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Mercurial > core / lisp/lib/dat/parquet/io.lisp

changeset 548: b57066450cfa
parent: ec1d4d544c36
author: Richard Westhaver <ellis@rwest.io>
date: Mon, 15 Jul 2024 20:59:04 -0400
permissions: -rw-r--r--
description: init tcompact encoders 
     1 ;;; io.lisp --- Parquet IO
     2 
     3 ;;
     4 
     5 ;;; Code:
     6 (in-package :dat/parquet)
     7 
     8 ;;; Read/Write
     9 (defun parquet-write-magic (stream)
    10   (write-string +parquet-magic-number+ stream))
    11 
    12 (defun parquet-read-magic (stream)
    13   (assert (= #.(char-code (aref +parquet-magic-number+ 0)) (read-byte stream)))
    14   (assert (= #.(char-code (aref +parquet-magic-number+ 1)) (read-byte stream)))
    15   (assert (= #.(char-code (aref +parquet-magic-number+ 2)) (read-byte stream)))
    16   (assert (= #.(char-code (aref +parquet-magic-number+ 3)) (read-byte stream))))
    17 
    18 (defun parquet-read-unsigned (stream)
    19   (read-uleb128 stream))
    20 
    21 (defun parquet-read-signed (stream)
    22   (read-leb128 stream))
    23 
    24 (defun parquet-read-boolean (stream)
    25   (ecase (read-byte stream)
    26     (0 nil)
    27     (1 t)))
    28 
    29 (defun parquet-file-stream-p (stream)
    30   "Assert the start and end of a file STREAM are the parquet magic bytes."
    31   (parquet-read-magic stream)
    32   ;; set position to end - 4
    33   (file-position stream (- (the fixnum (file-length stream)) 4))
    34   (parquet-read-magic stream))
    35 
    36 (defun parquet-read-schema-element (stream))
    37 (defun parquet-read-schema (stream)
    38   "Read a parquet-schema which is repeated list of parquet-schema-element."
    39   
    40   )
    41 
    42 (defun parquet-read-file-meta-data (stream)
    43   "Read a parquet-file-meta-data object from STREAM."
    44   ;; version
    45   (make-instance 'parquet-file-meta-data
    46     :version (parquet-read-signed stream)
    47     :schema (list (parquet-read-signed stream))))
    48 
    49 (defun parquet-read-footer (stream)
    50   "Read the footer of parquet data in STREAM."
    51   (parquet-file-stream-p stream)
    52   ;; set file-position, read metadata length and magic
    53   (file-position stream (- (file-length stream) 8))
    54   (let ((len (parquet-read-unsigned stream)))
    55     (file-position stream (- (file-length stream) 8 len))
    56     (parquet-read-file-meta-data stream)))