term-root-gen.js

const HR = `

# sintaksa: regularni_izraz [dio_za_dodat]
# prva grupa u regularnom izrazu je i dio koji se brise

PFX (je|ni|ne|ho|naj|pra|is)
PFX (ne) i

SFX (i|mo|te|u) am

SFX (e|i|u|o) a
SFX (om|oj|og|im|em) a
SFX (ima|emu|oga|ome|omu|oma|oje|ije|jema) a

SFX (ea) u
SFX (e|emo|ste) u

SFX [ai](ma)

SFX (ci|aka) ka

SFX . ti
SFX (h|o|smo|ste|jah|jaše|jasmo|jaste|jahu) ti
SFX (jeh|ješe|jesmo|jeste|jehu) iti
SFX (la|lo|li|le) ti

SFX (a|u|e|i|m)
SFX (om|ovi|ova|ove|ima)
SFX (ovima)

SFX (a|u) o

SFX (čiju|čima|či) ko

SFX (ala) lo
SFX (ima) o

SFX (la|lo|li|le) ao

SFX (m|a|mo|ju|te) ti

SFX (na|ne|nu|no|ni) an
SFX (nim|noj|nom|nog|nima|nih) an
SFX (noga|nomu|nome) an

SFX (ju|ma)
SFX (oma|oje) i

SFX (če|ci|cima) k

SFX (a|mo|te)

SFX (gu) ći
SFX (žeš|žemo|žete) ći

SFX (e) i

SFX (žeš|žem|žemo|žete|že|žu) zati
`

function rootGeneratorFor(definition) {
  const rules = []

  for (const line of definition.split('\n')) {
    const [cmd, pat, add = ''] = line.trim().split(/\s+/g, 3)
    if (cmd === 'PFX') {
      rules.push([true, new RegExp(pat === '.' ? '.' : `^(?:${pat}).`), add])
    }
    if (cmd === 'SFX') {
      rules.push([false, new RegExp(pat === '.' ? '.' : `.(?:${pat})$`), add])
    }
  }

  return function * genRoots(term) {
    // yield term

    const rightOps = []
    const leftOps = []

    for (const [isPfx, re, add] of rules) {
      re.lastIndex = 0
      const m = term.match(re)
      if (!m) continue
      const rm = (m[1] || '').length
      if (isPfx) {
        yield add + term.slice(rm)
        leftOps.push([rm, add])
      } else {
        yield term.slice(0, term.length - rm) + add
        rightOps.push([rm, add])
      }
    }

    for (const [rmLeft, addLeft] of leftOps) {
      const maxRmRight = term.length - rmLeft - 1
      for (const [rmRight, addRight] of rightOps) {
        if (rmRight <= maxRmRight) {
          yield `${addLeft}${term.slice(rmLeft, term.length - rmRight)}${addRight}`
        }
      }
    }
  }
}

const genHrRoots = rootGeneratorFor(HR)

console.log([...genHrRoots('prakodovima')])