Start fixing #39, fix first verified problems (possibly not full)

Author: cowtowncoder

avro/src/main/java/com/fasterxml/jackson/dataformat/avro/AvroSchema.java

@@ -36,6 +36,33 @@ public String getSchemaType() {
 
     public Schema getAvroSchema() { return _avroSchema; }
 
+    /**
+     * Method that will consider this schema instance (used as so-called "Writer Schema"),
+     * and specified "Reader Schema" instance, and will either construct a new schema
+     * with appropriate translations, to use for reading (if reader and writer schemas are
+     * not same); or, if schemas are the same, return `this`.
+     *<p>
+     * Note that neither `this` instance nor `readerSchema` is ever modified: if an altered
+     * version is needed, a new schema object will be constructed.
+     *
+     * @param readerSchema "Reader Schema" to use (in Avro terms): schema that specified how
+     *    reader wants to see the data; specifies part of translation needed along with this
+     *    schema (which would be "Writer Schema" in Avro terms).
+     *
+     * @since 2.9
+     */
+    public AvroSchema withReaderSchema(AvroSchema readerSchema) {
+        Schema w = _avroSchema;
+        Schema r = readerSchema.getAvroSchema();
+        
+        if (r.equals(w)) {
+            return this;
+        }
+        Schema newSchema = Schema.applyAliases(w, r);
+System.err.println("Translated schema ->\n"+newSchema.toString(true));
+        return new AvroSchema(newSchema);
+    }
+
     public AvroStructureReader getReader()
     {
         AvroStructureReader r = _reader.get();
@@ -46,4 +73,22 @@ public AvroStructureReader getReader()
         }
         return r;
     }
+
+    @Override
+    public String toString() {
+        return String.format("{AvroSchema: name=%s}", _avroSchema.getFullName());
+    }
+
+    @Override
+    public int hashCode() {
+        return _avroSchema.hashCode();
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (o == this) return true;
+        if ((o == null) || o.getClass() != getClass()) return false;
+        AvroSchema other = (AvroSchema) o;
+        return _avroSchema.equals(other._avroSchema);
+    }
 }

avro/src/main/java/com/fasterxml/jackson/dataformat/avro/deser/AvroScalarReader.java

@@ -10,6 +10,11 @@
 import org.apache.avro.Schema;
 import org.apache.avro.io.BinaryDecoder;
 
+/**
+ * Helper classes for reading non-structured values, and can thereby usually
+ * be accessed using simpler interface (although sometimes not: if so,
+ * instances are wrapped in <code>ScalarReaderWrapper</code>s).
+ */
 public abstract class AvroScalarReader
 {
     protected abstract JsonToken readValue(AvroParserImpl parser, BinaryDecoder decoder)

avro/src/main/java/com/fasterxml/jackson/dataformat/avro/deser/MapReader.java

@@ -58,7 +58,7 @@ public JsonToken nextToken() throws IOException
         switch (_state) {
         case STATE_START:
             _parser.setAvroContext(this);
-            _count = _decoder.readArrayStart();
+            _count = _decoder.readMapStart();
             _state = (_count > 0) ? STATE_NAME : STATE_END;
             return (_currToken = JsonToken.START_OBJECT);
         case STATE_NAME:
@@ -68,7 +68,7 @@ public JsonToken nextToken() throws IOException
                 return (_currToken = JsonToken.FIELD_NAME);
             }
             // need more data...
-            _count = _decoder.arrayNext();
+            _count = _decoder.mapNext();
             // more stuff?
             if (_count > 0L) {
                 _index = 0;

avro/src/main/java/com/fasterxml/jackson/dataformat/avro/deser/ScalarReaderWrapper.java

@@ -14,22 +14,24 @@ final class ScalarReaderWrapper extends AvroStructureReader
     private final boolean _rootReader;
 
     public ScalarReaderWrapper(AvroScalarReader wrappedReader) {
-        this(wrappedReader, null, null, false);
+        this(null, null, null, wrappedReader, false);
     }
 
-    private ScalarReaderWrapper(AvroScalarReader wrappedReader,
-            AvroParserImpl parser, BinaryDecoder decoder, boolean root) {
-        super(null, TYPE_ROOT);
+    private ScalarReaderWrapper(AvroReadContext parent,
+            AvroParserImpl parser, BinaryDecoder decoder,
+            AvroScalarReader wrappedReader, boolean rootReader)
+    {
+        super(parent, TYPE_ROOT);
         _wrappedReader = wrappedReader;
         _parser = parser;
         _decoder = decoder;
-        _rootReader = root;
+        _rootReader = rootReader;
     }
 
     @Override
     public ScalarReaderWrapper newReader(AvroReadContext parent,
             AvroParserImpl parser, BinaryDecoder decoder) {
-        return new ScalarReaderWrapper(_wrappedReader, parser, decoder, parent.inRoot());
+        return new ScalarReaderWrapper(parent, parser, decoder, _wrappedReader, parent.inRoot());
     }
 
     @Override
@@ -41,6 +43,7 @@ public JsonToken nextToken() throws IOException
         if (_rootReader && _decoder.isEnd()) {
             return (_currToken = null);
         }
+        _parser.setAvroContext(getParent());
         return (_currToken = _wrappedReader.readValue(_parser, _decoder));
     }
 

avro/src/main/java/com/fasterxml/jackson/dataformat/avro/deser/UnionReader.java

@@ -51,9 +51,7 @@ public JsonToken nextToken() throws IOException
             // also: must pass our parent (not this instance)
             _currentReader = _memberReaders[index].newReader(_parent, _parser, _decoder);
         }
-        JsonToken t = _currentReader.nextToken();
-        _currToken = t;
-        return t;
+        return (_currToken = _currentReader.nextToken());
     }
 
     @Override
@@ -66,4 +64,4 @@ public String nextFieldName() throws IOException {
     protected void appendDesc(StringBuilder sb) {
         sb.append('?');
     }
-}
+}

avro/src/test/java/com/fasterxml/jackson/dataformat/avro/MapWithUnionTest.java

@@ -0,0 +1,36 @@
+package com.fasterxml.jackson.dataformat.avro;
+
+import java.util.*;
+
+public class MapWithUnionTest extends AvroTestBase
+{
+    protected final String MAP_WITH_UNION_SCHEMA_JSON = aposToQuotes(
+            "{"
+            +"'name': 'Map',\n"
+            +"'type': 'map',\n"
+            +"'values': [ 'string', {\n"
+            + "    'type' : 'map', 'values' : 'string' \n"
+            + "  }\n"
+            + " ] \n"
+            +"}\n");
+
+    private final AvroMapper MAPPER = getMapper();
+
+    public void testRecordWithMap() throws Exception
+    {
+        AvroSchema schema = MAPPER.schemaFrom(MAP_WITH_UNION_SCHEMA_JSON);
+        Map<String,Object> input = new LinkedHashMap<String,Object>();
+        input.put("a", "123");
+        input.put("xy", "foobar");
+        byte[] avro = MAPPER.writer(schema)
+                .writeValueAsBytes(input);
+
+        Map<String,Object> result = MAPPER.readerFor(Map.class)
+                .with(schema)
+                .readValue(avro);
+
+        assertEquals(2, result.size());
+        assertEquals("123", result.get("a"));
+        assertEquals("foobar", result.get("xy"));
+    }
+}