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cleanup parse_float.zig
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xackus
parent
d1202b1f66
commit
6809222d32
@ -30,6 +30,7 @@
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// - Does not handle denormals
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const std = @import("../std.zig");
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const ascii = std.ascii;
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const max_digits = 25;
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@ -190,14 +191,6 @@ const ParseResult = enum {
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MinusInf,
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};
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inline fn isDigit(c: u8) bool {
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return c >= '0' and c <= '9';
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}
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inline fn isSpace(c: u8) bool {
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return (c >= 0x09 and c <= 0x13) or c == 0x20;
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}
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fn parseRepr(s: []const u8, n: *FloatRepr) !ParseResult {
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var digit_index: usize = 0;
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var negative = false;
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@ -207,52 +200,49 @@ fn parseRepr(s: []const u8, n: *FloatRepr) !ParseResult {
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var state = State.MaybeSign;
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var i: usize = 0;
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loop: while (i < s.len) {
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while (i < s.len) {
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const c = s[i];
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switch (state) {
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State.MaybeSign => {
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state = State.LeadingMantissaZeros;
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.MaybeSign => {
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state = .LeadingMantissaZeros;
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if (c == '+') {
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i += 1;
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} else if (c == '-') {
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n.negative = true;
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i += 1;
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} else if (isDigit(c) or c == '.') {
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} else if (ascii.isDigit(c) or c == '.') {
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// continue
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} else {
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return error.InvalidCharacter;
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}
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},
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State.LeadingMantissaZeros => {
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.LeadingMantissaZeros => {
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if (c == '0') {
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i += 1;
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} else if (c == '.') {
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i += 1;
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state = State.LeadingFractionalZeros;
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state = .LeadingFractionalZeros;
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} else {
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state = State.MantissaIntegral;
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state = .MantissaIntegral;
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}
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},
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State.LeadingFractionalZeros => {
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.LeadingFractionalZeros => {
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if (c == '0') {
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i += 1;
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if (n.exponent > std.math.minInt(i32)) {
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n.exponent -= 1;
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}
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} else {
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state = State.MantissaFractional;
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state = .MantissaFractional;
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}
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},
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State.MantissaIntegral => {
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if (isDigit(c)) {
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.MantissaIntegral => {
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if (ascii.isDigit(c)) {
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if (digit_index < max_digits) {
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n.mantissa *%= 10;
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n.mantissa += s[i] - '0';
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n.mantissa += c - '0';
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digit_index += 1;
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} else if (n.exponent < std.math.maxInt(i32)) {
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n.exponent += 1;
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@ -261,14 +251,13 @@ fn parseRepr(s: []const u8, n: *FloatRepr) !ParseResult {
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i += 1;
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} else if (c == '.') {
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i += 1;
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state = State.MantissaFractional;
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state = .MantissaFractional;
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} else {
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state = State.MantissaFractional;
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state = .MantissaFractional;
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}
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},
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State.MantissaFractional => {
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if (isDigit(c)) {
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.MantissaFractional => {
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if (ascii.isDigit(c)) {
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if (digit_index < max_digits) {
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n.mantissa *%= 10;
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n.mantissa += c - '0';
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@ -279,13 +268,12 @@ fn parseRepr(s: []const u8, n: *FloatRepr) !ParseResult {
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i += 1;
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} else if (c == 'e' or c == 'E') {
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i += 1;
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state = State.ExponentSign;
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state = .ExponentSign;
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} else {
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state = State.ExponentSign;
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state = .ExponentSign;
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}
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},
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State.ExponentSign => {
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.ExponentSign => {
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if (c == '+') {
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i += 1;
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} else if (c == '-') {
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@ -293,19 +281,17 @@ fn parseRepr(s: []const u8, n: *FloatRepr) !ParseResult {
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i += 1;
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}
