Add codegen support in smoke

pkg/smoke/lib/codegen/generator.dart

+// 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.
+
+/// Library to generate code that can initialize the `StaticConfiguration` in
+/// `package:smoke/static.dart`.
+///
+/// This library doesn't have any specific logic to extract information from
+/// Dart source code. To extract code using the analyzer, take a look at the
+/// `smoke.codegen.recorder` library.
+library smoke.codegen.generator;
+
+import 'dart:collection' show SplayTreeMap, SplayTreeSet;
+
+/// Collects the necessary information and generates code to initialize a
+/// `StaticConfiguration`. After setting up the generator by calling
+/// [addGetter], [addSetter], [addSymbol], and [addDeclaration], you can
+/// retrieve the generated code using the following three methods:
+///
+///   * [writeImports] writes a list of imports directives,
+///   * [writeTopLevelDeclarations] writes additional declarations used to
+///     represent mixin classes by name in the generated code.
+///   * [writeInitCall] writes the actual code that allocates the static
+///     configuration.
+///
+/// You'd need to include all three in your generated code, since the
+/// initialization code refers to symbols that are only available from the
+/// generated imports or the generated top-level declarations.
+class SmokeCodeGenerator {
+  // Note: we use SplayTreeSet/Map here and below to keep generated code sorted.
+  /// Names used as getters via smoke.
+  final Set<String> _getters = new SplayTreeSet();
+
+  /// Names used as setters via smoke.
+  final Set<String> _setters = new SplayTreeSet();
+
+  /// Subclass relations needed to run smoke queries.
+  final Map<TypeIdentifier, TypeIdentifier> _parents = new SplayTreeMap();
+
+  /// Declarations requested via `smoke.getDeclaration or `smoke.query`.
+  final Map<TypeIdentifier, Map<String, _DeclarationCode>> _declarations =
+      new SplayTreeMap();
+
+  /// Names that are used both as strings and symbols.
+  final Set<String> _names = new SplayTreeSet();
+
+  /// Prefixes associated with imported libraries.
+  final Map<String, String> _libraryPrefix = {};
+
+  /// Register that [name] is used as a getter in the code.
+  void addGetter(String name) { _getters.add(name); }
+
+  /// Register that [name] is used as a setter in the code.
+  void addSetter(String name) { _setters.add(name); }
+
+  /// Register that [name] might be needed as a symbol.
+  void addSymbol(String name) { _names.add(name); }
+
+  int _mixins = 0;
+
+  /// Creates a new type to represent a mixin. Use [comment] to help users
+  /// figure out what mixin is being represented.
+  TypeIdentifier createMixinType([String comment = '']) =>
+      new TypeIdentifier(null, '_M${_mixins++}', comment);
+
+  /// Register that we care to know that [child] extends [parent].
+  void addParent(TypeIdentifier child, TypeIdentifier parent) {
+    var existing = _parents[child];
+    if (existing != null) {
+      if (existing == parent) return;
+      throw new StateError('$child already has a different parent associated'
+          '($existing instead of $parent)');
+    }
+    _addLibrary(child.importUrl);
+    _addLibrary(parent.importUrl);
+    _parents[child] = parent;
+  }
+
+  /// Register a declaration of a field, property, or method. Note that one and
+  /// only one of [isField], [isMethod], or [isProperty] should be set at a
+  /// given time.
+  void addDeclaration(TypeIdentifier cls, String name, TypeIdentifier type,
+      {bool isField: false, bool isProperty: false, bool isMethod: false,
+      bool isFinal: false, bool isStatic: false,
+      List<ConstExpression> annotations: const []}) {
+    final count = (isField ? 1 : 0) + (isProperty ? 1 : 0) + (isMethod ? 1 : 0);
+    if (count != 1) {
+      throw new ArgumentError('Declaration must be one (and only one) of the '
+          'following: a field, a property, or a method.');
+    }
+    var kind = isField ? 'FIELD' : isProperty ? 'PROPERTY' : 'METHOD';
+    _declarations.putIfAbsent(cls,
+        () => new SplayTreeMap<String, _DeclarationCode>());
+    _addLibrary(cls.importUrl);
+    var map = _declarations[cls];
+
+    for (var exp in annotations) {
+      for (var lib in exp.librariesUsed) {
+        _addLibrary(lib);
+      }
+    }
+
+    _addLibrary(type.importUrl);
+    var decl = new _DeclarationCode(name, type, kind, isFinal, isStatic,
+        annotations);
+    if (map.containsKey(name) && map[name] != decl) {
+      throw new StateError('$type.$name already has a different declaration'
+          ' (${map[name]} instead of $decl).');
+    }
+    map[name] = decl;
+  }
+
+  /// Register that we might try to read declarations of [type], even if no
+  /// declaration exists. This informs the smoke system that querying for a
+  /// member in this class might be intentional and not an error.
