Python Simple one-pass

  • 1

    If we think about it, the only time a new line can be added to the result set is if the parsed line is not empty.

    Furthermore, we only have to check if we can add the current parsed line at the end of each input line.

    Therefore, at each end of input line we just need to check if the parsed line is not empty and if we're not currently in a comment block.

    We just have to iterate over each character of each line and modify the flag value to keep track of whether we're in a comment block, and then handle accordingly when we reach the end of each line.

     def removeComments(self, source):
            result, parseLine, flag, fInd = [], [], False, -1
            for line in source:
                for i,c in enumerate(line):
                    if not flag:
                        if c == '/' and i != len(line)-1 and line[i+1] in ('*', '/'): # comment start token
                            if line[i+1] == '/': # if line comment, skip to end
                            flag, fInd = True, i+1 # activate flag and record position
                            parseLine.append(c) # valid char
                    elif c == '/': # potential block end
                        prev = max(0, i-1)
                        flag = (fInd == prev) or (line[prev] != '*')
                if not flag: # a parsed line can only be complete at the end of a line
                    if parseLine: # only append if line isn't empty
                        parseLine = []
                fInd = -1 # reset block comment start as the current line is done.
            return result

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