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merged 10 commits into from
Sep 11, 2025
Merged

Support Infinity, NaN, and -0 #57

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2a1d485
Support Infinity, NaN, and -0 as strings
jessealama Sep 5, 2025
ad9f51c
Update AO name
jessealama Sep 5, 2025
c0d104a
Update spec.emu
jessealama Sep 8, 2025
bc6d9c0
Update spec.emu
jessealama Sep 8, 2025
2eed0fc
Use 402's `StringIntlMV` SDO
jessealama Sep 9, 2025
f38d4fe
Use existing terminology
jessealama Sep 10, 2025
5dbbd12
Remove unnecessary assertions
jessealama Sep 10, 2025
b962b7d
Support -0 with precision
jessealama Sep 10, 2025
9481e8a
Borrow & use StringIntlMV from proposal-intl-keep-trailing-zeros
jessealama Sep 11, 2025
dc7be46
Calculate significant digits directly from the rounded value.
jessealama Sep 11, 2025
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2 changes: 1 addition & 1 deletion intl.emu
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Expand Up @@ -152,7 +152,7 @@
</dd>
</dl>
<emu-alg>
1. <ins>If _value_ has the [[Value]] and [[FractionDigits]] internal slots, let _primValue_ be RenderMVWithFractionDigits(_value_.[[Value]], _value_.[[FractionDigits]]) else</ins><del>Let</del> <ins>let</ins _primValue_ be ? ToPrimitive(_value_, ~number~).
1. <ins>If _value_ has the [[Value]] and [[FractionDigits]] internal slots, let _primValue_ be RenderAmountValueWithFractionDigits(_value_.[[Value]], _value_.[[FractionDigits]]) else</ins><del>Let</del> <ins>let</ins _primValue_ be ? ToPrimitive(_value_, ~number~).
1. If _primValue_ is a BigInt, return ℝ(_primValue_).
1. If _primValue_ is a String, then
1. Let _str_ be _primValue_.
Expand Down
216 changes: 123 additions & 93 deletions spec.emu
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Expand Up @@ -71,27 +71,83 @@ location: https://github.com/tc39/proposal-measure/
</emu-clause>
</emu-clause>

