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fixed comments

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svn: r1347

original commit: df94948e8fb9fe1c881499401fb4e95bc6a0820f
tokens
Matthew Flatt 19 years ago
parent 020a0a39a9
commit 79465df15c
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 ;; `parser', except that it works on an arbitrary CFG (returning
;; the first sucecssful parse). ;; the first sucecssful parse).
;; It's a backtracking parser. Alternative for a non-terminal are ;; I'm pretty sure that this is an implementation of Earley's
;; computed in parallel, and multiple attempts to compute the same ;; algorithm.
;; result block until the first one completes. If you get into
;; deadlock, such as when trying to match ;; 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> ;; <foo> := <foo>
;; then it means that there's no successful parse, so everything ;; then it means that there's no successful parse, so everything
;; that's blocked fails. ;; that's blocked fails.
;; Caching remember the series of results for a particular ;; A cache holds the series of results for a particular non-terminal
;; non-terminal at a particular starting location. Otherwise, the ;; at a particular starting location. (A series is used, instead of a
;; parser uses backtracking search. Backtracking is implemented ;; sinlge result, for backtracking.) Otherwise, the parser uses
;; through explicit success and failure continuations. Multiple ;; backtracking search. Backtracking is implemented through explicit
;; results for a particular nonterminal and location are kept only ;; success and failure continuations. Multiple results for a
;; when they have different lengths. (Otherwise, in the spirit of ;; particular nonterminal and location are kept only when they have
;; finding one successful parse, only the first result is kept.) ;; 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 ;; The parser-tools's `parse' is used to transform tokens in the
;; grammar to tokens specific to this parser. In other words, this ;; grammar to tokens specific to this parser. In other words, this

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