authorgravatar for mail@linusgroh.deLinus Groh <mail@linusgroh.de> 2025-02-22 10:13:24+00:00
committergravatar for mail@linusgroh.deLinus Groh <mail@linusgroh.de> 2025-02-23 11:25:35+00:00
logc44f4501e79744a2744f7e0c72ff71cdbcb62440
treefb052790e9bdbb70b9cf49ef0889da083225be29
parent5e20e9b4491dead0c56d9b0351677d5832058673

std.math.big.int: Support strings up to base 36

Co-Authored-By: samy007 <samy2014@free.fr>

2 files changed, 32 insertions(+), 9 deletions(-)

lib/std/math/big/int.zig+13-9
......@@ -57,8 +57,11 @@ pub fn calcSetStringLimbsBufferLen(base: u8, string_len: usize) usize {
5757 return calcMulLimbsBufferLen(limb_count, limb_count, 2);
5858}
5959
60/// Assumes `string_len` doesn't account for minus signs if the number is negative.
6061pub fn calcSetStringLimbCount(base: u8, string_len: usize) usize {
61 return (string_len + (limb_bits / base - 1)) / (limb_bits / base);
62 const base_f: f32 = @floatFromInt(base);
63 const string_len_f: f32 = @floatFromInt(string_len);
64 return 1 + @as(usize, @intFromFloat(@ceil(string_len_f * std.math.log2(base_f) / limb_bits)));
6265}
6366
6467pub fn calcPowLimbsBufferLen(a_bit_count: usize, y: usize) usize {
......@@ -280,7 +283,7 @@ pub const Mutable = struct {
280283 ///
281284 /// Asserts there is enough memory for the value in `self.limbs`. An upper bound on number of limbs can
282285 /// be determined with `calcSetStringLimbCount`.
283 /// Asserts the base is in the range [2, 16].
286 /// Asserts the base is in the range [2, 36].
284287 ///
285288 /// Returns an error if the value has invalid digits for the requested base.
286289 ///
......@@ -296,7 +299,8 @@ pub const Mutable = struct {
296299 limbs_buffer: []Limb,
297300 allocator: ?Allocator,
298301 ) error{InvalidCharacter}!void {
299 assert(base >= 2 and base <= 16);
302 assert(base >= 2);
303 assert(base <= 36);
300304
301305 var i: usize = 0;
302306 var positive = true;
......@@ -2283,11 +2287,11 @@ pub const Const = struct {
22832287
22842288 /// Converts self to a string in the requested base.
22852289 /// Caller owns returned memory.
2286 /// Asserts that `base` is in the range [2, 16].
2290 /// Asserts that `base` is in the range [2, 36].
22872291 /// See also `toString`, a lower level function than this.
22882292 pub fn toStringAlloc(self: Const, allocator: Allocator, base: u8, case: std.fmt.Case) Allocator.Error![]u8 {
22892293 assert(base >= 2);
2290 assert(base <= 16);
2294 assert(base <= 36);
22912295
22922296 if (self.eqlZero()) {
22932297 return allocator.dupe(u8, "0");
......@@ -2302,7 +2306,7 @@ pub const Const = struct {
23022306 }
23032307
23042308 /// Converts self to a string in the requested base.
2305 /// Asserts that `base` is in the range [2, 16].
2309 /// Asserts that `base` is in the range [2, 36].
23062310 /// `string` is a caller-provided slice of at least `sizeInBaseUpperBound` bytes,
23072311 /// where the result is written to.
23082312 /// Returns the length of the string.
......@@ -2312,7 +2316,7 @@ pub const Const = struct {
23122316 /// See also `toStringAlloc`, a higher level function than this.
23132317 pub fn toString(self: Const, string: []u8, base: u8, case: std.fmt.Case, limbs_buffer: []Limb) usize {
23142318 assert(base >= 2);
2315 assert(base <= 16);
2319 assert(base <= 36);
23162320
23172321 if (self.eqlZero()) {
23182322 string[0] = '0';
......@@ -2816,7 +2820,7 @@ pub const Managed = struct {
28162820 ///
28172821 /// self's allocator is used for temporary storage to boost multiplication performance.
28182822 pub fn setString(self: *Managed, base: u8, value: []const u8) !void {
2819 if (base < 2 or base > 16) return error.InvalidBase;
2823 if (base < 2 or base > 36) return error.InvalidBase;
28202824 try self.ensureCapacity(calcSetStringLimbCount(base, value.len));
28212825 const limbs_buffer = try self.allocator.alloc(Limb, calcSetStringLimbsBufferLen(base, value.len));
28222826 defer self.allocator.free(limbs_buffer);
......@@ -2843,7 +2847,7 @@ pub const Managed = struct {
28432847 /// Converts self to a string in the requested base. Memory is allocated from the provided
28442848 /// allocator and not the one present in self.
28452849 pub fn toString(self: Managed, allocator: Allocator, base: u8, case: std.fmt.Case) ![]u8 {
2846 if (base < 2 or base > 16) return error.InvalidBase;
2850 if (base < 2 or base > 36) return error.InvalidBase;
28472851 return self.toConst().toStringAlloc(allocator, base, case);
28482852 }
28492853
lib/std/math/big/int_test.zig+19
......@@ -275,6 +275,14 @@ test "string set case insensitive number" {
275275 try testing.expect((try a.toInt(u32)) == 0xabcdef);
276276}
277277
278test "string set base 36" {
279 var a = try Managed.init(testing.allocator);
280 defer a.deinit();
281
282 try a.setString(36, "fifvthrv1mzt79ez9");
283 try testing.expect((try a.to(u128)) == 123456789123456789123456789);
284}
285
278286test "string set bad char error" {
279287 var a = try Managed.init(testing.allocator);
280288 defer a.deinit();
......@@ -353,6 +361,17 @@ test "string to base 16" {
353361 try testing.expect(mem.eql(u8, as, es));
354362}
355363
364test "string to base 36" {
365 var a = try Managed.initSet(testing.allocator, 123456789123456789123456789);
366 defer a.deinit();
367
368 const as = try a.toString(testing.allocator, 36, .lower);
369 defer testing.allocator.free(as);
370 const es = "fifvthrv1mzt79ez9";
371
372 try testing.expect(mem.eql(u8, as, es));
373}
374
356375test "neg string to" {
357376 var a = try Managed.initSet(testing.allocator, -123907434);
358377 defer a.deinit();