/**
* 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.avro.io.parsing;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import org.apache.avro.AvroTypeException;
import org.apache.avro.Schema;
import org.apache.avro.Schema.Field;
import org.apache.avro.io.Encoder;
import org.apache.avro.io.EncoderFactory;
import org.codehaus.jackson.JsonNode;
/**
* The class that generates a resolving grammar to resolve between two
* schemas.
*/
public class ResolvingGrammarGenerator extends ValidatingGrammarGenerator {
/**
* Resolves the writer schema <tt>writer</tt> and the reader schema
* <tt>reader</tt> and returns the start symbol for the grammar generated.
* @param writer The schema used by the writer
* @param reader The schema used by the reader
* @return The start symbol for the resolving grammar
* @throws IOException
*/
public final Symbol generate(Schema writer, Schema reader)
throws IOException {
return Symbol.root(generate(writer, reader, new HashMap<LitS, Symbol>()));
}
/**
* Resolves the writer schema <tt>writer</tt> and the reader schema
* <tt>reader</tt> and returns the start symbol for the grammar generated.
* If there is already a symbol in the map <tt>seen</tt> for resolving the
* two schemas, then that symbol is returned. Otherwise a new symbol is
* generated and returnd.
* @param writer The schema used by the writer
* @param reader The schema used by the reader
* @param seen The <reader-schema, writer-schema> to symbol
* map of start symbols of resolving grammars so far.
* @return The start symbol for the resolving grammar
* @throws IOException
*/
public Symbol generate(Schema writer, Schema reader,
Map<LitS, Symbol> seen) throws IOException
{
final Schema.Type writerType = writer.getType();
final Schema.Type readerType = reader.getType();
if (writerType == readerType) {
switch (writerType) {
case NULL:
return Symbol.NULL;
case BOOLEAN:
return Symbol.BOOLEAN;
case INT:
return Symbol.INT;
case LONG:
return Symbol.LONG;
case FLOAT:
return Symbol.FLOAT;
case DOUBLE:
return Symbol.DOUBLE;
case STRING:
return Symbol.STRING;
case BYTES:
return Symbol.BYTES;
case FIXED:
if (writer.getFullName().equals(reader.getFullName())
&& writer.getFixedSize() == reader.getFixedSize()) {
return Symbol.seq(Symbol.intCheckAction(writer.getFixedSize()),
Symbol.FIXED);
}
break;
case ENUM:
if (writer.getFullName() == null
|| writer.getFullName().equals(reader.getFullName())) {
return Symbol.seq(mkEnumAdjust(writer.getEnumSymbols(),
reader.getEnumSymbols()), Symbol.ENUM);
}
break;
case ARRAY:
return Symbol.seq(Symbol.repeat(Symbol.ARRAY_END,
generate(writer.getElementType(),
reader.getElementType(), seen)),
Symbol.ARRAY_START);
case MAP:
return Symbol.seq(Symbol.repeat(Symbol.MAP_END,
generate(writer.getValueType(),
reader.getValueType(), seen), Symbol.STRING),
Symbol.MAP_START);
case RECORD:
return resolveRecords(writer, reader, seen);
case UNION:
return resolveUnion(writer, reader, seen);
default:
throw new AvroTypeException("Unkown type for schema: " + writerType);
}
} else { // writer and reader are of different types
if (writerType == Schema.Type.UNION) {
return resolveUnion(writer, reader, seen);
}
switch (readerType) {
case LONG:
switch (writerType) {
case INT:
return Symbol.resolve(super.generate(writer, seen), Symbol.LONG);
}
break;
case FLOAT:
switch (writerType) {
case INT:
case LONG:
return Symbol.resolve(super.generate(writer, seen), Symbol.FLOAT);
}
break;
case DOUBLE:
switch (writerType) {
case INT:
case LONG:
case FLOAT:
return Symbol.resolve(super.generate(writer, seen), Symbol.DOUBLE);
}
break;
case BYTES:
switch (writerType) {
case STRING:
return Symbol.resolve(super.generate(writer, seen), Symbol.BYTES);
}
break;
case STRING:
switch (writerType) {
case BYTES:
return Symbol.resolve(super.generate(writer, seen), Symbol.STRING);
}
break;
case UNION:
int j = bestBranch(reader, writer);
if (j >= 0) {
Symbol s = generate(writer, reader.getTypes().get(j), seen);
return Symbol.seq(Symbol.unionAdjustAction(j, s), Symbol.UNION);
}
break;
case NULL:
case BOOLEAN:
case INT:
case ENUM:
case ARRAY:
case MAP:
case RECORD:
case FIXED:
break;
default:
throw new RuntimeException("Unexpected schema type: " + readerType);
}
}
return Symbol.error("Found " + writer.getFullName()
+ ", expecting " + reader.getFullName());
}
private Symbol resolveUnion(Schema writer, Schema reader,
Map<LitS, Symbol> seen) throws IOException {
List<Schema> alts = writer.getTypes();
final int size = alts.size();
Symbol[] symbols = new Symbol[size];
String[] labels = new String[size];
/**
* We construct a symbol without filling the arrays. Please see
* {@link Symbol#production} for the reason.
