[dexter] Replace old style line label references (='label') with the new style (=ref('label')).

make_label_refs.py

# Replace old style line label references (='label') with the new style (=ref('label')).
import os
import re
import sys

def help_and_quit():
    print('usage: python3 make_label_refs.py <directory|file>')
    exit(1)
try:
    path = sys.argv[1]
except:
    help_and_quit()

# DexExpectWatchValue and DexExpectWatchType line number fields:
#   on_line='label'
#   to_line='label'
#   from_line='label'
#   ^--------^^-----^
#   <arg>      <label>
watch_patt = re.compile(r'(?P<arg>(to|from|on)_line\s*=\s*)(?P<label>(\'|")(.+?)(\'|"))', re.M)

# DexExpectProgramState line number fields:
#   'lineno': 'label'
#   ^--------^^-----^
#   <arg>      <label>
state_patt = re.compile(r'(?P<arg>(\'|")\s*lineno\s*(\'|")\s*:\s*)(?P<label>(\'|")(.+?)(\'|"))', re.M)

def replace_in_text(text):
    text, changes1 = re.subn(watch_patt, r'\g<arg>ref(\g<label>)', text)
    text, changes2 = re.subn(state_patt, r'\g<arg>ref(\g<label>)', text)
    return (text, changes1 + changes2)

def update_in_file(file):
    with open(file, 'r+') as f:
        try:
            text = f.read()
        except:
            print(f'Can\'t read {file}')
            return
        text, changes = replace_in_text(text)
        if changes != 0:
            print(f'Modifying {file}')
            with open(file, 'w') as f:
                f.write(text)

if os.path.isdir(path):
    for dirpath, dirnames, filenames in os.walk(path):
        for filename in filenames:
            update_in_file(os.path.join(dirpath, filename))
elif os.path.isfile(path):
    update_in_file(path)
else:
    help_and_quit()