bahaghari/lib: init generateBaseDigitType

subprojects/bahaghari/lib/default.nix

@@ -21,6 +21,6 @@ pkgs.lib.makeExtensible
     tinted-theming = callLibs ./tinted-theming.nix;
 
     inherit (self.trivial) importYAML toYAML toBaseDigitsWithGlyphs
-      generateGlyphSet generateConversionTable pow;
-    inherit (self.hex) toHexString isHexString hexToDec;
+      generateGlyphSet generateConversionTable generateBaseDigitType pow;
+
   })

subprojects/bahaghari/lib/trivial.nix

@@ -1,6 +1,6 @@
 { pkgs, lib }:
 
-{
+rec {
   inherit (pkgs.lib.generators) toYAML;
 
   /* Read YAML files into a Nix expression similar to lib.importJSON and
@@ -99,6 +99,59 @@
     in
     pkgs.lib.listToAttrs glyphsList';
 
+    /* A factory function for generating an attribute set containing a glyph
+       set, a conversion table, and a conversion function to and from decimal.
+       Accepts the same list as `generateGlyphSet` and
+       `generateConversionTable` where it assumes it is sorted and
+       zero-indexed.
+
+       Type: generateBaseDigitType :: [ String ] -> Attrs
+
+       Example:
+        generateBaseDigitType [ "0" "1" ]
+        => {
+          base = 2;
+          glyphSet = { "0" = "0"; "1" = "1"; };
+          conversionTable = { "0" = 0; "1" = 1; };
+          isValidDigit = <function>;
+          fromDec = <function>;
+          toDec = <function>;
+        }
+    */
+    generateBaseDigitType = glyphsList: rec {
+      base = pkgs.lib.length glyphsList;
+      glyphSet = generateGlyphSet glyphsList;
+      conversionTable = generateConversionTable glyphsList;
+
+      # Unfortunately, these functions cannot handle negative numbers unless we
+      # implement something like Two's complement. For now, we're not worrying
+      # about that since most of the use cases here will be mostly for color
+      # generation that typically uses hexadecimal (RGB). Plus I don't want to
+      # open a can of worms about implementing this with stringy types.
+      fromDec = decimal:
+        let
+          iter = product: value:
+            let
+              quotient = value / base;
+              remainder = value - (base * quotient);
+              baseDigit = glyphSet.${builtins.toString remainder} + product;
+            in
+            if quotient <= 0
+            then baseDigit
+            else iter baseDigit quotient;
+        in
+        iter "" decimal;
+
+      toDec = digit:
+        let
+          chars = pkgs.lib.stringToCharacters digit;
+          maxDigits = (pkgs.lib.length chars) - 1;
+          convertDigitToDec =
+            pkgs.lib.lists.imap0 (i: v: conversionTable.${v} * (pow base (maxDigits - i))) chars;
+        in
+        pkgs.lib.foldl (sum: v: sum + v) 0 convertDigitToDec;
+    };
+
   /* Exponentiates the given base with the exponent.
 
      Type: pow :: Int -> Int -> Int

subprojects/bahaghari/tests/lib/trivial/default.nix

@@ -12,6 +12,33 @@ let
     "7" = "H";
   };
 
+  base24GlyphsList = [
+    "0"
+    "1"
+    "2"
+    "3"
+    "4"
+    "5"
+    "6"
+    "7"
+    "8"
+    "9"
+    "A"
+    "B"
+    "C"
+    "D"
+    "E"
+    "F"
+    "G"
+    "H"
+    "I"
+    "J"
+    "K"
+    "L"
+    "M"
+    "N"
+  ];
+
   customBase24Glyphs = {
     "0" = "0";
     "1" = "1";
@@ -33,11 +60,13 @@ let
     "17" = "H";
     "18" = "I";
     "19" = "J";
-    "20" = "M";
-    "21" = "N";
-    "22" = "O";
-    "23" = "P";
+    "20" = "K";
+    "21" = "L";
+    "22" = "M";
+    "23" = "N";
   };
+
+  base24Set = lib.trivial.generateBaseDigitType base24GlyphsList;
 in
 pkgs.lib.runTests {
   testGenerateCustomGlyphSet = {
@@ -46,34 +75,7 @@ pkgs.lib.runTests {
   };
 
   testGenerateBase24GlyphSet = {
-    expr =
-      lib.trivial.generateGlyphSet
-        [
-          "0"
-          "1"
-          "2"
-          "3"
-          "4"
-          "5"
-          "6"
-          "7"
-          "8"
-          "9"
-          "A"
-          "B"
-          "C"
-          "D"
-          "E"
-          "F"
-          "G"
-          "H"
-          "I"
-          "J"
-          "M"
-          "N"
-          "O"
-          "P"
-        ];
+    expr = lib.trivial.generateGlyphSet base24GlyphsList;
     expected = customBase24Glyphs;
   };
 
@@ -91,6 +93,41 @@ pkgs.lib.runTests {
     };
   };
 
+  testGenerateConversionTable2 = {
+    expr = lib.trivial.generateConversionTable
+      [ "0" "1" "2" "3" "4" "5" "6" "7"
+        "8" "9" "A" "B" "C" "D" "E" "F" ];
+    expected = {
+      "0" = 0;
+      "1" = 1;
+      "2" = 2;
+      "3" = 3;
+      "4" = 4;
+      "5" = 5;
+      "6" = 6;
+      "7" = 7;
+      "8" = 8;
+      "9" = 9;
+      "A" = 10;
+      "B" = 11;
+      "C" = 12;
+      "D" = 13;
+      "E" = 14;
+      "F" = 15;
+    };
+  };
+
+  # Testing out the custom factory methods if they are working as intended.
+  testCustomBaseDigitSetToDec = {
+    expr = base24Set.toDec "12H";
+    expected = 641;
+  };
+
+  testCustomBaseDigitSetFromDec = {
+    expr = base24Set.fromDec 641;
+    expected = "12H";
+  };
+
   testBaseDigitWithCustomOctalGlyph = {
     expr = lib.trivial.toBaseDigitsWithGlyphs 8 9 customOctalGlyphs;
     expected = "BB";