On Sat, 20 Feb 2021 10:17:35 GMT, Serguei Spitsyn <[email protected]> wrote:
>> See the CR for a description of the 3 issues fixed. There's also a new test
>> added. I'll explain the fix related to quoting the '!' here since it's not
>> that obvious how it works.
>>
>> There's a complex pattern called `historyPattern` that is used to find
>> various uses of ! to do expansion of commands and arguments in the history
>>
>> static Pattern historyPattern =
>> Pattern.compile("([\\\]?)((!\*)|(!\$)|(!!-?)|(!-?[0-9][0-9]*)|(![a-zA-Z][^
>> ]*))");
>>
>> I added the `([\\\]?)` part to handle allowing a '!' to be quoted with a
>> backslash so it will just be treated as a '!' instead of being used for
>> history expansion. This part of the pattern basically says match 1 backslash
>> if present. Yes, you need 4 backslashes to do this. javac will reduce it to
>> two, and then the pattern compilation reduces it down to just one backslash
>> (not to be used for quoting).
>>
>> The above pattern for searching for the backslash before a '!' is in the
>> first pattern grouping, and the part that matches on the '!' and what
>> follows is in the 2nd pattern grouping. Thus the code I added checks if the
>> first pattern grouping matches something (and at most it will match just one
>> backslash), and if so then we eat it and don't treat the '!' that follows as
>> a history expansion:
>>
>> if (m.group(1).length() != 0) {
>> // This means we matched a `` before the '!'. Don't
>> do any history
>> // expansion in this case. Just capture what matched
>> after the ``.
>> result.append(m.group(2));
>> continue;
>> }
>
> Looks good.
Thanks for the reviews!
-------------
PR: https://git.openjdk.java.net/jdk/pull/2565
