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| author | Boutade <thegoofist@protonmail.com> | 2020-03-06 13:33:23 -0600 |
|---|---|---|
| committer | Boutade <thegoofist@protonmail.com> | 2020-03-06 13:33:23 -0600 |
| commit | f448fcdb3319e74644d66c671c30c232d770615f (patch) | |
| tree | e53a4aaa4621fb10e0fe93ef7a106d6ba8c404e0 | |
| parent | edf93e1b1b942d3f0967597c3d13375e1805fb83 (diff) | |
added <<first combinator
| -rw-r--r-- | package.lisp | 1 | ||||
| -rw-r--r-- | parzival.lisp | 12 |
2 files changed, 12 insertions, 1 deletions
diff --git a/package.lisp b/package.lisp index ed0cee9..8b33dac 100644 --- a/package.lisp +++ b/package.lisp @@ -22,6 +22,7 @@ #:<<bind #:<<let #:<<and + #:<<first #:<<ending #:<<sat #:<<~sat diff --git a/parzival.lisp b/parzival.lisp index 85a6632..35d6304 100644 --- a/parzival.lisp +++ b/parzival.lisp @@ -176,7 +176,7 @@ in then. If the parse fails the combinator else is run instead." (defun <<and (parser1 parser2 &rest parsers) - "Just like <<AND-THEN but where parse results are ignored. I.e. Applies each + "Just like <<BIND but where parse results are ignored. I.e. Applies each parser in sequence, ignoring any intermediate results. The result (<<AND P1 P2 ... PN) is the result of PN." (if parsers @@ -184,6 +184,16 @@ in then. If the parse fails the combinator else is run instead." (<<bind parser1 (returning parser2)))) +(defun <<first (parser other &rest others-still) + "A bit like <<AND in reverse. Returns the parse result of the first parser, + but only if the other parsers all succeed." + (<<bind parser + (lambda (first) + (apply #'<<and (append (list other) + others-still + (list (<<result first))))))) + + (defun <<ending (parser) "Creates a parser that succeeds if PARSER succeeds and the end of the input has been reached." (<<bind parser |