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/*
* Copyright 2011 10gen 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.mongodb.hadoop.pig;
import com.mongodb.BasicDBObjectBuilder;
import com.mongodb.util.JSON;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.pig.ResourceSchema;
import org.apache.pig.ResourceSchema.ResourceFieldSchema;
import org.apache.pig.data.Tuple;
import org.apache.pig.impl.logicalLayer.schema.Schema;
import org.apache.pig.impl.util.Utils;
import org.bson.BasicBSONObject;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
/*
* Defines pretty simplified and MongoDB-like
* Domain Specific Language that helps with updating
* documents in a collection.
*
* Can be used to specify 'query', 'update', and 'options'
* in a MongoDB update operation on a collection.
*
*/
public class JSONPigReplace {
// create logger for use, in debugging
private static final Log LOG = LogFactory.getLog(JSONPigReplace.class);
// BSON representing initStrs
private final BasicBSONObject[] initBSONs;
// string used to represent pig object that should be 'unnamed'
private String unnamedStr;
// Map of keys to replace in initStr to objects they represent
private HashMap reps;
/*
* @param String[] str : Array of BSONObject JSON String representations
* (potentially with some values to replace --> in the form $elem)
*/
public JSONPigReplace(final String[] str) {
initBSONs = new BasicBSONObject[str.length];
reps = new HashMap();
for (int i = 0; i < str.length; i++) {
initBSONs[i] = (BasicBSONObject) JSON.parse(str[i]);
// extract all strings that start with a $ in initStr
try {
Matcher m = Pattern.compile("\\$(\\w+)").matcher(str[i]);
while (m.find()) {
reps.put(m.group(1), null);
}
} catch (Exception e) {
LOG.error("Error while extracting strings to replace");
}
}
}
/*
* Returns result of substituting pig objects in Tuple t into
* initStr
*
* @param Tuple t : Pig tuple containing pig objects
* @param Object s : Schema representing Tuple t
* @param String un : String to represent un-named Schema Fields
*
* @return Array of BasicBSONObjects that contain all replacements for "marked" strings
*/
public BasicBSONObject[] substitute(final Tuple t,
final Object s,
final String un) throws Exception {
unnamedStr = un;
final ResourceFieldSchema[] fields;
try {
final ResourceSchema schema;
if (s instanceof String) {
schema = new ResourceSchema(Utils.getSchemaFromString((String) s));
} else if (s instanceof Schema) {
schema = new ResourceSchema((Schema) s);
} else if (s instanceof ResourceSchema) {
schema = (ResourceSchema) s;
} else {
throw new IllegalArgumentException("Schema must be represented either by a string or a Schema object");
}
fields = schema.getFields();
} catch (Exception e) {
throw new IllegalArgumentException("Invalid Schema Format");
}
// Make Tuple t into BSONObject using schema provided and store result in pObj
final BasicDBObjectBuilder builder = BasicDBObjectBuilder.start();
for (int i = 0; i < fields.length; i++) {
writeField(builder, fields[i], t.get(i));
}
// BSONObject that represents Pig Tuple input using Pig Schema
BasicBSONObject pObj = (BasicBSONObject) builder.get();
// fill map of replacement strings to corresponding objects to replace these strings with
fillReplacementMap(pObj);
// Now, replace replacement strings (of form $elem) with corresponding objects in pObj
return replaceAll(initBSONs, reps);
}
/*
* Fills map of replacement strings (reps) with entries that
* map replacement strings to corresponding objects to replace these strings with
*
* @param Object pObj : Object representing pig tuple
*/
private void fillReplacementMap(final Object pObj) throws IOException {
if (pObj instanceof BasicBSONObject || pObj instanceof Map) {
@SuppressWarnings("unchecked")
Map p = (Map) pObj;
Object val;
for (String k : p.keySet()) {
val = p.get(k);
if (reps.containsKey(k)) {
reps.put(k, val);
}
// check if 'val' is an array or an embedded BSON document
else if (val instanceof BasicBSONObject || val instanceof ArrayList) {
fillReplacementMap(val);
}
}
} else if (pObj instanceof ArrayList) {
for (Object o : (ArrayList) pObj) {
fillReplacementMap(o);
}
}
}
/*
* static method to
* use reps (map of strings to replace to object -> corresponding replacements)
* to make replacements in the BSONObject to act on
*
* @param BasicBSONObject[] ins : BSONObjects to make replacements in
* @param HashMap reps : replacement map
*
* @return Array of BasicBSONObjects : the result of replacements
*/
public static BasicBSONObject[] replaceAll(final BasicBSONObject[] ins, final Map reps) {
// results of replacements
BasicBSONObject[] res = new BasicBSONObject[ins.length];
for (int i = 0; i < res.length; i++) {
try {
res[i] = replaceAll(ins[i], reps);
} catch (Exception e) {
LOG.error(e.getMessage(), e);
}
}
return res;
}
/*
* static method to
* use reps (map of strings to replace to object -> corresponding replacements)
* to make replacements in the BSONObject to act on
*
* @param BasicBSONObject in : BSONObject to make replacements in
* @param HashMap reps : replacement map
*
* @return BasicBSONObject : result of replacing "marked" strings specified in reps
*/
public static BasicBSONObject replaceAll(final BasicBSONObject in, final Map reps) {
if (in == null) {
throw new IllegalArgumentException("JSON/BasicBSONObject to make substitutions in cannot be null!");
}
BasicBSONObject res = new BasicBSONObject();
String k;
Object v;
for (Entry e : in.entrySet()) {
k = e.getKey();
v = e.getValue();
// v is a nested BasicBSONObject or an array
if (v instanceof BasicBSONObject) {
res.put(k, replaceAll((BasicBSONObject) v, reps));
} else {
if (v instanceof String && ((String) v).startsWith("$")) {
res.put(k, reps.get(((String) v).substring(1)));
} else {
res.put(k, v);
}
}
}
return res;
}
/*
* Writes value in field in Object d into builder
*
* @param BasicDBObjectBuilder builder : builds BSON Object
* @param ResourceFieldSchema field : field in schema
*/
private void writeField(final BasicDBObjectBuilder builder,
final ResourceFieldSchema field,
final Object d) throws Exception {
// top-level fields should have a name
if (field == null) {
throw new IllegalArgumentException("Top-level fields should have a name");
}
// convert Object d into BSON format more suited for storage
Object convertedType = BSONStorage.getTypeForBSON(d, field, unnamedStr);
if (convertedType instanceof Map) {
//noinspection unchecked
for (Entry entry : ((Map) convertedType).entrySet()) {
builder.add(entry.getKey(), entry.getValue());
}
} else {
builder.add(field.getName(), convertedType);
}
}
}
