Support optional 'path' config type

Initial work needed for this to work (config definition and config library)

4 files changed, 124 insertions, 0 deletions

diff --git a/config-lib/abi-spec.json b/config-lib/abi-spec.json
index caae2ebf1cf..07e61c63237 100644
--- a/config-lib/abi-spec.json
+++ b/config-lib/abi-spec.json
@@ -273,6 +273,7 @@
       "public static java.util.Map asNodeMap(java.util.Map, com.yahoo.config.LeafNode)",
       "public static java.util.Map asFileNodeMap(java.util.Map)",
       "public static java.util.Map asPathNodeMap(java.util.Map)",
+      "public static java.util.Map asOptionalPathNodeMap(java.util.Map)",
       "public static java.util.Map asUrlNodeMap(java.util.Map)",
       "public static java.util.Map asModelNodeMap(java.util.Map)"
     ],
@@ -289,6 +290,7 @@
       "public java.util.List asList()",
       "public static com.yahoo.config.LeafNodeVector createFileNodeVector(java.util.Collection)",
       "public static com.yahoo.config.LeafNodeVector createPathNodeVector(java.util.Collection)",
+      "public static com.yahoo.config.LeafNodeVector createOptionalPathNodeVector(java.util.Collection)",
       "public static com.yahoo.config.LeafNodeVector createUrlNodeVector(java.util.Collection)",
       "public static com.yahoo.config.LeafNodeVector createModelNodeVector(java.util.Collection)"
     ],
@@ -420,6 +422,27 @@
       "protected final java.util.ArrayList vector"
     ]
   },
+  "com.yahoo.config.OptionalPathNode" : {
+    "superClass" : "com.yahoo.config.LeafNode",
+    "interfaces" : [ ],
+    "attributes" : [
+      "public"
+    ],
+    "methods" : [
+      "public void <init>()",
+      "public void <init>(com.yahoo.config.FileReference)",
+      "public void <init>(java.util.Optional)",
+      "public java.util.Optional value()",
+      "public java.lang.String getValue()",
+      "public java.lang.String toString()",
+      "protected boolean doSetValue(java.lang.String)",
+      "public java.util.Optional getFileReference()",
+      "public static java.util.List toFileReferences(java.util.List)",
+      "public static java.util.Map toFileReferenceMap(java.util.Map)",
+      "public bridge synthetic java.lang.Object value()"
+    ],
+    "fields" : [ ]
+  },
   "com.yahoo.config.PathNode" : {
     "superClass" : "com.yahoo.config.LeafNode",
     "interfaces" : [ ],
diff --git a/config-lib/src/main/java/com/yahoo/config/LeafNodeMaps.java b/config-lib/src/main/java/com/yahoo/config/LeafNodeMaps.java
index 82663fa8bfd..214d8c52caa 100644
--- a/config-lib/src/main/java/com/yahoo/config/LeafNodeMaps.java
+++ b/config-lib/src/main/java/com/yahoo/config/LeafNodeMaps.java
@@ -4,6 +4,7 @@ package com.yahoo.config;
 import java.util.Collections;
 import java.util.LinkedHashMap;
 import java.util.Map;
+import java.util.Optional;
 import java.util.stream.Collectors;
 
 /**
@@ -60,6 +61,14 @@ public class LeafNodeMaps {
         return Collections.unmodifiableMap(pathNodeMap);
     }
 
+    public static Map<String, OptionalPathNode> asOptionalPathNodeMap(Map<String, Optional<FileReference>> fileReferenceMap) {
+        Map<String, OptionalPathNode> pathNodeMap = new LinkedHashMap<>();
+        for (Map.Entry<String, Optional<FileReference>> e : fileReferenceMap.entrySet()) {
+            pathNodeMap.put(e.getKey(), new OptionalPathNode(e.getValue()));
+        }
+        return Collections.unmodifiableMap(pathNodeMap);
+    }
+
     public static Map<String, UrlNode> asUrlNodeMap(Map<String, UrlReference> urlReferenceMap) {
         return Collections.unmodifiableMap(
                     urlReferenceMap.entrySet().stream().collect(
diff --git a/config-lib/src/main/java/com/yahoo/config/LeafNodeVector.java b/config-lib/src/main/java/com/yahoo/config/LeafNodeVector.java
index a4fea95088d..cfb8cd4eebd 100644
--- a/config-lib/src/main/java/com/yahoo/config/LeafNodeVector.java
+++ b/config-lib/src/main/java/com/yahoo/config/LeafNodeVector.java
@@ -8,6 +8,7 @@ import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
+import java.util.Optional;
 
