diff options
Diffstat (limited to 'users/sterni/nix/char')
-rw-r--r-- | users/sterni/nix/char/all-chars.bin | 2 | ||||
-rw-r--r-- | users/sterni/nix/char/default.nix | 99 | ||||
-rw-r--r-- | users/sterni/nix/char/tests/default.nix | 31 |
3 files changed, 132 insertions, 0 deletions
diff --git a/users/sterni/nix/char/all-chars.bin b/users/sterni/nix/char/all-chars.bin new file mode 100644 index 000000000000..017b909e8e8e --- /dev/null +++ b/users/sterni/nix/char/all-chars.bin @@ -0,0 +1,2 @@ + + !"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~ \ No newline at end of file diff --git a/users/sterni/nix/char/default.nix b/users/sterni/nix/char/default.nix new file mode 100644 index 000000000000..9c6ce2fb250b --- /dev/null +++ b/users/sterni/nix/char/default.nix @@ -0,0 +1,99 @@ +{ depot, lib, pkgs, ... }: + +let + + inherit (depot.users.sterni.nix.flow) + cond + ; + + inherit (depot.nix) + yants + ; + + inherit (depot.users.sterni.nix) + string + ; + + # A char is the atomic element of a nix string + # which is essentially an array of arbitrary bytes + # as long as they are not a NUL byte. + # + # A char is neither a byte nor a unicode codepoint! + char = yants.restrict "char" (s: builtins.stringLength s == 1) yants.string; + + # integer representation of char + charval = yants.restrict "charval" (i: i >= 1 && i < 256) yants.int; + + allChars = builtins.readFile ./all-chars.bin; + + # Originally I searched a list for this, but came to the + # conclusion that this can never be fast enough in Nix. + # We therefore use a solution similar to infinisil's. + ordMap = builtins.listToAttrs + (lib.imap1 (i: v: { name = v; value = i; }) + (string.toChars allChars)); + + # Note on performance: + # chr and ord have been benchmarked using the following cases: + # + # builtins.map ord (lib.stringToCharacters allChars) + # builtins.map chr (builtins.genList (int.add 1) 255 + # + # The findings are as follows: + # 1. Searching through either strings using recursion is + # unbearably slow in Nix, leading to evaluation times + # of up to 3s for the following very small test case. + # This is why we use the trusty attribute set for ord. + # 2. String indexing is much faster than list indexing which + # is why we use the former for chr. + ord = c: ordMap."${c}"; + + chr = i: string.charAt (i - 1) allChars; + + asciiAlpha = c: + let + v = ord c; + in + (v >= 65 && v <= 90) + || (v >= 97 && v <= 122); + + asciiNum = c: + let + v = ord c; + in + v >= 48 && v <= 57; + + asciiAlphaNum = c: asciiAlpha c || asciiNum c; + +in +{ + inherit + allChars + char + charval + ord + chr + asciiAlpha + asciiNum + asciiAlphaNum + ; + + # originally I generated a nix file containing a list of + # characters, but infinisil uses a better way which I adapt + # which is using builtins.readFile instead of import. + __generateAllChars = pkgs.runCommandCC "generate-all-chars" + { + source = '' + #include <stdio.h> + + int main(void) { + for(int i = 1; i <= 0xff; i++) { + putchar(i); + } + } + ''; + passAsFile = [ "source" ]; + } '' + $CC -o "$out" -x c "$sourcePath" + ''; +} diff --git a/users/sterni/nix/char/tests/default.nix b/users/sterni/nix/char/tests/default.nix new file mode 100644 index 000000000000..313df474514c --- /dev/null +++ b/users/sterni/nix/char/tests/default.nix @@ -0,0 +1,31 @@ +{ depot, ... }: + +let + inherit (depot.nix.runTestsuite) + it + assertEq + runTestsuite + ; + + inherit (depot.users.sterni.nix) + char + string + int + fun + ; + + charList = string.toChars char.allChars; + + testAllCharConversion = it "tests conversion of all chars" [ + (assertEq "char.chr converts to char.allChars" + (builtins.genList (fun.rl char.chr (int.add 1)) 255) + charList) + (assertEq "char.ord converts from char.allChars" + (builtins.genList (int.add 1) 255) + (builtins.map char.ord charList)) + ]; + +in +runTestsuite "char" [ + testAllCharConversion +] |