feat(content): Declaration, DeclarationMap

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

.eslintrc.cjs

@@ -10,7 +10,15 @@
  */
 const config = {
   extends: ['./.eslintrc.base.cjs'],
-  overrides: [...require('./.eslintrc.base.cjs').overrides],
+  overrides: [
+    ...require('./.eslintrc.base.cjs').overrides,
+    {
+      files: ['src/content/declaration.ts'],
+      rules: {
+        'unicorn/no-keyword-prefix': 0
+      }
+    }
+  ],
   root: true
 }
 

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

@@ -0,0 +1,36 @@
+/**
+ * @file Type Tests - declaration
+ * @module esast/content/tests/unit-d/declaration
+ */
+
+import type { NodeObject } from '#tests/types'
+import type {
+  FunctionDeclaration,
+  VariableDeclaration
+} from '@flex-development/esast'
+import type * as TestSubject from '../declaration'
+
+describe('unit-d:content/declaration', () => {
+  describe('Declaration', () => {
+    it('should equal DeclarationMap[keyof DeclarationMap]', () => {
+      // Arrange
+      type K = keyof TestSubject.DeclarationMap
+      type Expect = TestSubject.DeclarationMap[K]
+
+      // Expect
+      expectTypeOf<TestSubject.Declaration>().toEqualTypeOf<Expect>
+    })
+  })
+
+  describe('DeclarationMap', () => {
+    it('should match NodeObject<FunctionDeclaration>', () => {
+      expectTypeOf<TestSubject.DeclarationMap>()
+        .toMatchTypeOf<NodeObject<FunctionDeclaration>>()
+    })
+
+    it('should match NodeObject<VariableDeclaration>', () => {
+      expectTypeOf<TestSubject.DeclarationMap>()
+        .toMatchTypeOf<NodeObject<VariableDeclaration>>()
+    })
+  })
+})

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

@@ -9,6 +9,7 @@ import type {
   BreakStatement,
   ContinueStatement,
   DebuggerStatement,
+  DeclarationMap,
   DoWhileStatement,
   EmptyStatement,
   ExpressionStatement,
@@ -26,6 +27,10 @@ describe('unit-d:content/statement', () => {
   })
 
   describe('StatementMap', () => {
+    it('should extend DeclarationMap', () => {
+      expectTypeOf<TestSubject.StatementMap>().toMatchTypeOf<DeclarationMap>()
+    })
+
     it('should match NodeObject<BlockStatement>', () => {
       expectTypeOf<TestSubject.StatementMap>()
         .toMatchTypeOf<NodeObject<BlockStatement>>()

src/content/declaration.ts

@@ -0,0 +1,37 @@
+/**
+ * @file Content - declaration
+ * @module esast/content/declaration
+ */
+
+import type {
+  FunctionDeclaration,
+  VariableDeclaration
+} from '@flex-development/esast'
+
+/**
+ * Union of registered esast nodes that can occur where a non-module declaration
+ * is expected.
+ *
+ * To register custom esast nodes, augment {@linkcode DeclarationMap}.
+ * They will be added to this union automatically.
+ */
+type Declaration = DeclarationMap[keyof DeclarationMap]
+
+/**
+ * Registry of nodes that can occur where a {@linkcode Declaration} is expected.
+ *
+ * This interface can be augmented to register custom node types.
+ *
+ * @example
+ *  declare module '@flex-development/esast' {
+ *    interface DeclarationMap {
+ *      customDeclaration: CustomDeclaration
+ *    }
+ *  }
+ */
+interface DeclarationMap {
+  functionDeclaration: FunctionDeclaration
+  variableDeclaration: VariableDeclaration
+}
+
+export type { Declaration, DeclarationMap }

src/content/index.ts

@@ -3,6 +3,7 @@
  * @module esast/content
  */
 
+export type * from './declaration'
 export type * from './expression'
 export type * from './literal'
 export type * from './pattern'

src/content/statement.ts

@@ -8,6 +8,7 @@ import type {
   BreakStatement,
   ContinueStatement,
   DebuggerStatement,
+  DeclarationMap,
   DoWhileStatement,
   EmptyStatement,
   ExpressionStatement,
@@ -34,8 +35,10 @@ type Statement = StatementMap[keyof StatementMap]
  *      customStatement: CustomStatement
  *    }
  *  }
+ *
+ * @extends {DeclarationMap}
  */
-interface StatementMap {
+interface StatementMap extends DeclarationMap {
   blockStatement: BlockStatement
   breakStatement: BreakStatement
   continueStatement: ContinueStatement