Remove dependency on the Path class from dart:io

lib/file_generator.dart

 // Copyright (c) 2013, 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.
 
 part of protoc;
 
 class FileGenerator implements ProtobufContainer {
   final FileDescriptorProto _fileDescriptor;
   final ProtobufContainer _parent;
   final GenerationContext _context;
@@ skipping 14 matching lines @@
     for (FieldDescriptorProto extension in _fileDescriptor.extension) {
       extensionGenerators.add(
           new ExtensionGenerator(extension, this, _context));
     }
   }
 
   String get classname => '';
   String get fqname => _fileDescriptor.package == null
       ? '' : '.${_fileDescriptor.package}';
 
-  _generatedFilePath(Path path) {
-    Path withoutExtension = path.directoryPath
-        .join(new Path(path.filenameWithoutExtension));
-    return '${withoutExtension.toNativePath()}.pb.dart';
+  // Extract the filename from a URI and remove the extension.
+  String _fileNameWithoutExtension(Uri filePath) {
+    String fileName = filePath.pathSegments.last;
+    int index = fileName.lastIndexOf(".");
+    return index == -1 ? fileName : fileName.substring(0, index);
+  }
+
+  // Create the URI for the generated Dart file from the URI of the
+  // .proto file.
+  Uri _generatedFilePath(Uri protoFilePath) {
+    var dartFileName = _fileNameWithoutExtension(protoFilePath) + ".pb.dart";

[Anton Muhin, 2013/09/02 09:26:10]

nit: mix of ' and "

[Anton Muhin, 2013/09/02 09:26:10]

nit: I'd rather use interpolation, but completely up to you

+    return protoFilePath.resolve(dartFileName);
+  }
+
+  String _generateClassName(Uri protoFilePath) {
+    String s = _fileNameWithoutExtension(protoFilePath).replaceAll('-', '_');
+    return '${s[0].toUpperCase()}${s.substring(1)}';
+  }
+
+  Uri _relative(Uri target, Uri base) {

[Siggi Cherem (dart-lang), 2013/08/19 16:44:48]

could we instead depend on the path package and use the relative implementation
there?

[Søren Gjesse, 2013/08/20 07:35:33]

I would rather not rely on other packages in the protocol buffer compiler. We
will add relative (or relativeTo) to the Uri class in dart:core, and then we can
get rid of this again.

[Siggi Cherem (dart-lang), 2013/08/20 17:42:48]

Sounds good, especially since this should be going away. Consider maybe adding a
TODO about it.

In general, I think it's totally ok to have extra dependencies in this package.
If this is distributed as a pub package, then doing pub install will
automatically include the dependencies we need. 

+    // Ignore the last segment of the base.
+    List<String> baseSegments =

[Anton Muhin, 2013/09/02 09:26:10]

absolutely up to you, but I rather use new
List<String>.from(base.pathSegments)..removeLast()

+        base.pathSegments.sublist(0, base.pathSegments.length - 1);
+    List<String> targetSegments = target.pathSegments;
+    if (baseSegments.length == 1 && baseSegments[0] == '.') {

[Anton Muhin, 2013/09/02 09:26:10]

what if baseSegments is [ '.', '.', '.' ] or alike?  overall, is path
normalization in this code good enough?

+      baseSegments = [];
+    }
+    if (targetSegments.length == 1 && targetSegments[0] == '.') {
+      targetSegments = [];
+    }
+    int common = 0;
+    int length = min(targetSegments.length, baseSegments.length);
+    while (common < length && targetSegments[common] == baseSegments[common]) {
+      common++;
+    }
+
+    final segments = <String>[];
+    if (common < baseSegments.length && baseSegments[common] == '..') {
+      throw new ArgumentError(
+          "Cannot create a relative path from $base to $target");
+    }
+    for (int i = common; i < baseSegments.length; i++) {
+      segments.add('..');
+    }
+    for (int i = common; i < targetSegments.length; i++) {
+      segments.add('${targetSegments[i]}');
+    }
+    if (segments.isEmpty) {
+      segments.add('.');
+    }
+    return new Uri(pathSegments: segments);
   }
 
