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1b728e1834
There were two primary issues at play here:
1. The hex float prefix was not handled correctly when the stream was
reset for the fallback parsing path, which occured when the mantissa was
longer max mantissa digits.
2. The implied exponent was not adjusted for hex-floats in this branch.
Additionally, some of the float parsing routines have been condensed, making
use of comptime.
closes #20275
241 lines
12 KiB
Zig
241 lines
12 KiB
Zig
const std = @import("std");
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const math = std.math;
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const testing = std.testing;
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const expect = testing.expect;
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const expectEqual = testing.expectEqual;
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const expectError = testing.expectError;
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const approxEqAbs = std.math.approxEqAbs;
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const epsilon = 1e-7;
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const parse = @import("parse_float/parse.zig");
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const convertHex = @import("parse_float/convert_hex.zig").convertHex;
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const convertFast = @import("parse_float/convert_fast.zig").convertFast;
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const convertEiselLemire = @import("parse_float/convert_eisel_lemire.zig").convertEiselLemire;
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const convertSlow = @import("parse_float/convert_slow.zig").convertSlow;
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pub const ParseFloatError = error{
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InvalidCharacter,
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};
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pub fn parseFloat(comptime T: type, s: []const u8) ParseFloatError!T {
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if (@typeInfo(T) != .Float) {
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@compileError("Cannot parse a float into a non-floating point type.");
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}
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if (T == f80) {
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@compileError("TODO support parsing float to f80");
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}
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if (s.len == 0) {
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return error.InvalidCharacter;
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}
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var i: usize = 0;
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const negative = s[i] == '-';
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if (s[i] == '-' or s[i] == '+') {
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i += 1;
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}
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if (s.len == i) {
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return error.InvalidCharacter;
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}
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const n = parse.parseNumber(T, s[i..], negative) orelse {
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return parse.parseInfOrNan(T, s[i..], negative) orelse error.InvalidCharacter;
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};
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if (n.hex) {
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return convertHex(T, n);
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}
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if (convertFast(T, n)) |f| {
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return f;
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}
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if (T == f16 or T == f32 or T == f64) {
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// If significant digits were truncated, then we can have rounding error
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// only if `mantissa + 1` produces a different result. We also avoid
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// redundantly using the Eisel-Lemire algorithm if it was unable to
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// correctly round on the first pass.
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if (convertEiselLemire(T, n.exponent, n.mantissa)) |bf| {
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if (!n.many_digits) {
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return bf.toFloat(T, n.negative);
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}
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if (convertEiselLemire(T, n.exponent, n.mantissa + 1)) |bf2| {
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if (bf.eql(bf2)) {
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return bf.toFloat(T, n.negative);
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}
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}
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}
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}
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// Unable to correctly round the float using the Eisel-Lemire algorithm.
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// Fallback to a slower, but always correct algorithm.
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return convertSlow(T, s[i..]).toFloat(T, negative);
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}
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// See https://github.com/tiehuis/parse-number-fxx-test-data for a wider-selection of test-data.
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test parseFloat {
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inline for ([_]type{ f16, f32, f64, f128 }) |T| {
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try testing.expectError(error.InvalidCharacter, parseFloat(T, ""));
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try testing.expectError(error.InvalidCharacter, parseFloat(T, " 1"));
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try testing.expectError(error.InvalidCharacter, parseFloat(T, "1abc"));
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try testing.expectError(error.InvalidCharacter, parseFloat(T, "+"));
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try testing.expectError(error.InvalidCharacter, parseFloat(T, "-"));
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try expectEqual(try parseFloat(T, "0"), 0.0);
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try expectEqual(try parseFloat(T, "0"), 0.0);
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try expectEqual(try parseFloat(T, "+0"), 0.0);
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try expectEqual(try parseFloat(T, "-0"), 0.0);
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try expectEqual(try parseFloat(T, "0e0"), 0);
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try expectEqual(try parseFloat(T, "2e3"), 2000.0);
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try expectEqual(try parseFloat(T, "1e0"), 1.0);
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try expectEqual(try parseFloat(T, "-2e3"), -2000.0);
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try expectEqual(try parseFloat(T, "-1e0"), -1.0);
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try expectEqual(try parseFloat(T, "1.234e3"), 1234);
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try expect(approxEqAbs(T, try parseFloat(T, "3.141"), 3.141, epsilon));
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try expect(approxEqAbs(T, try parseFloat(T, "-3.141"), -3.141, epsilon));
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try expectEqual(try parseFloat(T, "1e-5000"), 0);
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try expectEqual(try parseFloat(T, "1e+5000"), std.math.inf(T));
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try expectEqual(try parseFloat(T, "0.4e0066999999999999999999999999999999999999999999999999999"), std.math.inf(T));
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try expect(approxEqAbs(T, try parseFloat(T, "0_1_2_3_4_5_6.7_8_9_0_0_0e0_0_1_0"), @as(T, 123456.789000e10), epsilon));
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// underscore rule is simple and reduces to "can only occur between two digits" and multiple are not supported.
