@brimdata/zealot/src/zed/types/type-union.ts

The Javascript Client for Zed Lakes

import * as zjson from "../../zjson"
import {DecodeStream} from "../decode-stream"
import {EncodeStream} from "../encode-stream"
import {Union} from "../values/union"
import {TypeNull} from "./type-null"
import {Type} from "./types"

export class TypeUnion implements Type {
  kind = "union"
  id?: number | string

  constructor(public types: Type[]) {}

  static stringify(types: Type[]) {
    return `(${types.map((t) => t.toString()).join(",")})`
  }

  create(value: zjson.UnionValue, stream: DecodeStream) {
    if (value === null) {
      return new Union(this, TypeNull, null, null)
    } else {
      const index = parseInt(value[0])
      const innerType = this.types[index]
      const innerValue = innerType.create(value[1], stream)
      return new Union(this, innerType, index, innerValue)
    }
  }

  serialize(stream: EncodeStream): zjson.NoId<zjson.UnionType> {
    return {
      kind: "union",
      types: this.types.map((t) => stream.encodeType(t)),
    }
  }

  toString() {
    return `(${this.types.map((t) => t.toString()).join(",")})`
  }
}