feat(content): Statement, StatementMap

Signed-off-by: Lexus Drumgold <unicornware@flexdevelopment.llc>

src/content/__tests__/statement.spec-d.ts

@@ -0,0 +1,24 @@
+/**
+ * @file Type Tests - statement
+ * @module esast/content/tests/unit-d/statement
+ */
+
+import type { EmptyStatement } from '@flex-development/esast'
+import type * as TestSubject from '../statement'
+
+describe('unit-d:content/statement', () => {
+  describe('Statement', () => {
+    it('should equal StatementMap[keyof StatementMap]', () => {
+      expectTypeOf<TestSubject.Statement>()
+        .toEqualTypeOf<TestSubject.StatementMap[keyof TestSubject.StatementMap]>
+    })
+  })
+
+  describe('StatementMap', () => {
+    it('should match [emptyStatement: EmptyStatement]', () => {
+      expectTypeOf<TestSubject.StatementMap>()
+        .toHaveProperty('emptyStatement')
+        .toEqualTypeOf<EmptyStatement>
+    })
+  })
+})

src/content/index.ts

@@ -5,3 +5,4 @@
 
 export type * from './literal'
 export type * from './primitive'
+export type * from './statement'

src/content/statement.ts

@@ -0,0 +1,32 @@
+/**
+ * @file Content - statement
+ * @module esast/content/statement
+ */
+
+import type { EmptyStatement } from '@flex-development/esast'
+
+/**
+ * Union of registered esast nodes that can occur where a statement is expected.
+ *
+ * To register custom esast nodes, augment {@linkcode StatementMap}. They will
+ * be added to this union automatically.
+ */
+type Statement = StatementMap[keyof StatementMap]
+
+/**
+ * Registry of nodes that can occur where a {@linkcode Statement} is expected.
+ *
+ * This interface can be augmented to register custom node types.
+ *
+ * @example
+ *  declare module '@flex-development/docast' {
+ *    interface StatementMap {
+ *      customStatement: CustomStatement
+ *    }
+ *  }
+ */
+interface StatementMap {
+  emptyStatement: EmptyStatement
+}
+
+export type { Statement, StatementMap }