39 lines
1.3 KiB
JavaScript
39 lines
1.3 KiB
JavaScript
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import {values} from 'micromark-util-symbol'
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/**
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* Normalize an identifier (as found in references, definitions).
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*
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* Collapses markdown whitespace, trim, and then lower- and uppercase.
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*
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* Some characters are considered “uppercase”, such as U+03F4 (`ϴ`), but if their
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* lowercase counterpart (U+03B8 (`θ`)) is uppercased will result in a different
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* uppercase character (U+0398 (`Θ`)).
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* So, to get a canonical form, we perform both lower- and uppercase.
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*
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* Using uppercase last makes sure keys will never interact with default
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* prototypal values (such as `constructor`): nothing in the prototype of
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* `Object` is uppercase.
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*
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* @param {string} value
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* Identifier to normalize.
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* @returns {string}
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* Normalized identifier.
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*/
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export function normalizeIdentifier(value) {
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return (
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value
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// Collapse markdown whitespace.
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.replace(/[\t\n\r ]+/g, values.space)
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// Trim.
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.replace(/^ | $/g, '')
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// Some characters are considered “uppercase”, but if their lowercase
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// counterpart is uppercased will result in a different uppercase
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// character.
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// Hence, to get that form, we perform both lower- and uppercase.
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// Upper case makes sure keys will not interact with default prototypal
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// methods: no method is uppercase.
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.toLowerCase()
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.toUpperCase()
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)
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}
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