Use prepended length for bit-packed hybrid bool columns (#62)

src/datapage.js

@@ -38,7 +38,8 @@ export function readDataPage(bytes, daph, schemaPath, { type }) {
     const bitWidth = type === 'BOOLEAN' ? 1 : view.getUint8(reader.offset++)
     if (bitWidth) {
       dataPage = new Array(nValues)
-      readRleBitPackedHybrid(reader, bitWidth, view.byteLength - reader.offset, dataPage)
+      const encodedLength = type === 'BOOLEAN' ? 0 : view.byteLength - reader.offset
+      readRleBitPackedHybrid(reader, bitWidth, encodedLength, dataPage)
     } else {
       dataPage = new Uint8Array(nValues) // nValue zeroes
     }

src/encoding.js

@@ -22,7 +22,7 @@ export function bitWidth(value) {
  */
 export function readRleBitPackedHybrid(reader, width, length, output) {
   if (!length) {
-    // length = reader.view.getUint32(reader.offset, true)
+    length = reader.view.getUint32(reader.offset, true)
     reader.offset += 4
   }
   let seen = 0

test/files/boolean_rle.json

@@ -0,0 +1,17 @@
+[
+    [1],
+    [1],
+    [1],
+    [1],
+    [1],
+    [null],
+    [null],
+    [null],
+    [null],
+    [null],
+    [0],
+    [0],
+    [0],
+    [0],
+    [0]
+]

test/files/boolean_rle.metadata.json

@@ -0,0 +1,61 @@
+{
+  "created_by": "Polars",
+  "key_value_metadata": [
+    {
+      "key": "ARROW:schema",
+      "value": "/////3YAAAAEAAAA8v///xQAAAAEAAEAAAAKAAsACAAKAAQA+P///wwAAAAIAAgAAAAEAAEAAAAEAAAA7P///ywAAAAgAAAAGAAAAAEGAAAQABIABAAQABEACAAAAAwAAAAAAPz///8EAAQADQAAAEJvb2xlYW5Db2x1bW4A"
+    }
+  ],
+  "metadata_length": 308,
+  "num_rows": 15,
+  "row_groups": [
+    {
+      "columns": [
+        {
+          "column_index_length": 17,
+          "column_index_offset": 89,
+          "crypto_metadata": 17,
+          "file_offset": 47,
+          "meta_data": {
+            "codec": "SNAPPY",
+            "data_page_offset": 4,
+            "encodings": [
+              "RLE"
+            ],
+            "num_values": 15,
+            "path_in_schema": [
+              "BooleanColumn"
+            ],
+            "statistics": {
+              "max_value": true,
+              "min_value": false,
+              "null_count": 5
+            },
+            "total_compressed_size": 43,
+            "total_uncompressed_size": 41,
+            "type": "BOOLEAN"
+          },
+          "offset_index_length": 10,
+          "offset_index_offset": 106
+        }
+      ],
+      "file_offset": 4,
+      "num_rows": 15,
+      "ordinal": 0,
+      "total_byte_size": 41,
+      "total_compressed_size": 43
+    }
+  ],
+  "schema": [
+    {
+      "name": "root",
+      "num_children": 1
+    },
+    {
+      "name": "BooleanColumn",
+      "repetition_type": "OPTIONAL",
+      "type": "BOOLEAN"
+    }
+  ],
+  "version": 1
+}