*/
int i = 0;
for (Schema w : alts) {
symbols[i] = generate(w, reader, seen);
labels[i] = w.getFullName();
i++;
}
return Symbol.seq(Symbol.alt(symbols, labels),
Symbol.writerUnionAction());
}
private Symbol resolveRecords(Schema writer, Schema reader,
Map<LitS, Symbol> seen) throws IOException {
LitS wsc = new LitS2(writer, reader);
Symbol result = seen.get(wsc);
if (result == null) {
List<Field> wfields = writer.getFields();
List<Field> rfields = reader.getFields();
// First, compute reordering of reader fields, plus
// number elements in the result's production
Field[] reordered = new Field[rfields.size()];
int ridx = 0;
int count = 1 + wfields.size();
for (Field f : wfields) {
Field rdrField = reader.getField(f.name());
if (rdrField != null) {
reordered[ridx++] = rdrField;
}
}
for (Field rf : rfields) {
String fname = rf.name();
if (writer.getField(fname) == null) {
if (rf.defaultValue() == null) {
result = Symbol.error("Found " + writer.getFullName()
+ ", expecting " + reader.getFullName()
+ ", missing required field " + fname);
seen.put(wsc, result);
return result;
} else {
reordered[ridx++] = rf;
count += 3;
}
}
}
Symbol[] production = new Symbol[count];
production[--count] = Symbol.fieldOrderAction(reordered);
/**
* We construct a symbol without filling the array. Please see
* {@link Symbol#production} for the reason.
*/
result = Symbol.seq(production);
seen.put(wsc, result);
/*
* For now every field in read-record with no default value
* must be in write-record.
* Write record may have additional fields, which will be
* skipped during read.
*/
// Handle all the writer's fields
for (Field wf : wfields) {
String fname = wf.name();
Field rf = reader.getField(fname);
if (rf == null) {
production[--count] =
Symbol.skipAction(generate(wf.schema(), wf.schema(), seen));
} else {
production[--count] =
generate(wf.schema(), rf.schema(), seen);
}
}
// Add default values for fields missing from Writer
for (Field rf : rfields) {
String fname = rf.name();
Field wf = writer.getField(fname);
if (wf == null) {
byte[] bb = getBinary(rf.schema(), rf.defaultValue());
production[--count] = Symbol.defaultStartAction(bb);
production[--count] = generate(rf.schema(), rf.schema(), seen);
production[--count] = Symbol.DEFAULT_END_ACTION;
}
}
}
return result;
}
private static EncoderFactory factory = new EncoderFactory().configureBufferSize(32);
/**
* Returns the Avro binary encoded version of <tt>n</tt> according to
* the schema <tt>s</tt>.
* @param s The schema for encoding
* @param n The Json node that has the value to be encoded.
* @return The binary encoded version of <tt>n</tt>.
* @throws IOException
*/
private static byte[] getBinary(Schema s, JsonNode n) throws IOException {
ByteArrayOutputStream out = new ByteArrayOutputStream();
Encoder e = factory.binaryEncoder(out, null);
encode(e, s, n);
e.flush();
return out.toByteArray();
}
/**
* Encodes the given Json node <tt>n</tt> on to the encoder <tt>e</tt>
* according to the schema <tt>s</tt>.
* @param e The encoder to encode into.
* @param s The schema for the object being encoded.
* @param n The Json node to encode.
