Refactor code-style

Author: wooorm

index.js

@@ -1,9 +1,9 @@
 /**
- * @typedef {import('./lib/types.js').Handler} Handler
- * @typedef {import('./lib/types.js').Handlers} Handlers
+ * @typedef {import('./lib/index.js').Handler} Handler
+ * @typedef {import('./lib/index.js').Handlers} Handlers
  * @typedef {import('./lib/index.js').Options} Options
  * @typedef {import('./lib/index.js').Result} Result
- * @typedef {import('./lib/types.js').State} State
+ * @typedef {import('./lib/index.js').State} State
  */
 
 export {toJs} from './lib/index.js'

lib/index.js

@@ -1,117 +1,145 @@
 /**
+ * @typedef {import('astring').State} State
+ * @typedef {import('estree-jsx').Node} Nodes
  * @typedef {import('estree-jsx').Program} Program
  * @typedef {typeof import('source-map').SourceMapGenerator} SourceMapGenerator
  * @typedef {import('source-map').RawSourceMap} Map
- * @typedef {import('./types.js').Handlers} Handlers
  */
 
 /**
- * @typedef BaseFields
+ * @typedef {Record<Nodes['type'], Handler>} Generator
+ *
+ * @callback Handler
+ *  Handle a particular node.
+ * @param {Generator} this
+ *   `astring` generator.
+ * @param {any} node
+ *   Node to serialize.
+ * @param {State} state
+ *   Info passed around.
+ * @returns {undefined}
+ *   Nothing.
+ *
+ * @typedef {Partial<import('astring').Generator>} Handlers
+ */
+
+/**
+ * @typedef {OptionsWithMaybeMapGenerator} Options
+ *   Configuration.
+ *
+ * @typedef OptionsFieldsBase
+ *   Base shared option fields.
  * @property {Handlers | null | undefined} [handlers]
  *   Object mapping node types to functions handling the corresponding nodes.
  *
- * @typedef SourceMapFieldsWithoutSourceMapGenerator
+ * @typedef OptionsFieldsWithoutSourceMapGenerator
+ *   Extra option fields where there’s definitely no source map generator.
  * @property {null | undefined} [SourceMapGenerator]
  *   Generate a source map by passing a `SourceMapGenerator` from `source-map`
- *   in.
- *   This works if there is positional info on nodes.
+ *   in; this works if there is positional info on nodes.
  * @property {null | undefined} [filePath]
- *   Path to input file.
- *   Only used in source map.
+ *   Path to input file; only used in source map.
  *
- * @typedef SourceMapFieldsWithSourceMapGenerator
+ * @typedef OptionsFieldsWithSourceMapGenerator
+ *   Extra option fields where there’s definitely a source map generator.
  * @property {SourceMapGenerator} SourceMapGenerator
  *   Generate a source map by passing a `SourceMapGenerator` from `source-map`
- *   in.
- *   This works if there is positional info on nodes.
+ *   in; this works if there is positional info on nodes.
  * @property {string | null | undefined} [filePath]
- *   Path to input file.
- *   Only used in source map.
+ *   Path to input file; only used in source map.
  *
- * @typedef SourceMapFieldsMaybeSourceMapGenerator
- * @property {SourceMapGenerator | null | undefined} SourceMapGenerator
+ * @typedef OptionsFieldsMaybeSourceMapGenerator
+ *   Extra option fields where there may or may not be a source map generator.
+ * @property {SourceMapGenerator | null | undefined} [SourceMapGenerator]
  *   Generate a source map by passing a `SourceMapGenerator` from `source-map`
- *   in.
- *   This works if there is positional info on nodes.
+ *   in; this works if there is positional info on nodes.
  * @property {string | null | undefined} [filePath]
- *   Path to input file.
- *   Only used in source map.
+ *   Path to input file; only used in source map.
  *
- * @typedef {BaseFields & SourceMapFieldsWithoutSourceMapGenerator} OptionsWithoutSourceMapGenerator
- * @typedef {BaseFields & SourceMapFieldsWithSourceMapGenerator} OptionsWithSourceMapGenerator
- * @typedef {BaseFields & SourceMapFieldsMaybeSourceMapGenerator} OptionsWithMaybeMapGenerator
+ * @typedef {OptionsFieldsBase & OptionsFieldsWithoutSourceMapGenerator} OptionsWithoutSourceMapGenerator
+ *   Options where there’s definitely no source map generator.
+ * @typedef {OptionsFieldsBase & OptionsFieldsWithSourceMapGenerator} OptionsWithSourceMapGenerator
+ *   Options where there’s definitely a source map generator.
+ * @typedef {OptionsFieldsBase & OptionsFieldsMaybeSourceMapGenerator} OptionsWithMaybeMapGenerator
+ *   Options where there may or may not be a source map generator.
  *
- * @typedef {OptionsWithMaybeMapGenerator} Options
- *   Configuration (optional).
+ * @typedef {ResultWithMaybeSourceMapGenerator} Result
+ *   Result.
  *
- * @typedef BaseResultFields
+ * @typedef ResultFieldsBase
+ *   Base shared result fields.
  * @property {string} value
  *   Serialized JavaScript.
  *
  * @typedef ResultFieldsWithoutSourceMapGenerator
+ *   Extra result fields where there’s definitely no source map generator.
  * @property {undefined} map
  *   Source map as (parsed) JSON, if `SourceMapGenerator` is passed.
  *
  * @typedef ResultFieldsWithSourceMapGenerator
+ *   Extra result fields where there’s definitely a source map generator.
  * @property {Map} map
  *   Source map as (parsed) JSON, if `SourceMapGenerator` is not passed.
  *
  * @typedef ResultFieldsMaybeSourceMapGenerator
+ *   Extra result fields where there may or may not be a source map generator.
  * @property {Map | undefined} map
  *   Source map as (parsed) JSON, if `SourceMapGenerator` might be passed.
  *
- * @typedef {BaseResultFields & ResultFieldsWithoutSourceMapGenerator} ResultWithoutSourceMapGenerator
- * @typedef {BaseResultFields & ResultFieldsWithSourceMapGenerator} ResultWithSourceMapGenerator
- * @typedef {BaseResultFields & ResultFieldsMaybeSourceMapGenerator} ResultMaybeSourceMapGenerator
- *
- * @typedef {ResultMaybeSourceMapGenerator} Result
+ * @typedef {ResultFieldsBase & ResultFieldsWithoutSourceMapGenerator} ResultWithoutSourceMapGenerator
+ *   Result where there’s definitely no source map generator.
+ * @typedef {ResultFieldsBase & ResultFieldsWithSourceMapGenerator} ResultWithSourceMapGenerator
+ *   Result where there’s definitely a source map generator.
+ * @typedef {ResultFieldsBase & ResultFieldsMaybeSourceMapGenerator} ResultWithMaybeSourceMapGenerator
+ *   Result where there may or may not be a source map generator.
  */
 
