Add --package-root option to the compiler.

dart/lib/compiler/implementation/dart2js.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #library('dart2js');
 
 #import('dart:io');
 #import('dart:uri');
 #import('dart:utf');
 
@@ skipping 11 matching lines @@
   String pattern;
   HandleOption handle;
 
   OptionHandler(this.pattern, this.handle);
 }
 
 String extractParameter(String argument) {
   return argument.substring(argument.indexOf('=') + 1);
 }
 
+String extractPath(String argument) {
+  String path = nativeToUriPath(extractParameter(argument));
+  return path.endsWith("/") ? path : "$path/";
+}
+
 void parseCommandLine(List<OptionHandler> handlers, List<String> argv) {
   // TODO(ahe): Use ../../args/args.dart for parsing options instead.
   var patterns = <String>[];
   for (OptionHandler handler in handlers) {
     patterns.add(handler.pattern);
   }
   var pattern = new RegExp('^(${Strings.join(patterns, ")\$|(")})\$');
   OUTER: for (String argument in argv) {
     Match match = pattern.firstMatch(argument);
     assert(match.groupCount() == handlers.length);
     for (int i = 0; i < handlers.length; i++) {
       if (match[i + 1] !== null) {
         handlers[i].handle(argument);
         continue OUTER;
       }
     }
     throw 'Internal error: "$argument" did not match';
   }
 }
 
 void compile(List<String> argv) {
   Uri cwd = getCurrentDirectory();
   bool throwOnError = false;
   bool showWarnings = true;
   bool verbose = false;
   Uri libraryRoot = cwd;
   Uri out = cwd.resolve('out.js');
+  Uri packageRoot = null;
   List<String> options = new List<String>();
   bool explicitOut = false;
   bool wantHelp = false;
 
   passThrough(String argument) => options.add(argument);
 
+  setLibraryRoot(String argument) {
+    libraryRoot = cwd.resolve(extractPath(argument));
+  }
+
+  setPackageRoot(String argument) {
+    packageRoot = cwd.resolve(extractPath(argument));
+  }
+
+  setOutput(String argument) {
+    explicitOut = true;
+    out = cwd.resolve(nativeToUriPath(extractParameter(argument)));
+  }
+
   List<String> arguments = <String>[];
   List<OptionHandler> handlers = <OptionHandler>[
     new OptionHandler('--throw-on-error', (_) => throwOnError = true),
     new OptionHandler('--suppress-warnings', (_) => showWarnings = false),
     new OptionHandler('--output-type=dart|--output-type=js', passThrough),
     new OptionHandler('--verbose|-v', (_) => verbose = true),
-    new OptionHandler('--library-root=.+', (String argument) {
-      String path = nativeToUriPath(extractParameter(argument));
-      if (!path.endsWith("/")) path = "$path/";
-      libraryRoot = cwd.resolve(path);
-    }),
-    new OptionHandler('--out=.+|-o.+', (String argument) {
-      explicitOut = true;
-      out = cwd.resolve(nativeToUriPath(extractParameter(argument)));
-    }),
+    new OptionHandler('--library-root=.+', setLibraryRoot),
+    new OptionHandler('--out=.+|-o.+', setOutput),
     new OptionHandler('--allow-mock-compilation', passThrough),
     new OptionHandler('--no-colors', (_) => colors.enabled = false),
     new OptionHandler('--enable[_-]checked[_-]mode|--checked|-c',
                       (_) => passThrough('--enable-checked-mode')),
     new OptionHandler(@'--help|-h|/\?|/h', (_) => wantHelp = true),
+    new OptionHandler(@'--package-root=.+|-p.+', setPackageRoot),
     // The following two options must come last.
     new OptionHandler('-.*', (String argument) {
       helpAndFail('Error: Unknown option "$argument".');
     }),
     new OptionHandler('.*', (String argument) {
       arguments.add(nativeToUriPath(argument));
     })
   ];
 
   parseCommandLine(handlers, argv);
@@ skipping 48 matching lines @@
       SourceFile file = sourceFiles[uri.toString()];
       print(file.getLocationMessage(message, begin, end, true));
     }
     if (fatal && throwOnError) {
       isAborting = true;
       throw new AbortLeg(message);
     }
   }
 
   Uri uri = cwd.resolve(arguments[0]);
+  if (packageRoot === null) {
+    packageRoot = uri.resolve('./packages/');
+  }
+
   info('compiling $uri');
+  info('package root is $packageRoot');
 
   // TODO(ahe): We expect the future to be complete and call value
   // directly. In effect, we don't support truly asynchronous API.
-  String code = api.compile(uri, libraryRoot, provider, handler, options).value;
+  String code = api.compile(uri, libraryRoot, packageRoot, provider, handler,
+                            options).value;
   if (code === null) {
     fail('Error: Compilation failed.');
   }
   writeString(out, code);
   int jsBytesWritten = code.length;
   info('compiled $dartBytesRead bytes Dart -> $jsBytesWritten bytes JS '
        'in ${relativize(cwd, out)}');
   if (!explicitOut) {
     String input = uriPathToNative(arguments[0]);
     String output = relativize(cwd, out);
@@ skipping 64 matching lines @@
 
   -c, --enable-checked-mode, --checked
     Insert runtime type checks and enable assertions (checked mode).
 
   -h, /h, /?, --help
     Display this message (add -v for information about all options).
 
   -v, --verbose
     Display verbose information.
 
-  --output-type=<value>
-    Output either JavaScript code (if value is 'js') or Dart code (if value is 'dart').
-    Default value is 'js'.
+  -p<path>, --package-root=<path>
+    Where to find packages, that is, "package:..." imports.
+
+  --output-type=dart

[ahe, 2012/05/22 11:42:49]

@anton: I decided to simplify this. We only recognize this specific string
anyways.

A related note, I think we want to change line 246 when your work is complete.

+    Output Dart code instead of JavaScript.
 
   --suppress-warnings
     Do not display any warnings.
 
   --no-colors
     Do not add colors to diagnostic messages.
 
 The following options are only used for compiler development and may
 be removed in a future version:
   --throw-on-error
@@ skipping 31 matching lines @@
     } catch (var ignored) {
       print('Internal error: error while printing exception');
     }
     try {
       print(trace);
     } finally {
       exit(253); // 253 is recognized as a crash by our test scripts.
     }
   }
 }