Updates to Stream Serialization Libraries (Azure#33270)

Author: alzimmermsft

sdk/core/azure-core/src/main/java/com/azure/core/implementation/http/rest/ReflectionSerializable.java

@@ -566,9 +566,9 @@ public static BinaryData fromByteBuffer(ByteBuffer data) {
      *
      * <!-- src_embed com.azure.core.util.BinaryData.fromListByteBuffer#List -->
      * <pre>
-     * final List&lt;ByteBuffer&gt; data = Stream.of("Some ", "data")
-     *     .map(s -> ByteBuffer.wrap(s.getBytes(StandardCharsets.UTF_8)))
-     *     .collect(Collectors.toList());
+     * final List&lt;ByteBuffer&gt; data = Stream.of&#40;&quot;Some &quot;, &quot;data&quot;&#41;
+     *     .map&#40;s -&gt; ByteBuffer.wrap&#40;s.getBytes&#40;StandardCharsets.UTF_8&#41;&#41;&#41;
+     *     .collect&#40;Collectors.toList&#40;&#41;&#41;;
      * BinaryData binaryData = BinaryData.fromListByteBuffer&#40;data&#41;;
      * System.out.println&#40;binaryData&#41;;
      * </pre>

sdk/core/azure-core/src/main/java/com/azure/core/util/BinaryData.java

@@ -8,6 +8,9 @@
 
 ### Bugs Fixed
 
+- Fixed a bug where `GsonJsonReader.bufferObject` would throw an exception if the starting `JsonToken` was a field name
+  not followed by a start object. Buffering now supports field starting points.
+
 ### Other Changes
 
 ## 1.0.0-beta.1 (2022-09-22)

sdk/core/azure-json-gson/CHANGELOG.md

@@ -233,12 +233,9 @@ public void skipChildren() throws IOException {
 
     @Override
     public JsonReader bufferObject() throws IOException {
-        if (currentToken == JsonToken.START_OBJECT
-            || (currentToken == JsonToken.FIELD_NAME && nextToken() == JsonToken.START_OBJECT)) {
+        if (currentToken == JsonToken.START_OBJECT || currentToken == JsonToken.FIELD_NAME) {
             consumed = true;
-            StringBuilder bufferedObject = new StringBuilder();
-            readChildren(bufferedObject);
-            String json = bufferedObject.toString();
+            String json = readRemainingFieldsAsJsonObject();
             return new GsonJsonReader(new StringReader(json), true, null, json, nonNumericNumbersSupported);
         } else {
             throw new IllegalStateException("Cannot buffer a JSON object from a non-object, non-field name "

sdk/core/azure-json-gson/src/main/java/com/azure/json/gson/GsonJsonReader.java

@@ -301,12 +301,9 @@ public void skipChildren() throws IOException {
 
     @Override
     public JsonReader bufferObject() throws IOException {
-        if (currentToken == JsonToken.START_OBJECT
-            || (currentToken == JsonToken.FIELD_NAME && nextToken() == JsonToken.START_OBJECT)) {
+        if (currentToken == JsonToken.START_OBJECT || currentToken == JsonToken.FIELD_NAME) {
             consumed = true;
-            StringBuilder bufferedObject = new StringBuilder();
-            readChildren(bufferedObject);
-            String json = bufferedObject.toString();
+            String json = readRemainingFieldsAsJsonObject();
             return new GsonJsonReader(new StringReader(json), true, null, json, nonNumericNumbersSupported);
         } else {
             throw new IllegalStateException("Cannot buffer a JSON object from a non-object, non-field name "

sdk/core/azure-json-reflect/src/main/java/com/azure/json/reflect/GsonJsonReader.java

@@ -232,11 +232,8 @@ public void skipChildren() throws IOException {
     @Override
     public JsonReader bufferObject() throws IOException {
         JsonToken currentToken = currentToken();
-        if (currentToken == JsonToken.START_OBJECT
-            || (currentToken == JsonToken.FIELD_NAME && nextToken() == JsonToken.START_OBJECT)) {
-            StringBuilder bufferedObject = new StringBuilder();
-            readChildren(bufferedObject);
-            String json = bufferedObject.toString();
+        if (currentToken == JsonToken.START_OBJECT || currentToken == JsonToken.FIELD_NAME) {
+            String json = readRemainingFieldsAsJsonObject();
             return new JacksonJsonReader(new StringReader(json), true, null, json, nonNumericNumbersSupported);
         } else {
             throw new IllegalStateException("Cannot buffer a JSON object from a non-object, non-field name "

sdk/core/azure-json-reflect/src/main/java/com/azure/json/reflect/JacksonJsonReader.java

@@ -4,10 +4,16 @@
 
 ### Features Added
 
+- Add `JsonReader.readRemainingFieldsAsJsonObject` to support reading the remainder of a JSON object from a field starting
+  point.
+
 ### Breaking Changes
 
