latvian-grammar/src/palatalize.js

Latvian grammar library

// http://valoda.ailab.lv/latval/vidusskolai/morfol/lietv-mija.htm

const palatalize = (word, { declensionCase, suffix }) => {
  const base = word.slice(0, -suffix.length);
  if (
    !table[declensionCase] ||
    exceptions[declensionCase].includes(word) ||
    exceptionSuffixes[declensionCase].some((x) => word.endsWith(x))
  ) {
    return base;
  }

  for (const [from, to] of entryTable[declensionCase]) {
    if (base.endsWith(from)) {
      return `${base.slice(0, -from.length)}${to}`;
    }
  }
};

export default palatalize;

// NB: relies on key order to be in descending length
export const table = {
  2: {
    dz: "dž",
    sn: "šņ",
    zn: "žņ",
    sl: "šļ",
    zl: "žļ",
    ln: "ļņ",
    b: "bj",
    m: "mj",
    p: "pj",
    v: "vj",
    t: "š",
    d: "ž",
    c: "č",
    s: "š",
    z: "ž",
    n: "ņ",
    l: "ļ",
  },
  5: {
    sn: "šņ",
    zn: "žņ",
    dz: "dž",
    kst: "kp",
    b: "bj",
    m: "mj",
    p: "pj",
    v: "vj",
    c: "č",
    t: "š",
    d: "ž",
    s: "š",
    z: "ž",
    n: "ņ",
    l: "ļ",
  },
  6: {
    sn: "šņ",
    st: "š",
    v: "vj",
    t: "š",
    d: "ž",
    s: "š",
    z: "ž",
    n: "ņ",
    l: "ļ",
  },
};

const entryTable = Object.fromEntries(
  Object.entries(table).map(([k, v]) => [k, Object.entries(v)])
);

const exceptionSuffixes = {
  2: ["astis", "jis", "ķis", "ģis", "ris", "skatis"],
  5: ["aste", "fe", "ģe", "ķe", "mate", "pēde", "ste"],
};

const exceptions = {
  2: ["tētis", "viesis"],
  5: [
    "apaļmute",
    "apšaude",
    "balamute",
    "balle (mērvienība)",
    "bāze",
    "bise",
    "bote",
    "brīze",
    "flote",
    "fronte",
    "gāze (vielas stāvoklis)",
    "gide",
    "kase",
    "kušete",
    "mise",
    "mute",
    "pase",
    "piešaude",
    "planšete",
    "rase",
    "sarakste",
    "šprote",
    "takse",
    "tirāde",
  ],
  6: [
    "acs",
    "aktis",
    "ass",
    "auss",
    "balss",
    "brokastis",
    "Cēsis",
    "dakts",
    "debess",
    "dzelzs",
    "kūts",
    "maksts",
    "pirts",
    "šalts",
    "takts (mūzikā)",
    "uts",
    "uzacs",
    "valsts",
    "vēsts",
    "zoss",
    "žults",
  ],
};

for (const i of Array.from({ length: 6 }, (_, i) => i + 1)) {
  if (!exceptionSuffixes[i]) {
    exceptionSuffixes[i] = [];
  }
  if (!exceptions[i]) {
    exceptions[i] = [];
  }
}

// const masculinePluralOnly = ["akmens", "asmens", "rudens", "zibens", "ūdens", "mēness", "sāls"];
// const masculineTwoSyllableSuffixes = ["tis", "dis"];