Packrat: Simple Packrat Parsing
David Van Horn <dvanhorn@ccs.neu.edu>
This module provides a small library of Packrat parsing combinators and a syntax for defining parsers.
This code is based on the portable packrat parsing library by
Tony Garnock-Jones:
1 Main
(require (planet dvanhorn/packrat:2:3)) |
This module provides bindings from the combinator library and the parser syntax.
2 Combinator library
(require (planet dvanhorn/packrat:2:3/combinator)) |
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filename : string? | ||||||
line : number? | ||||||
column : number? |
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successful? : boolean? | ||||||
semantic-value : any/c | ||||||
next : (or/c false? parse-results?) | ||||||
error : (or/c false? parse-error?) |
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position : (or/c false? parse-position?) | ||||||
base : any/c | ||||||
next* : (or/c false? parse-results? (-> parse-results?)) | ||||||
map : (hash/c symbol? (or/c false? parse-result?)) |
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position : (or/c parse-position? false?) | ||||||
expected : (or/c false? (listof any/c)) | ||||||
messages : (listof string?) |
(top-parse-position filename) → parse-position? |
filename : string? |
(update-parse-position pos ch) → parse-position? |
pos : parse-position? |
ch : char? |
(empty-results pos) → parse-results? |
pos : (or/c parse-position? false?) |
(make-results pos base next-generator) → parse-results? |
pos : (or/c parse-position? false?) |
base : (or/c false? (cons/c any/c any/c)) |
next-generator : (-> parse-results?) |
(make-error-expected pos thing) → parse-error? |
pos : (or/c parse-position? false?) |
thing : any/c |
(make-error-message pos msg) → parse-error? |
pos : parse-position? |
msg : string? |
(make-result semantic-value next) → parse-result? |
semantic-value : any/c |
next : parse-results? |
(parse-error->parse-result err) → parse-result? |
err : parse-error? |
(make-expected-result pos thing) → parse-result? |
pos : (or/c parse-position? false?) |
thing : any/c |
(make-message-result pos msg) → parse-result? |
pos : (or/c parse-position? false?) |
msg : string? |
(base-generator->results generator) → parse-results? | ||||||||
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(parse-results-next results) → parse-results? |
results : parse-results? |
(results->result results key fn) → parse-result? |
results : parse-results? |
key : symbol? |
fn : (-> parse-result?) |
(parse-position>? a b) → boolean? |
a : (or/c parse-position? false?) |
b : (or/c parse-position? false?) |
(parse-error-empty? e) → boolean? |
e : parse-error? |
(merge-parse-errors e1 e2) → (or/c parse-error? false?) |
e1 : (or/c parse-error? false?) |
e2 : (or/c parse-error? false?) |
(merge-result-errors result errs) → parse-result? |
result : parse-result? |
errs : (or/c parse-error? false?) |
(packrat-check-base token-kind k) |
→ (-> parse-results? parse-result?) |
token-kind : any/c |
k : (-> any/c (-> parse-results? parse-result?)) |
(packrat-check-pred token-pred k) |
→ (-> parse-results? parse-result?) |
token-pred : (-> any/c boolean?) |
k : (-> any/c (-> parse-results? parse-result?)) |
(packrat-check parser k) → (-> parse-results? parse-result?) |
parser : (-> parse-results? parse-result?) |
k : (-> any/c (-> parse-results? parse-result?)) |
(packrat-or p1 p2) → (-> parse-results? parse-result?) |
p1 : (-> parse-results? parse-result?) |
p2 : (-> parse-results? parse-result?) |
(packrat-unless explanation p1 p2) |
→ (-> parse-results? parse-result?) |
explanation : string? |
p1 : (-> parse-results? parse-result?) |
p2 : (-> parse-results? parse-result?) |
(packrat-port-results filename p) → parse-results? |
filename : string? |
p : port? |
(packrat-string-results filename s) → parse-results? |
filename : string? |
s : string? |
(packrat-list-results tokens) → parse-results? |
tokens : (listof any/c) |
3 Parser syntax
(require (planet dvanhorn/packrat:2:3/parser)) |
(parse id ([nonterminal-id (sequence body body0 ...)] ...)) | ||||||||||||||||||||||||||||||||||||||||||||||||||
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4 Examples
Here is an example of a simple calculator.
Examples: | |||||||||||||
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> (parse-result-semantic-value (calc g)) | |||||||||||||
7 |
See the tests source file for an example of a parser for a simplified Scheme grammar.
5 Test suite
(require (planet dvanhorn/packrat:2:3/test)) |
Requiring this module will run the test suite.