103 lines
2.5 KiB
Nim
103 lines
2.5 KiB
Nim
# history.nim
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import ../multiline
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import os
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import options
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type HistoryElement* = ref object
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original*: Multiline
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current*: Multiline
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temp: bool
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type History* = ref object
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elements: seq[HistoryElement]
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index: int
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lowestTouchedIndex: int
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proc newHistory*: History =
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new(result)
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result.index = 0
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result.lowestTouchedIndex = 0
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result.elements = @[]
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template newIndex(h: History): Option[Multiline] =
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if h.lowestTouchedIndex > h.index:
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h.lowestTouchedIndex = h.index
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some(h.elements[h.index].current)
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proc delta*(h: History, amt: int): Option[Multiline] =
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# move up/down in history and return reference to current
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# also update lowest touched index
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if h.elements.len() == 0:
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return none[Multiline]()
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if h.index + amt <= 0:
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h.index = 0
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elif h.index + amt >= h.elements.high():
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h.index = h.elements.high()
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else:
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h.index += amt
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h.newIndex()
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proc toEnd*(h: History): Option[Multiline] =
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if h.elements.len() == 0:
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return none[Multiline]()
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h.index = h.elements.high()
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h.newIndex()
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proc toStart*(h: History): Option[Multiline] =
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if h.elements.len() == 0:
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return none[Multiline]()
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h.index = 0
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h.newIndex()
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proc clean*(h: History) =
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# restore originals to current
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# from lowest touched index to the top
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if h.lowestTouchedIndex <= h.elements.high():
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for i in countup(h.lowestTouchedIndex, h.elements.high()):
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if h.elements[i].temp:
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h.elements.delete(i)
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else:
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h.elements[i].current = h.elements[i].original.copy()
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h.lowestTouchedIndex = h.elements.len()
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proc newEntry*(h: History, ml: Multiline, temp: bool = false) =
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if not temp:
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h.elements.add(HistoryElement(original: ml, current: ml.copy(), temp: temp))
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else:
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h.elements.add(HistoryElement(original: ml, current: ml, temp: temp))
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proc save*(h: History, path: string) =
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# discards currents and temps, only saves originals
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if dirExists(path):
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raise newException(CatchableError, "Attempt to save history to " & path & ", but a directory at that path exists")
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let file = open(path, fmWrite)
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for el in h.elements:
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if el.temp:
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continue
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file.writeLine(el.original.serialize())
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file.close()
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proc loadHistory*(path: string): History =
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if not fileExists(path):
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raise newException(CatchableError, "Attempt to read history from a non-existant file")
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let file = open(path, fmRead)
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let h = newHistory()
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var line: string
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while readLine(file, line):
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h.newEntry(line.deserialize())
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file.close()
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return h
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