A BBEdit Text Filter script to "pretty print" GitHub Flavored Markdown tables.

Normalize Table.py

#!/usr/local/bin/python3
#
# Normalize Table.py
# https://gist.github.com/levigroker/630b9920ff5d74840c37aa3538b5c78f
#
# A BBEdit Text Filter script to "pretty print" GitHub Flavored Markdown tables.
# See http://bbeditextras.org/wiki/index.php?title=Text_Filters
# See # GitHub Flavored Markdown Spec: https://github.github.com/gfm/
#
# Originally from http://www.leancrew.com/all-this/2012/11/markdown-table-scripts-for-bbedit/
# and https://github.com/drdrang/wp-md
#
# Modified by Levi Brown
# @levigroker
# levigroker@gmail.com
# 2022-07-27
##

import sys

def just(string, type, n):
    "Justify a string to length n according to type."
    
    if type == '::':
        return string.center(n)
    elif type == '-:':
        return string.rjust(n)
    elif type == ':-':
        return string.ljust(n)
    else:
        return string


def normtable(text):
    "Aligns the vertical bars in a text table."
    
    # Start by turning the text into a list of lines.
    lines = text.splitlines()
    rows = len(lines)
    
    # Figure out the cell formatting.
    # First, find the separator line.
    for i in range(rows):
        if set(lines[i]).issubset('| :.-'):
            formatline = lines[i]
            formatrow = i
            break
    
    # Delete the separator line from the content.
    del lines[formatrow]
    
    # Determine how each column is to be justified.
    formatline = formatline.strip(' ')
    if formatline[0] == '|': formatline = formatline[1:]
    if formatline[-1] == '|': formatline = formatline[:-1]
    fstrings = formatline.split('|')
    justify = []
    for cell in fstrings:
        ends = cell[0] + cell[-1]
        if ends == '::':
            justify.append('::')
        elif ends == '-:':
            justify.append('-:')
        else:
            justify.append(':-')
    
    # Assume the number of columns in the separator line is the number
    # for the entire table.
    columns = len(justify)
    
    # Extract the content into a matrix.
    content = []
    for line in lines:
        line = line.strip(' ')
        if line[0] == '|': line = line[1:]
        if line[-1] == '|': line = line[:-1]
        cells = line.split('|')
        # Put exactly one space at each end as "bumpers."
        linecontent = [ ' ' + x.strip() + ' ' for x in cells ]
        content.append(linecontent)
    
    # Append cells to rows that don't have enough.
    rows = len(content)
    for i in range(rows):
        while len(content[i]) < columns:
            content[i].append('')
    
    # Get the width of the content in each column. The minimum width will
    # be 2, because that's the shortest length of a formatting string and
    # because that matches an empty column with "bumper" spaces.
    widths = [2] * columns
    for row in content:
        for i in range(columns):
            widths[i] = max(len(row[i]), widths[i])
    
    # Add whitespace to make all the columns the same width and 
    formatted = []
    for row in content:
        formatted.append('|' + '|'.join([ just(s, t, n) for (s, t, n) in zip(row, justify, widths) ]) + '|')
    
    # Recreate the format line with the appropriate column widths.
    formatline = '|' + '|'.join([ s[0] + '-'*(n-2) + s[-1] for (s, n) in zip(justify, widths) ]) + '|'
    
    # Insert the formatline back into the table.
    formatted.insert(formatrow, formatline)
    
    # Return the formatted table.
    return '\n'.join(formatted)

        
# Read the input, process, and print.
unformatted = sys.stdin.read()   
print(normtable(unformatted))