@brimdata/zealot/src/zed/encode-stream.ts

The Javascript Client for Zed Lakes

import * as zed from "../zed"
import * as zjson from "../zjson"
import {Type} from "./types/types"
import {Value} from "./values/types"
import {TypeValue} from "./values/type-value"

export class EncodeStream {
  private id = 30
  private map = new Map<Type, number>()

  encode(value: Value): zjson.Object {
    return {
      type: this.encodeType(value.type) as zjson.Type,
      value: this.encodeValue(value),
    }
  }

  encodeType(type: Type): zjson.Type {
    if (zed.isPrimitiveType(type)) {
      return type.serialize() as zjson.PrimitiveType
    } else if (this.hasSeen(type)) {
      return {kind: "ref", id: this.getId(type)} as zjson.RefType
    } else {
      const zjson = type.serialize(this)
      const id = this.id++
      this.map.set(type, id)
      return {id, ...zjson} as zjson.Type
    }
  }

  encodeValue(value: Value | null): zjson.Value {
    if (!value) return null
    if (value instanceof TypeValue) {
      if (value.value === null) return null
      return this.encodeType(value.value)
    } else {
      return value.serialize(this)
    }
  }

  private hasSeen(type: Type) {
    return this.map.has(type)
  }

  private getId(type: Type) {
    return this.map.get(type)
  }
}