   CodeGeneratorResponse_File generateResponse() {
     MemoryWriter writer = new MemoryWriter();
     IndentingWriter out = new IndentingWriter('  ', writer);
 
     generate(out);
 
-    Path filePath = new Path(_fileDescriptor.name);
+    Uri filePath = new Uri(scheme: 'file', path: _fileDescriptor.name);
     return new CodeGeneratorResponse_File()
-        ..name = _generatedFilePath(filePath)
+        ..name = _generatedFilePath(filePath).path
         ..content = writer.toString();
   }
 
   void generate(IndentingWriter out) {
+    Uri filePath = new Uri.file(_fileDescriptor.name);
+    if (filePath.isAbsolute) {
+        // protoc should never generate an file descriptor an absolute path.
+        throw("FAILURE: file with absolute path is not supported");
+    }
 
-    Path filePath = new Path(_fileDescriptor.name);
-    Path directoryPath = filePath.directoryPath.canonicalize();
-
-    String className = filePath.filenameWithoutExtension.replaceAll('-', '_');
-    className = '${className[0].toUpperCase()}${className.substring(1)}';
+    String className = _generateClassName(filePath);
 
     String libraryName = className + '.pb';
 
     out.println(
       '///\n'
       '//  Generated code. Do not modify.\n'
       '///\n'
       'library $libraryName;\n'
       '\n'
       "import 'dart:typed_data';\n\n"
       "import 'package:protobuf/protobuf.dart';"
     );
 
     for (String import in _fileDescriptor.dependency) {
-      Path relativeProtoPath =
-          new Path(import).relativeTo(directoryPath).canonicalize();
+      Uri importPath = new Uri.file(import);
+      if (importPath.isAbsolute) {
+        // protoc should never generate an import with an absolute path.
+        throw("FAILURE: Import with absolute path is not supported");

[Anton Muhin, 2013/09/02 09:26:10]

nit: mix of ' and "

+      }
+      // Create a relative path from the current file to the import.
+      Uri relativeProtoPath = _relative(importPath, filePath);

[Siggi Cherem (dart-lang), 2013/08/19 16:44:48]

What do imports look like in the descriptor? Are they only paths or can they be
URI themselves?

In particular, if they could be 'package:foo/bar/baz' imports, we might be
restricted to only use _relative if the import and the base path are on the same
package.

[Søren Gjesse, 2013/08/20 07:35:33]

The imports in the descriptor are the literal strings (unquoted) from the import
directive in the .proto file. What I found was that these have to be relative,
and are searched for relative to the current directory and relative to the
directories set with the -I option given to protoc. So they are only paths as
protoc need to be able to find and open them as well.

[Siggi Cherem (dart-lang), 2013/08/20 17:42:48]

I see, thanks.

In the future we might want to start looking into how this will integrate with
pub packages, pub-serve and pub-deploy. For instance, in polymer and other code
generation tools we've written, we started seeing that people want to refer to
paths in other packages. One way we allow to do that is to use paths that
include a 'packages/' folder. For example: 'packages/foo/bar.proto'  is then
resolved as the lib/bar.proto path inside the 'foo' package.

       out.println("import '${_generatedFilePath(relativeProtoPath)}';");
     }
     out.println('');
 
     // Initialize Field.
     for (MessageGenerator m in messageGenerators) {
       m.initializeFields();
     }
 
     // Generate code.
@@ skipping 29 matching lines @@
       <String, ProtobufContainer>{};
 
   GenerationContext(this.options);
 
   void register(ProtobufContainer container) {
     _registry[container.fqname] = container;
   }
 
   ProtobufContainer operator [](String fqname) => _registry[fqname];
 }