data: exposeWhetherDependencyAvailable

3 files changed, 44 insertions, 0 deletions

diff --git a/src/data/composite/control-flow/exposeWhetherDependencyAvailable.js b/src/data/composite/control-flow/exposeWhetherDependencyAvailable.js
new file mode 100644
index 00000000..a2fdd6b0
--- /dev/null
+++ b/src/data/composite/control-flow/exposeWhetherDependencyAvailable.js
@@ -0,0 +1,42 @@
+// Exposes true if a dependency is available, and false otherwise,
+// or the reverse if the `negate` input is set true.
+//
+// See withResultOfAvailabilityCheck for {mode} options.
+
+import {input, templateCompositeFrom} from '#composite';
+
+import inputAvailabilityCheckMode from './inputAvailabilityCheckMode.js';
+import withResultOfAvailabilityCheck from './withResultOfAvailabilityCheck.js';
+
+export default templateCompositeFrom({
+  annotation: `exposeWhetherDependencyAvailable`,
+
+  compose: false,
+
+  inputs: {
+    dependency: input({acceptsNull: true}),
+
+    mode: inputAvailabilityCheckMode(),
+
+    negate: input({type: 'boolean', defaultValue: false}),
+  },
+
+  steps: () => [
+    withResultOfAvailabilityCheck({
+      from: input('dependency'),
+      mode: input('mode'),
+    }),
+
+    {
+      dependencies: ['#availability', input('negate')],
+
+      compute: ({
+        ['#availability']: availability,
+        [input('negate')]: negate,
+      }) =>
+        (negate
+          ? !availability
+          : availability),
+    },
+  ],
+});
diff --git a/src/data/composite/control-flow/index.js b/src/data/composite/control-flow/index.js
index 7fad88b2..6148d465 100644
--- a/src/data/composite/control-flow/index.js
+++ b/src/data/composite/control-flow/index.js
@@ -9,6 +9,7 @@ export {default as exposeConstant} from './exposeConstant.js';
 export {default as exposeDependency} from './exposeDependency.js';
 export {default as exposeDependencyOrContinue} from './exposeDependencyOrContinue.js';
 export {default as exposeUpdateValueOrContinue} from './exposeUpdateValueOrContinue.js';
+export {default as exposeWhetherDependencyAvailable} from './exposeWhetherDependencyAvailable.js';
 export {default as raiseOutputWithoutDependency} from './raiseOutputWithoutDependency.js';
 export {default as raiseOutputWithoutUpdateValue} from './raiseOutputWithoutUpdateValue.js';
 export {default as withResultOfAvailabilityCheck} from './withResultOfAvailabilityCheck.js';
diff --git a/src/data/composite/control-flow/withResultOfAvailabilityCheck.js b/src/data/composite/control-flow/withResultOfAvailabilityCheck.js
index a6942014..1d90b324 100644
--- a/src/data/composite/control-flow/withResultOfAvailabilityCheck.js
+++ b/src/data/composite/control-flow/withResultOfAvailabilityCheck.js
@@ -17,6 +17,7 @@
 //  - exitWithoutUpdateValue
 //  - exposeDependencyOrContinue
 //  - exposeUpdateValueOrContinue
+//  - exposeWhetherDependencyAvailable
 //  - raiseOutputWithoutDependency
 //  - raiseOutputWithoutUpdateValue
 //