Matcher.replaceAll(Function<MatchResult, String> f) [was: Re: hg: lambda/lambda/jdk: Pattern.splitAsStream.]
Paul Sandoz
paul.sandoz at oracle.com
Mon Apr 22 07:24:42 PDT 2013
On Apr 22, 2013, at 4:11 PM, Peter Levart <peter.levart at gmail.com> wrote:
> On 04/22/2013 02:54 PM, Paul Sandoz wrote:
>> Hi Jürgen,
>>
>> Three issues:
>>
>> - we should probably include replaceFirst
>>
>> - we need to use different method names since replaceAll(null) is now ambiguous
>
> But only if used with literal 'null' and then it throws NPE if the match is found, so I doubt anyone is using "matcher.replaceAll(null)" as a shorthand for "if (matcher.find()) throw new NullPointerException()" in disguise...
>
I hope not too :-) Note that such a change does result in a compilation failure for the regex tests.
I don't quite know what the source code level compatibility requirements are here. How high is the bar set? I was presuming it was quite high.
Paul.
> Regards, Peter
>
>>
>> - need tests :-) (see jdk/tests/java/util/regex/RegExTest.java)
>>
>> While these are nice to have i am not sure they carry their weight given the time constraints we have. If you can help us provide a more complete solution the better chance we have of getting this into JDK8.
>>
>> Thanks,
>> Paul.
>>
>> On Apr 19, 2013, at 12:59 AM, jk at blackdown.de wrote:
>>
>>> Hi Paul,
>>>
>>> Paul Sandoz <paul.sandoz at oracle.com> writes:
>>>
>>>> Hi Jürgen,
>>>>
>>>> That seems useful as a more general approach than Matcher.replaceAll(String ) e.g.
>>>>
>>>> Matcher.replaceAll(Function<MatchResult, String> f)
>>>>
>>>> Ben, thoughts?
>>> like this?
>>>
>>> # HG changeset patch
>>> # User Jürgen Kreileder <jk at blackdown.de>
>>> # Date 1366322703 -7200
>>> # Node ID 59766f458701af5fbb23d195dd48a928505f3306
>>> # Parent 3ec06ef568a8ded0a7ecc7624df9d3a025dad6bc
>>> Matcher.replaceAll(Function<MatchResult, String> f)
>>>
>>> diff --git a/src/share/classes/java/util/regex/Matcher.java b/src/share/classes/java/util/regex/Matcher.java
>>> --- a/src/share/classes/java/util/regex/Matcher.java
>>> +++ b/src/share/classes/java/util/regex/Matcher.java
>>> @@ -25,6 +25,7 @@
>>>
>>> package java.util.regex;
>>>
>>> +import java.util.function.Function;
>>>
>>> /**
>>> * An engine that performs match operations on a {@link java.lang.CharSequence
>>> @@ -916,6 +917,54 @@
>>> }
>>>
>>> /**
>>> + * Replaces every subsequence of the input sequence that matches the
>>> + * pattern with the string returned by the given replacement function.
>>> + *
>>> + * <p> This method first resets this matcher. It then scans the input
>>> + * sequence looking for matches of the pattern. Characters that are not
>>> + * part of any match are appended directly to the result string; each match
>>> + * is replaced in the result by the string returned by the replacement
>>> + * function. The replacement strings may contain references to captured
>>> + * subsequences as in the {@link #appendReplacement appendReplacement}
>>> + * method.
>>> + *
>>> + * <p> Note that backslashes (<tt>\</tt>) and dollar signs (<tt>$</tt>) in
>>> + * the string returned by the replacement function may cause the results to
>>> + * be different than if they were being treated as a literal strings. Dollar
>>> + * signs may be treated as references to captured subsequences as described
>>> + * above, and backslashes are used to escape literal characters in the
>>> + * replacement string.
