Generate constants in server as we do in plugin

pkg/analysis_server/tool/spec/codegen_protocol_constants.dart

+// 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.
+
+import 'package:analyzer/src/codegen/tools.dart';
+import 'package:front_end/src/codegen/tools.dart';
+
+import 'api.dart';
+import 'codegen_dart.dart';
+import 'from_html.dart';
+
+final GeneratedFile target =
+    new GeneratedFile('lib/protocol/protocol_constants.dart', (String pkgPath) {
+  CodegenVisitor visitor = new CodegenVisitor(readApi(pkgPath));
+  return visitor.collectCode(visitor.visitApi);
+});
+
+/**
+ * A visitor that produces Dart code defining constants associated with the API.
+ */
+class CodegenVisitor extends DartCodegenVisitor with CodeGenerator {
+  CodegenVisitor(Api api) : super(api) {
+    codeGeneratorSettings.commentLineLength = 79;
+    codeGeneratorSettings.languageName = 'dart';
+  }
+
+  /**
+   * Generate all of the constants associates with the [api].
+   */
+  void generateConstants() {
+    _ConstantVisitor visitor = new _ConstantVisitor(api);
+    visitor.visitApi();
+    List<_Constant> constants = visitor.constants;
+    constants.sort((first, second) => first.name.compareTo(second.name));
+    for (_Constant constant in constants) {
+      generateContant(constant);
+    }
+  }
+
+  /**
+   * Generate the given [constant].
+   */
+  void generateContant(_Constant constant) {
+    write('const String ');
+    write(constant.name);
+    write(' = ');
+    write(constant.value);
+    writeln(';');
+  }
+
+  @override
+  visitApi() {
+    outputHeader(year: '2017');
+    writeln();
+    generateConstants();
+  }
+}
+
+/**
+ * A representation of a constant that is to be generated.
+ */
+class _Constant {
+  /**
+   * The name of the constant.
+   */
+  final String name;
+
+  /**
+   * The value of the constant.
+   */
+  final String value;
+
+  /**
+   * Initialize a newly created constant.
+   */
+  _Constant(this.name, this.value);
+}
+
+/**
+ * A visitor that visits an API to compute a list of constants to be generated.
+ */
+class _ConstantVisitor extends HierarchicalApiVisitor {
+  /**
+   * The list of constants to be generated.
+   */
+  List<_Constant> constants = <_Constant>[];
+
+  /**
+   * Initialize a newly created visitor to visit the given [api].
+   */
+  _ConstantVisitor(Api api) : super(api);
+
+  @override
+  void visitNotification(Notification notification) {
+    String domainName = notification.domainName;
+    String event = notification.event;
+
+    String constantName = _generateName(domainName, 'notification', event);
+    constants.add(new _Constant(constantName, "'$domainName.$event'"));
+    _addFieldConstants(constantName, notification.params);
+  }
+
+  @override
+  void visitRequest(Request request) {
+    String domainName = request.domainName;
+    String method = request.method;
+
+    String requestConstantName = _generateName(domainName, 'request', method);
+    constants.add(new _Constant(requestConstantName, "'$domainName.$method'"));
+    _addFieldConstants(requestConstantName, request.params);
+
+    String responseConstantName = _generateName(domainName, 'response', method);
+    _addFieldConstants(responseConstantName, request.result);
+  }
+
+  /**
+   * Generate a constant for each of the fields in the given [type], where the
+   * name of each constant will be composed from the [parentName] and the name
+   * of the field.
+   */
+  void _addFieldConstants(String parentName, TypeObject type) {
+    if (type == null) {
+      return;
+    }
+    type.fields.forEach((TypeObjectField field) {
+      String name = field.name;
+      String fieldConstantName = parentName + '_' + name.toUpperCase();
+      constants.add(new _Constant(fieldConstantName, "'$name'"));
+    });
+  }
+
+  /**
+   * Generate a name from the [domainName], [kind] and [name] components.
+   */
+  String _generateName(String domainName, String kind, String name) {
+    List<String> components = <String>[];
+    components.addAll(_split(domainName));
+    components.add(kind);
+    components.addAll(_split(name));
+    return components
+        .map((String component) => component.toUpperCase())
+        .join('_');
+  }
+
+  /**
+   * Return the components of the given [string] that are indicated by an upper
+   * case letter.
+   */
+  Iterable<String> _split(String first) {
+    RegExp regExp = new RegExp('[A-Z]');
+    List<String> components = <String>[];
+    int start = 1;
+    int index = first.indexOf(regExp, start);
+    while (index >= 0) {
+      components.add(first.substring(start - 1, index));
+      start = index + 1;
+      index = first.indexOf(regExp, start);
+    }
+    components.add(first.substring(start - 1));
+    return components;
+  }
+}