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32 lines
1.1 KiB
Racket
32 lines
1.1 KiB
Racket
#lang racket/base
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(require racket/class)
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(provide indent-brag)
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(define (line text pos)
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(send text position-line pos))
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(define (previous-line text pos)
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(define this-line (line text pos))
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(and (positive? this-line) (sub1 this-line)))
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(define (line-first-visible-char text line)
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(define (char text pos) (and pos (send text get-character pos)))
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(char text (for*/first ([pos (in-range (send text line-start-position line)
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(send text line-end-position line))]
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[c (in-value (char text pos))]
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#:unless (char-blank? c))
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pos)))
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(define (indent-brag tbox [posn 0])
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(define prev-line (previous-line tbox posn))
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(define this-line (line tbox posn))
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(cond
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[(not prev-line) #f]
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[(eqv? (line-first-visible-char tbox this-line) #\|)
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(define start (send tbox line-start-position prev-line))
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(define end (send tbox line-end-position prev-line))
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(for*/first ([pos (in-range start end)]
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[c (in-value (send tbox get-character pos))]
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#:when (memv c '(#\: #\|)))
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(- pos start))]
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[else #f])) |