<!-- This is copied directly from proposal-intl-keep-trailing-zeros -->
<!-- See http://tc39.es/proposal-intl-keep-trailing-zeros/ -->
<emu-clause id="sec-runtime-semantics-stringintlmv" type="sdo" number="15">
<h1>Runtime Semantics: StringIntlMV</h1>
<dl class="header">
</dl>
<emu-note>
<del class="block">
<p>The
conversion of a |StringNumericLiteral| to a Number value is similar overall to the determination of the NumericValue of a |NumericLiteral| (see <emu-xref href="#sec-literals-numeric-literals"></emu-xref>), but some of the details are different.</p>
</del>
<ins class="block">
<p>
The conversion of a |StringNumericLiteral| to a mathematical value and a precision is similar overall to the determination of the NumericValue of a |NumericLiteral| (see <emu-xref href="#sec-literals-numeric-literals"></emu-xref>), but some of the details are different.
The result of StringIntlMV is a List value with two elements, a mathematical value and the count of decimal digits in the source text.
</p>
</ins>
</emu-note>
<emu-grammar>StringNumericLiteral ::: StrWhiteSpace?</emu-grammar>
<emu-alg>
1. Return <del>0</del><ins>« 0, 0 »</ins>.
</emu-alg>
<emu-grammar>StringNumericLiteral ::: StrWhiteSpace? StrNumericLiteral StrWhiteSpace?</emu-grammar>
<emu-alg>
1. Return StringIntlMV of |StrNumericLiteral|.
</emu-alg>
<emu-grammar>StrNumericLiteral ::: NonDecimalIntegerLiteral</emu-grammar>
<emu-alg>
1. <del>Return MV of |NonDecimalIntegerLiteral|.</del>
1. <ins>Let _i_ be MV of |NonDecimalIntegerLiteral|.</ins>
1. <ins>Return « _i_, 0 ».</ins>
</emu-alg>
<emu-grammar>StrDecimalLiteral ::: `-` StrUnsignedDecimalLiteral</emu-grammar>
<emu-alg>
1. Let <del>_a_</del><ins>_x_</ins> be StringIntlMV of |StrUnsignedDecimalLiteral|.
1. <ins>Let _a_ be the first element of _x_.</ins>
1. <ins>Let _n_ be the second element of _x_.</ins>
1. If _a_ is 0, return <del>~negative-zero~</del><ins>« ~negative-zero~, _n_ »</ins>.
1. If _a_ is ~positive-infinity~, return <del>~negative-infinity~</del><ins>« ~negative-infinity~, 0 »</ins>.
1. Return <del>-_a_</del><ins>« -_a_, _n_ »</ins>.
</emu-alg>
<emu-grammar>StrUnsignedDecimalLiteral ::: `Infinity`</emu-grammar>
<emu-alg>
1. Return <del>~positive-infinity~</del><ins>« ~positive-infinity~, 0 »</ins>.
</emu-alg>
<emu-grammar>StrUnsignedDecimalLiteral ::: DecimalDigits `.` DecimalDigits? ExponentPart?</emu-grammar>
<emu-alg>
1. Let _a_ be MV of the first |DecimalDigits|.
1. <ins>Let _m_ be the number of code points in the first |DecimalDigits|.</ins>
1. If the second |DecimalDigits| is present, then
1. Let _b_ be MV of the second |DecimalDigits|.
1. Let _n_ be the number of code points in the second |DecimalDigits|.
1. Else,
1. Let _b_ be 0.
1. Let _n_ be 0.
1. If |ExponentPart| is present, let _e_ be MV of |ExponentPart|. Otherwise, let _e_ be 0.
1. Return <ins>«</ins> (_a_ + (_b_ × 10<sup>-_n_</sup>)) × 10<sup>_e_</sup><ins>, _m_ + _n_ »</ins>.
</emu-alg>
<emu-grammar>StrUnsignedDecimalLiteral ::: `.` DecimalDigits ExponentPart?</emu-grammar>
<emu-alg>
1. Let _b_ be MV of |DecimalDigits|.
1. If |ExponentPart| is present, let _e_ be MV of |ExponentPart|. Otherwise, let _e_ be 0.
1. Let _n_ be the number of code points in |DecimalDigits|.
1. Return <ins>«</ins> _b_ × 10<sup>_e_ - _n_</sup><ins>, _n_ ».</ins>
</emu-alg>
<emu-grammar>StrUnsignedDecimalLiteral ::: DecimalDigits ExponentPart?</emu-grammar>
<emu-alg>
1. Let _a_ be MV of |DecimalDigits|.
1. <ins>Let _m_ be the number of code points in |DecimalDigits|.</ins>
1. If |ExponentPart| is present, let _e_ be MV of |ExponentPart|. Otherwise, let _e_ be 0.
1. Return <ins>«</ins> _a_ × 10<sup>_e_</sup><ins>, _m_ »</ins>.
</emu-alg>
</emu-clause>

<emu-clause id="sec-amount-abstract-ops-decimal-digit-strings">
<h1>Operations on Decimal Digit Strings</h1>

<emu-clause id="sec-amount-countsignificantdigits" type="abstract operation">
<h1>CountSignificantDigits(
_s_: a decimal digit String
): a positive integer
</h1>
<dl class="header">
<dt>description</dt>
<dd>It computes the number of significant digits in a given <emu-xref href="#dfn-decimal-digit-string">decimal digit String</emu-xref>.</dd>
</dl>
<emu-alg>
1. Let _digitsToCount_ be _s_.
1. If _digitsToCount_ contains an *e* character, set _digitsToCount_ be the substring of _s_ before the first occurence of *"e"*.
1. If _digitsToCount_ contains a *"."* character, set _digitsToCount_ to the result of replacing all occurrences of *"."* in _digitsToCount_ by *""*.
1. Let _l_ be the length of _digitsToCount_.
1. Return _l_.
</emu-alg>
</emu-clause>

<emu-clause id="sec-amount-countfractiondigits" type="abstract operation">
<h1>CountFractionDigits(
_s_: a decimal digit String
Expand Down Expand Up @@ -142,7 +198,7 @@ location: https://github.com/tc39/proposal-measure/
</emu-clause>

<emu-clause id="sec-amount-roundtofractiondigits" type="abstract operation">
<h1>RoundToFractionDigits(
<h1>RoundAmountValueToFractionDigits(
_v_: a mathematical value,
_n_: a non-negative integer,
optional _roundingMode_: a rounding mode
Expand All @@ -161,7 +217,7 @@ location: https://github.com/tc39/proposal-measure/
1. If _roundingMode_ is *"ceil"*, set _reverseRoundingMode_ to *"floor"*.
1. If _roundingMode_ is *"halfCeil"*, set _reverseRoundingMode_ to *"halfFloor"*.
1. If _roundingMode_ is *"halfFloor"*, set _reverseRoundingMode_ to *"halfCeil"*.
1. Let _d_ be RoundToFractionDigits(–_v_, _n_, _reverseRoundingMode_).
1. Let _d_ be RoundAmountValueToFractionDigits(–_v_, _n_, _reverseRoundingMode_).
1. Return –_d_.
1. Let _e_ be the unique integer such that 10<sup>_e_</sup> ≤ _v_ < 10<sup>_e_+1</sup>.
1. Let _pow_ be _e_ + _n_.
Expand Down Expand Up @@ -203,17 +259,20 @@ location: https://github.com/tc39/proposal-measure/
</emu-clause>

