| 1 | const std = @import("std"); |
| 2 | const string = []const u8; |
| 3 | const extras = @import("./lib.zig"); |
| 4 | |
| 5 | /// Simple number parser with no extra detection or handling. Alphabet is [0-9][a-z] with respect to base. |
| 6 | /// Partially motivated by https://codeberg.org/ziglang/zig/issues/30881 + https://github.com/ziglang/zig/issues/24687 |
| 7 | pub fn parseDigits(comptime T: type, buf: []const u8, base: u8) !T { |
| 8 | std.debug.assert(base > 0); |
| 9 | std.debug.assert(base <= 36); |
| 10 | if (buf.len == 0) return error.InvalidCharacter; |
| 11 | |
| 12 | var result: T = 0; |
| 13 | for (0..buf.len) |i| { |
| 14 | const c = buf[buf.len - 1 - i]; |
| 15 | const d = switch (c) { |
| 16 | '0'...'9' => |a| a - '0', |
| 17 | 'a'...'z' => |a| a - 'a' + 10, |
| 18 | 'A'...'Z' => |a| a - 'A' + 10, |
| 19 | else => return error.InvalidCharacter, |
| 20 | }; |
| 21 | if (d == 0) continue; |
| 22 | if (d >= base) return error.Overflow; |
| 23 | const _x = if (i == 0) 1 else std.math.powi(T, @intCast(base), @intCast(i)) catch return error.Overflow; |
| 24 | const _y = try std.math.mul(T, @intCast(d), _x); |
| 25 | const _z = try std.math.add(T, result, _y); |
| 26 | result = _z; |
| 27 | } |
| 28 | return result; |
| 29 | } |
| 30 | |
| 31 | test { |
| 32 | try std.testing.expect(try parseDigits(u8, "10", 10) == 10); |
| 33 | } |
| 34 | test { |
| 35 | try std.testing.expect(try parseDigits(u8, "20", 16) == 32); |
| 36 | } |
| 37 | test { |
| 38 | try std.testing.expect(try parseDigits(u8, "EF", 16) == 239); |
| 39 | } |