+  void addEmptyDeclaration(TypeIdentifier type) {
+    _addLibrary(type.importUrl);
+    _declarations.putIfAbsent(type,
+        () => new SplayTreeMap<String, _DeclarationCode>());
+  }
+
+  /// Writes to [buffer] a line for each import that is needed by the generated
+  /// code. The code added by [writeInitCall] depends on these imports.
+  void writeImports(StringBuffer buffer) {
+    DEFAULT_IMPORTS.forEach((i) => buffer.writeln(i));
+    _libraryPrefix.forEach((url, prefix) {
+      buffer.writeln("import '$url' as $prefix;");
+    });
+  }
+
+  /// Writes to [buffer] top-level declarations that are used by the code
+  /// generated in [writeInitCall]. These are typically declarations of empty
+  /// classes that are then used as placeholders for mixin superclasses.
+  void writeTopLevelDeclarations(StringBuffer buffer) {
+    var types = new Set()
+        ..addAll(_parents.keys)
+        ..addAll(_parents.values)
+        ..addAll(_declarations.keys)
+        ..addAll(_declarations.values.expand(
+              (m) => m.values.map((d) => d.type)))
+        ..removeWhere((t) => t.importUrl != null);
+    for (var type in types) {
+      buffer.write('abstract class ${type.name} {}');
+      if (type.comment != null) buffer.write(' // ${type.comment}');
+      buffer.writeln();
+    }
+  }
+
+  /// Appends to [buffer] code that will initialize smoke's static
+  /// configuration. For example, the code might be of the form:
+  ///
+  ///    useGeneratedCode(new StaticConfiguration(
+  ///      getters: {
+  ///         #i: (o) => o.i,
+  ///         ...
+  ///      names: {
+  ///         #i: "i",
+  ///      }));
+  ///
+  /// The optional [indent] argument is used for formatting purposes. All
+  /// entries in each map (getters, setters, names, declarations, parents) are
+  /// sorted alphabetically.
+  ///
+  /// **Note**: this code assumes that imports from [writeImports] and top-level
+  /// declarations from [writeTopLevelDeclarations] are included in the same
+  /// library where this code will live.
+  void writeInitCall(StringBuffer buffer, [int indent = 2]) {
+    final spaces = new List.filled(indent, ' ').join('');
+    var args = {};
+
+    if (_getters.isNotEmpty) {
+      args['getters'] = _getters.map((n) => '#$n: (o) => o.$n');
+    }
+    if (_setters.isNotEmpty) {
+      args['setters'] = _setters.map((n) => '#$n: (o, v) { o.$n = v; }');
+    }
+
+    if (_parents.isNotEmpty) {
+      var parentsMap = [];
+      _parents.forEach((child, parent) {
+        var parent = _parents[child];
+        parentsMap.add('${child.asCode(_libraryPrefix)}: '
+          '${parent.asCode(_libraryPrefix)}');
+      });
+      args['parents'] = parentsMap;
+    }
+
+    if (_declarations.isNotEmpty) {
+      var declarations = [];
+      _declarations.forEach((type, members) {
+        final sb = new StringBuffer()
+            ..write(type.asCode(_libraryPrefix))
+            ..write(': ');
+        if (members.isEmpty) {
+          sb.write('const {}');
+        } else {
+          sb.write('{\n');
+          members.forEach((name, decl) {
+            var decl = members[name].asCode(_libraryPrefix);
+            sb.write('$spaces        #$name: $decl,\n');
+          });
+          sb.write('$spaces      }');
+        }
+        declarations.add(sb.toString());
+      });
+      args['declarations'] = declarations;
+    }
+
+    if (_names.isNotEmpty) {
+      args['names'] = _names.map((n) => "#$n: '$n'");
+    }
+
+    buffer..write(spaces)
+        ..writeln('useGeneratedCode(new StaticConfiguration(')
+        ..write('$spaces    checkedMode: false');
+
+    args.forEach((name, mapContents) {
+      buffer.writeln(',');
+      // TODO(sigmund): use const map when Type can be keys (dartbug.com/17123)
+      buffer.writeln('$spaces    $name: {');
+      for (var entry in mapContents) {
+        buffer.writeln('$spaces      $entry,');
+      }
+      buffer.write('$spaces    }');
+    });
+    buffer.writeln('));');
+  }
+
+  /// Adds a library that needs to be imported.
