43 lines
1.2 KiB
JavaScript
43 lines
1.2 KiB
JavaScript
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import {codes, values} from 'micromark-util-symbol'
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/**
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* Turn the number (in string form as either hexa- or plain decimal) coming from
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* a numeric character reference into a character.
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*
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* Sort of like `String.fromCodePoint(Number.parseInt(value, base))`, but makes
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* non-characters and control characters safe.
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*
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* @param {string} value
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* Value to decode.
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* @param {number} base
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* Numeric base.
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* @returns {string}
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* Character.
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*/
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export function decodeNumericCharacterReference(value, base) {
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const code = Number.parseInt(value, base)
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if (
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// C0 except for HT, LF, FF, CR, space.
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code < codes.ht ||
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code === codes.vt ||
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(code > codes.cr && code < codes.space) ||
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// Control character (DEL) of C0, and C1 controls.
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(code > codes.tilde && code < 160) ||
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// Lone high surrogates and low surrogates.
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(code > 55_295 && code < 57_344) ||
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// Noncharacters.
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(code > 64_975 && code < 65_008) ||
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/* eslint-disable no-bitwise */
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(code & 65_535) === 65_535 ||
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(code & 65_535) === 65_534 ||
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/* eslint-enable no-bitwise */
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// Out of range
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code > 1_114_111
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) {
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return values.replacementCharacter
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}
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return String.fromCodePoint(code)
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}
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