Question

Let me explain. Suppose I want to teach Python to someone who only speaks Spanish. As you know, in most programming languages all keywords are in English. How complex would it be to create a program that will find all keywords in a given source code and translate them? Would I need to use a parser and stuff, or will a couple of regexes and string functions be enough?

If it depends on the source programming language, then Python and Javascript would be the most important.

What I mean by “how complex would it be” is that would it be enough to have a list of keywords, and parse the source code to find keywords not in quotes? Or are there enough syntactical weirdnesses that something more complicated is required?

Answer 1

If all you want is to translate keywords, then (while you definitely DO need a proper parser, as otherwise avoiding any change in strings, comments &c becomes a nightmare) the task is quite simple. For example, since you mentioned Python:

import cStringIO
import keyword
import token
import tokenize

samp = '''\
for x in range(8):
  if x%2:
    y = x
    while y>0:
      print y,
      y -= 3
    print
'''

translate = {'for': 'per', 'if': 'se', 'while': 'mentre', 'print': 'stampa'}

def toks(tokens):
  for tt, ts, src, erc, ll in tokens:
    if tt == token.NAME and keyword.iskeyword(ts):
      ts = translate.get(ts, ts)
    yield tt, ts

def main():
  rl = cStringIO.StringIO(samp).readline
  toki = toks(tokenize.generate_tokens(rl))
  print tokenize.untokenize(toki)

main()

I hope it’s obvious how to generalize this to “translate” any Python source and in any language (I’m supplying only a very partial Italian keyword translation dict). This emits:

per x in range (8 ):
  se x %2 :
    y =x 
    mentre y >0 :
      stampa y ,
      y -=3 
    stampa 

(strange though correct whitespace, but that could be easily enough remedied). As an Italian speaker I can tell you this is terrible to read, but that’s par for the course for any “programming language translation” as you desire. Worse, NON-keywords such as range remain un-translated (as per your specs) — of course, you don’t have to constrain your translation to keywords-only (it’s easy enough to remove the if that does that above;-).