| // Copyright (c) 2013, 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 matcher.pretty_print; |
| |
| import 'description.dart'; |
| import 'interfaces.dart'; |
| |
| /// Returns a pretty-printed representation of [object]. |
| /// |
| /// If [maxLineLength] is passed, this will attempt to ensure that each line is |
| /// no longer than [maxLineLength] characters long. This isn't guaranteed, since |
| /// individual objects may have string representations that are too long, but |
| /// most lines will be less than [maxLineLength] long. |
| /// |
| /// If [maxItems] is passed, [Iterable]s and [Map]s will only print their first |
| /// [maxItems] members or key/value pairs, respectively. |
| String prettyPrint(object, {int maxLineLength, int maxItems}) { |
| String _prettyPrint(object, int indent, Set seen, bool top) { |
| // If the object is a matcher, use its description. |
| if (object is Matcher) { |
| var description = new StringDescription(); |
| object.describe(description); |
| return "<$description>"; |
| } |
| |
| // Avoid looping infinitely on recursively-nested data structures. |
| if (seen.contains(object)) return "(recursive)"; |
| seen = seen.union(new Set.from([object])); |
| String pp(child) => _prettyPrint(child, indent + 2, seen, false); |
| |
| if (object is Iterable) { |
| // Print the type name for non-List iterables. |
| var type = object is List ? "" : _typeName(object) + ":"; |
| |
| // Truncate the list of strings if it's longer than [maxItems]. |
| var strings = object.map(pp).toList(); |
| if (maxItems != null && strings.length > maxItems) { |
| strings.replaceRange(maxItems - 1, strings.length, ['...']); |
| } |
| |
| // If the printed string is short and doesn't contain a newline, print it |
| // as a single line. |
| var singleLine = "$type[${strings.join(', ')}]"; |
| if ((maxLineLength == null || |
| singleLine.length + indent <= maxLineLength) && |
| !singleLine.contains("\n")) { |
| return singleLine; |
| } |
| |
| // Otherwise, print each member on its own line. |
| return "$type[\n" + strings.map((string) { |
| return _indent(indent + 2) + string; |
| }).join(",\n") + "\n" + _indent(indent) + "]"; |
| } else if (object is Map) { |
| // Convert the contents of the map to string representations. |
| var strings = object.keys.map((key) { |
| return '${pp(key)}: ${pp(object[key])}'; |
| }).toList(); |
| |
| // Truncate the list of strings if it's longer than [maxItems]. |
| if (maxItems != null && strings.length > maxItems) { |
| strings.replaceRange(maxItems - 1, strings.length, ['...']); |
| } |
| |
| // If the printed string is short and doesn't contain a newline, print it |
| // as a single line. |
| var singleLine = "{${strings.join(", ")}}"; |
| if ((maxLineLength == null || |
| singleLine.length + indent <= maxLineLength) && |
| !singleLine.contains("\n")) { |
| return singleLine; |
| } |
| |
| // Otherwise, print each key/value pair on its own line. |
| return "{\n" + strings.map((string) { |
| return _indent(indent + 2) + string; |
| }).join(",\n") + "\n" + _indent(indent) + "}"; |
| } else if (object is String) { |
| // Escape strings and print each line on its own line. |
| var lines = object.split("\n"); |
| return "'" + lines.map(_escapeString) |
| .join("\\n'\n${_indent(indent + 2)}'") + "'"; |
| } else { |
| var value = object.toString().replaceAll("\n", _indent(indent) + "\n"); |
| var defaultToString = value.startsWith("Instance of "); |
| |
| // If this is the top-level call to [prettyPrint], wrap the value on angle |
| // brackets to set it apart visually. |
| if (top) value = "<$value>"; |
| |
| // Print the type of objects with custom [toString] methods. Primitive |
| // objects and objects that don't implement a custom [toString] don't need |
| // to have their types printed. |
| if (object is num || object is bool || object is Function || |
| object == null || defaultToString) { |
| return value; |
| } else { |
| return "${_typeName(object)}:$value"; |
| } |
| } |
| } |
| |
| return _prettyPrint(object, 0, new Set(), true); |
| } |
| |
| String _indent(int length) => new List.filled(length, ' ').join(''); |
| |
| /// Returns the name of the type of [x], or "Unknown" if the type name can't be |
| /// determined. |
| String _typeName(x) { |
| // dart2js blows up on some objects (e.g. window.navigator). |
| // So we play safe here. |
| try { |
| if (x == null) return "null"; |
| var type = x.runtimeType.toString(); |
| // TODO(nweiz): if the object's type is private, find a public superclass to |
| // display once there's a portable API to do that. |
| return type.startsWith("_") ? "?" : type; |
| } catch (e) { |
| return "?"; |
| } |
| } |
| |
| /// Returns [source] with any control characters replaced by their escape |
| /// sequences. |
| /// |
| /// This doesn't add quotes to the string, but it does escape single quote |
| /// characters so that single quotes can be applied externally. |
| String _escapeString(String source) => |
| source.split("").map(_escapeChar).join(""); |
| |
| /// Return the escaped form of a character [ch]. |
| String _escapeChar(String ch) { |
| if (ch == "'") |
| return "\\'"; |
| else if (ch == '\n') |
| return '\\n'; |
| else if (ch == '\r') |
| return '\\r'; |
| else if (ch == '\t') |
| return '\\t'; |
| else |
| return ch; |
| } |
| |