40 lines
1.5 KiB
Plaintext
Executable File
40 lines
1.5 KiB
Plaintext
Executable File
import { getMagnitude } from '../utils';
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import { ComputeExponentForMagnitude } from './ComputeExponentForMagnitude';
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import { FormatNumericToString } from './FormatNumericToString';
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/**
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* The abstract operation ComputeExponent computes an exponent (power of ten) by which to scale x
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* according to the number formatting settings. It handles cases such as 999 rounding up to 1000,
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* requiring a different exponent.
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*
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* NOT IN SPEC: it returns [exponent, magnitude].
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*/
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export function ComputeExponent(numberFormat, x, _a) {
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var getInternalSlots = _a.getInternalSlots;
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if (x === 0) {
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return [0, 0];
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}
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if (x < 0) {
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x = -x;
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}
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var magnitude = getMagnitude(x);
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var exponent = ComputeExponentForMagnitude(numberFormat, magnitude, {
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getInternalSlots: getInternalSlots,
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});
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// Preserve more precision by doing multiplication when exponent is negative.
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x = exponent < 0 ? x * Math.pow(10, -exponent) : x / Math.pow(10, exponent);
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var formatNumberResult = FormatNumericToString(getInternalSlots(numberFormat), x);
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if (formatNumberResult.roundedNumber === 0) {
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return [exponent, magnitude];
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}
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var newMagnitude = getMagnitude(formatNumberResult.roundedNumber);
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if (newMagnitude === magnitude - exponent) {
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return [exponent, magnitude];
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}
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return [
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ComputeExponentForMagnitude(numberFormat, magnitude + 1, {
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getInternalSlots: getInternalSlots,
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}),
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magnitude + 1,
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];
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}
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