<emu-clause id="sec-amount-rendermvwithfractiondigits" type="abstract operation">
<h1>RenderMVWithFractionDigits(
_v_: a mathematical value,
<h1>RenderAmountValueWithFractionDigits(
_v_: an Intl mathematical value,
_numDigits_: a non-negative integer,
optional _roundingMode_: a rounding mode
): a String
</h1>
<dl class="header">
<dt>description</dt>
<dd>It renders the given mathematical value with a given number of fractional digits, possibly rounding if necessary, using the given rounding mode, which, if missing, is *"halfEven"*.</dd>
<dd>It renders the given mathematical value or a suitable enum (~positive-infinity~, ~negative-infinity~, ~not-a-number~, or ~minus-zero~) with a given number of fractional digits, possibly rounding if necessary, using the given rounding mode, which, if missing, is *"halfEven"*.</dd>
</dl>
<emu-alg>
1. If _v_ is ~not-a-number~, return *"NaN"*.
1. If _v_ is ~negative-infinity~, return *"-Infinity"*.
1. If _v_ is ~positive-infinity~, return *"Infinity"*.
1. If _roundingMode_ is *undefined*, let _mode_ be *"halfEven"*, else let _mode_ be _roundingMode_.
1. If _v_ < 0, let _prefix_ be *"-"*, else let _prefix_ be "".
1. If _v_ < 0, set _v_ to -_v_.
Expand All @@ -222,10 +281,10 @@ location: https://github.com/tc39/proposal-measure/
1. Let _e_ be the smallest non-negative integer such that _v_ × 10<sup>-_numDigits_</sup> is an integer.
1. Let _s_ be the unique decimal string representation of _v_ without leading zeroes.
1. If _numDigits_ > _e_, then
1. If _v_ is an integer, return the string concatenation of _prefix, _s_, *"."*, and *"0"* repeated _numDigits_ times.
1. Otherwise, return the string concatenation of _prefix_, _s_ and *"0"* repeated _numDigits_ - _e_ times.
1. If _v_ is an integer, return the string-concatenation of _prefix, _s_, *"."*, and *"0"* repeated _numDigits_ times.
1. Otherwise, return the string-concatenation of _prefix_, _s_ and *"0"* repeated _numDigits_ - _e_ times.
1. Otherwise:
1. Return the string concatenation of _prefix, _s_ and *"0"* repeated _e_ - _numDigits_ times.
1. Return the string-concatenation of _prefix, _s_ and *"0"* repeated _e_ - _numDigits_ times.
</emu-alg>
</emu-clause>

