Add strutils in-place

changelog.md

@@ -94,6 +94,8 @@ echo f
 - Added `times.isLeapDay`
 - Added a new module, `std / compilesettings` for querying the compiler about
   diverse configuration settings.
+- Added in-place `strutils.toLowerAsciiInPlace`,  `strutils.toUpperAsciiInPlace`,
+  faster than the copy versions, at least from ~1.5x to ~5x performance approx.
 
 
 ## Library changes

lib/pure/strutils.nim

@@ -2860,6 +2860,44 @@ proc isNilOrWhitespace*(s: string): bool {.noSideEffect, procvar, rtl,
   ## Alias for isEmptyOrWhitespace
   result = isEmptyOrWhitespace(s)
 
+
+since (1, 1):
+  func toLowerAsciiInPlace*(s: var string) {.inline.} =
+    ## Converts string `s` into lower case.
+    ##
+    ## This works only for the letters ``A-Z``. See `unicode.toLower
+    ## <unicode.html#toLower,string>`_ for a version that works for any Unicode
+    ## character.
+    ##
+    ## See also:
+    ## * `normalize proc<#normalize,string>`_
+    runnableExamples:
+      var x = "abcdefghijklmnopqrstuvwxyz01234567890ABCDEFGHIJKLMNOPQRSTUVWXYZ*+,-./:;<=>?@[]_{|}~"
+      toLowerAsciiInPlace(x)
+      doAssert x == "abcdefghijklmnopqrstuvwxyz01234567890abcdefghijklmnopqrstuvwxyz*+,-./:;<=>?@[]_{|}~"
+    const t = "abcdefghijklmnopqrstuvwxyz".indent(65).cstring
+    for c in mitems(s):
+      if c in {'A'..'Z'}: c = t[c.ord]
+
+
+  func toUpperAsciiInPlace*(s: var string) {.inline.} =
+    ## Converts string `s` into upper case.
+    ##
+    ## This works only for the letters ``A-Z``.  See `unicode.toUpper
+    ## <unicode.html#toUpper,string>`_ for a version that works for any Unicode
+    ## character.
+    ##
+    ## See also:
+    ## * `capitalizeAscii proc<#capitalizeAscii,string>`_
+    runnableExamples:
+      var z = "abcdefghijklmnopqrstuvwxyz01234567890ABCDEFGHIJKLMNOPQRSTUVWXYZ*+,-./:;<=>?@[]_{|}~"
+      toUpperAsciiInPlace(z)
+      doAssert z == "ABCDEFGHIJKLMNOPQRSTUVWXYZ01234567890ABCDEFGHIJKLMNOPQRSTUVWXYZ*+,-./:;<=>?@[]_{|}~"
+    const t = "ABCDEFGHIJKLMNOPQRSTUVWXYZ".indent(97).cstring
+    for c in mitems(s):
+      if c in {'a'..'z'}: c = t[c.ord]
+
+
 when isMainModule:
   proc nonStaticTests =
     doAssert formatBiggestFloat(1234.567, ffDecimal, -1) == "1234.567000"