 ### Bugs Fixed
 
+- Fixed a bug where the default `JsonReader` would throw an exception if the starting `JsonToken` was a field name
+  not followed by a start object when calling `bufferObject`. Buffering now supports field starting points.
+
 ### Other Changes
 
 ## 1.0.0-beta.1 (2022-09-22)

sdk/core/azure-json/CHANGELOG.md

@@ -11,6 +11,7 @@
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
 
 /**
  * Reads a JSON encoded value as a stream of tokens.
@@ -233,8 +234,12 @@ public final <T> T getNullable(ReadValueCallback<JsonReader, T> nonNullGetter) t
      * Reads and returns the current JSON object the {@link JsonReader} is pointing to. This will mutate the current
      * location of this {@link JsonReader}.
      * <p>
-     * If the {@link #currentToken()} isn't {@link JsonToken#START_OBJECT} or {@link JsonToken#FIELD_NAME} followed by
-     * {@link JsonToken#START_OBJECT} an {@link IllegalStateException} will be thrown.
+     * If the {@link #currentToken()} isn't {@link JsonToken#START_OBJECT} or {@link JsonToken#FIELD_NAME} an
+     * {@link IllegalStateException} will be thrown.
+     * <p>
+     * If the {@link #currentToken()} is {@link JsonToken#FIELD_NAME} this will create a JSON object where the first
+     * JSON field is the {@link #currentToken()} field, meaning this can be called from the middle of a JSON object to
+     * create a new JSON object with only a subset of fields (those remaining from when the method is called).
      * <p>
      * The returned {@link JsonReader} is able to be {@link #reset()} to replay the underlying JSON stream.
      *
@@ -268,37 +273,87 @@ public final <T> T getNullable(ReadValueCallback<JsonReader, T> nonNullGetter) t
      * Recursively reads the JSON token sub-stream if the current token is either {@link JsonToken#START_ARRAY} or
      * {@link JsonToken#START_OBJECT}.
      * <p>
-     * If the current token isn't the beginning of an array or object this method is a no-op.
+     * If the {@link #currentToken()} isn't {@link JsonToken#START_OBJECT} or {@link JsonToken#START_ARRAY} nothing will
+     * be read.
      *
      * @return The raw textual value of the JSON token sub-stream.
      * @throws IOException If the children cannot be read.
      */
     public final String readChildren() throws IOException {
-        return readChildrenInternal(new StringBuilder()).toString();
+        return readInternal(new StringBuilder(), true, false).toString();
     }
 
     /**
      * Recursively reads the JSON token sub-stream if the current token is either {@link JsonToken#START_ARRAY} or
      * {@link JsonToken#START_OBJECT} into the passed {@link StringBuilder}.
      * <p>
-     * If the current token isn't the beginning of an array or object this method is a no-op.
+     * If the {@link #currentToken()} isn't {@link JsonToken#START_OBJECT} or {@link JsonToken#START_ARRAY} nothing will
+     * be read.
      *
      * @param buffer The {@link StringBuilder} where the read sub-stream will be written.
+     * @throws NullPointerException If {@code buffer} is null.
      * @throws IOException If the children cannot be read.
      */
     public final void readChildren(StringBuilder buffer) throws IOException {
-        readChildrenInternal(buffer);
+        readInternal(buffer, true, false);
+    }
+
+    /**
+     * Reads the remaining fields in the current JSON object as a JSON object.
+     * <p>
+     * If the {@link #currentToken()} is {@link JsonToken#START_OBJECT} this functions the same as
+     * {@link #readChildren()}. If the {@link #currentToken()} is {@link JsonToken#FIELD_NAME} this creates a JSON
+     * object where the first field is the current field and reads the remaining fields in the JSON object.
+     * <p>
+     * If the {@link #currentToken()} isn't {@link JsonToken#START_OBJECT} or {@link JsonToken#FIELD_NAME} nothing will
+     * be read.
+     *
+     * @return The raw textual value of the remaining JSON fields.
+     * @throws IOException If the remaining JSON fields cannot be read.
+     */
+    public final String readRemainingFieldsAsJsonObject() throws IOException {
+        return readInternal(new StringBuilder(), false, true).toString();
+    }
+
+    /**
+     * Reads the remaining fields in the current JSON object as a JSON object.
+     * <p>
+     * If the {@link #currentToken()} is {@link JsonToken#START_OBJECT} this functions the same as
+     * {@link #readChildren(StringBuilder)}. If the {@link #currentToken()} is {@link JsonToken#FIELD_NAME} this creates
+     * a JSON object where the first field is the current field and reads the remaining fields in the JSON object.
+     * <p>
+     * If the {@link #currentToken()} isn't {@link JsonToken#START_OBJECT} or {@link JsonToken#FIELD_NAME} nothing will
+     * be read.
+     *
+     * @param buffer The {@link StringBuilder} where the remaining JSON fields will be written.
+     * @throws NullPointerException If {@code buffer} is null.
+     * @throws IOException If the remaining JSON fields cannot be read.
+     */
+    public final void readRemainingFieldsAsJsonObject(StringBuilder buffer) throws IOException {
+        readInternal(buffer, false, true);
     }
 
