aliaset/packages/core/src/internal/merge.ts

twind monorepo

import type { TwindRule } from '../types'

export function merge(rules: TwindRule[], name: string): TwindRule[] {
  // merge:
  // - same conditions
  // - replace name with hash of name + condititions + declarations
  // - precedence:
  //   - combine bits or use max precendence
  //   - set layer bit to merged
  const result: TwindRule[] = []

  let current: TwindRule | undefined

  for (const rule of rules) {
    // only merge rules with declarations and names (eg no global rules)
    if (!(rule.d && rule.n)) {
      result.push({ ...rule, n: rule.n && name })
    } else if (current?.p == rule.p && '' + current.r == '' + rule.r) {
      current.c = [current.c, rule.c].filter(Boolean).join(' ')
      current.d = current.d + ';' + rule.d
    } else {
      // only set name for named rules eg not for global or className propagation rules
      result.push((current = { ...rule, n: rule.n && name }))
    }
  }

  return result
}