Function getLoop

packages/effect/src/JsonPatch.ts:186–239

(
  oldValue: Schema.Json,
  newValue: Schema.Json,
  path: string,
  patches: Array<JsonPatchOperation>
)

}

function getLoop(
  oldValue: Schema.Json,
  newValue: Schema.Json,
  path: string,
  patches: Array<JsonPatchOperation>
): void {
  if (Object.is(oldValue, newValue)) return
  if (Array.isArray(oldValue) && Array.isArray(newValue)) {
    const len1 = oldValue.length
    const len2 = newValue.length

    // Compare shared prefix by index
    const shared = Math.min(len1, len2)
    for (let i = 0; i < shared; i++) {
      getLoop(oldValue[i], newValue[i], `${path}/${i}`, patches)
    }

    // Remove from end to start so later indices do not shift.
    for (let i = len1 - 1; i >= len2; i--) {
      patches.push({ op: "remove", path: `${path}/${i}` })
    }

    // Add from beginning to end.
    for (let i = len1; i < len2; i++) {
      patches.push({ op: "add", path: `${path}/${i}`, value: newValue[i] })
    }

    return
  }

  if (isJsonObject(oldValue) && isJsonObject(newValue)) {
    const keys1 = Object.keys(oldValue)
    const keys2 = Object.keys(newValue)
    const allKeys = Array.from(new Set([...keys1, ...keys2])).sort()

    for (const key of allKeys) {
      const keyPath = `${path}/${escapeToken(key)}`
      const hasKey1 = Object.hasOwn(oldValue, key)
      const hasKey2 = Object.hasOwn(newValue, key)

      if (hasKey1 && hasKey2) {
        getLoop(oldValue[key], newValue[key], keyPath, patches)
      } else if (!hasKey1 && hasKey2) {
        patches.push({ op: "add", path: keyPath, value: newValue[key] })
      } else {
        patches.push({ op: "remove", path: keyPath })
      }
    }

    return
  }

  patches.push({ op: "replace", path, value: newValue })
}

/**
 * Applies a JSON Patch to a JSON document.