 /**
  * A vector of leaf nodes.
@@ -71,6 +72,13 @@ public class LeafNodeVector<REAL, NODE extends LeafNode<REAL>> extends NodeVecto
         return new LeafNodeVector<>(paths, new PathNode());
     }
 
+    public static LeafNodeVector<Optional<Path>, OptionalPathNode> createOptionalPathNodeVector(Collection<Optional<FileReference>> values) {
+        List<Optional<Path>> paths = new ArrayList<>();
+        for (Optional<FileReference> fileReference : values)
+            paths.add(fileReference.map(reference -> Paths.get(reference.value())));
+        return new LeafNodeVector<>(paths, new OptionalPathNode());
+    }
+
     public static LeafNodeVector<File, UrlNode> createUrlNodeVector(Collection<UrlReference> values) {
         List<File> files = new ArrayList<>();
         for (UrlReference urlReference : values)
diff --git a/config-lib/src/main/java/com/yahoo/config/OptionalPathNode.java b/config-lib/src/main/java/com/yahoo/config/OptionalPathNode.java
new file mode 100644
index 00000000000..8a6414d798f
--- /dev/null
+++ b/config-lib/src/main/java/com/yahoo/config/OptionalPathNode.java
@@ -0,0 +1,84 @@
+// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.config;
+
+import java.nio.file.Path;
+import java.util.ArrayList;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+
+/**
+ * Represents a 'path' in a {@link ConfigInstance}, usually a filename, can be optional
+ *
+ * @author hmusum
+ */
+public class OptionalPathNode extends LeafNode<Optional<Path>> {
+
+    private final Optional<FileReference> fileReference;
+
+    public OptionalPathNode() {
+        fileReference = Optional.empty();
+    }
+
+    public OptionalPathNode(FileReference fileReference) {
+        super(true);
+        this.value = Optional.of(Path.of(fileReference.value()));
+        this.fileReference = Optional.of(fileReference);
+    }
+
+    public OptionalPathNode(Optional<FileReference> fileReference) {
+        super(true);
+        this.value = fileReference.map(reference -> Path.of(reference.value()));
+        this.fileReference = fileReference;
+    }
+
+    public Optional<Path> value() {
+        return value;
+    }
+
+    @Override
+    public String getValue() {
+        return value.toString();
+    }
+
+    @Override
+    public String toString() {
+        return (value.isEmpty()) ? "(empty)" : '"' + value.get().toString() + '"';
+    }
+
+    @Override
+    protected boolean doSetValue(String stringVal) {
+        throw new UnsupportedOperationException("doSetValue should not be necessary anymore!");
+    }
+
+    @Override
+    void serialize(String name, Serializer serializer) {
+        value.ifPresent(path -> serializer.serialize(name, path.toString()));
+    }
+
+    @Override
+    void serialize(Serializer serializer) {
+        value.ifPresent(path -> serializer.serialize(path.toString()));
+    }
+
+    public Optional<FileReference> getFileReference() {
+        return fileReference;
+    }
+
+    public static List<Optional<FileReference>> toFileReferences(List<OptionalPathNode> pathNodes) {
+        List<Optional<FileReference>> fileReferences = new ArrayList<>();
+        for (OptionalPathNode pathNode : pathNodes)
+            fileReferences.add(pathNode.getFileReference());
+        return fileReferences;
+    }
+
+    public static Map<String, Optional<FileReference>> toFileReferenceMap(Map<String, OptionalPathNode> map) {
+        Map<String, Optional<FileReference>> ret = new LinkedHashMap<>();
+        for (Map.Entry<String, OptionalPathNode> e : map.entrySet()) {
+            ret.put(e.getKey(), e.getValue().getFileReference());
+        }
+        return ret;
+    }
+
+}