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try expectError(error.InvalidCharacter, parseFloat(T, "0123456.789000e_0010")); // cannot occur immediately after exponent
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try expectError(error.InvalidCharacter, parseFloat(T, "_0123456.789000e0010")); // cannot occur before any digits
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try expectError(error.InvalidCharacter, parseFloat(T, "0__123456.789000e_0010")); // cannot occur twice in a row
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try expectError(error.InvalidCharacter, parseFloat(T, "0123456_.789000e0010")); // cannot occur before decimal point
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try expectError(error.InvalidCharacter, parseFloat(T, "0123456.789000e0010_")); // cannot occur at end of number
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try expect(approxEqAbs(T, try parseFloat(T, "1e-2"), 0.01, epsilon));
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try expect(approxEqAbs(T, try parseFloat(T, "1234e-2"), 12.34, epsilon));
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try expect(approxEqAbs(T, try parseFloat(T, "1."), 1, epsilon));
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try expect(approxEqAbs(T, try parseFloat(T, "0."), 0, epsilon));
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try expect(approxEqAbs(T, try parseFloat(T, ".1"), 0.1, epsilon));
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try expect(approxEqAbs(T, try parseFloat(T, ".0"), 0, epsilon));
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try expect(approxEqAbs(T, try parseFloat(T, ".1e-1"), 0.01, epsilon));
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try expectError(error.InvalidCharacter, parseFloat(T, ".")); // At least one digit is required.
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try expectError(error.InvalidCharacter, parseFloat(T, ".e1")); // At least one digit is required.
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try expectError(error.InvalidCharacter, parseFloat(T, "0.e")); // At least one digit is required.
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try expect(approxEqAbs(T, try parseFloat(T, "123142.1"), 123142.1, epsilon));
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try expect(approxEqAbs(T, try parseFloat(T, "-123142.1124"), @as(T, -123142.1124), epsilon));
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try expect(approxEqAbs(T, try parseFloat(T, "0.7062146892655368"), @as(T, 0.7062146892655368), epsilon));
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try expect(approxEqAbs(T, try parseFloat(T, "2.71828182845904523536"), @as(T, 2.718281828459045), epsilon));
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}
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}
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test "nan and inf" {
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inline for ([_]type{ f16, f32, f64, f128 }) |T| {
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const Z = std.meta.Int(.unsigned, @typeInfo(T).Float.bits);
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try expectEqual(@as(Z, @bitCast(try parseFloat(T, "nAn"))), @as(Z, @bitCast(std.math.nan(T))));
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try expectEqual(try parseFloat(T, "inF"), std.math.inf(T));
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try expectEqual(try parseFloat(T, "-INF"), -std.math.inf(T));
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}
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}
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test "largest normals" {
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try expectEqual(@as(u16, @bitCast(try parseFloat(f16, "65504"))), 0x7bff);
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try expectEqual(@as(u32, @bitCast(try parseFloat(f32, "3.4028234664E38"))), 0x7f7f_ffff);
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try expectEqual(@as(u64, @bitCast(try parseFloat(f64, "1.7976931348623157E308"))), 0x7fef_ffff_ffff_ffff);
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try expectEqual(@as(u128, @bitCast(try parseFloat(f128, "1.1897314953572317650857593266280070162E4932"))), 0x7ffe_ffff_ffff_ffff_ffff_ffff_ffff_ffff);
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}
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test "#11169" {
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try expectEqual(try parseFloat(f128, "9007199254740993.0"), 9007199254740993.0);
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}
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test "many_digits hex" {
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const a: f32 = try std.fmt.parseFloat(f32, "0xffffffffffffffff.0p0");
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const b: f32 = @floatCast(try std.fmt.parseFloat(f128, "0xffffffffffffffff.0p0"));
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try std.testing.expectEqual(a, b);
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}
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test "hex.special" {
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try testing.expect(math.isNan(try parseFloat(f32, "nAn")));
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try testing.expect(math.isPositiveInf(try parseFloat(f32, "iNf")));
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try testing.expect(math.isPositiveInf(try parseFloat(f32, "+Inf")));
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try testing.expect(math.isNegativeInf(try parseFloat(f32, "-iNf")));
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}
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test "hex.zero" {
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try testing.expectEqual(@as(f32, 0.0), try parseFloat(f32, "0x0"));
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try testing.expectEqual(@as(f32, 0.0), try parseFloat(f32, "-0x0"));
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try testing.expectEqual(@as(f32, 0.0), try parseFloat(f32, "0x0p42"));
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try testing.expectEqual(@as(f32, 0.0), try parseFloat(f32, "-0x0.00000p42"));
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try testing.expectEqual(@as(f32, 0.0), try parseFloat(f32, "0x0.00000p666"));
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}
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test "hex.f16" {
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try testing.expectEqual(try parseFloat(f16, "0x1p0"), 1.0);
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try testing.expectEqual(try parseFloat(f16, "-0x1p-1"), -0.5);
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try testing.expectEqual(try parseFloat(f16, "0x10p+10"), 16384.0);
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try testing.expectEqual(try parseFloat(f16, "0x10p-10"), 0.015625);
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// Max normalized value.
