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| -rw-r--r-- | lib/pure/cstrutils.nim | 79 |
1 files changed, 79 insertions, 0 deletions
diff --git a/lib/pure/cstrutils.nim b/lib/pure/cstrutils.nim new file mode 100644 index 000000000..437140892 --- /dev/null +++ b/lib/pure/cstrutils.nim @@ -0,0 +1,79 @@ +# +# +# 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 + +proc startsWith*(s, prefix: cstring): bool {.noSideEffect, + rtl, extern: "csuStartsWith".} = + ## Returns true iff ``s`` starts with ``prefix``. + ## + ## If ``prefix == ""`` true is returned. + 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 iff ``s`` ends with ``suffix``. + ## + ## If ``suffix == ""`` true is returned. + 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".} = + ## Compares two strings normalized (i.e. case and + ## underscores do not matter). Returns: + ## + ## | 0 iff a == b + ## | < 0 iff a < b + ## | > 0 iff a > b + 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 iff a == b + ## | < 0 iff a < b + ## | > 0 iff a > b + 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) |