+  void _addLibrary(String url) {
+    if (url == null || url == 'dart:core') return;
+    _libraryPrefix.putIfAbsent(url, () => 'smoke_${_libraryPrefix.length}');
+  }
+}
+
+/// Information used to generate code that allocates a `Declaration` object.
+class _DeclarationCode extends ConstExpression {
+  final String name;
+  final TypeIdentifier type;
+  final String kind;
+  final bool isFinal;
+  final bool isStatic;
+  final List<ConstExpression> annotations;
+
+  _DeclarationCode(this.name, this.type, this.kind, this.isFinal, this.isStatic,
+      this.annotations);
+
+  List<String> get librariesUsed => []
+      ..addAll(type.librariesUsed)
+      ..addAll(annotations.expand((a) => a.librariesUsed));
+
+  String asCode(Map<String, String> libraryPrefixes) {
+    var sb = new StringBuffer();
+    sb.write("const Declaration(#$name, ${type.asCode(libraryPrefixes)}");
+    if (kind != 'FIELD') sb.write(', kind: $kind');
+    if (isFinal) sb.write(', isFinal: true');
+    if (isStatic) sb.write(', isStatic: true');
+    if (annotations != null && annotations.isNotEmpty) {
+      sb.write(', annotations: const [');
+      bool first = true;
+      for (var e in annotations) {
+        if (!first) sb.write(', ');
+        first = false;
+        sb.write(e.asCode(libraryPrefixes));
+      }
+      sb.write(']');
+    }
+    sb.write(')');
+    return sb.toString();
+  }
+
+  String toString() =>
+      '(decl: $type.$name - $kind, $isFinal, $isStatic, $annotations)';
+  operator== (other) => other is _DeclarationCode && name == other.name && 
+      type == other.type && kind == other.kind && isFinal == other.isFinal &&
+      isStatic == other.isStatic &&
+      _compareLists(annotations, other.annotations);
+  int get hashCode => name.hashCode + (31 * type.hashCode);
+}
+
+/// A constant expression that can be used as an annotation.
+abstract class ConstExpression {
+
+  /// Returns the library URLs that needs to be imported for this
+  /// [ConstExpression] to be a valid annotation.
+  List<String> get librariesUsed;
+
+  /// Return a string representation of the code in this expression.
+  /// [libraryPrefixes] describes what prefix has been associated with each
+  /// import url mentioned in [libraryUsed].
+  String asCode(Map<String, String> libraryPrefixes);
+
+  ConstExpression();
+
+  /// Create a string expression of the form `'string'`, where [string] is
+  /// normalized so we can correctly wrap it in single quotes.
+  factory ConstExpression.string(String string) {
+    var value = string.replaceAll(r'\', r'\\').replaceAll(r"'", r"\'");
+    return new CodeAsConstExpression("'$value'");
+  }
+
+  /// Create an expression of the form `prefix.variable_name`.
+  factory ConstExpression.identifier(String importUrl, String name) =>
+      new TopLevelIdentifier(importUrl, name);
+
+  /// Create an expression of the form `prefix.Constructor(v1, v2, p3: v3)`.
+  factory ConstExpression.constructor(String importUrl, String name,
+      List<ConstExpression> positionalArgs,
+      Map<String, ConstExpression> namedArgs) =>
+      new ConstructorExpression(importUrl, name, positionalArgs, namedArgs);
+}
+
+/// A constant expression written as a String. Used when the code is self
+/// contained and it doesn't depend on any imported libraries.
+class CodeAsConstExpression extends ConstExpression {
+  String code;
+  List<String> get librariesUsed => const [];
+
+  CodeAsConstExpression(this.code);
+
+  String asCode(Map<String, String> libraryPrefixes) => code;
+
+  String toString() => '(code: $code)';
+  operator== (other) => other is CodeAsConstExpression && code == other.code;
+  int get hashCode => code.hashCode;
+}
+
+/// Describes a reference to some symbol that is exported from a library. This
+/// is typically used to refer to a type or a top-level variable from that
+/// library.
