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// 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.
import 'core_matchers.dart';
import 'equals_matcher.dart';
import 'interfaces.dart';
/// A [Map] between whitespace characters and their escape sequences.
const _escapeMap = {
'\n': r'\n',
'\r': r'\r',
'\f': r'\f',
'\b': r'\b',
'\t': r'\t',
'\v': r'\v',
'\x7F': r'\x7F', // delete
/// A [RegExp] that matches whitespace characters that should be escaped.
final _escapeRegExp = RegExp(
/// Useful utility for nesting match states.
void addStateInfo(Map matchState, Map values) {
var innerState = Map.from(matchState);
matchState['state'] = innerState;
/// Takes an argument and returns an equivalent [Matcher].
/// If the argument is already a matcher this does nothing,
/// else if the argument is a function, it generates a predicate
/// function matcher, else it generates an equals matcher.
Matcher wrapMatcher(x) {
if (x is Matcher) {
return x;
} else if (x is bool Function(Object?)) {
// x is already a predicate that can handle anything
return predicate(x);
} else if (x is bool Function(Never)) {
// x is a unary predicate, but expects a specific type
// so wrap it.
// ignore: unnecessary_lambdas
return predicate((a) => (x as dynamic)(a));
} else {
return equals(x);
/// Returns [str] with all whitespace characters represented as their escape
/// sequences.
/// Backslash characters are escaped as `\\`
String escape(String str) {
str = str.replaceAll('\\', r'\\');
return str.replaceAllMapped(_escapeRegExp, (match) {
var mapped = _escapeMap[match[0]];
if (mapped != null) return mapped;
return _getHexLiteral(match[0]!);
/// Given single-character string, return the hex-escaped equivalent.
String _getHexLiteral(String input) {
var rune = input.runes.single;
return r'\x' + rune.toRadixString(16).toUpperCase().padLeft(2, '0');