Expand Down Expand Up @@ -275,80 +334,51 @@ location: https://github.com/tc39/proposal-measure/
1. Else if _x_ is a Number, set _toParse_ to Number::toString(_x_, 10).
1. Otherwise, if _x_ is a String, set _toParse_ to _x_.
1. If _toParse_ is not a String, throw a *TypeError* exception.
1. If _toParse_ is in « *"NaN"*, *"Infinity"*, *"-Infinity"* », throw a *RangeError* exception.
1. Let _parseResult_ be ParseText(_toParse_, |StrDecimalLiteral|).
1. Let _intlMV_ be the StringIntlMV of _toParse_.
1. Let _amountValue_ be _intlMV_[0].
1. Let _numDigits_ be _intlMV_[1].
1. Let _validatedOpts_ be ? GetAmountOptions(_opts_).
1. If _parseResult_ is a List of errors, throw a *SyntaxError* exception.
1. Let _amountValue_ be ? StringDecimalValue of _parseResult_.
1. Let _fractionDigits_ be _validatedOpts_.[[FractionDigits]].
1. Let _roundingMode_ be _validatedOpts_.[[RoundingMode]].
1. Let _significantDigits_ be _validatedOpts_.[[SignificantDigits]].
1. Let _unit_ be _validatedOpts_.[[Unit]].
1. Let _roundedValue_ be _amountValue_.
1. Assert: If _fractionDigits_ is not *undefined*, then _significantDigits_ is *undefined*.
1. Assert: If _significantDigits_ is not *undefined*, then _fractionDigits_ is *undefined*.
1. If both _significantDigits_ and _fractionDigits_ are *undefined*, then
1. Set _significantDigits_ to CountSignificantDigits(_toParse_).
1. Set _fractionDigits_ to CountFractionDigits(_toParse_).
1. Else if _significantDigits_ is *undefined*, then
1. Set _roundedValue_ be RoundToFractionDigits(_amountValue_, _fractionDigits_, _roundingMode_).
1. Let _digitStr_ be the unique decimal string representation of _roundedValue_ without leading zeroes.
1. Set _significantDigits_ to CountSignificantDigits(_digitStr_).
1. Otherwise:
1. Set _roundedValue_ be RoundToSignificantDigits(_amountValue_, _significantDigits_, _roundingMode_).
1. Let _digitStr_ be the unique decimal string representation of _roundedValue_ without leading zeroes.
1. Set _fractionDigits_ to CountFractionDigits(_digitStr_).
1. Let _O_ be OrdinaryObjectCreate(%Amount.prototype%, « [[FractionDigits]], [[SignificantDigits]], [[Unit]], [[Value]] »).
1. Set _O_.[[Value]] to _roundedValue_.
1. Set _O_.[[SignificantDigits]] to _significantDigits_.
1. Set _O_.[[FractionDigits]] to _fractionDigits_.
1. If _amountValue_ is a mathematical value, then
1. Let _roundedValue_ be _amountValue_.
1. If both _significantDigits_ and _fractionDigits_ are *undefined*, then
1. Set _significantDigits_ to _numDigits_.
1. Set _fractionDigits_ to CountFractionDigits(_toParse_).
1. Else if _significantDigits_ is *undefined*, then
1. Set _roundedValue_ be RoundAmountValueToFractionDigits(_amountValue_, _fractionDigits_, _roundingMode_).
1. Let _e_ be the smallest non-negative integer such that _roundedValue_ × 10<sup>-_e_</sup> is an integer.
1. Let _scaledRoundedValue_ be _roundedValue_ × 10<sup>-_e_</sup>.
1. If _scaledRoundedValue_ = 0, then
1. Set _significantDigits_ to 1.
1. Else,
1. Let _l_ be the log-10 of abs(_scaledRoundedValue_).
1. Set _significantDigits_ to floor(_l_) + 1.
1. Otherwise:
1. Set _roundedValue_ be RoundToSignificantDigits(_amountValue_, _significantDigits_, _roundingMode_).
1. Let _digitStr_ be the unique decimal string representation of _roundedValue_ without leading zeroes.
1. Set _fractionDigits_ to CountFractionDigits(_digitStr_).
1. Set _O_.[[Value]] to _roundedValue_.
1. Set _O_.[[SignificantDigits]] to _significantDigits_.
1. Set _O_.[[FractionDigits]] to _fractionDigits_.
1. Else if _amountValue_ is ~minus-zero~, then
1. Set _O_.[[Value]] to ~minus-zero~.
1. Set _O_.[[SignificantDigits]] to _numDigits_.
1. Assert: _numDigits_ ≥ 1.
1. Set _O_.[[FractionDigits]] to _numDigits_ - 1.
1. Otherwise:
1. Set _O_.[[Value]] to _amountValue_.
1. Set _O_.[[SignificantDigits]] to _numDigits_..
1. Set _O_.[[FractionDigits]] to 0.
1. If _unit_ is not *undefined*, set _O_.[[Unit]] to _unit_.
1. Return _O_.
</emu-alg>
<emu-note>
<p>Given a Number argument, the constructor converts it to a String using the <emu-xref href="#sec-number.prototype.tostring">toString</emu-xref> method (with no arguments). In some cases, this may not be desired; consider passing in a String form of a Number using the <emu-xref href="#sec-number.prototype.tofixed">toFixed</emu-xref> or <emu-xref href="#sec-number.prototype.toprecision">toPrecision</emu-xref> methods.</p>
</emu-note>
<emu-clause id="sec-runtime-semantics-stringdecimalvalue" type="sdo">
<h1>Runtime Semantics: StringDecimalValue ( ): either a normal completion containing a mathematical value or a throw completion</h1>
<dl class="header">
</dl>
<emu-grammar>StrDecimalLiteral ::: `-` StrUnsignedDecimalLiteral</emu-grammar>
<emu-alg>
1. Let _a_ be ? StringAmountValue of |StrUnsignedDecimalLiteral|.
1. Assert: _a_ is finite.
1. Return −_a_.
</emu-alg>
<emu-grammar>StrUnsignedDecimalLiteral ::: `Infinity`</emu-grammar>
<emu-alg>
1. Throw a *RangeError* exception.
</emu-alg>
<emu-grammar>StrUnsignedDecimalLiteral ::: DecimalDigits `.` DecimalDigits? ExponentPart?</emu-grammar>
<emu-alg>
1. Let _a_ be MV of the first |DecimalDigits|.
1. If the second |DecimalDigits| is present, then
1. Let _b_ be MV of the second |DecimalDigits|.
1. Let _n_ be the number of code points in the second |DecimalDigits|.
1. Else,
1. Let _b_ be 0.
1. Let _n_ be 0.
1. If |ExponentPart| is present, let _e_ be MV of |ExponentPart|. Otherwise, let _e_ be 0.
1. Return (_a_ + (_b_ × 10<sup>−_n_</sup>)) × 10<sup>_e_</sup>.
</emu-alg>
<emu-grammar>StrUnsignedDecimalLiteral ::: `.` DecimalDigits ExponentPart?</emu-grammar>
<emu-alg>
1. Let _b_ be MV of |DecimalDigits|.
1. If |ExponentPart| is present, let _e_ be MV of |ExponentPart|. Otherwise, let _e_ be 0.
1. Let _n_ be the number of code points in |DecimalDigits|.
1. Let _newValue_ be _b_ × 10<sup>_e_ − _n_</sup>.
1. Return _newValue_.
</emu-alg>
<emu-grammar>StrUnsignedDecimalLiteral ::: DecimalDigits ExponentPart?</emu-grammar>
<emu-alg>
1. Let _a_ be MV of |DecimalDigits|.
1. If |ExponentPart| is present, let _e_ be MV of |ExponentPart|. Otherwise, let _e_ be 0.
1. Return _a_ × 10<sup>_e_</sup>.
</emu-alg>
</emu-clause>
</emu-clause>
</emu-clause>
</emu-clause>
Expand All @@ -369,13 +399,13 @@ location: https://github.com/tc39/proposal-measure/
1. Let _u_ be _O_.[[Unit]].
1. Let _v_ be _O_.[[Value]].
1. Let _fractionDigits_ be _O_.[[FractionDigits]].
1. Let _s_ be RenderMVWithFractionDigits(_v_, _fractionDigits_).
1. Let _s_ be RenderAmountValueWithFractionDigits(_v_, _fractionDigits_).
1. If _displayUnit_ is *"never"*, return _s_.
1. If _u_ is *undefined*, then
1. If _displayUnit_ is *"always"*, return the string-concatenation of _s_ and *"[1]"*.
1. Else, return _s_.
1. Else,
1. Return the string concatenation of _s_, *"["*, _u_, and *"]"*.
1. Return the string-concatenation of _s_, *"["*, _u_, and *"]"*.
</emu-alg>
</emu-clause>

