tests/corelib_2/regexp/unicode-regexp-backrefs_test.dart

// Copyright (c) 2019, the Dart project authors. All rights reserved.
// Copyright 2016 the V8 project authors. All rights reserved.
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import 'package:expect/expect.dart';

import 'v8_regexp_utils.dart';

String replace(String string) {
  return string
      .replaceAll("L", "\ud800")
      .replaceAll("l", "\ud801")
      .replaceAll("T", "\udc00")
      .replaceAll(".", "[^]");
}

void test(List<String> expectation, String regexp_source, String subject) {
  if (expectation != null) expectation = expectation.map(replace).toList();
  subject = replace(subject);
  regexp_source = replace(regexp_source);
  shouldBe(new RegExp(regexp_source, unicode: true).firstMatch(subject),
      expectation);
}

void main() {
  // Back reference does not end in the middle of a surrogate pair.
  test(null, "(L)\\1", "LLT");
  test(["LLTLl", "L", "l"], "(L).*\\1(.)", "LLTLl");
  test(null, "(aL).*\\1", "aLaLT");
  test(["aLaLTaLl", "aL", "l"], "(aL).*\\1(.)", "aLaLTaLl");

  var s = "TabcLxLTabcLxTabcLTyTabcLz";
  test([s, "TabcL", "z"], "([^x]+).*\\1(.)", s);

  // Back reference does not start in the middle of a surrogate pair.
  test(["TLTabTc", "T", "c"], "(T).*\\1(.)", "TLTabTc");

  // Lookbehinds.
  test(null, "(?<=\\1(T)x)", "LTTx");
  test(["", "b", "T"], "(?<=(.)\\2.*(T)x)", "bTaLTTx");
  test(null, "(?<=\\1.*(L)x)", "LTLx");
  test(["", "b", "L"], "(?<=(.)\\2.*(L)x)", "bLaLTLx");

  test(null, "([^x]+)x*\\1", "LxLT");
  test(null, "([^x]+)x*\\1", "TxLT");
  test(null, "([^x]+)x*\\1", "LTxL");
  test(null, "([^x]+)x*\\1", "LTxT");
  test(null, "([^x]+)x*\\1", "xLxLT");
  test(null, "([^x]+)x*\\1", "xTxLT");
  test(null, "([^x]+)x*\\1", "xLTxL");
  test(null, "([^x]+)x*\\1", "xLTxT");
  test(null, "([^x]+)x*\\1", "xxxLxxLTxx");
  test(null, "([^x]+)x*\\1", "xxxTxxLTxx");
  test(null, "([^x]+)x*\\1", "xxxLTxxLxx");
  test(null, "([^x]+)x*\\1", "xxxLTxxTxx");
  test(["LTTxxLTT", "LTT"], "([^x]+)x*\\1", "xxxLTTxxLTTxx");
}