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state = State.LeadingExponentZeros;
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state = .LeadingExponentZeros;
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},
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State.LeadingExponentZeros => {
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.LeadingExponentZeros => {
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if (c == '0') {
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i += 1;
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} else {
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state = State.Exponent;
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state = .Exponent;
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}
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},
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State.Exponent => {
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if (isDigit(c)) {
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.Exponent => {
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if (ascii.isDigit(c)) {
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if (exponent < std.math.maxInt(i32) / 10) {
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exponent *= 10;
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exponent += @intCast(i32, c - '0');
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@ -323,29 +309,21 @@ fn parseRepr(s: []const u8, n: *FloatRepr) !ParseResult {
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n.exponent += exponent;
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if (n.mantissa == 0) {
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return if (n.negative) ParseResult.MinusZero else ParseResult.PlusZero;
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return if (n.negative) .MinusZero else .PlusZero;
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} else if (n.exponent > 309) {
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return if (n.negative) ParseResult.MinusInf else ParseResult.PlusInf;
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return if (n.negative) .MinusInf else .PlusInf;
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} else if (n.exponent < -328) {
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return if (n.negative) ParseResult.MinusZero else ParseResult.PlusZero;
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return if (n.negative) .MinusZero else .PlusZero;
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}
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return ParseResult.Ok;
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}
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inline fn isLower(c: u8) bool {
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return c -% 'a' < 26;
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}
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inline fn toUpper(c: u8) u8 {
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return if (isLower(c)) (c & 0x5f) else c;
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return .Ok;
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}
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fn caseInEql(a: []const u8, b: []const u8) bool {
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if (a.len != b.len) return false;
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for (a) |_, i| {
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if (toUpper(a[i]) != toUpper(b[i])) {
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if (ascii.toUpper(a[i]) != ascii.toUpper(b[i])) {
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return false;
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}
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}
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@ -373,11 +351,11 @@ pub fn parseFloat(comptime T: type, s: []const u8) !T {
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};
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return switch (try parseRepr(s, &r)) {
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ParseResult.Ok => convertRepr(T, r),
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ParseResult.PlusZero => 0.0,
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ParseResult.MinusZero => -@as(T, 0.0),
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ParseResult.PlusInf => std.math.inf(T),
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ParseResult.MinusInf => -std.math.inf(T),
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.Ok => convertRepr(T, r),
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.PlusZero => 0.0,
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.MinusZero => -@as(T, 0.0),
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.PlusInf => std.math.inf(T),
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.MinusInf => -std.math.inf(T),
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};
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}
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@ -396,26 +374,26 @@ test "fmt.parseFloat" {
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testing.expectError(error.InvalidCharacter, parseFloat(T, "1abc"));
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expectEqual(try parseFloat(T, "0"), 0.0);
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expectEqual((try parseFloat(T, "0")), 0.0);
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expectEqual((try parseFloat(T, "+0")), 0.0);
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expectEqual((try parseFloat(T, "-0")), 0.0);
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expectEqual(try parseFloat(T, "0"), 0.0);
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expectEqual(try parseFloat(T, "+0"), 0.0);
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expectEqual(try parseFloat(T, "-0"), 0.0);
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expectEqual((try parseFloat(T, "0e0")), 0);
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expectEqual((try parseFloat(T, "2e3")), 2000.0);
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expectEqual((try parseFloat(T, "1e0")), 1.0);
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expectEqual((try parseFloat(T, "-2e3")), -2000.0);
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expectEqual((try parseFloat(T, "-1e0")), -1.0);
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expectEqual((try parseFloat(T, "1.234e3")), 1234);
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expectEqual(try parseFloat(T, "0e0"), 0);
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expectEqual(try parseFloat(T, "2e3"), 2000.0);
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expectEqual(try parseFloat(T, "1e0"), 1.0);
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expectEqual(try parseFloat(T, "-2e3"), -2000.0);
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expectEqual(try parseFloat(T, "-1e0"), -1.0);
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expectEqual(try parseFloat(T, "1.234e3"), 1234);
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expect(approxEq(T, try parseFloat(T, "3.141"), 3.141, epsilon));
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expect(approxEq(T, try parseFloat(T, "-3.141"), -3.141, epsilon));
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expectEqual((try parseFloat(T, "1e-700")), 0);
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expectEqual((try parseFloat(T, "1e+700")), std.math.inf(T));
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expectEqual(try parseFloat(T, "1e-700"), 0);
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expectEqual(try parseFloat(T, "1e+700"), std.math.inf(T));
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expectEqual(@bitCast(Z, try parseFloat(T, "nAn")), @bitCast(Z, std.math.nan(T)));
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expectEqual((try parseFloat(T, "inF")), std.math.inf(T));
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expectEqual((try parseFloat(T, "-INF")), -std.math.inf(T));
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expectEqual(try parseFloat(T, "inF"), std.math.inf(T));
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expectEqual(try parseFloat(T, "-INF"), -std.math.inf(T));
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expectEqual(try parseFloat(T, "0.4e0066999999999999999999999999999999999999999999999999999"), std.math.inf(T));
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