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try testing.expectEqual(try parseFloat(f16, "0x1.ffcp+15"), math.floatMax(f16));
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try testing.expectEqual(try parseFloat(f16, "-0x1.ffcp+15"), -math.floatMax(f16));
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// Min normalized value.
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try testing.expectEqual(try parseFloat(f16, "0x1p-14"), math.floatMin(f16));
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try testing.expectEqual(try parseFloat(f16, "-0x1p-14"), -math.floatMin(f16));
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// Min denormal value.
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try testing.expectEqual(try parseFloat(f16, "0x1p-24"), math.floatTrueMin(f16));
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try testing.expectEqual(try parseFloat(f16, "-0x1p-24"), -math.floatTrueMin(f16));
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}
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test "hex.f32" {
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try testing.expectError(error.InvalidCharacter, parseFloat(f32, "0x"));
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try testing.expectEqual(try parseFloat(f32, "0x1p0"), 1.0);
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try testing.expectEqual(try parseFloat(f32, "-0x1p-1"), -0.5);
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try testing.expectEqual(try parseFloat(f32, "0x10p+10"), 16384.0);
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try testing.expectEqual(try parseFloat(f32, "0x10p-10"), 0.015625);
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try testing.expectEqual(try parseFloat(f32, "0x0.ffffffp128"), 0x0.ffffffp128);
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try testing.expectEqual(try parseFloat(f32, "0x0.1234570p-125"), 0x0.1234570p-125);
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// Max normalized value.
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try testing.expectEqual(try parseFloat(f32, "0x1.fffffeP+127"), math.floatMax(f32));
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try testing.expectEqual(try parseFloat(f32, "-0x1.fffffeP+127"), -math.floatMax(f32));
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// Min normalized value.
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try testing.expectEqual(try parseFloat(f32, "0x1p-126"), math.floatMin(f32));
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try testing.expectEqual(try parseFloat(f32, "-0x1p-126"), -math.floatMin(f32));
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// Min denormal value.
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try testing.expectEqual(try parseFloat(f32, "0x1P-149"), math.floatTrueMin(f32));
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try testing.expectEqual(try parseFloat(f32, "-0x1P-149"), -math.floatTrueMin(f32));
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}
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test "hex.f64" {
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try testing.expectEqual(try parseFloat(f64, "0x1p0"), 1.0);
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try testing.expectEqual(try parseFloat(f64, "-0x1p-1"), -0.5);
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try testing.expectEqual(try parseFloat(f64, "0x10p+10"), 16384.0);
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try testing.expectEqual(try parseFloat(f64, "0x10p-10"), 0.015625);
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// Max normalized value.
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try testing.expectEqual(try parseFloat(f64, "0x1.fffffffffffffp+1023"), math.floatMax(f64));
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try testing.expectEqual(try parseFloat(f64, "-0x1.fffffffffffffp1023"), -math.floatMax(f64));
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// Min normalized value.
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try testing.expectEqual(try parseFloat(f64, "0x1p-1022"), math.floatMin(f64));
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try testing.expectEqual(try parseFloat(f64, "-0x1p-1022"), -math.floatMin(f64));
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// Min denormalized value.
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try testing.expectEqual(try parseFloat(f64, "0x1p-1074"), math.floatTrueMin(f64));
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try testing.expectEqual(try parseFloat(f64, "-0x1p-1074"), -math.floatTrueMin(f64));
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}
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test "hex.f128" {
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try testing.expectEqual(try parseFloat(f128, "0x1p0"), 1.0);
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try testing.expectEqual(try parseFloat(f128, "-0x1p-1"), -0.5);
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try testing.expectEqual(try parseFloat(f128, "0x10p+10"), 16384.0);
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try testing.expectEqual(try parseFloat(f128, "0x10p-10"), 0.015625);
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// Max normalized value.
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try testing.expectEqual(try parseFloat(f128, "0xf.fffffffffffffffffffffffffff8p+16380"), math.floatMax(f128));
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try testing.expectEqual(try parseFloat(f128, "-0xf.fffffffffffffffffffffffffff8p+16380"), -math.floatMax(f128));
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// Min normalized value.
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try testing.expectEqual(try parseFloat(f128, "0x1p-16382"), math.floatMin(f128));
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try testing.expectEqual(try parseFloat(f128, "-0x1p-16382"), -math.floatMin(f128));
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// // Min denormalized value.
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try testing.expectEqual(try parseFloat(f128, "0x1p-16494"), math.floatTrueMin(f128));
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try testing.expectEqual(try parseFloat(f128, "-0x1p-16494"), -math.floatTrueMin(f128));
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// ensure round-to-even
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try testing.expectEqual(try parseFloat(f128, "0x1.edcb34a235253948765432134674fp-1"), 0x1.edcb34a235253948765432134674fp-1);
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}
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