135 lines
3.4 KiB
Zig
135 lines
3.4 KiB
Zig
const std = @import("std");
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pub const ArgOpts = struct {
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L: isize = 0,
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M: isize = 0,
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T: isize = 0,
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I: isize = 0,
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Tp: isize = 0,
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N: isize = 0,
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J: isize = 0,
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};
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pub const Dimension = enum {
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/// Length
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L,
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/// Mass
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M,
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/// Time
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T,
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/// Electric Current
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I,
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/// Temperature
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Tp,
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/// Amount of Substance
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N,
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/// Luminous Intensity
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J,
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pub fn unit(self: @This()) []const u8 {
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return switch (self) {
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.L => "m",
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.M => "g",
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.T => "s",
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.I => "A",
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.Tp => "K",
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.N => "mol",
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.J => "cd",
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};
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}
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};
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// --------- Dimensions struct ---------
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/// Holds the exponent of each SI base dimension for a given quantity (e.g. velocity = L¹T⁻¹).
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/// All values are `comptime_int` — no runtime storage.
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const Self = @This();
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data: std.EnumArray(Dimension, comptime_int),
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/// Create a `Dimensions` from a struct literal, e.g. `.{ .L = 1, .T = -1 }`.
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/// Unspecified dimensions default to 0.
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pub fn init(init_val: ArgOpts) Self {
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var s = Self{ .data = std.EnumArray(Dimension, comptime_int).initFill(0) };
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for (std.meta.fields(@TypeOf(init_val))) |f|
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s.data.set(@field(Dimension, f.name), @field(init_val, f.name));
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return s;
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}
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pub fn initFill(val: comptime_int) Self {
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return .{ .data = std.EnumArray(Dimension, comptime_int).initFill(val) };
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}
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pub fn get(self: Self, key: Dimension) comptime_int {
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return self.data.get(key);
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}
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pub fn set(self: *Self, key: Dimension, val: i8) void {
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self.data.set(key, val);
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}
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pub fn argsOpt(self: Self) ArgOpts {
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var args: ArgOpts = undefined;
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for (std.enums.values(Dimension)) |d|
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@field(args, @tagName(d)) = self.get(d);
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return args;
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}
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/// Add exponents component-wise. Used internally by `mul`.
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pub fn add(a: Self, b: Self) Self {
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var result = Self.initFill(0);
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for (std.enums.values(Dimension)) |d|
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result.set(d, a.get(d) + b.get(d));
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return result;
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}
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/// Subtract exponents component-wise. Used internally by `div`.
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pub fn sub(a: Self, b: Self) Self {
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var result = Self.initFill(0);
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for (std.enums.values(Dimension)) |d|
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result.set(d, a.get(d) - b.get(d));
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return result;
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}
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/// Multiply exponents by a scalar integer. Used internally by `pow` in Scalar.
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pub fn scale(a: Self, exp: comptime_int) Self {
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var result = Self.initFill(0);
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for (std.enums.values(Dimension)) |d|
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result.set(d, a.get(d) * exp);
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return result;
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}
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pub fn div(a: Self, exp: comptime_int) Self {
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var result = Self.initFill(0);
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for (std.enums.values(Dimension)) |d|
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result.set(d, a.get(d) / exp);
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return result;
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}
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/// Returns true if every dimension exponent is equal. Used to enforce type compatibility in `add`, `sub`, `to`.
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pub fn eql(a: Self, b: Self) bool {
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for (std.enums.values(Dimension)) |d|
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if (a.get(d) != b.get(d)) return false;
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return true;
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}
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pub fn isSquare(a: Self) bool {
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for (std.enums.values(Dimension)) |d|
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if (a.get(d) % 2 != 0) return false;
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return true;
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}
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pub fn str(a: Self) []const u8 {
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var out: []const u8 = "";
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const dims = std.enums.values(Dimension);
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for (dims) |d| {
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const val = a.get(d);
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if (val != 0) {
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out = out ++ @tagName(d) ++ std.fmt.comptimePrint("{d}", .{val});
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}
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}
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return if (out.len == 0) "Dimensionless" else out;
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}
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