-    private StringBuilder readChildrenInternal(StringBuilder buffer) throws IOException {
+    private StringBuilder readInternal(StringBuilder buffer, boolean canStartAtArray, boolean canStartAtFieldName)
+        throws IOException {
+        Objects.requireNonNull(buffer, "The 'buffer' used to read the JSON object cannot be null.");
+
         JsonToken token = currentToken();
 
-        // Not pointing to an array or object start, no-op.
-        if (!isStartArrayOrObject(token)) {
+        boolean canRead = (token == JsonToken.START_OBJECT)
+            || (canStartAtArray && token == JsonToken.START_ARRAY)
+            || (canStartAtFieldName && token == JsonToken.FIELD_NAME);
+
+        // Not a valid starting poing.
+        if (!canRead) {
             return buffer;
         }
 
-        buffer.append(getText());
+        if (token == JsonToken.FIELD_NAME) {
+            buffer.append("{\"").append(getText()).append("\":");
+            token = nextToken();
+        }
+
+        appendJson(buffer, token);
 
         // Initial array or object depth is 1.
         int depth = 1;
@@ -328,18 +383,31 @@ private StringBuilder readChildrenInternal(StringBuilder buffer) throws IOExcept
                 buffer.append(',');
             }
 
-            if (token == JsonToken.FIELD_NAME) {
-                buffer.append("\"").append(getFieldName()).append("\":");
-            } else if (token == JsonToken.STRING) {
-                buffer.append("\"").append(getString()).append("\"");
-            } else {
-                buffer.append(getText());
-            }
+            appendJson(buffer, token);
         }
 
         return buffer;
     }
 
+    /**
+     * Convenience method to read a JSON element into a buffer.
+     *
+     * @param buffer The buffer where the JSON element value will be written.
+     * @param token The type of the JSON element.
+     * @throws IOException If an error occurs while reading the JSON element.
+     */
+    private void appendJson(StringBuilder buffer, JsonToken token) throws IOException {
+        // TODO (alzimmer): Think of making this a protected method. This will allow for optimizations such as where
+        //  Jackson can read text directly into a StringBuilder which removes a String copy.
+        if (token == JsonToken.FIELD_NAME) {
+            buffer.append("\"").append(getFieldName()).append("\":");
+        } else if (token == JsonToken.STRING) {
+            buffer.append("\"").append(getString()).append("\"");
+        } else {
+            buffer.append(getText());
+        }
+    }
+
     /**
      * Reads a JSON object.
      * <p>

sdk/core/azure-json/src/main/java/com/azure/json/JsonReader.java

@@ -156,11 +156,8 @@ public void skipChildren() throws IOException {
     @Override
     public JsonReader bufferObject() throws IOException {
         JsonToken currentToken = currentToken();
-        if (currentToken == JsonToken.START_OBJECT
-            || (currentToken == JsonToken.FIELD_NAME && nextToken() == JsonToken.START_OBJECT)) {
-            StringBuilder bufferedObject = new StringBuilder();
-            readChildren(bufferedObject);
-            String json = bufferedObject.toString();
+        if (currentToken == JsonToken.START_OBJECT || currentToken == JsonToken.FIELD_NAME) {
+            String json = readRemainingFieldsAsJsonObject();
             try {
                 return new DefaultJsonReader(FACTORY.createParser(json), true, null, json, nonNumericNumbersSupported);
             } catch (IOException ex) {

sdk/core/azure-json/src/main/java/com/azure/json/implementation/DefaultJsonReader.java

@@ -582,8 +582,8 @@ public void bufferObject(String json, int nextCount) throws IOException {
 
     private static Stream<Arguments> bufferObjectSupplier() {
         return Stream.of(
-            // Arguments.of("{\"test\":\"test\"}", 1),
-            Arguments.of("{\"outerfield\":{\"test\":\"test\"}}", 2)
+            Arguments.of("{\"test\":\"test\"}", 1),
+            Arguments.of("{\"outerfield\":{\"test\":\"test\"}}", 3)
         );
     }
 
@@ -606,11 +606,10 @@ private static Stream<Arguments> bufferObjectIllegalStateSupplier() {
             Arguments.of("null", 1),
             Arguments.of("true", 1),
             Arguments.of("\"hello\"", 1),
-            Arguments.of("{\"outerfield\": []}", 2),
-            Arguments.of("{\"outerfield\": 12}", 2),
-            Arguments.of("{\"outerfield\": null}", 2),
-            Arguments.of("{\"outerfield\": true}", 2),
-            Arguments.of("{\"outerfield\": \"hello\"}", 2)
+            Arguments.of("{\"outerfield\": 12}", 3),
+            Arguments.of("{\"outerfield\": null}", 3),
+            Arguments.of("{\"outerfield\": true}", 3),
+            Arguments.of("{\"outerfield\": \"hello\"}", 3)
         );
     }