Translate comments in (Java) source code using Google Translate

translate_java_comments.py

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""
Created on Tue Nov 10 20:28:00 2020

Translate the comments found in a given (Java) source code file
from Japanese to English using Google Translate.
Run from bash as follows to iterate over all files found in a given directory:
> for i in `find src/jp/riken/kscope/ -name "*.java"` ; do python3 ../translate_java_comments.py $i ; done

@author: Jonathan Schilling (jonathan.schilling@mail.de)
"""

# https://pypi.org/project/googletrans/
from googletrans import Translator
translator = Translator()

import time
import sys

if len(sys.argv) > 1:
    currentFile = sys.argv[1]
else:
    # debugging
    currentFile = "/data/jonathan/work/code/K-scope/src/jp/riken/kscope/profiler/common/MagicKey.java"

# logging
print(currentFile)

# read source code file
srcCode = None
with open(currentFile, "r") as f:
    srcCode = "".join(f.readlines())

totalCodeLen = len(srcCode)
# print("length of source code: %d"%(totalCodeLen))
    
# target for translated code
target = ""

# position in source code file
currentStart = 0

# keep track of comments
numComment = 1

# loop over whole source code file
while currentStart < totalCodeLen:
            
    # find comments: /* ... */ or /** ... */
    commentStart1 = sys.maxsize
    commentEnd1 = sys.maxsize
    try:
        commentStart1 = srcCode.index("/*", currentStart)
        commentEnd1 = srcCode.index("*/", commentStart1)+2
        # print("found /* ... */ comment at %d"%(commentStart1,))
    except ValueError:
        pass

    # find comments: // ... \n
    commentStart2 = sys.maxsize
    commentEnd2 = sys.maxsize
    try:
        commentStart2 = srcCode.index("//", currentStart)
        commentEnd2 = srcCode.index("\n", commentStart2)+1
        # print("found // ... \\n comment at %d"%(commentStart2,))
    except ValueError:
        pass
    
    if commentStart1 != sys.maxsize or commentStart2 != sys.maxsize:
    
        # print(" found any comment")
    
        # look which of /*... */ or // ... \n comment comes first
        needNewline = False

        commentStart = sys.maxsize
        commentEnd = sys.maxsize
        if commentStart1 < commentStart2:
            commentStart = commentStart1
            commentEnd = commentEnd1
            # print("  comment /* ... */ is first")
        else:
            commentStart = commentStart2
            commentEnd = commentEnd2
            needNewline = True
            # print("  comment // ... \\n is first")
            
        print("   comment %d from %d to %d"%(numComment, commentStart, commentEnd))
        #print("'"+srcCode[commentStart:commentEnd]+"'")
        
        # code before start of comment
        target += srcCode[currentStart:commentStart]
        
        # extract comment
        comment = srcCode[commentStart:commentEnd]
        translatedComment = comment
        
        numRetries = 2
        for i in range(numRetries):
            
            # check if comment contains only ASCII characters --> skip translation
            allAscii = all(ord(c) < 128 for c in translatedComment)
            if not allAscii:
                
                if i==numRetries-1:
                    raise RuntimeError("Could not get translation. Try again!")
                elif i>0: # WTF? Why is this necessary?
                    print("retry %d/%d"%(i,numRetries-1))
                    
                    # if a retry was necessary since translation did not remove
                    # all non-ASCII characters, list the remaining ones here:
                    for c in translatedComment:
                        if ord(c) >= 128:
                            print("non-ascii: "+str(ord(c)))
                    
                    print("    comment: '"+translatedComment+"'")
                
                
                # if i > 1:
                #     print("retry since still non-ascii characters present")
                
                # translate; retry in case something weird happens
                try:
                    # actually translate
                    translationSuggestion = translator.translate(comment, src='ja').text
                    
                    # after each translate, wait just a little bit to prevent clobbering
                    time.sleep(0.2)
                    
                    if translationSuggestion.strip() == "":
                        print("   no translated response...")
                        raise AttributeError("no response from translation!")
                except AttributeError:
                    time.sleep(5)
                    #print("  retry %d/%d"%(i+1,numRetries))
                    continue
                
                # if we got to this point, the translation succeeded eventually
                translatedComment = translationSuggestion
                
                # fix common translation errors;
                # seems like Google Translate is not so much optimized
                # for source code...
                translatedComment = translatedComment.replace("/ *", "/*") # also handles "/ **" --> "/**"
                translatedComment = translatedComment.replace("* /", "*/")
                translatedComment = translatedComment.replace("<br />", "<br/>")
                
                # zero-width space
                translatedComment = translatedComment.replace(chr(8203), '')
                translatedComment = translatedComment.replace(chr(8211), '-')
                translatedComment = translatedComment.replace(chr(8213), '-')
                translatedComment = translatedComment.replace(chr(8722), '-')
                
                if needNewline:
                    translatedComment += "\n"
                
                #print("    translated: '"+comment.replace("\n", "\\n")+"' --> '"+translatedComment.replace("\n", "\\n")+"'")
                #print("    translated: '"+translatedComment+"'")
                
        target += translatedComment
        
        # print("'"+target+"'")
       
        numComment += 1
        currentStart = commentEnd
    else:
        # no comments found anymore --> done with this file
        break
        
# code part after end of last comment
target += srcCode[commentEnd:]

# print(target)

# replace source code file contents
with open(currentFile, "w") as f:
    f.write(target)