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#
#
# Nim's Runtime Library
# (c) Copyright 2017 Nim contributors
#
# See the file "copying.txt", included in this
# distribution, for details about the copyright.
#
## This module supports helper routines for working with ``cstring``
## without having to convert ``cstring`` to ``string`` in order to
## save allocations.
include "system/inclrtl"
proc toLowerAscii(c: char): char {.inline.} =
if c in {'A'..'Z'}:
result = chr(ord(c) + (ord('a') - ord('A')))
else:
result = c
when defined(js):
proc startsWith*(s, prefix: cstring): bool {.noSideEffect,
importjs: "#.startsWith(#)".}
proc endsWith*(s, suffix: cstring): bool {.noSideEffect,
importjs: "#.endsWith(#)".}
# JS string has more operations that might warrant its own module:
# https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String
else:
proc startsWith*(s, prefix: cstring): bool {.noSideEffect,
rtl, extern: "csuStartsWith".} =
## Returns true if ``s`` starts with ``prefix``.
##
## If ``prefix == ""`` true is returned.
##
## JS backend uses native ``String.prototype.startsWith``.
var i = 0
while true:
if prefix[i] == '\0': return true
if s[i] != prefix[i]: return false
inc(i)
proc endsWith*(s, suffix: cstring): bool {.noSideEffect,
rtl, extern: "csuEndsWith".} =
## Returns true if ``s`` ends with ``suffix``.
##
## If ``suffix == ""`` true is returned.
##
## JS backend uses native ``String.prototype.endsWith``.
let slen = s.len
var i = 0
var j = slen - len(suffix)
while i+j <% slen:
if s[i+j] != suffix[i]: return false
inc(i)
if suffix[i] == '\0': return true
proc cmpIgnoreStyle*(a, b: cstring): int {.noSideEffect,
rtl, extern: "csuCmpIgnoreStyle".} =
## Semantically the same as ``cmp(normalize($a), normalize($b))``. It
## is just optimized to not allocate temporary strings. This should
## NOT be used to compare Nim identifier names. use `macros.eqIdent`
## for that. Returns:
##
## | 0 if a == b
## | < 0 if a < b
## | > 0 if a > b
##
## Not supported for JS backend, use `strutils.cmpIgnoreStyle
## <strutils.html#cmpIgnoreStyle%2Cstring%2Cstring>`_ instead.
var i = 0
var j = 0
while true:
while a[i] == '_': inc(i)
while b[j] == '_': inc(j) # BUGFIX: typo
var aa = toLowerAscii(a[i])
var bb = toLowerAscii(b[j])
result = ord(aa) - ord(bb)
if result != 0 or aa == '\0': break
inc(i)
inc(j)
proc cmpIgnoreCase*(a, b: cstring): int {.noSideEffect,
rtl, extern: "csuCmpIgnoreCase".} =
## Compares two strings in a case insensitive manner. Returns:
##
## | 0 if a == b
## | < 0 if a < b
## | > 0 if a > b
##
## Not supported for JS backend, use `strutils.cmpIgnoreCase
## <strutils.html#cmpIgnoreCase%2Cstring%2Cstring>`_ instead.
var i = 0
while true:
var aa = toLowerAscii(a[i])
var bb = toLowerAscii(b[i])
result = ord(aa) - ord(bb)
if result != 0 or aa == '\0': break
inc(i)
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