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https://github.com/nim-lang/Nim.git
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1c37d9a50e
`strbasics.add` uses `copymem` when available. CT conditional
scaffolding mirrors the same from system.
Follow-up to #15951
Compile-time test for `strbasics.add` undiscarded and passes, though
pending bug #15952 is still open.
126 lines
3.3 KiB
Nim
126 lines
3.3 KiB
Nim
#
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#
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# Nim's Runtime Library
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# (c) Copyright 2021 Nim Contributors
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#
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# See the file "copying.txt", included in this
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# distribution, for details about the copyright.
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#
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## This module provides some high performance string operations.
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##
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## Experimental API, subject to change.
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when defined(nimPreviewSlimSystem):
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import std/assertions
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const whitespaces = {' ', '\t', '\v', '\r', '\l', '\f'}
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const notJSnotNims = not defined(js) and not defined(nimscript)
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template whenNotVmJsNims(normalBody, restrictedBody: untyped) =
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## hack, see: #12517 #12518; Edit together with identical in `system`
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when nimvm:
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restrictedBody
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else:
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when notJSnotNims:
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normalBody
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else:
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restrictedBody
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proc add*(x: var string, y: openArray[char]) =
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## Concatenates `x` and `y` in place. `y` must not overlap with `x`
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# Use `{.noalias.}` ?
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if y.len == 0: return
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let oldLen = x.len
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x.setLenUninit(oldLen + y.len)
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whenNotVmJsNims():
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{.cast(noSideEffect).}:
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copyMem(beginStore(x, oldLen + y.len, oldLen), addr(y[0]), y.len)
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endStore(x)
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do:
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for i, ch in y:
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x[oldLen + i] = ch
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func stripSlice(s: openArray[char], leading = true, trailing = true, chars: set[char] = whitespaces): Slice[int] =
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## Returns the slice range of `s` which is stripped `chars`.
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runnableExamples:
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assert stripSlice(" abc ") == 1 .. 3
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var
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first = 0
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last = high(s)
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if leading:
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while first <= last and s[first] in chars: inc(first)
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if trailing:
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while last >= first and s[last] in chars: dec(last)
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result = first .. last
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func setSlice*(s: var string, slice: Slice[int]) =
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## Inplace version of `substr`.
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runnableExamples:
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import std/sugar
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var a = "Hello, Nim!"
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doAssert a.dup(setSlice(7 .. 9)) == "Nim"
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doAssert a.dup(setSlice(0 .. 0)) == "H"
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doAssert a.dup(setSlice(0 .. 1)) == "He"
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doAssert a.dup(setSlice(0 .. 10)) == a
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doAssert a.dup(setSlice(1 .. 0)).len == 0
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doAssert a.dup(setSlice(20 .. -1)).len == 0
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doAssertRaises(AssertionDefect):
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discard a.dup(setSlice(-1 .. 1))
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doAssertRaises(AssertionDefect):
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discard a.dup(setSlice(1 .. 11))
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let first = slice.a
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let last = slice.b
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assert first >= 0
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assert last <= s.high
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if first > last:
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s.setLen(0)
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return
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if first > 0:
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whenNotVmJsNims():
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let p = beginStore(s, s.len)
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moveMem(p, addr p[first], last - first + 1)
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endStore(s)
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do:
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for index in first .. last:
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s[index - first] = s[index]
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s.setLen(last - first + 1)
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func strip*(a: var string, leading = true, trailing = true, chars: set[char] = whitespaces) {.inline.} =
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## Inplace version of `strip`. Strips leading or
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## trailing `chars` (default: whitespace characters).
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##
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## If `leading` is true (default), leading `chars` are stripped.
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## If `trailing` is true (default), trailing `chars` are stripped.
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## If both are false, the string is unchanged.
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runnableExamples:
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var a = " vhellov "
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strip(a)
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assert a == "vhellov"
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a = " vhellov "
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a.strip(leading = false)
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assert a == " vhellov"
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a = " vhellov "
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a.strip(trailing = false)
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assert a == "vhellov "
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var c = "blaXbla"
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c.strip(chars = {'b', 'a'})
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assert c == "laXbl"
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c = "blaXbla"
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c.strip(chars = {'b', 'a', 'l'})
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assert c == "X"
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setSlice(a, stripSlice(a, leading, trailing, chars))
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