mirror of
https://github.com/janet-lang/janet
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53 lines
1.3 KiB
Plaintext
53 lines
1.3 KiB
Plaintext
# Implements a simple pretty printer. Offers similar functionality
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# as the describe function.
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(defn- pp-seq [pp seen buf a start end]
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(if (get seen a)
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(buffer-push-string buf "<cycle>")
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(do
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(put seen a true)
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(def len (length a))
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(buffer-push-string buf start)
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(for [i 0 len]
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(when (not= i 0) (buffer-push-string buf " "))
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(pp seen buf (get a i)))
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(buffer-push-string buf end)))
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buf)
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(defn- pp-dict [pp seen buf a start end]
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(if (get seen a)
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(buffer-push-string buf "<cycle>")
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(do
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(put seen a true)
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(var k (next a nil))
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(buffer-push-string buf start)
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(while k
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(def v (get a k))
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(pp seen buf k)
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(buffer-push-string buf " ")
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(pp seen buf v)
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(varset! k (next a k))
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(when k (buffer-push-string buf " ")))
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(buffer-push-string buf end)))
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buf)
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(def printers :private {
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:array (fn [pp seen buf x] (pp-seq pp seen buf x "[" "]"))
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:tuple (fn [pp seen buf x] (pp-seq pp seen buf x "(" ")"))
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:table (fn [pp seen buf x] (pp-dict pp seen buf x "@{" "}"))
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:struct (fn [pp seen buf x] (pp-dict pp seen buf x "{" "}"))
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})
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(defn- default_printer [pp seen buf x]
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(buffer-push-string buf (string x))
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buf)
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(defn- pp1 [seen buf x]
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(def pmaybe (get printers (type x)))
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(def p (if pmaybe pmaybe default_printer))
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(p pp1 seen buf x))
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(defn pp
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"Pretty print a value x."
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[x] (print (pp1 @{} @"" x)))
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