Move some of analyzer's code generation utilities into front_end.

pkg/front_end/lib/src/codegen/tools.dart

Index: pkg/front_end/lib/src/codegen/tools.dart
diff --git a/pkg/front_end/lib/src/codegen/tools.dart b/pkg/front_end/lib/src/codegen/tools.dart
new file mode 100644
index 0000000000000000000000000000000000000000..45d5a23971cdac1597b5b9c3577e21b7de1ce58b
--- /dev/null
+++ b/pkg/front_end/lib/src/codegen/tools.dart
@@ -0,0 +1,221 @@
+// 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 'dart:io';
+
+import 'package:path/path.dart';
+
+/**
+ * Type of functions used to compute the contents of a set of generated files.
+ * [pkgPath] is the path to the current package.
+ */
+typedef Map<String, FileContentsComputer> DirectoryContentsComputer(
+    String pkgPath);
+
+/**
+ * Type of functions used to compute the contents of a generated file.
+ * [pkgPath] is the path to the current package.
+ */
+typedef String FileContentsComputer(String pkgPath);
+
+/**
+ * Abstract base class representing behaviors common to generated files and
+ * generated directories.
+ */
+abstract class GeneratedContent {
+  /**
+   * Check whether the [output] has the correct contents, and return true if it
+   * does.  [pkgPath] is the path to the current package.
+   */
+  bool check(String pkgPath);
+
+  /**
+   * Replace the [output] with the correct contents.  [pkgPath] is the path to
+   * the current package.
+   */
+  void generate(String pkgPath);
+
+  /**
+   * Get a [FileSystemEntity] representing the output file or directory.
+   * [pkgPath] is the path to the current package.
+   */
+  FileSystemEntity output(String pkgPath);
+
+  /**
+   * Check that all of the [targets] are up to date.  If they are not, print
+   * out a message instructing the user to regenerate them, and exit with a
+   * nonzero error code.
+   *
+   * [pkgPath] is the path to the current package.  [generatorRelPath] is the
+   * path to a .dart script the user may use to regenerate the targets.
+   *
+   * To avoid mistakes when run on Windows, [generatorRelPath] always uses
+   * POSIX directory separators.
+   */
+  static void checkAll(String pkgPath, String generatorRelPath,
+      Iterable<GeneratedContent> targets) {
+    bool generateNeeded = false;
+    for (GeneratedContent target in targets) {
+      if (!target.check(pkgPath)) {
+        print(
+            '${target.output(pkgPath).absolute} does not have expected contents.');
+        generateNeeded = true;
+      }
+    }
+    if (generateNeeded) {
+      print('Please regenerate using:');
+      String executable = Platform.executable;
+      String packageRoot = '';
+      if (Platform.packageRoot != null) {
+        packageRoot = ' --package-root=${Platform.packageRoot}';
+      }
+      String generateScript =
+          join(pkgPath, joinAll(posix.split(generatorRelPath)));
+      print('  $executable$packageRoot $generateScript');
+      exit(1);
+    } else {
+      print('All generated files up to date.');
+    }
+  }
+
+  /**
+   * Regenerate all of the [targets].  [pkgPath] is the path to the current
+   * package.
+   */
+  static void generateAll(String pkgPath, Iterable<GeneratedContent> targets) {
+    for (GeneratedContent target in targets) {
+      target.generate(pkgPath);
+    }
+  }
+}
+
+/**
+ * Class representing a single output directory (either generated code or
+ * generated HTML). No other content should exist in the directory.
+ */
+class GeneratedDirectory extends GeneratedContent {
+  /**
+   * The path to the directory that will have the generated content.
+   */
+  final String outputDirPath;
+
+  /**
+   * Callback function that computes the directory contents.
