First implementation

src/Dimensions.zig

@@ -0,0 +1,90 @@
+const std = @import("std");
+
+pub const Dimension = enum {
+    /// Length
+    L,
+    /// Mass
+    M,
+    /// Time
+    T,
+    /// Electric Current
+    I,
+    /// Temperature
+    Tp,
+    /// Amount of Substance
+    N,
+    /// Luminous Intensity
+    J,
+
+    pub fn unit(self: @This()) []const u8 {
+        return switch (self) {
+            .L => "m",
+            .M => "g",
+            .T => "s",
+            .I => "A",
+            .Tp => "K",
+            .N => "mol",
+            .J => "cd",
+        };
+    }
+};
+
+// --------- Dimensions struct ---------
+
+const Self = @This();
+
+data: std.EnumArray(Dimension, i8),
+
+pub fn init(comptime init_val: anytype) Self {
+    var s = Self{ .data = std.EnumArray(Dimension, i8).initFill(0) };
+    inline for (std.meta.fields(@TypeOf(init_val))) |f|
+        s.data.set(@field(Dimension, f.name), @field(init_val, f.name));
+    return s;
+}
+
+pub fn initFill(val: i8) Self {
+    return .{ .data = std.EnumArray(Dimension, i8).initFill(val) };
+}
+
+pub fn get(self: Self, key: Dimension) i8 {
+    return self.data.get(key);
+}
+
+pub fn set(self: *Self, key: Dimension, val: i8) void {
+    self.data.set(key, val);
+}
+
+pub fn add(comptime a: Self, comptime b: Self) Self {
+    var result = Self.initFill(0);
+    for (std.enums.values(Dimension)) |d|
+        result.set(d, a.get(d) + b.get(d));
+    return result;
+}
+
+pub fn sub(comptime a: Self, comptime b: Self) Self {
+    @setEvalBranchQuota(10_000);
+    var result = Self.initFill(0);
+    for (std.enums.values(Dimension)) |d|
+        result.set(d, a.get(d) - b.get(d));
+    return result;
+}
+
+pub fn eql(comptime a: Self, comptime b: Self) bool {
+    for (std.enums.values(Dimension)) |d|
+        if (a.get(d) != b.get(d)) return false;
+    return true;
+}
+
+pub fn str(comptime a: Self) []const u8 {
+    var out: []const u8 = "";
+    const dims = std.enums.values(Dimension);
+
+    inline for (dims) |d| {
+        const val = a.get(d);
+        if (val != 0) {
+            out = out ++ @tagName(d) ++ std.fmt.comptimePrint("{d}", .{val});
+        }
+    }
+
+    return if (out.len == 0) "Dimensionless" else out;
+}