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touchups

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pull/28/head
Matthew Butterick 3 years ago
parent 555e2e0193
commit 066ef315e2
4 changed files with 40 additions and 73 deletions
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48
brag-lib/brag/codegen/expander.rkt
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@ -71,44 +71,38 @@
(cons eof token-EOF)
(cons 'TOKEN-TYPE TOKEN-TYPE-CONSTRUCTOR) ...)))
(define-syntax (MAKE-RULE-PARSER rule-id-stx)
(syntax-case rule-id-stx ()
[(_ start-rule)
(and (identifier? #'start-rule)
(member (syntax-e #'start-rule) 'RULE-IDS))
(define-syntax (MAKE-RULE-PARSER stx)
(syntax-case stx ()
[(_ START-RULE-ID)
(and (identifier? #'START-RULE-ID) (member (syntax-e #'START-RULE-ID) 'RULE-IDS))
;; The cfg-parser depends on the start-rule provided in (start ...) to have the same
;; context as the rest of this body. Hence RECOLORED-START-RULE
(with-syntax ([RECOLORED-START-RULE (datum->syntax #'RULES-STX (syntax-e #'start-rule))]
[PARSE-NAME (datum->syntax #'RULES-STX (string->symbol (format "~a-rule-parser" 'start-rule)))])
#'(let* ([THE-GRAMMAR (cfg-parser (tokens enumerated-tokens)
(with-syntax ([RECOLORED-START-RULE (datum->syntax #'RULES-STX (syntax-e #'START-RULE-ID))])
#'(let ()
(define (rule-parser tokenizer)
(define rule-grammar (cfg-parser (tokens enumerated-tokens)
(src-pos)
(start RECOLORED-START-RULE)
(end EOF)
(error THE-ERROR-HANDLER)
(grammar . GENERATED-RULE-CODES))]
[THE-BODY (lambda (tokenizer)
(define next-token
(make-permissive-tokenizer tokenizer all-tokens-hash/mutable))
;; little post-processor to support cuts on top rule name
(define parse-tree-stx (THE-GRAMMAR next-token))
(define top-rule-name-stx (syntax-case parse-tree-stx ()
[(TRN . REST) #'TRN]
(error the-error-handler)
(grammar . GENERATED-RULE-CODES)))
(define next-token (make-permissive-tokenizer tokenizer all-tokens-hash/mutable))
;; here's how we support grammar "cuts" on top rule name
(define parse-tree-stx (rule-grammar next-token))
(syntax-case parse-tree-stx ()
[(TOP-RULE-NAME . _)
(if (eq? (syntax-property #'TOP-RULE-NAME 'hide-or-splice?) 'hide)
(remove-rule-name parse-tree-stx) ; use `remove-rule-name` so we get the same housekeeping
parse-tree-stx)]
[_ (error 'malformed-parse-tree)]))
(if (eq? (syntax-property top-rule-name-stx 'hide-or-splice?) 'hide)
;; use `remove-rule-name` so we get the same housekeeping
(remove-rule-name parse-tree-stx)
parse-tree-stx))])
(procedure-rename
(case-lambda [(tokenizer)
(THE-BODY tokenizer)]
(case-lambda [(tokenizer) (rule-parser tokenizer)]
[(source tokenizer)
(parameterize ([current-source source])
(THE-BODY tokenizer))])
(string->symbol (format "~a-rule-parser" 'start-rule)))))]
(rule-parser tokenizer))])))]
[(_ not-a-rule-id)
(raise-syntax-error #f
(format "Rule ~a is not defined in the grammar" (syntax-e #'not-a-rule-id))
rule-id-stx)]))
stx)]))
;; start-id has to be a value, not an expr, because make-rule-parser is a macro
(define PARSE (procedure-rename (MAKE-RULE-PARSER START-ID) 'PARSE))

4
brag-lib/brag/codegen/runtime.rkt
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@ -7,7 +7,7 @@
brag/private/internal-support)
(provide THE-ERROR-HANDLER
(provide the-error-handler
make-permissive-tokenizer
atomic-datum->syntax
positions->srcloc
@ -19,7 +19,7 @@
;; The level of indirection here is necessary since the yacc grammar wants a
;; function value for the error handler up front. We want to delay that decision
;; till parse time.
(define (THE-ERROR-HANDLER tok-ok? tok-name tok-value start-pos end-pos)
(define (the-error-handler tok-ok? tok-name tok-value start-pos end-pos)
(match (positions->srcloc start-pos end-pos)
[(list src line col offset span)
((current-parser-error-handler) tok-name

0
brag-lib/brag/test/make-rule-parser-grammar.rkt → brag-lib/brag/examples/subrule.rkt
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45
brag-lib/brag/test/test-make-rule-parser.rkt
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@ -1,44 +1,17 @@
#lang racket/base
(require rackunit
brag/support
br-parser-tools/lex
brag/rules/parser
brag/rules/lexer
)
(require "make-rule-parser-grammar.rkt")
(define parse-next
(make-rule-parser next))
(define parse-start
(make-rule-parser start))
brag/examples/subrule)
(define (lex ip)
(port-count-lines! ip)
(lambda ()
(define next-char (read-char ip))
(cond [(eof-object? next-char)
(token eof)]
[(char=? next-char #\0)
(token "0" "0")]
[(char=? next-char #\1)
(token "1" "1")])))
(define parse-next (make-rule-parser next))
(define parse-start (make-rule-parser start))
(check-equal? (syntax->datum (parse #f "0")) '(start (next "0")))
(check-equal? (syntax->datum (parse #f "0")) (syntax->datum (parse "0")))
(check-equal? (syntax->datum (parse #f (lex (open-input-string "0"))))
'(start (next "0")))
(check-equal? (syntax->datum (parse #f (lex (open-input-string "0"))))
(syntax->datum (parse (lex (open-input-string "0")))))
(check-equal? (syntax->datum (parse-start #f "0")) '(start (next "0")))
(check-equal? (syntax->datum (parse-start #f "0")) (syntax->datum (parse-start "0")))
(check-equal? (syntax->datum (parse-start #f (lex (open-input-string "0"))))
'(start (next "0")))
(check-equal? (syntax->datum (parse-start #f (lex (open-input-string "0"))))
(syntax->datum (parse-start (lex (open-input-string "0")))))
(check-equal? (syntax->datum (parse-next #f "0")) '(next "0"))
(check-equal? (syntax->datum (parse-next #f "0")) (syntax->datum (parse-next "0")))
(check-equal? (syntax->datum (parse-next #f (lex (open-input-string "0"))))
'(next "0"))
(check-equal? (syntax->datum (parse-next #f (lex (open-input-string "0"))))
(syntax->datum (parse-next (lex (open-input-string "0")))))
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