Support $prepend for inserting & array creation (#92, #93, #127)

Author: fsteeg

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

@@ -170,6 +170,9 @@ void apply(final Array array, final String field, final Value value) {
                     final ReservedField reservedField = ReservedField.fromString(field);
                     if (reservedField != null) {
                         switch (reservedField) {
+                            case $prepend:
+                                array.add(0, value);
+                                break;
                             case $append:
                                 array.add(value);
                                 break;
@@ -276,7 +279,7 @@ else if (isReference(field)) {
         }
         else {
             if (!hash.containsField(field)) {
-                if (ReservedField.$append.name().equals(tail(path)[0])) {
+                if (ReservedField.$prepend.name().equals(tail(path)[0]) || ReservedField.$append.name().equals(tail(path)[0])) {
                     hash.put(field, Value.newArray().withPathSet(newValue.getPath()));
                 }
                 else {
@@ -312,7 +315,7 @@ private String[] tail(final String[] fields) {
     }
 
     private enum ReservedField {
-        $append, $first, $last;
+        $prepend, $append, $first, $last;
 
         private static final Map<String, ReservedField> STRING_TO_ENUM = new HashMap<>();
         static {
@@ -352,6 +355,10 @@ private Value getReferencedValue(final Array array, final String field, final St
                     referencedValue = Value.newHash().withPathSet(p); // TODO: append non-hash?
                     array.add(referencedValue);
                     break;
+                case $prepend:
+                    referencedValue = Value.newHash().withPathSet(p);
+                    array.add(0, referencedValue);
+                    break;
                 default:
                     break;
             }

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

@@ -438,6 +438,12 @@ public void add(final Value value) {
             }
         }
 
+        /* package-private */ void add(final int index, final Value value) {
+            if (!isNull(value)) {
+                list.add(index, value);
+            }
+        }
+
         public boolean isEmpty() {
             return list.isEmpty();
         }

metafix/src/test/java/org/metafacture/metafix/MetafixRecordTest.java

@@ -348,6 +348,51 @@ public void addWithAppendInImplicitArray() {
         );
     }
 
+    @Test
+    public void addWithPrependInImplicitArray() {
+        MetafixTestHelpers.assertFix(streamReceiver, Arrays.asList(
+                "add_field('my.name.$prepend','patrick')",
+                "add_field('my.name.$prepend','nicolas')"
+            ),
+            i -> {
+                i.startRecord("1");
+                i.endRecord();
+
+                i.startRecord("2");
+                i.startEntity("my");
+                i.literal("name", "max");
+                i.endEntity();
+                i.endRecord();
+
+                i.startRecord("3");
+                i.endRecord();
+            },
+            o -> {
+                o.get().startRecord("1");
+                o.get().startEntity("my");
+                o.get().literal("name", "nicolas");
+                o.get().literal("name", "patrick");
+                o.get().endEntity();
+                o.get().endRecord();
+
+                o.get().startRecord("2");
+                o.get().startEntity("my");
+                o.get().literal("name", "nicolas");
+                o.get().literal("name", "patrick");
+                o.get().literal("name", "max");
+                o.get().endEntity();
+                o.get().endRecord();
+
+                o.get().startRecord("3");
+                o.get().startEntity("my");
+                o.get().literal("name", "nicolas");
+                o.get().literal("name", "patrick");
+                o.get().endEntity();
+                o.get().endRecord();
+            }
+        );
+    }
+
     @Test
     public void addWithAppendInArray() {
         MetafixTestHelpers.assertFix(streamReceiver, Arrays.asList(
@@ -1488,6 +1533,33 @@ public void copyIntoArrayOfHashesImplicitAppend() {
             });
     }
 
+    @Test
+    public void copyIntoArrayOfHashesImplicitPrepend() {
+        MetafixTestHelpers.assertFix(streamReceiver, Arrays.asList(
+                "copy_field('your.name','author[].$prepend.name')",
+                "remove_field('your')"),
+            i -> {
+                i.startRecord("1");
+                i.startEntity("your");
+                i.literal("name", "max");
+                i.endEntity();
+                i.startEntity("your");
+                i.literal("name", "mo");
+                i.endEntity();
+                i.endRecord();
+            }, (o, f) -> {
+                o.get().startRecord("1");
+                o.get().startEntity("author[]");
+                o.get().startEntity("1");
+                o.get().literal("name", "mo");
+                o.get().endEntity();
+                o.get().startEntity("2");
+                o.get().literal("name", "max");
+                f.apply(2).endEntity();
+                o.get().endRecord();
+            });
+    }
+
     @Test
     public void copyIntoArrayOfHashesExplicitAppend() {
         MetafixTestHelpers.assertFix(streamReceiver, Arrays.asList(

metafix/src/test/resources/org/metafacture/metafix/integration/record/fromJson/toJson/add_fieldPrependAndCreateArray/todo.txt

@@ -1 +1 @@
-copy_field("test_2", "test[].$prepend")
+move_field("test_2", "test[].$prepend")