PageType enum to string

src/column.js

@@ -1,5 +1,4 @@
 import { assembleObjects } from './assemble.js'
-import { PageType } from './constants.js'
 import { convert } from './convert.js'
 import { readDataPage, readDictionaryPage } from './datapage.js'
 import { readDataPageV2 } from './datapageV2.js'
@@ -49,7 +48,7 @@ export function readColumn(arrayBuffer, columnOffset, rowGroup, columnMetadata,
     )
 
     // parse page data by type
-    if (header.type === PageType.DATA_PAGE) {
+    if (header.type === 'DATA_PAGE') {
       const daph = header.data_page_header
       if (!daph) throw new Error('parquet data page header is undefined')
 
@@ -95,7 +94,7 @@ export function readColumn(arrayBuffer, columnOffset, rowGroup, columnMetadata,
       // you need the total number of children, not the number of top-level values.
 
       concat(rowData, values)
-    } else if (header.type === PageType.DICTIONARY_PAGE) {
+    } else if (header.type === 'DICTIONARY_PAGE') {
       const diph = header.dictionary_page_header
       if (!diph) throw new Error('parquet dictionary page header is undefined')
 
@@ -103,7 +102,7 @@ export function readColumn(arrayBuffer, columnOffset, rowGroup, columnMetadata,
         compressedBytes, Number(header.uncompressed_page_size), columnMetadata.codec, compressors
       )
       dictionary = readDictionaryPage(page, diph, schema, columnMetadata)
-    } else if (header.type === PageType.DATA_PAGE_V2) {
+    } else if (header.type === 'DATA_PAGE_V2') {
       const daph2 = header.data_page_header_v2
       if (!daph2) throw new Error('parquet data page header v2 is undefined')
 
@@ -200,6 +199,7 @@ export function decompressPage(compressedBytes, uncompressed_page_size, codec, c
 
 /**
  * Expand data page list with nulls and convert to utf8.
+ *
  * @param {number[]} definitionLevels
  * @param {number} maxDefinitionLevel
  * @param {ArrayLike<any>} dataPage

src/constants.js

@@ -94,9 +94,13 @@ export const CompressionCodec = [
   'LZ4_RAW',
 ]
 
-export const PageType = {
-  DATA_PAGE: 0,
-  INDEX_PAGE: 1,
-  DICTIONARY_PAGE: 2,
-  DATA_PAGE_V2: 3,
-}
+/**
+ * @typedef {import('./types.js').PageType} PageType
+ * @type {PageType[]}
+ */
+export const PageType = [
+  'DATA_PAGE',
+  'INDEX_PAGE',
+  'DICTIONARY_PAGE',
+  'DATA_PAGE_V2',
+]

src/datapage.js

@@ -1,26 +1,16 @@
 import { readData, readPlain, readRleBitPackedHybrid, widthFromMaxInt } from './encoding.js'
-import {
-  getMaxDefinitionLevel,
-  getMaxRepetitionLevel,
-  isRequired,
-  schemaElement,
-  skipDefinitionBytes,
-} from './schema.js'
+import { getMaxDefinitionLevel, getMaxRepetitionLevel, isRequired, schemaElement, skipDefinitionBytes } from './schema.js'
 
 const skipNulls = false // TODO
 
 /**
+ * Read a data page from the given Uint8Array.
+ *
  * @typedef {{ definitionLevels: number[], numNulls: number }} DefinitionLevels
  * @typedef {import("./types.d.ts").DataPage} DataPage
  * @typedef {import("./types.d.ts").ColumnMetaData} ColumnMetaData
  * @typedef {import("./types.d.ts").DataPageHeader} DataPageHeader
- * @typedef {import("./types.d.ts").DictionaryPageHeader} DictionaryPageHeader
  * @typedef {import("./types.d.ts").SchemaElement} SchemaElement
- */
-
-/**
- * Read a data page from the given Uint8Array.
- *
  * @param {Uint8Array} bytes raw page data (should already be decompressed)
  * @param {DataPageHeader} daph data page header
  * @param {SchemaElement[]} schema schema for the file
@@ -92,6 +82,7 @@ export function readDataPage(bytes, daph, schema, columnMetadata) {
 /**
  * Read a page containing dictionary data.
  *
+ * @typedef {import("./types.d.ts").DictionaryPageHeader} DictionaryPageHeader
  * @param {Uint8Array} bytes raw page data
  * @param {DictionaryPageHeader} diph dictionary page header
  * @param {SchemaElement[]} schema schema for the file

src/encoding.js

@@ -331,9 +331,6 @@ function readBitPacked(reader, header, bitWidth, remaining) {
       reader.offset++
       left += 8
     } else {
-      // otherwise, read bitWidth number of bits
-      // don't write more than remaining number of rows
-      // even if there are still bits to read
       if (remaining > 0) {
         // emit value by shifting off to the right and masking
         value.push((data >> right) & mask)
@@ -344,7 +341,6 @@ function readBitPacked(reader, header, bitWidth, remaining) {
     }
   }
 
-  // return values and number of bytes read
   return value
 }
 

src/header.js

@@ -1,10 +1,7 @@
-import { Encoding } from './constants.js'
+import { Encoding, PageType } from './constants.js'
 import { deserializeTCompactProtocol } from './thrift.js'
 
 /**
- * Return type with bytes read.
- * This is useful to advance an offset through a buffer.
- *
  * @typedef {import("./types.d.ts").Decoded<T>} Decoded
  * @template T
  */
@@ -21,7 +18,7 @@ export function parquetHeader(arrayBuffer, offset) {
   const { value: header, byteLength } = deserializeTCompactProtocol(arrayBuffer, offset)
 
   // Parse parquet header from thrift data
-  const type = header.field_1
+  const type = PageType[header.field_1]
   const uncompressed_page_size = header.field_2
   const compressed_page_size = header.field_3
   const crc = header.field_4
@@ -52,7 +49,7 @@ export function parquetHeader(arrayBuffer, offset) {
     encoding: Encoding[header.field_8.field_4],
     definition_levels_byte_length: header.field_8.field_5,
     repetition_levels_byte_length: header.field_8.field_6,
-    is_compressed: header.field_8.field_7 === undefined ? true : header.field_8.field_7, // default to true
+    is_compressed: header.field_8.field_7 === undefined ? true : header.field_8.field_7, // default true
     statistics: header.field_8.field_8,
   }
 

src/read.js

@@ -67,7 +67,6 @@ export async function parquetRead(options) {
 
 /**
  * Read a row group from a file-like object.
- * Reads the minimal number of columns to satisfy the request.
  *
  * @typedef {import('./types.js').RowGroup} RowGroup
  * @param {object} options read options

src/types.d.ts

@@ -195,12 +195,11 @@ interface PageEncodingStats {
   count: number
 }
 
-export enum PageType {
-  DATA_PAGE = 0,
-  INDEX_PAGE = 1,
-  DICTIONARY_PAGE = 2,
-  DATA_PAGE_V2 = 3,
-}
+export type PageType =
+  'DATA_PAGE' |
+  'INDEX_PAGE' |
+  'DICTIONARY_PAGE' |
+  'DATA_PAGE_V2'
 
 interface SortingColumn {
   column_idx: number