Expand All @@ -399,7 +429,7 @@ location: https://github.com/tc39/proposal-measure/
1. Let _fractionDigits_ be _processedOptions_.[[FractionDigits]].
1. Let _significantDigits_ be _processedOptions_.[[SignificantDigits]].
1. Let _value_ be _O_.[[Value]].
1. If _fractionDigits_ is not *undefined*, set _value_ to RoundToFractionDigits(_value_, _fractionDigits_).
1. If _fractionDigits_ is not *undefined*, set _value_ to RoundAmountValueToFractionDigits(_value_, _fractionDigits_).
1. Else if _significantDigits_ is not *undefined*, set _value_ to RoundToSignificantDigits(_value_, _significantDigits_).
1. Otherwise, throw a *TypeError* exception.
1. Let _N_ be OrdinaryObjectCreate(*"%Amount.prototype%"*, « [[FractionDigits]], [[SignificantDigits]], [[Unit]], [[Value]] »).
Expand Down Expand Up @@ -427,9 +457,9 @@ location: https://github.com/tc39/proposal-measure/
1. Let _mv_ be _O_.[[Value]].
1. If _hint_ is *"string"*, then
1. Let _fractionDigits_ be _O_.[[FractionDigits]].
1. Let _str_ be RenderMVWithFractionDigits(_mv_, _fractionDigits_).
1. Let _str_ be RenderAmountValueWithFractionDigits(_mv_, _fractionDigits_).
1. If _unit_ is *undefined*, return _str_.
1. Else, return the string concatenation of _str_, *"["*, _unit_, and *"]"*.
1. Else, return the string-concatenation of _str_, *"["*, _unit_, and *"]"*.
1. Else,
1. If _unit_ is not *undefined*, throw a *TypeError* exception.
1. Return the Number value for _mv_.
Expand Down