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// Copyright (c) 2017, 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 specification in-memory representation.
///
/// Many dart tools are configurable to support different target platforms. For
/// a given target, they need to know what libraries are available and where are
/// the sources and target-specific patches.
///
/// Here we define APIs to represent this specification and implement
/// serialization to (and deserialization from) a JSON file.
///
/// Here is an example specification JSON file:
///
/// {
/// "vm": {
/// "libraries": {
/// "core": {
/// "uri": "async/core.dart",
/// "patches": [
/// "path/to/core_patch.dart",
/// "path/to/list_patch.dart"
/// ]
/// }
/// "async": {
/// "uri": "async/async.dart",
/// "patches": "path/to/async_patch.dart"
/// }
/// "convert": {
/// "uri": "convert/convert.dart",
/// }
/// "mirrors": {
/// "uri": "mirrors/mirrors.dart",
/// "supported": false
/// }
/// }
/// }
/// }
///
/// The format contains:
/// - a top level entry for each target. Keys are target names (e.g. "vm"
/// above), and values contain the entire specification of a target.
///
/// - each target specification is a map. Today, only one key is supported on
/// this map: "libraries".
///
/// - The "libraries" entry contains details for how each platform library is
/// implemented. The entry is a map, where keys are the name of the platform
/// library and values contain details for where to find the implementation
/// fo that library.
///
/// - The name of the library is a single token (e.g. "core") that matches the
/// Uri path used after `dart:` (e.g. "dart:core").
///
/// - The "uri" entry on the library information is mandatory. The value is a
/// string URI reference. The "patches" entry is optional and may have as a
/// value a string URI reference or a list of URI references.
///
/// All URI references can either be a file URI or a relative URI path,
/// which will be resolved relative to the location of the library
/// specification file.
///
/// - The "supported" entry on the library information is optional. The value
/// is a boolean indicating whether the library is supported in the
/// underlying target. However, since the libraries are assumed to be
/// supported by default, we only expect users to use `false`.
///
/// The purpose of this value is to configure conditional imports and
/// environment constants. By default every platform library that is
/// available in the "libraries" section implicitly defines an environment
/// variable `dart.library.name` as `"true"`, to indicate that the library
/// is supported. Some backends allow imports to an unsupported platform
/// library (turning a static error into a runtime error when the library is
/// eventually accessed). These backends can use `supported: false` to
/// report that such library is still not supported in conditional imports
/// and const `fromEnvironment` expressions.
///
///
/// Note: we currently have several different files that need to be updated
/// when changing libraries, sources, and patch files:
/// * .platform files (for dart2js)
/// * .gypi files (for vm)
/// * sdk_library_metadata/lib/libraries.dart (for analyzer, ddc)
///
/// we are in the process of unifying them all under this format (see
/// https://github.com/dart-lang/sdk/issues/28836), but for now we need to pay
/// close attention to change them consistently.
import 'dart:convert' show jsonDecode, jsonEncode;
import 'relativize.dart' show relativizeUri, isWindows;
/// Contents from a single library specification file.
///
/// Contains information about all libraries on all target platforms defined in
/// that file.
class LibrariesSpecification {
final Map<String, TargetLibrariesSpecification> _targets;
const LibrariesSpecification(
[this._targets = const <String, TargetLibrariesSpecification>{}]);
/// The library specification for a given [target], or throws if none is
/// available.
TargetLibrariesSpecification specificationFor(String target) {
TargetLibrariesSpecification? targetSpec = _targets[target];
if (targetSpec == null) {
throw new LibrariesSpecificationException(
'No library specification for target "$target"');
}
return targetSpec;
}
/// Parse the given [json] as a library specification, resolving any relative
/// paths from [baseUri].
