thi-ng/umbrella

/**
 * @remarks
 * References:
 * - https://en.wikipedia.org/wiki/List_of_XML_and_HTML_character_entity_references
 * - https://www.w3.org/TR/xml-entity-names/byalpha.html
 */
export const ENTITIES: Record<string, string> = {
    "&": "&amp;",
    "<": "&lt;",
    ">": "&gt;",
    "≤": "&le;",
    "≥": "&ge;",
    '"': "&quot;",
    "'": "&apos;",
    "—": "&mdash;",
    "–": "&ndash;",
    "…": "&hellip;",
    "⋮": "&vellip;",
    "⋯": "&ctdot;",
    "¢": "&cent;",
    "€": "&euro;",
    "£": "&pound;",
    "¥": "&yen;",
    "₹": "&#8377;",
    元: "&#20803;",
    "§": "&sect;",
    "¶": "&para;",
    "©": "&copy;",
    "®": "&reg;",
    "™": "&trade;",
    "℃": "&#8451;",
    "℉": "&#8457;",
    "\u212a": "&#8490;", // Kelvin
    "◂": "&ltrif;",
    "▸": "&rtrif;",
    "▴": "&utrif;",
    "▾": "&dtrif;",
    "←": "&larr;",
    "→": "&rarr;",
    "↑": "&uarr;",
    "↓": "&darr;",
    "↵": "&crarr;",
    "↩": "&larrhk;",
    "⇐": "&lArr;",
    "⇒": "&rArr;",
    "↺": "&olarr;",
    "↻": "&orarr;",
    "¹": "&sup1;",
    "²": "&sup2;",
    "³": "&sup3;",
    "½": "&frac12;",
    "⅓": "&frac13;",
    "⅔": "&frac23;",
    "¼": "&frac14;",
    "¾": "&frac34;",
    "⅕": "&frac15;",
    "⅙": "&frac16;",
    "⅛": "&frac18;",
    Ä: "&Auml;",
    Ë: "&Euml;",
    Ï: "&Iuml;",
    Ö: "&Ouml;",
    Ü: "&Uuml;",
    ä: "&auml;",
    ë: "&euml;",
    ï: "&iuml;",
    ö: "&ouml;",
    ü: "&uuml;",
    ß: "&szlig;",
    α: "&alpha;",
    β: "&beta;",
    γ: "&gamma;",
    δ: "&delta;",
    ε: "&epsi;",
    θ: "&theta;",
    λ: "&lambda;",
    μ: "&mu;",
    π: "&pi;",
    σ: "&sigma;",
    τ: "&tau;",
    φ: "&phi;",
    ω: "&omega;",
    Δ: "&Delta;",
    Ω: "&Omega;",
    "∞": "&infin;",
    "±": "&plusmn;",
    "⨯": "&Cross;",
    "°": "&deg;",
    "∑": "&sum;",
    "∏": "&prod;",
    "∫": "&int;",
    "√": "&radic;",
    "∠": "&angle;",
    "∧": "&and;",
    "∨": "&or;",
    "∩": "&cap;",
    "∪": "&cup;",
    "⊂": "&sub;",
    "⊃": "&sup;",
    "∈": "&isin;",
    "∉": "&notin;",
    "∅": "&empty;",
    "⊕": "&oplus;",
    "⊖": "&ominus;",
    "⊗": "&otimes;",
    "⌖": "&target;",
    "☆": "&star;",
    "★": "&starf;",
    "✓": "&check;",
    "✗": "&cross;",
    "\xa0": "&nbsp;",
};

export const RE_ENTITIES = new RegExp(
    `[${Object.keys(ENTITIES).join("")}]`,
    "gu"
);

export const ENTITIES_REV = Object.entries(ENTITIES).reduce(
    (acc, [k, v]) => ((acc[v] = k), acc),
    <Record<string, string>>{}
);

export const RE_ENTITIES_REV = new RegExp(
    `(${Object.keys(ENTITIES_REV).join("|")})`,
    "g"
);

export const RE_ENTITIES_NUM = /&#(x?)([0-9a-f]+);/gi;

/**
 * Replaces all occurrences of character keys in {@link ENTITIES} with their
 * named HTML entities.
 *
 * @remarks
 * Only use this function when targetting HTML output. For XML/SVG etc. use
 * {@link escapeEntitiesNum}.
 *
 * @param src
 */
export const escapeEntities = (src: string) =>
    src.replace(RE_ENTITIES, (x) => ENTITIES[x]);

/**
 * Similar to {@link escapeEntities}, but only uses _named_ entities for `&`,
 * `<`, `>`, `'`, `"` and numeric entities for all others.
 *
 * @remarks
 * This function is used as default by thi.ng/hiccup `serialize()` to escape
 * characters and ensure compatibility with XML (which by default only supports
 * named entities for the above 5 characters).
 *
 * @param src
 */
export const escapeEntitiesNum = (src: string) =>
    src.replace(RE_ENTITIES, (x) => {
        const code = x.charCodeAt(0);
        return code < 128 ? ENTITIES[x] : `&#x${code.toString(16)};`;
    });

/**
 * Replace all known named and numeric entities with their original characters.
 * Opposite op of {@link escapeEntities} and {@link escapeEntitiesNum}.
 *
 * @param src
 */
export const unescapeEntities = (src: string) =>
    src
        .replace(RE_ENTITIES_REV, (x) => ENTITIES_REV[x])
        .replace(RE_ENTITIES_NUM, (_, hex, x) =>
            String.fromCharCode(parseInt(x, hex ? 16 : 10))
        );