schemaElement returns trees

.gitignore

@@ -1,7 +1,6 @@
 node_modules
 package-lock.json
 coverage
-dist
 *.tgz
 example.parquet
 .vscode

package.json

@@ -27,15 +27,15 @@
     "typecheck": "tsc"
   },
   "devDependencies": {
-    "@types/node": "20.11.21",
-    "@typescript-eslint/eslint-plugin": "7.1.0",
+    "@types/node": "20.11.26",
+    "@typescript-eslint/eslint-plugin": "7.2.0",
     "@vitest/coverage-v8": "1.3.1",
     "eslint": "8.57.0",
     "eslint-plugin-import": "2.29.1",
-    "eslint-plugin-jsdoc": "48.2.0",
+    "eslint-plugin-jsdoc": "48.2.1",
     "http-server": "14.1.1",
     "hysnappy": "0.3.0",
-    "typescript": "5.3.3",
+    "typescript": "5.4.2",
     "vitest": "1.3.1"
   }
 }

src/column.js

@@ -79,10 +79,10 @@ export function readColumn(arrayBuffer, columnOffset, rowGroup, columnMetadata,
       } else {
         if (dictionaryEncoding && dictionary) {
           dereferenceDictionary(dictionary, dataPage)
-          values = convert(dataPage, schemaElement(schema, columnMetadata.path_in_schema))
+          values = convert(dataPage, schemaElement(schema, columnMetadata.path_in_schema).element)
         } else if (Array.isArray(dataPage)) {
           // convert primitive types to rich types
-          values = convert(dataPage, schemaElement(schema, columnMetadata.path_in_schema))
+          values = convert(dataPage, schemaElement(schema, columnMetadata.path_in_schema).element)
         } else {
           values = dataPage // TODO: data page shouldn't be a fixed byte array?
         }

src/datapage.js

@@ -61,8 +61,8 @@ export function readDataPage(bytes, daph, schema, columnMetadata) {
   // read values based on encoding
   const nValues = daph.num_values - numNulls
   if (daph.encoding === 'PLAIN') {
-    const se = schemaElement(schema, columnMetadata.path_in_schema)
-    const utf8 = se.converted_type === 'UTF8'
+    const { element } = schemaElement(schema, columnMetadata.path_in_schema)
+    const utf8 = element.converted_type === 'UTF8'
     const plainObj = readPlain(dataView, columnMetadata.type, nValues, offset, utf8)
     values = Array.isArray(plainObj.value) ? plainObj.value : Array.from(plainObj.value)
     offset += plainObj.byteLength

src/datapageV2.js

@@ -47,8 +47,8 @@ export function readDataPageV2(compressedBytes, ph, schema, columnMetadata, comp
   // read values based on encoding
   const nValues = daph2.num_values - daph2.num_nulls
   if (daph2.encoding === 'PLAIN') {
-    const se = schemaElement(schema, columnMetadata.path_in_schema)
-    const utf8 = se.converted_type === 'UTF8'
+    const { element } = schemaElement(schema, columnMetadata.path_in_schema)
+    const utf8 = element.converted_type === 'UTF8'
     let page = compressedBytes.slice(offset)
     if (daph2.is_compressed && columnMetadata.codec !== 'UNCOMPRESSED') {
       page = decompressPage(page, uncompressedPageSize, columnMetadata.codec, compressors)

src/metadata.js

@@ -1,5 +1,5 @@
 import { CompressionCodec, ConvertedType, Encoding, FieldRepetitionType, ParquetType } from './constants.js'
-import { schemaTree } from './schema.js'
+import { schemaElement } from './schema.js'
 import { deserializeTCompactProtocol } from './thrift.js'
 
 /**
@@ -170,7 +170,7 @@ export function parquetMetadata(arrayBuffer) {
  * @returns {SchemaTree} tree of schema elements
  */
 export function parquetSchema(metadata) {
-  return schemaTree(metadata.schema, 0)
+  return schemaElement(metadata.schema, [])
 }
 
 /**

src/schema.js

@@ -10,7 +10,7 @@
  * @param {number} rootIndex index of the root element
  * @returns {SchemaTree} tree of schema elements
  */
-export function schemaTree(schema, rootIndex) {
+function schemaTree(schema, rootIndex) {
   const root = schema[rootIndex]
   const children = []
   let count = 1
@@ -32,7 +32,7 @@ export function schemaTree(schema, rootIndex) {
  *
  * @param {SchemaElement[]} schema
  * @param {string[]} name path to the element
- * @returns {SchemaElement} schema element
+ * @returns {SchemaTree} schema element
  */
 export function schemaElement(schema, name) {
   let tree = schemaTree(schema, 0)
@@ -42,7 +42,7 @@ export function schemaElement(schema, name) {
     if (!child) throw new Error(`parquet schema element not found: ${name}`)
     tree = child
   }
-  return tree.element
+  return tree
 }
 
 /**
@@ -77,7 +77,7 @@ export function isRequired(schema, name) {
 export function getMaxRepetitionLevel(schema, parts) {
   let maxLevel = 0
   parts.forEach((part, i) => {
-    const element = schemaElement(schema, parts.slice(0, i + 1))
+    const { element } = schemaElement(schema, parts.slice(0, i + 1))
     if (element.repetition_type === 'REPEATED') {
       maxLevel += 1
     }
@@ -95,7 +95,7 @@ export function getMaxRepetitionLevel(schema, parts) {
 export function getMaxDefinitionLevel(schema, parts) {
   let maxLevel = 0
   parts.forEach((part, i) => {
-    const element = schemaElement(schema, parts.slice(0, i + 1))
+    const { element } = schemaElement(schema, parts.slice(0, i + 1))
     if (element.repetition_type !== 'REQUIRED') {
       maxLevel += 1
     }

test/schema.test.js

@@ -20,7 +20,11 @@ describe('Parquet schema utils', () => {
 
   describe('schemaElement', () => {
     it('should return the correct schema element', () => {
-      expect(schemaElement(schema, ['child1'])).toEqual(schema[1])
+      expect(schemaElement(schema, ['child1'])).toEqual({
+        children: [],
+        count: 1,
+        element: { name: 'child1', repetition_type: 'OPTIONAL' },
+      })
     })
 
     it('should throw an error if element not found', () => {