Introduce type-safe record value abstraction. (#64)

Obviates the need for `instanceof` checks and unchecked casts.

A `Value` is a container/wrapper for either

- an `Array` (which in turn is a wrapper for `List<Value>`), or
- a `Hash` (which in turn is a wrapper for `Map<String, Value>`), or
- a `String` (which is the terminal type)

metafix/build.gradle

@@ -43,6 +43,10 @@ dependencies {
 
 test {
   useJUnitPlatform()
+
+  testlogger {
+    showFullStackTraces true
+  }
 }
 
 task install(dependsOn: publishToMavenLocal,

metafix/src/main/java/org/metafacture/metafix/FixPredicate.java

@@ -23,52 +23,58 @@
 enum FixPredicate {
 
     contain {
-        public Predicate<Object> of(final Object value) {
-            return v -> v.toString().contains(value.toString());
+        @Override
+        public Predicate<Value> of(final String string) {
+            return v -> v.toString().contains(string);
         }
     },
     equal {
-        public Predicate<Object> of(final Object value) {
-            return v ->  v.toString().equals(value.toString());
+        @Override
+        public Predicate<Value> of(final String string) {
+            return v ->  v.toString().equals(string);
         }
     },
     match {
-        public Predicate<Object> of(final Object value) {
-            return v -> v.toString().matches(value.toString());
+        @Override
+        public Predicate<Value> of(final String string) {
+            return v -> v.toString().matches(string);
         }
     };
 
-    abstract Predicate<Object> of(Object value);
+    abstract Predicate<Value> of(String string);
 
     enum Quantifier {
 
         all {
             @Override
-            public boolean test(final Record record, final FixPredicate p, final List<String> params) {
-                return test(record, params.get(0), s -> s.allMatch(p.of(params.get(1))));
+            protected boolean test(final Record record, final String fieldName, final Predicate<Value> p) {
+                return testStream(record, fieldName, s -> s.allMatch(p));
             }
 
         },
         any {
             @Override
-            public boolean test(final Record record, final FixPredicate p, final List<String> params) {
-                return test(record, params.get(0), s -> s.anyMatch(p.of(params.get(1))));
+            protected boolean test(final Record record, final String fieldName, final Predicate<Value> p) {
+                return testStream(record, fieldName, s -> s.anyMatch(p));
             }
         },
         none {
             @Override
-            public boolean test(final Record record, final FixPredicate p, final List<String> params) {
-                final Object fieldValue = FixMethod.find(record, FixMethod.split(params.get(0)));
-                final String valueToTest = params.get(1);
-                return fieldValue == null || Metafix.asList(fieldValue).stream().noneMatch(p.of(valueToTest));
+            protected boolean test(final Record record, final String fieldName, final Predicate<Value> p) {
+                return !any.test(record, fieldName, p);
             }
         };
 
-        boolean test(final Record record, final String fieldName, final Predicate<Stream<Object>> f) {
-            final Object value = FixMethod.find(record, FixMethod.split(fieldName));
-            return value != null && f.test(Metafix.asList(value).stream());
+        boolean testStream(final Record record, final String fieldName, final Predicate<Stream<Value>> p) {
+            final Value value = FixMethod.find(record, FixMethod.split(fieldName));
+            return value != null && p.test(Metafix.asList(value, null).asArray().stream());
         }
 
-        abstract boolean test(Record record, FixPredicate p, List<String> params);
+        public boolean test(final Record record, final FixPredicate p, final List<String> params) {
+            return test(record, params.get(0), p.of(params.get(1)));
+        }
+
+        protected abstract boolean test(Record record, String fieldName, Predicate<Value> p);
     }
+
 }

metafix/src/main/java/org/metafacture/metafix/Metafix.java

@@ -34,12 +34,12 @@
 import java.io.Reader;
 import java.io.StringReader;
 import java.util.ArrayList;
-import java.util.Arrays;
 import java.util.Collections;
 import java.util.Deque;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
+import java.util.function.Consumer;
 
 /**
  * Transforms a data stream sent via the {@link StreamReceiver} interface. Use
@@ -49,7 +49,7 @@
  * @author Christoph Böhme (Metamorph)
  * @author Fabian Steeg (Metafix)
  */
-public class Metafix implements StreamPipe<StreamReceiver> {
+public class Metafix implements StreamPipe<StreamReceiver> { // checkstyle-disable-line ClassDataAbstractionCoupling
 
     public static final String VAR_START = "$[";
     public static final String VAR_END = "]";
@@ -146,30 +146,30 @@ public void endRecord() {
         }
     }
 
-    private void emit(final Object key, final Object val) {
-        if (val == null) {
-            return;
-        }
-        final List<?> vals = asList(val);
-        final boolean isMulti = vals.size() > 1 || val instanceof List;
-        if (isMulti) {
-            outputStreamReceiver.startEntity(key.toString() + "[]");
-        }
-        for (int i = 0; i < vals.size(); ++i) {
-            final Object value = vals.get(i);
-            if (value instanceof Value.Hash) {
-                final Value.Hash nested = (Value.Hash) value;
-                outputStreamReceiver.startEntity(isMulti ? "" : key.toString());
-                nested.forEach(this::emit);
-                outputStreamReceiver.endEntity();
+    private void emit(final String key, final Value val) {
+        asList(val, vals -> {
+            final boolean isMulti = vals.size() > 1 || val.isArray();
+            if (isMulti) {
+                outputStreamReceiver.startEntity(key + "[]");
             }
-            else {
-                outputStreamReceiver.literal(isMulti ? (i + 1) + "" : key.toString(), value.toString());
+
+            for (int i = 0; i < vals.size(); ++i) {
+                final Value value = vals.get(i);
+
+                if (value.isHash()) {
+                    outputStreamReceiver.startEntity(isMulti ? "" : key);
+                    value.asHash().forEach(this::emit);
+                    outputStreamReceiver.endEntity();
+                }
+                else {
+                    outputStreamReceiver.literal(isMulti ? (i + 1) + "" : key, value.toString());
+                }
             }
-        }
-        if (isMulti) {
-            outputStreamReceiver.endEntity();
-        }
+
+            if (isMulti) {
+                outputStreamReceiver.endEntity();
+            }
+        });
     }
 
