implement rollup --watch

bin/help.md

@@ -9,6 +9,7 @@ Basic options:
 -h, --help               Show this help message
 -c, --config             Use this config file (if argument is used but value
                            is unspecified, defaults to rollup.config.js)
+-w, --watch              Watch files in bundle and rebuild on changes
 -i, --input              Input (alternative to <entry file>)
 -o, --output <output>    Output (if absent, prints to stdout)
 -f, --format [es6]       Type of output (amd, cjs, es6, iife, umd)

bin/rollup

@@ -20,7 +20,8 @@ command = minimist( process.argv.slice( 2 ), {
 		n: 'name',
 		o: 'output',
 		u: 'id',
-		v: 'version'
+		v: 'version',
+		w: 'watch'
 	}
 });
 

bin/runRollup.js

@@ -1,6 +1,7 @@
 require( 'source-map-support' ).install();
 
 var path = require( 'path' );
+var relative = require( 'require-relative' );
 var handleError = require( './handleError' );
 var rollup = require( '../' );
 
@@ -127,7 +128,20 @@ function execute ( options, command ) {
 	});
 
 	try {
+		if ( command.watch ) {
+			let watch;
+
+			try {
+				watch = relative( 'rollup-watch', process.cwd() );
+			} catch ( err ) {
+				// TODO offer to install rollup-watch
+				throw err;
+			}
+
+			watch( options );
+		} else {
 			bundle( options ).catch( handleError );
+		}
 	} catch ( err ) {
 		handleError( err );
 	}

package.json

@@ -63,6 +63,7 @@
   "dependencies": {
     "chalk": "^1.1.1",
     "minimist": "^1.2.0",
+    "require-relative": "^0.8.7",
     "source-map-support": "^0.4.0"
   },
   "files": [