chore: distribute commonjs, ES module, and type declaration files (#83)

This commit changes the distributable file format in the following ways:
- unbundles both the commonjs and ES module files from one file each to one for each original file for each format
- includes `.d.ts` files for each original source file
- adds `types` field to `package.json` per https://www.typescriptlang.org/docs/handbook/declaration-files/publishing.html
- removes rollup as the dist builder and uses a wrapper, `script/build`, that uses `tsc` directly
- removes `coffee-lex.js.flow`

I don't like that I had to write a custom build script for this. It makes me feel like I'm doing something incorrectly to support both commonjs and ES modules. I removed rollup because it didn't seem to play well with TypeScript from a publishing perspective. Specifically, I couldn't find any way to automatically build a `d.ts` file for the project bundle generated by rollup that didn't have serious shortcomings (https://github.com/rollup/rollup-plugin-typescript/issues/54). I considered keeping the bundled `.js` and `.mjs` files and using multiple `.d.ts` files, but there didn't seem to be much benefit over simply leaving all of them split up. Other rollup-based projects can still efficiently bundle coffee-lex with the modules split out as separate files.

package.json

@@ -1,11 +1,12 @@
 {
   "name": "coffee-lex",
   "description": "Stupid lexer for CoffeeScript.",
-  "main": "dist/coffee-lex.js",
-  "module": "dist/coffee-lex.mjs",
+  "main": "dist/index.js",
+  "module": "dist/index.mjs",
+  "types": "dist/index.d.ts",
   "scripts": {
     "prebuild": "rm -rf dist/",
-    "build": "rollup -c && cp src/coffee-lex.js.flow dist/",
+    "build": "./script/build",
     "lint": "tslint --config tslint.json --project tsconfig.json --type-check",
     "lint-fix": "tslint --config tslint.json --project tsconfig.json --type-check --fix",
     "pretest": "npm run lint",
@@ -37,9 +38,6 @@
     "@types/node": "^6.0.51",
     "decaffeinate-coffeescript": "^1.10.0-patch5",
     "mocha": "^3.2.0",
-    "reify": "^0.4.4",
-    "rollup": "^0.37.0",
-    "rollup-plugin-typescript": "^0.8.1",
     "semantic-release": "^6.3.2",
     "ts-node": "^1.7.2",
     "tslint": "^4.0.2",

script/build

@@ -0,0 +1,20 @@
+#!/usr/bin/env bash
+
+set -e
+
+DIST="${DIST:-dist}"
+TSC="${TSC:-node_modules/.bin/tsc}"
+
+# Build ES module version.
+"${TSC}" --project . --outDir "${DIST}" --module ES6
+for js in $(find "${DIST}" -name '*.js'); do
+  mv "${js}" "$(dirname "${js}")/$(basename "${js}" .js).mjs"
+done
+
+# Build CommonJS version.
+"${TSC}" --project . --outDir "${DIST}" --module commonjs
+
+# Restructure.
+rm -rf dist/test
+mv dist/src/* dist/
+rmdir dist/src

tsconfig.json

@@ -8,6 +8,11 @@
     "experimentalDecorators": true,
     "noUnusedParameters": true,
     "noUnusedLocals": true,
-    "noEmit": true
-  }
+    "noImplicitReturns": true,
+    "noFallthroughCasesInSwitch": true
+  },
+  "exclude": [
+    "node_modules",
+    "dist/**/*"
+  ]
 }