+   */
+  final DirectoryContentsComputer directoryContentsComputer;
+
+  GeneratedDirectory(this.outputDirPath, this.directoryContentsComputer);
+
+  @override
+  bool check(String pkgPath) {
+    Directory outputDirectory = output(pkgPath);
+    Map<String, FileContentsComputer> map = directoryContentsComputer(pkgPath);
+    try {
+      for (String file in map.keys) {
+        FileContentsComputer fileContentsComputer = map[file];
+        String expectedContents = fileContentsComputer(pkgPath);
+        File outputFile = new File(posix.join(outputDirectory.path, file));
+        String actualContents = outputFile.readAsStringSync();
+        // Normalize Windows line endings to Unix line endings so that the
+        // comparison doesn't fail on Windows.
+        actualContents = actualContents.replaceAll('\r\n', '\n');
+        if (expectedContents != actualContents) {
+          return false;
+        }
+      }
+      int nonHiddenFileCount = 0;
+      outputDirectory
+          .listSync(recursive: false, followLinks: false)
+          .forEach((FileSystemEntity fileSystemEntity) {
+        if (fileSystemEntity is File &&
+            !basename(fileSystemEntity.path).startsWith('.')) {
+          nonHiddenFileCount++;
+        }
+      });
+      if (nonHiddenFileCount != map.length) {
+        // The number of files generated doesn't match the number we expected to
+        // generate.
+        return false;
+      }
+    } catch (e) {
+      // There was a problem reading the file (most likely because it didn't
+      // exist).  Treat that the same as if the file doesn't have the expected
+      // contents.
+      return false;
+    }
+    return true;
+  }
+
+  @override
+  void generate(String pkgPath) {
+    Directory outputDirectory = output(pkgPath);
+    try {
+      // delete the contents of the directory (and the directory itself)
+      outputDirectory.deleteSync(recursive: true);
+    } catch (e) {
+      // Error caught while trying to delete the directory, this can happen if
+      // it didn't yet exist.
+    }
+    // re-create the empty directory
+    outputDirectory.createSync(recursive: true);
+
+    // generate all of the files in the directory
+    Map<String, FileContentsComputer> map = directoryContentsComputer(pkgPath);
+    map.forEach((String file, FileContentsComputer fileContentsComputer) {
+      File outputFile = new File(posix.join(outputDirectory.path, file));
+      outputFile.writeAsStringSync(fileContentsComputer(pkgPath));
+    });
+  }
+
+  @override
+  Directory output(String pkgPath) =>
+      new Directory(join(pkgPath, joinAll(posix.split(outputDirPath))));
+}
+
+/**
+ * Class representing a single output file (either generated code or generated
+ * HTML).
+ */
+class GeneratedFile extends GeneratedContent {
+  /**
+   * The output file to which generated output should be written, relative to
+   * the "tool/spec" directory.  This filename uses the posix path separator
+   * ('/') regardless of the OS.
+   */
+  final String outputPath;
+
+  /**
+   * Callback function which computes the file.
+   */
+  final FileContentsComputer computeContents;
+
+  GeneratedFile(this.outputPath, this.computeContents);
+
+  @override
+  bool check(String pkgPath) {
+    File outputFile = output(pkgPath);
+    String expectedContents = computeContents(pkgPath);
+    try {
+      String actualContents = outputFile.readAsStringSync();
+      // Normalize Windows line endings to Unix line endings so that the
+      // comparison doesn't fail on Windows.
+      actualContents = actualContents.replaceAll('\r\n', '\n');
+      return expectedContents == actualContents;
+    } catch (e) {
+      // There was a problem reading the file (most likely because it didn't
+      // exist).  Treat that the same as if the file doesn't have the expected
+      // contents.
+      return false;
+    }
+  }
+
+  @override
+  void generate(String pkgPath) {
+    output(pkgPath).writeAsStringSync(computeContents(pkgPath));
+  }
+
+  @override
+  File output(String pkgPath) =>
+      new File(join(pkgPath, joinAll(posix.split(outputPath))));
+}