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import {  AssertState,  Codec,  createCodec,  metadata,  ScaleAssertError,  ScaleDecodeError,  ScaleEncodeError,} from "../common/mod.ts"import { compact } from "./compact.ts"import { u32 } from "./int.ts"
const compactU32 = compact(u32)
export function iterable<TI, I extends Iterable<TI>, TO = TI, O = I>(  props: {    $el: Codec<TI, TO>    calcLength: (iterable: I) => number    rehydrate: (iterable: Iterable<TO>) => O    assert: (this: Codec<I, O>, assert: AssertState) => void  },): Codec<I, O> {  return createCodec({    _metadata: metadata("$.iterable", iterable, props),    _staticSize: compactU32._staticSize,    _encode(buffer, value) {      const length = props.calcLength(value)      compactU32._encode(buffer, length)      buffer.pushAlloc(length * props.$el._staticSize)      let i = 0      for (const el of value) {        props.$el._encode(buffer, el)        i++      }      if (i !== length) throw new ScaleEncodeError(this, value, "Incorrect length returned by calcLength")      buffer.popAlloc()    },    _decode(buffer) {      const length = compactU32._decode(buffer)      let done = false      const value = props.rehydrate(function*() {        for (let i = 0; i < length; i++) {          yield props.$el._decode(buffer)        }        done = true      }())      if (!done) throw new ScaleDecodeError(this, buffer, "Iterable passed to rehydrate must be immediately exhausted")      return value    },    _assert(assert) {      props.assert.call(this, assert)      const length = props.calcLength(assert.value as I)      let i = 0      for (const el of assert.value as I) {        props.$el._assert(new AssertState(el, `#iterator[${i}]`))        i++      }      if (i !== length) {        throw new ScaleAssertError(this, assert.value, `${assert.path}: Incorrect length returned by calcLength`)      }    },  })}