
+  }
+
+  /**
+   * Returns true if a {@link JsonElement} is available on the input for consumption
+   * @return true if a {@link JsonElement} is available on the input, false otherwise
+   * @since 1.4
+   */
+  public boolean hasNext() {
+    synchronized (lock) {
+      try {
+        return parser.peek() != JsonToken.END_DOCUMENT;
+      } catch (MalformedJsonException e) {
+        throw new JsonSyntaxException(e);
+      } catch (IOException e) {
+        throw new JsonIOException(e);
+      }
+    }
+  }
+
+  /**
+   * This optional {@link Iterator} method is not relevant for stream parsing and hence is not
+   * implemented.
+   * @since 1.4
+   */
+  public void remove() {
+    throw new UnsupportedOperationException();
+  }
+}