     @Override
@@ -187,16 +187,15 @@ public void startEntity(final String name) {
     }
 
     private Value.Hash currentEntity(final String name, final Value.Hash previousEntity) {
-        final Object existingValue = previousEntity != null ? previousEntity.get(name) : null;
+        final Value existingValue = previousEntity != null ? previousEntity.get(name) : null;
         final Value.Hash currentEntity;
-        if (existingValue instanceof Value.Hash) {
-            @SuppressWarnings("unchecked")
-            final Value.Hash existingEntity = (Value.Hash) previousEntity.get(name);
-            currentEntity = existingEntity;
+        if (existingValue != null && existingValue.isHash()) {
+            currentEntity = previousEntity.get(name).asHash();
         }
         else {
-            currentEntity = new Value.Hash();
-            add(previousEntity != null ? previousEntity : currentRecord, name, currentEntity);
+            final Value value = Value.newHash();
+            currentEntity = value.asHash();
+            add(previousEntity != null ? previousEntity : currentRecord, name, value);
         }
         return currentEntity;
     }
@@ -213,7 +212,7 @@ public void literal(final String name, final String value) {
         final Integer currentEntityIndex = entityCountStack.peek() - 1;
         final Value.Hash currentEntity = currentEntityIndex < 0 ||
                 entities.size() <= currentEntityIndex ? null : entities.get(currentEntityIndex);
-        add(currentEntity != null ? currentEntity : currentRecord, name, value);
+        add(currentEntity != null ? currentEntity : currentRecord, name, new Value(value));
         // TODO: keep flattener as option?
         // flattener.literal(name, value);
     }
@@ -253,33 +252,53 @@ public Record getCurrentRecord() {
     }
 
     static void addAll(final Value.Hash record, final String fieldName, final List<String> values) {
-        values.forEach(value -> add(record, fieldName, value));
+        values.forEach(value -> add(record, fieldName, new Value(value)));
     }
 
     static void addAll(final Value.Hash record, final Value.Hash values) {
         values.forEach((fieldName, value) -> add(record, fieldName, value));
     }
 
-    static void add(final Value.Hash record, final String name, final Object newValue) {
-        final Object oldValue = record.get(name);
+    static void add(final Value.Hash record, final String name, final Value newValue) {
+        final Value oldValue = record.get(name);
         record.put(name, oldValue == null ? newValue : merged(oldValue, newValue));
     }
 
-    @SuppressWarnings("unchecked")
-    static Object merged(final Object object1, final Object object2) {
-        if (object1 instanceof Value.Hash && object2 instanceof Value.Hash) {
-            final Value.Hash result = (Value.Hash) object1;
-            ((Value.Hash) object2).forEach(result::put);
-            return result;
+    static Value merged(final Value value1, final Value value2) {
+        if (value1.isHash() && value2.isHash()) {
+            final Value.Hash hash = value1.asHash();
+            value2.asHash().forEach(hash::put);
+            return value1;
+        }
+        else {
+            return asList(value1, a1 -> asList(value2, a2 -> a2.forEach(a1::add)));
         }
-        final List<Object> list = asList(object1);
-        asList(object2).forEach(list::add);
-        return list;
     }
 
-    @SuppressWarnings("unchecked")
-    static List<Object> asList(final Object object) {
-        return new ArrayList<>(object instanceof List ? (List<Object>) object : Arrays.asList(object));
+    static Value asList(final Value value, final Consumer<Value.Array> consumer) {
+        final Value result;
+
+        if (Value.isNull(value)) {
+            result = null;
+        }
+        else if (value.isArray()) {
+            if (consumer != null) {
+                consumer.accept(value.asArray());
+            }
+
+            result = value;
+        }
+        else {
+            result = Value.newArray(a -> {
+                a.add(value);
+
+                if (consumer != null) {
+                    consumer.accept(a);
+                }
+            });
+        }
+
+        return result;
     }
 
 }

metafix/src/main/java/org/metafacture/metafix/RecordTransformer.java

@@ -93,9 +93,9 @@ private void processBind(final Do theDo, final EList<String> params) {
         if (theDo.getName().equals("list")) { // TODO impl multiple binds via FixBind enum
             final Map<String, String> options = options(theDo.getOptions());
             final Record fullRecord = record.shallowClone();
-            final Object values = FixMethod.find(record, FixMethod.split(options.get("path")));
+            final Value values = FixMethod.find(record, FixMethod.split(options.get("path")));
 
-            Metafix.asList(values).stream().filter(val -> val != null).forEach(val -> {
+            Metafix.asList(values, a -> a.forEach(val -> {
                 // for each val, bind the current record/scope/context to the given var name:
                 record = new Record();
                 record.put(options.get("var"), val);
@@ -105,7 +105,7 @@ record = new Record();
 
                 // and remember the things we added while bound (this probably needs some tweaking):
                 Metafix.addAll(fullRecord, record);
-            });
+            }));
 
             record = fullRecord;
         }