Add propertyExists() method

Author: Myaamori

src/main/kotlin/myaa/subkt/tasks/plugin.kt

@@ -235,6 +235,17 @@ fun Task.evaluate(expression: String) =
 fun Task.getRawMaybe(propertyName: String) =
         taskGroup.subs.getRawMaybe(propertyName, entry = entry)
 
+/**
+ * Returns true if the given property exists in the [Subs] object's [SubProperties] instance
+ * for the given context.
+ *
+ * This function is run in a task context, using the [entry] and [release] values for this task.
+ *
+ * @param propertyName The property to find.
+ */
+fun Task.propertyExists(propertyName: String) =
+        taskGroup.subs.propertyExists(propertyName, entry = entry)
+
 /**
  * Searches for the given property in the [Subs] object's [SubProperties] instance,
  * and returns the raw string.
@@ -500,6 +511,20 @@ open class Subs(val project: Project) : ItemGroupContext() {
     fun getRawMaybe(propertyName: String, entry: String = "") =
             properties.match(propertyName, entry = entry, release = release.get())
 
+    /**
+     * Returns true if the given property exists in the [Subs] object's [SubProperties] instance
+     * for the given context.
+     *
+     * This function is run outside of a task context, using only [release] for lookup
+     * unless an entry is manually specified.
+     *
+     * @sample myaa.subkt.tasks.samples.subsPropertyExistsSample
+     * @param propertyName The property to find.
+     * @param entry Optional manually specified entry for property lookup.
+     */
+    fun propertyExists(propertyName: String, entry: String = "") =
+            getRawMaybe(propertyName, entry = entry) != null
+
     /**
      * Searches for the given property in the [Subs] object's [SubProperties] instance,
      * and returns the raw string.

src/main/kotlin/myaa/subkt/tasks/tasks.kt

@@ -497,6 +497,13 @@ class ValueClosure<T>(
     fun getRawMaybe(propertyName: String) =
             taskGroup.subs.getRawMaybe(propertyName, entry = entry)
 
+
+    /**
+     * Returns true if the given property exists. See [Task.propertyExists].
+     */
+    fun propertyExists(propertyName: String) =
+            taskGroup.subs.propertyExists(propertyName, entry = entry)
+
     /**
      * Searches for the given property. See [Task.getRaw].
      */

src/samples/kotlin/tasks.kt

@@ -414,6 +414,17 @@ fun Subs.subsEvaluateSample() {
     // Output: TV - $episode - $merge.out.get()
 }
 
+fun Subs.subsPropertyExistsSample() {
+    merge {
+        from(get("dialogue"))
+
+        // only include OP if defined for the current episode
+        if (propertyExists("op")) {
+            from(get("op"))
+        }
+    }
+}
+
 fun Subs.subsGetRawSample() {
     // property file: TV.*.value=hello{1..3}|test|$episode
     getRaw("value")