///
/// May throw an exception if [json] is not properly formatted or contains
/// invalid values.
static LibrariesSpecification parse(Uri baseUri, String? json) {
if (json == null) return const LibrariesSpecification();
Map<String, dynamic> jsonData;
try {
dynamic data = jsonDecode(json);
if (data is! Map<String, dynamic>) {
return _reportError('top-level specification is not a map');
}
jsonData = data;
} on FormatException catch (e) {
throw new LibrariesSpecificationException(e);
}
Map<String, TargetLibrariesSpecification> targets =
<String, TargetLibrariesSpecification>{};
jsonData.forEach((String targetName, targetData) {
if (targetName.startsWith("comment:")) return null;
Map<String, LibraryInfo> libraries = <String, LibraryInfo>{};
if (targetData is! Map) {
_reportError("target specification for '$targetName' is not a map");
}
if (!targetData.containsKey("libraries")) {
_reportError("target specification "
"for '$targetName' doesn't have a libraries entry");
}
dynamic librariesData = targetData["libraries"];
if (librariesData is! Map<String, dynamic>) {
_reportError("libraries entry for '$targetName' is not a map");
}
librariesData.forEach((String name, data) {
if (data is! Map<String, dynamic>) {
_reportError(
"library data for '$name' in target '$targetName' is not a map");
}
Uri checkAndResolve(uriString) {
if (uriString is! String) {
return _reportError("uri value '$uriString' is not a string"
"(from library '$name' in target '$targetName')");
}
Uri uri = Uri.parse(uriString);
if (uri.scheme != '' && uri.scheme != 'file') {
return _reportError("uri scheme in '$uriString' is not supported.");
}
return baseUri.resolveUri(uri);
}
Uri uri = checkAndResolve(data['uri']);
List<Uri> patches;
if (data['patches'] is List) {
patches =
data['patches'].map<Uri>((s) => baseUri.resolve(s)).toList();
} else if (data['patches'] is String) {
patches = [checkAndResolve(data['patches'])];
} else if (data['patches'] == null) {
patches = const [];
} else {
_reportError("patches entry for '$name' is not a list or a string");
}
dynamic supported = data['supported'] ?? true;
if (supported is! bool) {
_reportError("\"supported\" entry: expected a 'bool' but "
"got a '${supported.runtimeType}' ('$supported')");
}
libraries[name] =
new LibraryInfo(name, uri, patches, isSupported: supported);
});
targets[targetName] =
new TargetLibrariesSpecification(targetName, libraries);
});
return new LibrariesSpecification(targets);
}
static Never _reportError(String error) =>
throw new LibrariesSpecificationException(error);
/// Serialize this specification to json.
///
/// If possible serializes paths relative to [outputUri].
String toJsonString(Uri outputUri) => jsonEncode(toJsonMap(outputUri));
Map toJsonMap(Uri outputUri) {
Map result = {};
Uri dir = outputUri.resolve('.');
String pathFor(Uri uri) => relativizeUri(dir, uri, isWindows);
_targets.forEach((targetName, target) {
Map libraries = {};
target._libraries.forEach((name, lib) {
libraries[name] = {
'uri': pathFor(lib.uri),
'patches': lib.patches.map(pathFor).toList(),
};
if (!lib.isSupported) {
libraries[name]['supported'] = false;
}
});
result[targetName] = {'libraries': libraries};
});
return result;
}
}
/// Specifies information about all libraries supported by a given target.
class TargetLibrariesSpecification {
/// Name of the target platform.
final String targetName;
final Map<String, LibraryInfo> _libraries;
const TargetLibrariesSpecification(this.targetName,
[this._libraries = const <String, LibraryInfo>{}]);
/// Details about a library whose import is `dart:$name`.
LibraryInfo? libraryInfoFor(String name) => _libraries[name];
Iterable<LibraryInfo> get allLibraries => _libraries.values;
}
/// Information about a `dart:` library in a specific target platform.
class LibraryInfo {
/// The name of the library, which is the path developers use to import this
/// library (as `dart:$name`).
final String name;
/// The file defining the main implementation of the library.
final Uri uri;
/// Patch files used for this library in the target platform, if any.
final List<Uri> patches;
/// Whether the library is supported and thus `dart.library.name` is "true"
/// for conditional imports and fromEnvironment constants.
final bool isSupported;
const LibraryInfo(this.name, this.uri, this.patches,
{this.isSupported: true});
/// The import uri for the defined library.
Uri get importUri => Uri.parse('dart:${name}');
}
class LibrariesSpecificationException {
Object error;
LibrariesSpecificationException(this.error);
@override
String toString() => '$error';
}