Merge pull request #3131 from zachaysan/devel

Create chomp proc and tests

lib/pure/strutils.nim

@@ -168,7 +168,6 @@ proc cmpIgnoreStyle*(a, b: string): int {.noSideEffect,
     inc(i)
     inc(j)
 
-{.pop.}
 
 proc strip*(s: string, leading = true, trailing = true, chars: set[char] = Whitespace): string
   {.noSideEffect, rtl, extern: "nsuStrip".} =
@@ -1396,6 +1395,62 @@ proc format*(formatstr: string, a: varargs[string, `$`]): string {.noSideEffect,
 
 {.pop.}
 
+proc removeSuffix*(s: var string, chars: set[char] = Newlines) {.
+  rtl, extern: "nsuRemoveSuffixCharSet".} =
+  ## Removes the first matching character from the string (in-place) given a
+  ## set of characters. If the set of characters is only equal to `Newlines`
+  ## then it will remove both the newline and return feed.
+  ## .. code-block:: nim
+  ##   var
+  ##     userInput = "Hello World!\r\n"
+  ##     otherInput = "Hello!?!"
+  ##   userInput.removeSuffix
+  ##   userInput == "Hello World!"
+  ##   userInput.removeSuffix({'!', '?'})
+  ##   userInput == "Hello World"
+  ##   otherInput.removeSuffix({'!', '?'})
+  ##   otherInput == "Hello!?"
+
+  var last = len(s) - 1
+
+  if chars == Newlines:
+    if s[last] == '\10':
+      last -= 1
+
+    if s[last] == '\13':
+      last -= 1
+
+  else:
+    if s[last] in chars:
+      last -= 1
+
+  s.setLen(last + 1)
+
+proc removeSuffix*(s: var string, c: char) {.rtl, extern: "nsuRemoveSuffixChar".} =
+  ## Removes a single character (in-place) from a string.
+  ## .. code-block:: nim
+  ##   var
+  ##     table = "users"
+  ##   table.removeSuffix('s')
+  ##   table == "user"
+  removeSuffix(s, chars = {c})
+
+proc removeSuffix*(s: var string, suffix: string) {.
+  rtl, extern: "nsuRemoveSuffixString".} =
+  ## Remove the first matching suffix (in-place) from a string.
+  ## .. code-block:: nim
+  ##   var
+  ##     answers = "yeses"
+  ##   answers.removeSuffix("es")
+  ##   answers == "yes"
+
+  var newLen = s.len
+
+  if s.endsWith(suffix):
+    newLen -= len(suffix)
+
+  s.setLen(newLen)
+
 when isMainModule:
   doAssert align("abc", 4) == " abc"
   doAssert align("a", 0) == "a"

tests/stdlib/tstrutil.nim

@@ -10,8 +10,48 @@ import
 proc testStrip() =
   write(stdout, strip("  ha  "))
 
+proc testRemoveSuffix =
+  var s = "hello\n\r"
+  s.removeSuffix
+  assert s == "hello\n"
+  s.removeSuffix
+  assert s == "hello"
+  s.removeSuffix
+  assert s == "hello"
+
+  s = "hello\n\n"
+  s.removeSuffix
+  assert s == "hello\n"
+
+  s = "hello\r"
+  s.removeSuffix
+  assert s == "hello"
+
+  s = "hello \n there"
+  s.removeSuffix
+  assert s == "hello \n there"
+
+  s = "hello"
+  s.removeSuffix("llo")
+  assert s == "he"
+  s.removeSuffix('e')
+  assert s == "h"
+
+  s = "hellos"
+  s.removeSuffix({'s','z'})
+  assert s == "hello"
+  s.removeSuffix({'l','o'})
+  assert s == "hell"
+
+  # Contrary to Chomp in other languages
+  # empty string does not change behaviour
+  s = "hello\r\n\r\n"
+  s.removeSuffix("")
+  assert s == "hello\r\n\r\n"
+
 proc main() =
   testStrip()
+  testRemoveSuffix()
   for p in split("/home/a1:xyz:/usr/bin", {':'}):
     write(stdout, p)