Function createInterpolator

packages/shared/src/createInterpolator.ts:12–57

(
  range: readonly number[] | InterpolatorFn<any, any> | InterpolatorConfig<any>,
  output?: readonly Animatable[],
  extrapolate?: ExtrapolateType
)

} from '@react-spring/types'

export const createInterpolator: InterpolatorFactory = (
  range: readonly number[] | InterpolatorFn<any, any> | InterpolatorConfig<any>,
  output?: readonly Animatable[],
  extrapolate?: ExtrapolateType
) => {
  if (is.fun(range)) {
    return range
  }

  if (is.arr(range)) {
    return createInterpolator({
      range,
      output: output!,
      extrapolate,
    })
  }

  if (is.str(range.output[0])) {
    return G.createStringInterpolator(range as any) as any
  }

  const config = range as InterpolatorConfig<number>
  const outputRange = config.output
  const inputRange = config.range || [0, 1]

  const extrapolateLeft =
    config.extrapolateLeft || config.extrapolate || 'extend'
  const extrapolateRight =
    config.extrapolateRight || config.extrapolate || 'extend'
  const easing = config.easing || (t => t)

  return (input: number) => {
    const range = findRange(input, inputRange)
    return interpolate(
      input,
      inputRange[range],
      inputRange[range + 1],
      outputRange[range],
      outputRange[range + 1],
      easing,
      extrapolateLeft,
      extrapolateRight,
      config.map
    )
  }
}

function interpolate(
  input: number,