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fixed comments

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svn: r1347
This commit is contained in:
Matthew Flatt 2005-11-18 20:42:13 +00:00
parent 10815abe33
commit df94948e8f
1 changed files with 15 additions and 11 deletions
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26
collects/algol60/cfg-parser.ss
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@ -3,21 +3,25 @@
;; `parser', except that it works on an arbitrary CFG (returning
;; the first sucecssful parse).
;; It's a backtracking parser. Alternative for a non-terminal are
;; computed in parallel, and multiple attempts to compute the same
;; result block until the first one completes. If you get into
;; deadlock, such as when trying to match
;; I'm pretty sure that this is an implementation of Earley's
;; algorithm.
;; To a first approximation, it's a backtracking parser. Alternative
;; for a non-terminal are computed in parallel, and multiple attempts
;; to compute the same result block until the first one completes. If
;; you get into deadlock, such as when trying to match
;; <foo> := <foo>
;; then it means that there's no successful parse, so everything
;; that's blocked fails.
;; Caching remember the series of results for a particular
;; non-terminal at a particular starting location. Otherwise, the
;; parser uses backtracking search. Backtracking is implemented
;; through explicit success and failure continuations. Multiple
;; results for a particular nonterminal and location are kept only
;; when they have different lengths. (Otherwise, in the spirit of
;; finding one successful parse, only the first result is kept.)
;; A cache holds the series of results for a particular non-terminal
;; at a particular starting location. (A series is used, instead of a
;; sinlge result, for backtracking.) Otherwise, the parser uses
;; backtracking search. Backtracking is implemented through explicit
;; success and failure continuations. Multiple results for a
;; particular nonterminal and location are kept only when they have
;; different lengths. (Otherwise, in the spirit of finding one
;; successful parse, only the first result is kept.)
;; The parser-tools's `parse' is used to transform tokens in the
;; grammar to tokens specific to this parser. In other words, this