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Regexp Matching in Reducer

I'm looking at reducers.

There is a nice example in the Tutor for counting words:

(0 | it + 1 | /\w+/ := S)

where S is some longer string with several words. The reducer returns the count of such words.

I was wondering how to capture the matched substring and use it in the accumulating expression, something like

("" | it + e | str e ... /\w+/ := S)

so that the result would be the concatenation of all matched substrings.

Any idea?

Solution

  • Yes, the capture syntax is with the <name:regex> notation:

    ("" | it + e | /<e:\w+>/ := S)

    rascal>S  ="Jabberwocky by Lewis Carroll";
str: "Jabberwocky by Lewis Carroll"
rascal>("" | "<it>,<e>" | /<e:\w+>/ := S)[1..]
str: "Jabberwocky,by,Lewis,Carroll"

    or use the for-template syntax instead of a reducer expression:

    rascal>x = "<for (/<e:\w+>/ := S) {><e>;
>>>>>>>    '<}>";
str: "Jabberwocky;\nby;\nLewis;\nCarroll;\n"
rascal>import IO;
ok
rascal>println(x)
Jabberwocky;
by;
Lewis;
Carroll;

ok
rascal>