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64 lines
3.0 KiB
Racket
64 lines
3.0 KiB
Racket
#lang racket/base
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(require "rule-structs.rkt"
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br-parser-tools/lex
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racket/match
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syntax/strip-context)
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(provide rule->stx)
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(define (rule->stx source a-rule)
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(define id-stx
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(syntax-property
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(datum->syntax #f
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(string->symbol (lhs-id-val (rule-lhs a-rule)))
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(list source
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(pos-line (lhs-id-start (rule-lhs a-rule)))
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(pos-col (lhs-id-start (rule-lhs a-rule)))
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(pos-offset (lhs-id-start (rule-lhs a-rule)))
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(if (and (number? (pos-offset (lhs-id-start (rule-lhs a-rule))))
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(number? (pos-offset (lhs-id-end (rule-lhs a-rule)))))
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(- (pos-offset (lhs-id-end (rule-lhs a-rule)))
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(pos-offset (lhs-id-start (rule-lhs a-rule))))
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#f)))
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'hide-or-splice-lhs-id (lhs-id-splice (rule-lhs a-rule))))
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(define pattern-stx (pattern->stx source (rule-pattern a-rule)))
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(define line (pos-line (rule-start a-rule)))
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(define column (pos-col (rule-start a-rule)))
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(define position (pos-offset (rule-start a-rule)))
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(define span (if (and (number? (pos-offset (rule-start a-rule)))
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(number? (pos-offset (rule-end a-rule))))
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(- (pos-offset (rule-end a-rule))
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(pos-offset (rule-start a-rule)))
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#f))
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(datum->syntax #f
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`(rule ,id-stx ,pattern-stx)
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(list source line column position span)))
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(define (pattern->stx source a-pattern)
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(define (pat->srcloc source pat)
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(match-define (pos offset line col) (pattern-start pat))
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(define offset-end (pos-offset (pattern-end pat)))
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(define span (and (number? offset) (number? offset-end) (- offset-end offset)))
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(list source line col offset span))
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(let loop ([a-pattern a-pattern] [hide-state #f])
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(define (pat->stx val) (datum->syntax #f val (pat->srcloc source a-pattern)))
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(define-values (pat hide)
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(match a-pattern
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[(struct pattern-id (start end val hide)) (values `(id ,(pat->stx (string->symbol val))) hide)]
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[(struct pattern-lit (start end val hide)) (values `(lit ,(pat->stx val)) hide)]
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[(struct pattern-token (start end val hide)) (values `(token ,(pat->stx (string->symbol val))) hide)]
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;; propagate hide value of choice, repeat, and seq into subpatterns
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;; use `(or hide-state hide)` to capture parent value
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[(struct pattern-choice (start end vals hide))
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(values `(choice ,@(map (λ (val) (loop val (or hide-state hide))) vals)) hide)]
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[(struct pattern-repeat (start end min max val hide))
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(values `(repeat ,min ,max ,(loop val (or hide-state hide))) hide)]
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[(struct pattern-seq (start end vals hide))
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(values `(seq ,@(map (λ (val) (loop val (or hide-state hide))) vals)) hide)]))
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(syntax-property (pat->stx pat) 'hide (or hide-state hide))))
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