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// Copyright (c) 2014, 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.
/// Common methods used by transfomers for dealing with asset IDs.
library code_transformers.assets;
import 'dart:math' show min, max;
import 'package:barback/barback.dart';
import 'package:path/path.dart' as path;
import 'package:source_span/source_span.dart';
import 'messages/build_logger.dart';
import 'src/messages.dart';
/// Create an [AssetId] for a [url] seen in the [source] asset.
///
/// By default this is used to resolve relative urls that occur in HTML assets,
/// including cross-package urls of the form "packages/foo/bar.html". Dart
/// "package:" urls are not resolved unless [source] is Dart file (has a .dart
/// extension).
///
/// This function returns null if [url] can't be resolved. We log a warning
/// message in [logger] if we know the reason why resolution failed. This
/// happens, for example, when using incorrect paths to reach into another
/// package, or when [errorsOnAbsolute] is true and the url seems to be
/// absolute. If [span] is not `null` it is used to provide context for any
/// warning message(s) generated.
// TODO(sigmund): delete once this is part of barback (dartbug.com/12610)
AssetId uriToAssetId(
AssetId source, String url, TransformLogger logger, SourceSpan span,
{bool errorOnAbsolute: true}) {
if (url == null || url == '') return null;
var uri = Uri.parse(url);
var urlBuilder = path.url;
if (uri.host != '' || uri.scheme != '' || urlBuilder.isAbsolute(url)) {
if (source.extension == '.dart' && uri.scheme == 'package') {
var index = uri.path.indexOf('/');
if (index != -1) {
return new AssetId(
uri.path.substring(0, index), 'lib${uri.path.substring(index)}');
}
}
if (errorOnAbsolute) {
var msg = NO_ABSOLUTE_PATHS.create({'url': url});
logger.warning(logger is BuildLogger ? msg : msg.snippet, span: span);
}
return null;
}
var targetPath = urlBuilder
.normalize(urlBuilder.join(urlBuilder.dirname(source.path), url));
var segments = urlBuilder.split(targetPath);
var sourceSegments = urlBuilder.split(source.path);
assert(sourceSegments.length > 0);
var topFolder = sourceSegments[0];
var entryFolder = topFolder != 'lib' && topFolder != 'asset';
// Find the first 'packages/' or 'assets/' segment:
var packagesIndex = segments.indexOf('packages');
var assetsIndex = segments.indexOf('assets');
var index = (packagesIndex >= 0 && assetsIndex >= 0)
? min(packagesIndex, assetsIndex)
: max(packagesIndex, assetsIndex);
if (index > -1) {
if (entryFolder) {
// URLs of the form "packages/foo/bar" seen under entry folders (like
// web/, test/, example/, etc) are resolved as an asset in another
// package. 'packages' can be used anywhere, there is no need to walk up
// where the entrypoint file was.
// TODO(sigmund): this needs to change: Only resolve when index == 1 &&
// topFolder == segment[0], otherwise give a warning (dartbug.com/17596).
return _extractOtherPackageId(index, segments, logger, span);
} else if (index == 1 && segments[0] == '..') {
// Relative URLs of the form "../../packages/foo/bar" in an asset under
// lib/ or asset/ are also resolved as an asset in another package, but we
// check that the relative path goes all the way out where the packages
// folder lives (otherwise the app would not work in Dartium). Since
// [targetPath] has been normalized, "packages" or "assets" should be at
// index 1.
return _extractOtherPackageId(1, segments, logger, span);
} else {
var prefix = segments[index];
var fixedSegments = <String>[];
fixedSegments.addAll(sourceSegments.map((_) => '..'));
fixedSegments.addAll(segments.sublist(index));
var fixedUrl = urlBuilder.joinAll(fixedSegments);
var msg = INVALID_URL_TO_OTHER_PACKAGE
.create({'url': url, 'prefix': prefix, 'fixedUrl': fixedUrl});
logger.warning(logger is BuildLogger ? msg : msg.snippet, span: span);
return null;
}
}
// Otherwise, resolve as a path in the same package.
return new AssetId(source.package, targetPath);
}
AssetId _extractOtherPackageId(
int index, List<String> segments, TransformLogger logger, SourceSpan span) {
if (index >= segments.length) return null;
var prefix = segments[index];
if (prefix != 'packages' && prefix != 'assets') return null;
var folder = prefix == 'packages' ? 'lib' : 'asset';
if (segments.length < index + 3) {
var msg = INVALID_PREFIX_PATH.create({'prefix': prefix, 'folder': folder});
logger.warning(logger is BuildLogger ? msg : msg.snippet, span: span);
return null;
}
return new AssetId(segments[index + 1],
path.url.join(folder, path.url.joinAll(segments.sublist(index + 2))));
}
/// Gets a URI which would be appropriate for importing the file represented by
/// [assetId].
///
/// This function returns null if we cannot determine a uri for [assetId].
///
/// Note that [assetId] may represent a non-importable file such as a part.
String assetIdToUri(AssetId assetId,
{TransformLogger logger, SourceSpan span, AssetId from}) {
if (!assetId.path.startsWith('lib/')) {
// Cannot do absolute imports of non lib-based assets.
if (from == null) {
if (logger != null) {
var msg = UNSPECIFIED_FROM_IN_NON_LIB_ASSET.create({'id': '$assetId'});
logger.warning(logger is BuildLogger ? msg : msg.snippet, span: span);
}
return null;
}
if (assetId.package != from.package) {
if (logger != null) {
var msg = IMPORT_FROM_DIFFERENT_PACKAGE
.create({'toId': '$assetId', 'fromId': '$from'});
logger.warning(logger is BuildLogger ? msg : msg.snippet, span: span);
}
return null;
}
return new Uri(
path: path.url
.relative(assetId.path, from: path.url.dirname(from.path)))
.toString();
}
return Uri.parse('package:${assetId.package}/${assetId.path.substring(4)}')
.toString();
}