>>> + *
>>> + * <p> Given the regular expression <tt>(\\w)(\\w*)</tt>, the input
>>> + * <tt>"paTTern maTcher"</tt>, and the replacement function
>>> + * <tt>m -> m.group(1).toUpperCase() + m.group(2).toLowerCase()</tt>, an
>>> + * invocation of this method on a matcher for that expression would yield
>>> + * the string <tt>"Pattern Matcher"</tt>. </p>
>>> + *
>>> + * <p> Invoking this method changes this matcher's state. If the matcher
>>> + * is to be used in further matching operations then it should first be
>>> + * reset. </p>
>>> + *
>>> + * @param f
>>> + * The function providing replacement strings
>>> + * @return The string constructed by replacing each matching subsequence
>>> + * by the replacement string provide by the given function,
>>> + * substituting captured subsequences as needed
>>> + * @since 1.8
>>> + */
>>> + public String replaceAll(Function<MatchResult, String> f) {
>>> + reset();
>>> + if (find()) {
>>> + StringBuffer sb = new StringBuffer();
>>> + do {
>>> + appendReplacement(sb, f.apply(this));
>>> + } while (find());
>>> + return appendTail(sb).toString();
>>> + }
>>> + return text.toString();
>>> + }
>>> +
>>> + /**
>>> * Replaces the first subsequence of the input sequence that matches the
>>> * pattern with the given replacement string.
>>> *
>>> ==
>>>
>>>
>>> Juergen
>>>
>>>
>>>> On Apr 8, 2013, at 6:59 PM, jk at blackdown.de wrote:
>>>>
>>>>> Hi Paul,
>>>>>
>>>>> it would be nice if Pattern/Matcher offered a terse way to loop over all
>>>>> matches in a string and replace them via a callback.
>>>>>
>>>>> E.g. I'm currently using something like this:
>>>>>
>>>>> private static final PatternAndReplacement PASS2 = new PatternAndReplacement(
>>>>> Pattern.compile(" ( "
>>>>> + " \\A \\p{Punct}*" // start of title…
>>>>> + " |"
>>>>> + " [:.;?!]\\ +" // or of subsentence…
>>>>> + " | "
>>>>> + " \\ ['\"“‘(\\[] \\ *" // or of inserted subphrase…
>>>>> + ")"
>>>>> + "(" + SMALL_WORDS + ") \\b", // … followed by small word
>>>>> Pattern.COMMENTS | Pattern.CASE_INSENSITIVE | Pattern.UNICODE_CHARACTER_CLASS),
>>>>> m -> Matcher.quoteReplacement(m.group(1) + capitalize(m.group(2))));
>>>>>
>>>>> with PatternAndReplacement being
>>>>>
>>>>> private static class PatternReplacement implements Function<String, String> {
>>>>> private final Pattern pattern;
>>>>> private final Function<MatchResult, String> function;
>>>>>
>>>>> PatternReplacement(final Pattern p, final Function<MatchResult, String> f) {
>>>>> pattern = p;
>>>>> function = f;
>>>>> }
>>>>>
>>>>> @Override
>>>>> public final String apply(final String s) {
>>>>> Matcher m = pattern.matcher(s);
>>>>> if (m.find()) {
>>>>> StringBuffer sb = new StringBuffer(s.length());
>>>>> do {
>>>>> m.appendReplacement(sb, function.apply(m));
>>>>> } while (m.find());
>>>>> return m.appendTail(sb).toString();
>>>>> }
>>>>> return s;
>>>>> }
>>>>> }
>>>>>
>>>>> Any plans for something like this?
>>>>>
>>>>>
>>>>> Jürgen
>>>>>
>>>>>
>>>>> paul.sandoz at oracle.com writes:
>>>>>
>>>>>> Changeset: 526131346981
>>>>>> Author: psandoz
>>>>>> Date: 2013-04-08 17:16 +0200
>>>>>> URL: http://hg.openjdk.java.net/lambda/lambda/jdk/rev/526131346981
>>>>>>
>>>>>> Pattern.splitAsStream.
>>>>>> Contributed-by: Ben Evans <benjamin.john.evans at gmail.com>
>>>>>>
>>>>>> ! src/share/classes/java/util/regex/Pattern.java
>>>>>> + test-ng/tests/org/openjdk/tests/java/util/regex/PatternTest.java
>>> --
>>> https://blackdown.de/
>>
>
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