racket/collects/drracket/private/get-defs.rkt

139 lines
5.6 KiB
Racket

#lang racket/base
(require racket/class
racket/function
racket/list
string-constants)
(provide (struct-out defn)
get-definitions)
;; defn = (make-defn number string number number)
(define-struct defn (indent name start-pos end-pos) #:mutable)
;; get-definitions : string boolean text -> (listof defn)
(define (get-definitions tag-string indent? text)
(let* ([min-indent 0]
[defs (let loop ([pos 0])
(let ([defn-pos (send text find-string tag-string 'forward pos 'eof #t #f)])
(cond
[(not defn-pos) null]
[(in-semicolon-comment? text defn-pos)
(loop (+ defn-pos (string-length tag-string)))]
[else
(let ([indent (get-defn-indent text defn-pos)]
[name (get-defn-name text (+ defn-pos (string-length tag-string)))])
(set! min-indent (min indent min-indent))
(cons (make-defn indent name defn-pos defn-pos)
(loop (+ defn-pos (string-length tag-string)))))])))])
;; update end-pos's based on the start pos of the next defn
(unless (null? defs)
(let loop ([first (car defs)]
[defs (cdr defs)])
(cond
[(null? defs)
(set-defn-end-pos! first (send text last-position))]
[else (set-defn-end-pos! first (max (- (defn-start-pos (car defs)) 1)
(defn-start-pos first)))
(loop (car defs) (cdr defs))])))
(when indent?
(for-each (λ (defn)
(set-defn-name! defn
(string-append
(apply string
(vector->list
(make-vector
(- (defn-indent defn) min-indent) #\space)))
(defn-name defn))))
defs))
defs))
;; in-semicolon-comment: text number -> boolean
;; returns #t if `define-start-pos' is in a semicolon comment and #f otherwise
(define (in-semicolon-comment? text define-start-pos)
(let* ([para (send text position-paragraph define-start-pos)]
[start (send text paragraph-start-position para)])
(let loop ([pos start])
(cond
[(pos . >= . define-start-pos) #f]
[(char=? #\; (send text get-character pos)) #t]
[else (loop (+ pos 1))]))))
;; get-defn-indent : text number -> number
;; returns the amount to indent a particular definition
(define (get-defn-indent text pos)
(let* ([para (send text position-paragraph pos)]
[para-start (send text paragraph-start-position para #t)])
(let loop ([c-pos para-start]
[offset 0])
(if (< c-pos pos)
(let ([char (send text get-character c-pos)])
(cond
[(char=? char #\tab)
(loop (+ c-pos 1) (+ offset (- 8 (modulo offset 8))))]
[else
(loop (+ c-pos 1) (+ offset 1))]))
offset))))
;; whitespace-or-paren?
(define (whitespace-or-paren? char)
(or (char=? #\) char)
(char=? #\( char)
(char=? #\] char)
(char=? #\[ char)
(char-whitespace? char)))
;; skip : text number (char -> bool) -> number
;; Skips characters recognized by `skip?'
(define (skip text pos skip?)
(let loop ([pos pos])
(if (>= pos (send text last-position))
(send text last-position)
(let ([char (send text get-character pos)])
(cond
[(skip? char)
(loop (+ pos 1))]
[else pos])))))
;; skip-to-whitespace/paren : text number -> number
;; skips to the next parenthesis or whitespace after `pos', returns that position.
(define (skip-to-whitespace/paren text pos)
(skip text pos (negate whitespace-or-paren?)))
;; skip-whitespace/paren : text number -> number
;; skips past any parenthesis or whitespace
(define (skip-whitespace/paren text pos)
(skip text pos whitespace-or-paren?))
;; skip-past-non-whitespace : text number -> number
;; skips to the first whitespace character after the first non-whitespace character
(define (skip-past-non-whitespace text pos)
(skip text (skip text pos char-whitespace?) (negate char-whitespace?)))
;; get-defn-name : text number -> string
;; returns the name of the definition starting at `define-pos',
;; assuming that the bound name is the first symbol to appear
;; after the one beginning at `define-pos'. This heuristic
;; usually finds the bound name, but it breaks for Redex
;; metafunction definitions (thus the hack below).
(define (get-defn-name text define-pos)
(let* ([end-suffix-pos (skip-to-whitespace/paren text define-pos)]
[suffix (send text get-text define-pos end-suffix-pos)]
[end-header-pos
(cond [(regexp-match #rx"^-metafunction(/extension)?$" suffix)
=> (λ (m)
(let ([extension? (second m)])
(skip-past-non-whitespace
text
(if extension?
(skip-past-non-whitespace text end-suffix-pos)
end-suffix-pos))))]
[else end-suffix-pos])]
[start-name-pos (skip-whitespace/paren text end-header-pos)]
[end-name-pos (skip-to-whitespace/paren text start-name-pos)])
(if (>= end-suffix-pos (send text last-position))
(string-constant end-of-buffer-define)
(send text get-text start-name-pos end-name-pos))))