4 files changed, 128 insertions, 19 deletions
diff --git a/src/data/composite/wiki-data/index.js b/src/data/composite/wiki-data/index.js
index b4cf6d13..15ebaffa 100644
--- a/src/data/composite/wiki-data/index.js
+++ b/src/data/composite/wiki-data/index.js
@@ -6,6 +6,8 @@
 
 export {default as exitWithoutContribs} from './exitWithoutContribs.js';
 export {default as inputWikiData} from './inputWikiData.js';
+export {default as withDirectory} from './withDirectory.js';
+export {default as withDirectoryFromName} from './withDirectoryFromName.js';
 export {default as withParsedCommentaryEntries} from './withParsedCommentaryEntries.js';
 export {default as withResolvedContribs} from './withResolvedContribs.js';
 export {default as withResolvedReference} from './withResolvedReference.js';
diff --git a/src/data/composite/wiki-data/withDirectory.js b/src/data/composite/wiki-data/withDirectory.js
new file mode 100644
index 00000000..b08b6153
--- /dev/null
+++ b/src/data/composite/wiki-data/withDirectory.js
@@ -0,0 +1,55 @@
+// Select a directory, either using a manually specified directory, or
+// computing it from a name. By default these values are the current thing's
+// 'directory' and 'name' properties, so it can be used without any options
+// to get the current thing's effective directory (assuming no custom rules).
+
+import {input, templateCompositeFrom} from '#composite';
+
+import {isDirectory, isName} from '#validators';
+
+import {withResultOfAvailabilityCheck} from '#composite/control-flow';
+
+import withDirectoryFromName from './withDirectoryFromName.js';
+
+export default templateCompositeFrom({
+  annotation: `withDirectory`,
+
+  inputs: {
+    directory: input({
+      validate: isDirectory,
+      defaultDependency: 'directory',
+      acceptsNull: true,
+    }),
+
+    name: input({
+      validate: isName,
+      defaultDependency: 'name',
+      acceptsNull: true,
+    }),
+  },
+
+  outputs: ['#directory'],
+
+  steps: () => [
+    withResultOfAvailabilityCheck({
+      from: input('directory'),
+    }),
+
+    {
+      dependencies: ['#availability', input('directory')],
+      compute: (continuation, {
+        ['#availability']: availability,
+        [input('directory')]: directory,
+      }) =>
+        (availability
+          ? continuation.raiseOutput({
+              ['#directory']: directory
+            })
+          : continuation()),
+    },
+
+    withDirectoryFromName({
+      name: input('name'),
+    }),
+  ],
+});
diff --git a/src/data/composite/wiki-data/withDirectoryFromName.js b/src/data/composite/wiki-data/withDirectoryFromName.js
new file mode 100644
index 00000000..034464e4
--- /dev/null
+++ b/src/data/composite/wiki-data/withDirectoryFromName.js
@@ -0,0 +1,42 @@
+// Compute a directory from a name - by default the current thing's own name.
+
+import {input, templateCompositeFrom} from '#composite';
+
+import {isName} from '#validators';
+import {getKebabCase} from '#wiki-data';
+
+import {raiseOutputWithoutDependency} from '#composite/control-flow';
+
+export default templateCompositeFrom({
+  annotation: `withDirectoryFromName`,
+
+  inputs: {
+    name: input({
+      validate: isName,
+      defaultDependency: 'name',
+      acceptsNull: true,
+    }),
+  },
+
+  outputs: ['#directory'],
+
+  steps: () => [
+    raiseOutputWithoutDependency({
+      dependency: input('name'),
+      mode: input.value('falsy'),
+      output: input.value({
+        ['#directory']: null,
+      }),
+    }),
+
+    {
+      dependencies: [input('name')],
+      compute: (continuation, {
+        [input('name')]: name,
+      }) => continuation({
+        ['#directory']:
+          getKebabCase(name),
+      }),
+    },
+  ],
+});
diff --git a/src/data/composite/wiki-properties/directory.js b/src/data/composite/wiki-properties/directory.js
index 0b2181c9..41ce4b27 100644
--- a/src/data/composite/wiki-properties/directory.js
+++ b/src/data/composite/wiki-properties/directory.js
@@ -2,22 +2,32 @@
 // almost any data object. Also corresponds to a part of the URL which pages of
 // such objects are visited at.
 
-import {isDirectory} from '#validators';
-import {getKebabCase} from '#wiki-data';
-
-// TODO: Not templateCompositeFrom.
-
-export default function() {
-  return {
-    flags: {update: true, expose: true},
-    update: {validate: isDirectory},
-    expose: {
-      dependencies: ['name'],
-      transform(directory, {name}) {
-        if (directory === null && name === null) return null;
-        else if (directory === null) return getKebabCase(name);
-        else return directory;
-      },
-    },
-  };
-}
+import {input, templateCompositeFrom} from '#composite';
+
+import {isDirectory, isName} from '#validators';
+
+import {exposeDependency} from '#composite/control-flow';
+import {withDirectory} from '#composite/wiki-data';
+
+export default templateCompositeFrom({
+  annotation: `directory`,
+
+  compose: false,
+
+  inputs: {
+    name: input({
+      validate: isName,
+      defaultDependency: 'name',
+    }),
+  },
+
+  steps: () => [
+    withDirectory({
+      directory: input.updateValue({validate: isDirectory}),
+    }),
+
+    exposeDependency({
+      dependency: '#directory',
+    }),
+  ],
+});