-import * as astring from 'astring'
+import {GENERATOR, generate} from 'astring'
 
-/** @type {Handlers} */
-const GENERATOR = astring.GENERATOR
-
-const generate = astring.generate
+/** @type {Options} */
+const emptyOptions = {}
 
 /**
  * Serialize an estree as JavaScript.
  *
- * @param tree
+ * @overload
+ * @param {Program} tree
+ * @param {OptionsWithSourceMapGenerator} options
+ * @returns {ResultWithSourceMapGenerator}
+ *
+ * @overload
+ * @param {Program} tree
+ * @param {OptionsWithMaybeMapGenerator} options
+ * @returns {ResultWithMaybeSourceMapGenerator}
+ *
+ * @overload
+ * @param {Program} tree
+ * @param {OptionsWithoutSourceMapGenerator | null | undefined} [options]
+ * @returns {ResultWithoutSourceMapGenerator}
+ *
+ * @param {Program} tree
  *   Estree (esast).
- * @param options
+ * @param {Options | null | undefined} [options]
  *   Configuration (optional).
- * @returns
+ * @returns {Result}
  *   Result, optionally with source map.
  */
-export const toJs =
-  /**
-   * @type {(
-   *   ((value: Program, options: OptionsWithSourceMapGenerator) => ResultWithSourceMapGenerator) &
-   *   ((value: Program, options: OptionsWithMaybeMapGenerator) => ResultMaybeSourceMapGenerator) &
-   *   ((value: Program, options?: OptionsWithoutSourceMapGenerator | null | undefined) => ResultWithoutSourceMapGenerator)
-   * )}
-   */
-  (
-    /**
-     * @param {Program} tree
-     * @param {Options | null | undefined} [options]
-     * @returns {Result}
-     */
-    function (tree, options) {
-      const {SourceMapGenerator, filePath, handlers} = options || {}
-      const sourceMap = SourceMapGenerator
-        ? new SourceMapGenerator({file: filePath || '<unknown>.js'})
-        : undefined
+export function toJs(tree, options) {
+  const {SourceMapGenerator, filePath, handlers} = options || emptyOptions
+  const sourceMap = SourceMapGenerator
+    ? new SourceMapGenerator({file: filePath || '<unknown>.js'})
+    : undefined
 
-      const value = generate(tree, {
-        comments: true,
-        // @ts-expect-error: assume all handlers are defined.
-        generator: {...GENERATOR, ...handlers},
-        sourceMap
-      })
-      const map = sourceMap ? sourceMap.toJSON() : undefined
-
-      return {value, map}
+  const value = generate(
+    tree,
+    // @ts-expect-error: `sourceMap` can be undefined, `astring` types are buggy.
+    {
+      comments: true,
+      generator: {...GENERATOR, ...handlers},
+      sourceMap: sourceMap || undefined
     }
   )
+  const map = sourceMap ? sourceMap.toJSON() : undefined
+
+  return {value, map}
+}