Fasta infrastructure.

pkg/fasta/lib/src/command_line.dart

Index: pkg/fasta/lib/src/command_line.dart
diff --git a/pkg/fasta/lib/src/command_line.dart b/pkg/fasta/lib/src/command_line.dart
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+// Copyright (c) 2016, 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 fasta.command_line;
+
+import 'errors.dart' show
+    inputError,
+    internalError;
+
+argumentError(String usage, String message) {
+  if (usage != null) print(usage);
+  inputError(null, null, message);
+}
+
+class ParsedArguments {
+  final Map<String, dynamic> options = <String, dynamic>{};
+  final List<String> arguments = <String>[];
+
+  toString() => "ParsedArguments($options, $arguments)";
+}
+
+class CommandLine {
+  final Map<String, dynamic> options;
+
+  final List<String> arguments;
+
+  final String usage;
+
+  CommandLine.parsed(ParsedArguments p, this.usage)
+      : this.options = p.options,
+        this.arguments = p.arguments {
+    validate();
+    if (verbose) {
+      print(p);
+    }
+  }
+
+  CommandLine(List<String> arguments,
+      {Map<String, dynamic> specification, String usage})
+      : this.parsed(parse(arguments, specification, usage), usage);
+
+  bool get verbose {
+    return options.containsKey("-v") || options.containsKey("--verbose");
+  }
+
+  /// Override to validate arguments and options.
+  void validate() {
+  }
+
+  /// Parses a list of command-line [arguments] into options and arguments.
+  ///
+  /// An /option/ is something that, normally, starts with `-` or `--` (one or
+  /// two dashes). However, as a special case `/?` and `/h` are also recognized
+  /// as options for increased compatibility with Windows. An option can have a
+  /// value.
+  ///
+  /// An /argument/ is something that isn't an option, for example, a file name.
+  ///
+  /// The specification is a map of options to one of the type literals `Uri`,
+  /// `int`, `bool`, or `String`, or a comma (`","`) that represents option
+  /// values of type [Uri], [int], [bool], [String], or a comma-separated list
+  /// of [String], respectively.
+  ///
+  /// If [arguments] contains `"--"`, anything before is parsed as options, and
+  /// arguments; anything following is treated as arguments (even if starting
+  /// with, for example, a `-`).
+  ///
+  /// Anything that looks like an option is assumed to be a `bool` option set
+  /// to true, unless it's mentioned in [specification] in which case the
+  /// option requires a value, either on the form `--option value` or
+  /// `--option=value`.
+  ///
+  /// This method performs only a limited amount of validation, but if an error
+  /// occurs, it will print [usage] along with a specific error message.
+  static ParsedArguments parse(List<String> arguments,
+      Map<String, dynamic> specification, String usage) {
+    specification ??= const <String, dynamic>{};
+    ParsedArguments result = new ParsedArguments();
+    int index = arguments.indexOf("--");
+    Iterable<String> nonOptions = const <String>[];
+    Iterator<String> iterator = arguments.iterator;
+    if (index != -1) {
+      nonOptions = arguments.skip(index + 1);
+      iterator = arguments.take(index).iterator;
+    }
+    while (iterator.moveNext()) {
+      String argument = iterator.current;
+      if (argument.startsWith("-")) {
+        var valueSpecification = specification[argument];
+        String value;
+        if (valueSpecification != null) {
+          if (!iterator.moveNext()) {
+            return argumentError(usage, "Expected value after '$argument'.");
+          }
+          value = iterator.current;
+        } else {
+          index = argument.indexOf("=");
+          if (index != -1) {
+            value = argument.substring(index + 1);
+            argument = argument.substring(0, index);
+            valueSpecification = specification[argument];
+          }
+        }
+        if (valueSpecification == null) {
+          if (value != null) {
+            return argumentError(usage,
+                "Argument '$argument' doesn't take a value: '$value'.");
+          }
+          result.options[argument] = true;
+        } else {
+          if (valueSpecification is! String && valueSpecification is! Type) {
+            return argumentError(usage, "Unrecognized type of value "
+                "specification: ${valueSpecification.runtimeType}.");
+          }
+          switch ("$valueSpecification") {
+            case ",":
+              result.options.putIfAbsent(argument, () => <String>[])
+                  .addAll(value.split(","));
+              break;
+
+            case "int":
+            case "bool":
+            case "String":
+            case "Uri":
+              if (result.options.containsKey(argument)) {
+                return argumentError(usage, "Multiple values for '$argument': "
+                    "'${result.options[argument]}' and '$value'.");
+              }
+              var parsedValue;
+              if (valueSpecification == int) {
+                parsedValue = int.parse(value, onError: (_) {
+                  return argumentError(usage,
+                      "Value for '$argument', '$value', isn't an int.");
+                });
+              } else if (valueSpecification == bool) {
+                if (value == "true" || value == "yes") {
+                  parsedValue = true;
+                } else if (value == "false" || value == "no") {
+                  parsedValue = false;
+                } else {
+                  return argumentError(usage,
+                      "Value for '$argument' is '$value', "
+                      "but expected one of: 'true', 'false', 'yes', or 'no'.");
+                }
+              } else if (valueSpecification == Uri) {
+                parsedValue = Uri.base.resolve(value);
+              } else if (valueSpecification == String) {
+                parsedValue = value;
+              } else if (valueSpecification is String) {
+                return argumentError(usage, "Unrecognized value specification: "
+                    "'$valueSpecification', try using a type literal instead.");
+              } else {
+                // All possible cases should have been handled above.
+                return internalError("assertion failure");
+              }
+              result.options[argument] = parsedValue;
+              break;
+
+            default:
+              return argumentError(usage,
+                  "Unrecognized value specification: '$valueSpecification'.");
+          }
+        }
+      } else if (argument == "/?" || argument == "/h") {
+        result.options[argument] = true;
+      } else {
+        result.arguments.add(argument);
+      }
+    }
+    result.arguments.addAll(nonOptions);
+    return result;
+  }
+}