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preparations for string optimizations

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This commit is contained in:
Andreas Rumpf 2017-09-22 09:57:18 +02:00
commit c383e4d35e
3 changed files with 38 additions and 9 deletions
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27
lib/system/sysstr.nim
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@ -95,6 +95,11 @@ proc cstrToNimstr(str: cstring): NimString {.compilerRtl.} =
if str == nil: NimString(nil)
else: toNimStr(str, str.len)
when defined(nimImmutableStrings):
template wasMoved(x: NimString): bool = (x.reserved and seqShallowFlag) != 0
else:
template wasMoved(x: NimString): bool = false
proc copyString(src: NimString): NimString {.compilerRtl.} =
if src != nil:
if (src.reserved and seqShallowFlag) != 0:
@ -103,6 +108,16 @@ proc copyString(src: NimString): NimString {.compilerRtl.} =
result = rawNewStringNoInit(src.len)
result.len = src.len
copyMem(addr(result.data), addr(src.data), src.len + 1)
sysAssert((seqShallowFlag and result.reserved) == 0, "copyString")
when defined(nimImmutableStrings):
if (src.reserved and strlitFlag) != 0:
result.reserved = (result.reserved and not strlitFlag) or seqShallowFlag
proc newOwnedString(src: NimString; n: int): NimString =
result = rawNewStringNoInit(n)
result.len = n
copyMem(addr(result.data), addr(src.data), n)
result.data[n] = '\0'
proc copyStringRC1(src: NimString): NimString {.compilerRtl.} =
if src != nil:
@ -116,6 +131,10 @@ proc copyStringRC1(src: NimString): NimString {.compilerRtl.} =
result = rawNewStringNoInit(src.len)
result.len = src.len
copyMem(addr(result.data), addr(src.data), src.len + 1)
sysAssert((seqShallowFlag and result.reserved) == 0, "copyStringRC1")
when defined(nimImmutableStrings):
if (src.reserved and strlitFlag) != 0:
result.reserved = (result.reserved and not strlitFlag) or seqShallowFlag
proc copyDeepString(src: NimString): NimString {.inline.} =
if src != nil:
@ -144,6 +163,8 @@ proc addChar(s: NimString, c: char): NimString =
result = cast[NimString](growObj(result,
sizeof(TGenericSeq) + r + 1))
result.reserved = r
elif wasMoved(s):
result = newOwnedString(s, s.len)
result.data[result.len] = c
result.data[result.len+1] = '\0'
inc(result.len)
@ -180,7 +201,7 @@ proc addChar(s: NimString, c: char): NimString =
# s = rawNewString(0);
proc resizeString(dest: NimString, addlen: int): NimString {.compilerRtl.} =
if dest.len + addlen <= dest.space:
if dest.len + addlen <= dest.space and not wasMoved(dest):
result = dest
else: # slow path:
var sp = max(resize(dest.space), dest.len + addlen)
@ -201,7 +222,9 @@ proc appendChar(dest: NimString, c: char) {.compilerproc, inline.} =
proc setLengthStr(s: NimString, newLen: int): NimString {.compilerRtl.} =
var n = max(newLen, 0)
if n <= s.space:
if wasMoved(s):
result = newOwnedString(s, n)
elif n <= s.space:
result = s
else:
result = resizeString(s, n)