* @throws IOException
*/
public static void encode(Encoder e, Schema s, JsonNode n)
throws IOException {
switch (s.getType()) {
case RECORD:
for (Field f : s.getFields()) {
String name = f.name();
JsonNode v = n.get(name);
if (v == null) {
v = f.defaultValue();
}
if (v == null) {
throw new AvroTypeException("No default value for: " + name);
}
encode(e, f.schema(), v);
}
break;
case ENUM:
e.writeEnum(s.getEnumOrdinal(n.getTextValue()));
break;
case ARRAY:
e.writeArrayStart();
e.setItemCount(n.size());
Schema i = s.getElementType();
for (JsonNode node : n) {
e.startItem();
encode(e, i, node);
}
e.writeArrayEnd();
break;
case MAP:
e.writeMapStart();
e.setItemCount(n.size());
Schema v = s.getValueType();
for (Iterator<String> it = n.getFieldNames(); it.hasNext();) {
e.startItem();
String key = it.next();
e.writeString(key);
encode(e, v, n.get(key));
}
e.writeMapEnd();
break;
case UNION:
e.writeIndex(0);
encode(e, s.getTypes().get(0), n);
break;
case FIXED:
if (!n.isTextual())
throw new AvroTypeException("Non-string default value for fixed: "+n);
byte[] bb = n.getTextValue().getBytes("ISO-8859-1");
if (bb.length != s.getFixedSize()) {
bb = Arrays.copyOf(bb, s.getFixedSize());
}
e.writeFixed(bb);
break;
case STRING:
if (!n.isTextual())
throw new AvroTypeException("Non-string default value for string: "+n);
e.writeString(n.getTextValue());
break;
case BYTES:
if (!n.isTextual())
throw new AvroTypeException("Non-string default value for bytes: "+n);
e.writeBytes(n.getTextValue().getBytes("ISO-8859-1"));
break;
case INT:
if (!n.isNumber())
throw new AvroTypeException("Non-numeric default value for int: "+n);
e.writeInt(n.getIntValue());
break;
case LONG:
if (!n.isNumber())
throw new AvroTypeException("Non-numeric default value for long: "+n);
e.writeLong(n.getLongValue());
break;
case FLOAT:
if (!n.isNumber())
throw new AvroTypeException("Non-numeric default value for float: "+n);
e.writeFloat((float) n.getDoubleValue());
break;
case DOUBLE:
if (!n.isNumber())
throw new AvroTypeException("Non-numeric default value for double: "+n);
e.writeDouble(n.getDoubleValue());
break;
case BOOLEAN:
if (!n.isBoolean())
throw new AvroTypeException("Non-boolean default for boolean: "+n);
e.writeBoolean(n.getBooleanValue());
break;
case NULL:
if (!n.isNull())
throw new AvroTypeException("Non-null default value for null type: "+n);
e.writeNull();
break;
}
}
private static Symbol mkEnumAdjust(List<String> wsymbols,
List<String> rsymbols){
Object[] adjustments = new Object[wsymbols.size()];
for (int i = 0; i < adjustments.length; i++) {
int j = rsymbols.indexOf(wsymbols.get(i));
adjustments[i] = (j == -1 ? "No match for " + wsymbols.get(i)
: new Integer(j));
}
return Symbol.enumAdjustAction(rsymbols.size(), adjustments);
}
private static int bestBranch(Schema r, Schema w) {
Schema.Type vt = w.getType();
// first scan for exact match
int j = 0;
for (Schema b : r.getTypes()) {
if (vt == b.getType())
if (vt == Schema.Type.RECORD || vt == Schema.Type.ENUM ||
vt == Schema.Type.FIXED) {
String vname = w.getFullName();
String bname = b.getFullName();
if ((vname != null && vname.equals(bname))
|| vname == bname && vt == Schema.Type.RECORD)
return j;
} else
return j;
j++;
}
// then scan match via numeric promotion
j = 0;
for (Schema b : r.getTypes()) {
switch (vt) {
case INT:
switch (b.getType()) {
case LONG: case DOUBLE:
return j;
}
break;
case LONG:
case FLOAT:
switch (b.getType()) {
case DOUBLE:
return j;
}
break;
case STRING:
switch (b.getType()) {
case BYTES:
return j;
}
break;
case BYTES:
switch (b.getType()) {
case STRING:
return j;
}
break;
}
j++;
}
return -1;
}
/**
* Clever trick which differentiates items put into
* <code>seen</code> by {@link ValidatingGrammarGenerator#validating validating()}
* from those put in by {@link ValidatingGrammarGenerator#resolving resolving()}.
*/
static class LitS2 extends ValidatingGrammarGenerator.LitS {
public Schema expected;
public LitS2(Schema actual, Schema expected) {
super(actual);
this.expected = expected;
}
public boolean equals(Object o) {
if (! (o instanceof LitS2)) return false;
LitS2 other = (LitS2) o;
return actual == other.actual && expected == other.expected;
}
public int hashCode() {
return super.hashCode() + expected.hashCode();
}
}
}