+class TopLevelIdentifier extends ConstExpression {
+  final String importUrl;
+  final String name;
+  TopLevelIdentifier(this.importUrl, this.name);
+
+  List<String> get librariesUsed => [importUrl];
+  String asCode(Map<String, String> libraryPrefixes) {
+    if (importUrl == 'dart:core' || importUrl == null) return name;
+    return '${libraryPrefixes[importUrl]}.$name';
+  }
+
+  String toString() => '(identifier: $importUrl, $name)';
+  operator== (other) => other is TopLevelIdentifier && name == other.name
+      && importUrl == other.importUrl;
+  int get hashCode => 31 * importUrl.hashCode + name.hashCode;
+}
+
+/// Represents an expression that invokes a const constructor.
+class ConstructorExpression extends ConstExpression {
+  final String importUrl;
+  final String name;
+  final List<ConstExpression> positionalArgs;
+  final Map<String, ConstExpression> namedArgs;
+  ConstructorExpression(this.importUrl, this.name, this.positionalArgs,
+      this.namedArgs);
+
+  List<String> get librariesUsed => [importUrl]
+      ..addAll(positionalArgs.expand((e) => e.librariesUsed))
+      ..addAll(namedArgs.values.expand((e) => e.librariesUsed));
+
+  String asCode(Map<String, String> libraryPrefixes) {
+    var sb = new StringBuffer();
+    sb.write('const ');
+    if (importUrl != 'dart:core' && importUrl != null) {
+      sb.write('${libraryPrefixes[importUrl]}.');
+    }
+    sb.write('$name(');
+    bool first = true;
+    for (var e in positionalArgs) {
+      if (!first) sb.write(', ');
+      first = false;
+      sb.write(e.asCode(libraryPrefixes));
+    }
+    namedArgs.forEach((name, value) {
+      if (!first) sb.write(', ');
+      first = false;
+      sb.write('$name: ');
+      sb.write(value.asCode(libraryPrefixes));
+    });
+    sb.write(')');
+    return sb.toString();
+  }
+
+  String toString() => '(ctor: $importUrl, $name, $positionalArgs, $namedArgs)';
+  operator== (other) => other is ConstructorExpression && name == other.name
+      && importUrl == other.importUrl &&
+      _compareLists(positionalArgs, other.positionalArgs) &&
+      _compareMaps(namedArgs, other.namedArgs);
+  int get hashCode => 31 * importUrl.hashCode + name.hashCode;
+}
+
+
+/// Describes a type identifier, with the library URL where the type is defined.
+// TODO(sigmund): consider adding support for imprecise TypeIdentifiers, which
+// may be used by tools that want to generate code without using the analyzer
+// (they can syntactically tell the type comes from one of N imports).
+class TypeIdentifier extends TopLevelIdentifier
+    implements Comparable<TypeIdentifier> {
+  final String comment;
+  TypeIdentifier(importUrl, typeName, [this.comment])
+      : super(importUrl, typeName);
+
+  // We implement [Comparable] to sort out entries in the generated code.
+  int compareTo(TypeIdentifier other) {
+    if (importUrl == null && other.importUrl != null) return 1;
+    if (importUrl != null && other.importUrl == null) return -1;
+    var c1 = importUrl == null ? 0 : importUrl.compareTo(other.importUrl);
+    return c1 != 0 ? c1 : name.compareTo(other.name);
+  }
+
+  String toString() => '(type-identifier: $importUrl, $name, $comment)';
+  bool operator ==(other) => other is TypeIdentifier &&
+      importUrl == other.importUrl && name == other.name &&
+      comment == other.comment;
+  int get hashCode => super.hashCode;
+}
+
+/// Default set of imports added by [SmokeCodeGenerator].
+const DEFAULT_IMPORTS = const [
+    "import 'package:smoke/smoke.dart' show Declaration, PROPERTY, METHOD;",
+    "import 'package:smoke/static.dart' show "
+        "useGeneratedCode, StaticConfiguration;",
+  ];
+
+/// Shallow comparison of two lists.
+bool _compareLists(List a, List b) {
+  if (a == null && b != null) return false;
+  if (a != null && b == null) return false;
+  if (a.length != b.length) return false;
+  for (int i = 0; i < a.length; i++) {
+    if (a[i] != b[i]) return false;
+  }
+  return true;
+}
+
+/// Shallow comparison of two maps.
+bool _compareMaps(Map a, Map b) {
+  if (a == null && b != null) return false;
+  if (a != null && b == null) return false;
+  if (a.length != b.length) return false;
+  for (var k in a.keys) {
+    if (!b.containsKey(k) || a[k] != b[k]) return false;
+  }
+  return true;
+}