@loaders.gl/schema/src/types/schema.ts

Table format APIs for JSON, CSV, etc...

// loaders.gl
// SPDX-License-Identifier: MIT
// Copyright (c) vis.gl contributors

/** For dictionary type */
export type KeyType = 'int8' | 'int16' | 'int32' | 'uint8' | 'uint16' | 'uint32';

/** ArrowLike DataType class */
export type DataType =
  | 'null'
  // Primitive types
  | 'bool'
  | 'int'
  | 'int8'
  | 'int16'
  | 'int32'
  | 'int64'
  | 'uint8'
  | 'uint16'
  | 'uint32'
  | 'uint64'
  | 'float'
  | 'float16'
  | 'float32'
  | 'float64'
  | 'binary'
  | 'utf8'
  | 'date-day'
  | 'date-millisecond'
  | 'time-second'
  | 'time-millisecond'
  | 'time-microsecond'
  | 'time-nanosecond'
  | 'timestamp-second'
  | 'timestamp-millisecond'
  | 'timestamp-microsecond'
  | 'timestamp-nanosecond'
  | 'interval-daytime'
  | 'interval-yearmonth'
  // Composite types
  | {type: 'decimal'; bitWidth: number; precision: number; scale: number}
  | {type: 'list'; children: Field[]} // one child only
  | {type: 'struct'; children: Field[]}
  | {
      type: 'sparse-union';
      typeIds: Int32Array;
      children: Field[];
      typeIdToChildIndex: {[key: number]: number};
    }
  | {
      type: 'dense-union';
      typeIds: Int32Array;
      children: Field[];
      typeIdToChildIndex: {[key: number]: number};
    }
  | {type: 'fixed-size-binary'; byteWidth: number}
  | {type: 'fixed-size-list'; listSize: number; children: Field[]}
  | {type: 'map'; keysSorted: boolean; children: Field[]} // Field is "struct"
  | {type: 'dictionary'; id: number; indices: KeyType; dictionary: DataType; isOrdered: boolean};
// TODO - unions etc

/**
 * SchemaMetadata
 */
export type SchemaMetadata = Record<string, string>;
export type FieldMetadata = Record<string, string>;

export type Field = {
  name: string;
  type: DataType;
  nullable?: boolean;
  metadata?: FieldMetadata;
};

/**
 * `Schema` type that that can hold all data required by an Arrow Schema
 * but is fully serializable. Helper functions make it easy to convert to and from arrow schemas
 * https://loaders.gl/arrowjs/docs/api-reference/schema
 */
export type Schema = {
  fields: Field[];
  metadata: SchemaMetadata;
};