combinations() — tailwindcss Function Reference

Architecture documentation for the combinations() function in canonicalize-candidates.ts from the tailwindcss codebase.

Function typescript UpgradeToolkit TemplateAnalysis called by 1

Entity Profile

UpgradeToolkit→ TemplateAnalysis→ combinations() — tailwindcss Function Reference

Dependency Diagram

graph TD
  ab8d344f_10ae_ff6d_9378_cf7d5cb6ec72["combinations()"]
  7d350d81_5de1_f9f3_5b2c_19ec8fd3c37e["canonicalize-candidates.ts"]
  ab8d344f_10ae_ff6d_9378_cf7d5cb6ec72 -->|defined in| 7d350d81_5de1_f9f3_5b2c_19ec8fd3c37e
  6b36dfc9_f213_8083_55ea_8d0541032f05["collapseCandidates()"]
  6b36dfc9_f213_8083_55ea_8d0541032f05 -->|calls| ab8d344f_10ae_ff6d_9378_cf7d5cb6ec72
  style ab8d344f_10ae_ff6d_9378_cf7d5cb6ec72 fill:#6366f1,stroke:#818cf8,color:#fff

Relationship Graph

Source Code

packages/tailwindcss/src/canonicalize-candidates.ts lines 2574–2600

function* combinations<T>(arr: T[]): Generator<T[]> {
  let n = arr.length
  let limit = 1n << BigInt(n)

  for (let k = n; k >= 2; k--) {
    let mask = (1n << BigInt(k)) - 1n

    while (mask < limit) {
      let out = []
      for (let i = 0; i < n; i++) {
        if ((mask >> BigInt(i)) & 1n) {
          out.push(arr[i])
        }
      }
      yield out

      // Gosper's hack:
      // - https://programmingforinsomniacs.blogspot.com/2018/03/gospers-hack-explained.html
      // - https://rosettacode.org/wiki/Gosper%27s_hack
      //
      // We need to generate the next mask in lexicographical order.
      let carry = mask & -mask
      let ripple = mask + carry
      mask = (((ripple ^ mask) >> 2n) / carry) | ripple
    }
  }
}