On Thu, 9 Nov 2023 04:16:25 GMT, Roger Riggs <rri...@openjdk.org> wrote:
>> Strings, after construction, are immutable but may be constructed from >> mutable arrays of bytes, characters, or integers. >> The string constructors should guard against the effects of mutating the >> arrays during construction that might invalidate internal invariants for the >> correct behavior of operations on the resulting strings. In particular, a >> number of operations have optimizations for operations on pairs of latin1 >> strings and pairs of non-latin1 strings, while operations between latin1 and >> non-latin1 strings use a more general implementation. >> >> The changes include: >> >> - Adding a warning to each constructor with an array as an argument to >> indicate that the results are indeterminate >> if the input array is modified before the constructor returns. >> The resulting string may contain any combination of characters sampled >> from the input array. >> >> - Ensure that strings that are represented as non-latin1 contain at least >> one non-latin1 character. >> For latin1 inputs, whether the arrays contain ASCII, ISO-8859-1, UTF8, or >> another encoding decoded to latin1 the scanning and compression is unchanged. >> If a non-latin1 character is found, the string is represented as >> non-latin1 with the added verification that a non-latin1 character is >> present at the same index. >> If that character is found to be latin1, then the input array has been >> modified and the result of the scan may be incorrect. >> Though a ConcurrentModificationException could be thrown, the risk to an >> existing application of an unexpected exception should be avoided. >> Instead, the non-latin1 copy of the input is re-scanned and compressed; >> that scan determines whether the latin1 or the non-latin1 representation is >> returned. >> >> - The methods that scan for non-latin1 characters and their intrinsic >> implementations are updated to return the index of the non-latin1 character. >> >> - String construction from StringBuilder and CharSequence must also be >> guarded as their contents may be modified during construction. > > Roger Riggs has updated the pull request incrementally with three additional > commits since the last revision: > > - Refactored extractCodePoints to avoid multiple resizes if the array was > modified > - Replaced isLatin1 implementation with `getChar(buf, ndx) <= 0xff` > It performs better than the single byte array access by avoiding the > bounds check. > - Misc updates for review comments, javadoc cleanup > Extra checking on maximum string lengths when calling toBytes(). Contributed update to s390.ad. ------------- PR Comment: https://git.openjdk.org/jdk/pull/16425#issuecomment-1809008222
