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* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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 org.apache.olingo.odata2.core.uri.expression;
import java.io.IOException;
import java.io.StringWriter;
import java.util.List;
import org.apache.olingo.odata2.api.edm.Edm;
import org.apache.olingo.odata2.api.edm.EdmException;
import org.apache.olingo.odata2.api.edm.EdmLiteral;
import org.apache.olingo.odata2.api.edm.EdmType;
import org.apache.olingo.odata2.api.edm.EdmTyped;
import org.apache.olingo.odata2.api.uri.expression.BinaryExpression;
import org.apache.olingo.odata2.api.uri.expression.BinaryOperator;
import org.apache.olingo.odata2.api.uri.expression.CommonExpression;
import org.apache.olingo.odata2.api.uri.expression.ExpressionVisitor;
import org.apache.olingo.odata2.api.uri.expression.FilterExpression;
import org.apache.olingo.odata2.api.uri.expression.LiteralExpression;
import org.apache.olingo.odata2.api.uri.expression.MemberExpression;
import org.apache.olingo.odata2.api.uri.expression.MethodExpression;
import org.apache.olingo.odata2.api.uri.expression.MethodOperator;
import org.apache.olingo.odata2.api.uri.expression.OrderByExpression;
import org.apache.olingo.odata2.api.uri.expression.OrderExpression;
import org.apache.olingo.odata2.api.uri.expression.PropertyExpression;
import org.apache.olingo.odata2.api.uri.expression.SortOrder;
import org.apache.olingo.odata2.api.uri.expression.UnaryExpression;
import org.apache.olingo.odata2.api.uri.expression.UnaryOperator;
import org.apache.olingo.odata2.core.ep.util.JsonStreamWriter;
/**
*
*/
public class JsonVisitor implements ExpressionVisitor {
@Override
public Object visitFilterExpression(final FilterExpression filterExpression, final String expressionString,
final Object expression) {
return expression;
}
@Override
public Object visitBinary(final BinaryExpression binaryExpression, final BinaryOperator operator,
final Object leftSide, final Object rightSide) {
try {
StringWriter writer = new StringWriter();
JsonStreamWriter jsonStreamWriter = new JsonStreamWriter(writer);
jsonStreamWriter.beginObject().namedStringValueRaw("nodeType", binaryExpression.getKind().toString()).separator()
.namedStringValue("operator", operator.toUriLiteral()).separator().namedStringValueRaw("type",
getType(binaryExpression)).separator().name("left").unquotedValue(leftSide.toString()).separator().name(
"right").unquotedValue(rightSide.toString()).endObject();
writer.flush();
return writer.toString();
} catch (final IOException e) {
return null;
}
}
@Override
public Object visitOrderByExpression(final OrderByExpression orderByExpression, final String expressionString,
final List<Object> orders) {
try {
StringWriter writer = new StringWriter();
JsonStreamWriter jsonStreamWriter = new JsonStreamWriter(writer);
jsonStreamWriter.beginObject().namedStringValueRaw("nodeType", "order collection").separator().name("orders")
.beginArray();
boolean first = true;
for (final Object order : orders) {
if (first) {
first = false;
} else {
jsonStreamWriter.separator();
}
jsonStreamWriter.unquotedValue(order.toString());
}
jsonStreamWriter.endArray().endObject();
writer.flush();
return writer.toString();
} catch (final IOException e) {
return null;
}
}
@Override
public Object visitOrder(final OrderExpression orderExpression, final Object filterResult,
final SortOrder sortOrder) {
try {
StringWriter writer = new StringWriter();
JsonStreamWriter jsonStreamWriter = new JsonStreamWriter(writer);
jsonStreamWriter.beginObject().namedStringValueRaw("nodeType", orderExpression.getKind().toString()).separator()
.namedStringValueRaw("sortorder", sortOrder.toString()).separator().name("expression").unquotedValue(
filterResult.toString()).endObject();
writer.flush();
return writer.toString();
} catch (final IOException e) {
return null;
}
}
@Override
public Object visitLiteral(final LiteralExpression literal, final EdmLiteral edmLiteral) {
try {
StringWriter writer = new StringWriter();
JsonStreamWriter jsonStreamWriter = new JsonStreamWriter(writer);
jsonStreamWriter.beginObject().namedStringValueRaw("nodeType", literal.getKind().toString()).separator()
.namedStringValueRaw("type", getType(literal)).separator().namedStringValue("value", edmLiteral.getLiteral())
.endObject();
writer.flush();
return writer.toString();
} catch (final IOException e) {
return null;
}
}
@Override
public Object visitMethod(final MethodExpression methodExpression, final MethodOperator method,
final List<Object> parameters) {
try {
StringWriter writer = new StringWriter();
JsonStreamWriter jsonStreamWriter = new JsonStreamWriter(writer);
jsonStreamWriter.beginObject().namedStringValueRaw("nodeType", methodExpression.getKind().toString()).separator()
.namedStringValueRaw("operator", method.toUriLiteral()).separator().namedStringValueRaw("type",
getType(methodExpression)).separator().name("parameters").beginArray();
boolean first = true;
for (Object parameter : parameters) {
if (first) {
first = false;
} else {
jsonStreamWriter.separator();
}
jsonStreamWriter.unquotedValue(parameter.toString());
}
jsonStreamWriter.endArray().endObject();
writer.flush();
return writer.toString();
} catch (final IOException e) {
return null;
}
}
@Override
public Object visitMember(final MemberExpression memberExpression, final Object path, final Object property) {
try {
StringWriter writer = new StringWriter();
JsonStreamWriter jsonStreamWriter = new JsonStreamWriter(writer);
jsonStreamWriter.beginObject().namedStringValueRaw("nodeType", memberExpression.getKind().toString()).separator()
.namedStringValueRaw("type", getType(memberExpression)).separator().name("source").unquotedValue(
path.toString()).separator().name("path").unquotedValue(property.toString()).endObject();
writer.flush();
return writer.toString();
} catch (final IOException e) {
return null;
}
}
@Override
public Object visitProperty(final PropertyExpression propertyExpression, final String uriLiteral,
final EdmTyped edmProperty) {
try {
StringWriter writer = new StringWriter();
JsonStreamWriter jsonStreamWriter = new JsonStreamWriter(writer);
jsonStreamWriter.beginObject().namedStringValueRaw("nodeType", propertyExpression.getKind().toString())
.separator().namedStringValue("name", uriLiteral).separator().namedStringValueRaw("type",
getType(propertyExpression)).endObject();
writer.flush();
return writer.toString();
} catch (final IOException e) {
return null;
}
}
@Override
public Object visitUnary(final UnaryExpression unaryExpression, final UnaryOperator operator, final Object operand) {
try {
StringWriter writer = new StringWriter();
JsonStreamWriter jsonStreamWriter = new JsonStreamWriter(writer);
jsonStreamWriter.beginObject().namedStringValueRaw("nodeType", unaryExpression.getKind().toString()).separator()
.namedStringValueRaw("operator", operator.toUriLiteral()).separator().namedStringValueRaw("type",
getType(unaryExpression)).separator().name("operand").unquotedValue(operand.toString()).endObject();
writer.flush();
return writer.toString();
} catch (final IOException e) {
return null;
}
}
private static String getType(final CommonExpression expression) {
try {
final EdmType type = expression.getEdmType();
return type == null ? null : type.getNamespace() + Edm.DELIMITER + type.getName();
} catch (final EdmException e) {
return "EdmException occurred: " + e.getMessage();
}
}
}