Notepad++ Automatic Detection of Python Tabs or Spaces

Question

I normally write code with tabs but many python libraries use spaces. Is there any way for Notepad++ to automatically detect how the file is formatted and have it automatically switch to using spaces when the file is already formatted that way?

BTW, I know there was already an SO question on how to change Notepad++'s tab format. But it would be better if it automatically changed based on the current file's formatting.

Answer 1

If you install the "Python Script" plugin for Notepad++, you can write code to automatically switch between tabs and spaces.

Here's how:

1. In the menu: Plugins -> Python Script -> Configuration, and set Initialization to ATSTARTUP. When Notepad++ starts, the startup.py script will run.

2. Find startup.py and edit it. On my PC its path is c:\Program Files\Notepad++\plugins\PythonScript\scripts\startup.py, add the following code to startup.py.

The function buffer_active() is called every time when you switch tab, and guess_tab() checks whether the text is using tab indent or not. You can show the Python console to debug the code.

def guess_tab(text):
    count = 0
    for line in text.split("\n"):
        indents = line[:len(line)-len(line.lstrip())]
        if "\t" in indents:
            count += 1
    if count > 5: 
        return True
    else:
        return False

def buffer_active(arg):
    editor.setBackSpaceUnIndents(True)
    use_tab = guess_tab(editor.getText())
    editor.setUseTabs(use_tab)
    sys.stderr.write( "setUseTabs %s\n" % use_tab )

notepad.clearCallbacks([NOTIFICATION.BUFFERACTIVATED])    
notepad.callback(buffer_active, [NOTIFICATION.BUFFERACTIVATED])

This is only an example, feel free to make guess_tab() better yourself, maybe use a global dict to cache the result and speedup the callback function.

Answer 2

Here is an improved version based on HYRY's answer :

• Works on the startup tab (when you launch notepad++ to open a file)
• Doesn't need a minimal amount of rows to trigger indentation detection. Indentation guess is based on the first encountered indented line.
• Keeps indentation defaults when indentation cannot be detected
• Very efficient, doesn't slow down Notepad++ when opening big files (tested on a 220 MB file, indentation detection takes only < 300 ms)

Available for download here : https://gist.github.com/vincepare/8a204172d959defb2122

import re
import time

def indent_guess_tab(text):
    for line in text.split("\n"):
        pattern = re.compile("^( {4,}|\t)")
        match = pattern.match(line)
        if (match):
            return True if ("\t" in match.group(1)) else False

def indent_auto_detect(arg):
    start = time.clock()

    # Get text sample
    maxLen = 500000
    len = editor.getTextLength()
    len = len if len < maxLen else maxLen
    sample = editor.getTextRange(0, len)

    # Indent set
    current_use_tab = editor.getUseTabs()
    use_tab = indent_guess_tab(sample)

    if (use_tab != None and use_tab != current_use_tab):
        console.write("Indent use tab switch (%s => %s)\n" % (current_use_tab, use_tab))
        editor.setUseTabs(use_tab)

    end = time.clock()
    console.write("Indentation detection took %s ms\n" % (round((end-start)*1000, 3)))

notepad.clearCallbacks([NOTIFICATION.BUFFERACTIVATED, NOTIFICATION.READY])    
notepad.callback(indent_auto_detect, [NOTIFICATION.BUFFERACTIVATED])
notepad.callback(indent_auto_detect, [NOTIFICATION.READY])
console.write("Automatic indentation detection started\n")
indent_auto_detect(None)