1 files changed, 84 insertions, 0 deletions
diff --git a/vespajlib/src/main/java/com/yahoo/slime/Injector.java b/vespajlib/src/main/java/com/yahoo/slime/Injector.java
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index 00000000000..3e507cf29c2
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+++ b/vespajlib/src/main/java/com/yahoo/slime/Injector.java
@@ -0,0 +1,84 @@
+// Copyright 2019 Oath Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.slime;
+
+/**
+ * @author hakonhall
+ */
+public class Injector {
+    /**
+     * Inject a slime sub-structure described by an Inspector into a slime
+     * structure where the insertion point is described by an
+     * Inserter. This will copy all the values represented by the
+     * Inspector into the position described by the Inserter. Note that
+     * this can be used to either copy data from one Slime structure to
+     * another, or to copy data internally within a single slime
+     * structure. If the Inspector contains the insertion point it will
+     * only be expanded once to avoid infinite recursion.
+     *
+     * @param inspector what to inject
+     * @param inserter where to inject
+     **/
+    public void inject(Inspector inspector, Inserter inserter) {
+        if (inspector.valid()) {
+            injectValue(inserter, inspector, null);
+        }
+    }
+
+    private void injectValue(Inserter inserter, Inspector inspector, Inspector guard) {
+        switch (inspector.type()) {
+            case NIX:    inserter.insertNIX(); break;
+            case BOOL:   inserter.insertBOOL(inspector.asBool()); break;
+            case LONG:   inserter.insertLONG(inspector.asLong()); break;
+            case DOUBLE: inserter.insertDOUBLE(inspector.asDouble()); break;
+            case STRING: inserter.insertSTRING(inspector.asString()); break;
+            case DATA:   inserter.insertDATA(inspector.asData()); break;
+            case ARRAY:  injectArray(inserter, inspector, guard); break;
+            case OBJECT: injectObject(inserter, inspector, guard); break;
+            default:     throw new IllegalArgumentException("Unknown type " + inspector.type());
+        }
+    }
+
+    private void injectArray(Inserter inserter, Inspector inspector, Inspector guard) {
+        Cursor cursor = inserter.insertARRAY();
+        ArrayTraverser arrayTraverser = new NestedInjector(cursor, guard != null ? guard : cursor);
+        inspector.traverse(arrayTraverser);
+    }
+
+    private void injectObject(Inserter inserter, Inspector inspector, Inspector guard) {
+        Cursor cursor = inserter.insertOBJECT();
+        ObjectTraverser objectTraverser = new NestedInjector(cursor, guard != null ? guard : cursor);
+        inspector.traverse(objectTraverser);
+    }
+
+    private class NestedInjector implements ArrayTraverser, ObjectTraverser {
+        private final Cursor cursor;
+        private final Inspector guard;
+
+        public NestedInjector(Cursor cursor, Inspector guard) {
+            this.cursor = cursor;
+            this.guard = guard;
+        }
+
+        @Override
+        public void entry(int idx, Inspector inspector) {
+            if (inspector == guard) {
+                return;
+            }
+
+            var inserter = new ArrayInserter();
+            inserter.adjust(cursor);
+            injectValue(inserter, inspector, guard);
+        }
+
+        @Override
+        public void field(String name, Inspector inspector) {
+            if (inspector == guard) {
+                return;
+            }
+
+            var inserter = new ObjectInserter();
+            inserter.adjust(cursor, name);
+            injectValue(inserter, inspector, guard);
+        }
+    }
+}