tricu

An interpreted language for exploring Tree Calculus
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lexer.tri (1368B)

      1 !import 6aa33a710955e5746f322775b9078f57ba4145f6b723ff4b76a292285e919823 *
      2 !import 14282088469cc420dd014700da06998f6bb8dcf990fc885a464c0a1e1858e20d *
      3 !import 816df1a32853750a1254112aff8ae8c55ca86bf70e809d226969ab1d43a6688b *
      4 !import 7f87549d587fa8c3be88af0ea988db3adcc3b35f1ffb48973553491b075614db as N
      5 !export scanWord
      6 !export scanWhitespace
      7 
      8 -- Positioned prefix scans, not whole-input parsers. The remainder begins
      9 -- at the first nonmatching character. Positions count source characters,
     10 -- not UTF-8 bytes or display columns: only LF advances the line.
     11 -- Edit a predicate below and evaluate scanWord "hello,world" to compare.
     12 -- scanWhitespace accepts space, LF and tab, but deliberately not CR.
     13 report reply = (let
     14   payload = parserReplyPayload reply
     15   end = snd payload
     16   in [
     17     ["matched" 0 (fst payload)]
     18     ["remaining" 0 (parserReplyRest reply)]
     19     ["line" 1 (lexerPositionLine end)]
     20     ["column" 1 (lexerPositionColumn end)]
     21     ["offset" 1 (lexerPositionOffset end)]
     22     ["consumed" 2 (parserReplyConsumed reply)]])
     23 
     24 scan predicate text = report (lexerMapScan reverse
     25   (lexerScanWhile text lexerStart [] predicate (state character : pair character state)))
     26 scanWord text = scan (character : N.inRange character 97 122) text
     27 scanWhitespace text = scan (character : or? (equal? character 32)
     28   (or? (equal? character 9) (equal? character 10))) text