CSV Parser.

gistfile1.txt

    /*
    MIT LICENSE.
    (feel free to drop this entire comments section, and use for any commercial or open projects).
    Written by Tatarize. 
    
    Iterable fast csv stream parser.
    You would typically process this quite helpfully like:
    
    for (String[] csv : parseCSV(stream)) {
        <deal with parsed csv data>
    }
    
    */
    public static Iterable<String[]> parseCSV(final InputStream stream) throws IOException {
        return new Iterable<String[]>() {
            @Override
            public Iterator<String[]> iterator() {
                return new Iterator<String[]>() {
                    static final int UNCALCULATED = 0;
                    static final int READY = 1;
                    static final int FINISHED = 2;
                    int state = UNCALCULATED;
                    ArrayList<String> value_list = new ArrayList<>();
                    StringBuilder sb = new StringBuilder();
                    String[] return_value;

                    public void end() {
                        end_part();
                        return_value = new String[value_list.size()];
                        value_list.toArray(return_value);
                        value_list.clear();
                    }

                    public void end_part() {
                        value_list.add(sb.toString());
                        sb.setLength(0);
                    }

                    public void append(int ch) {
                        sb.append((char) ch);
                    }

                    public void calculate() throws IOException {
                        boolean inquote = false;
                        while (true) {
                            int ch = stream.read();
                            switch (ch) {
                                default: //regular character.
                                    append(ch);
                                    break;
                                case -1: //read has reached the end.
                                    if ((sb.length() == 0) && (value_list.isEmpty())) {
                                        state = FINISHED;
                                    } else {
                                        end();
                                        state = READY;
                                    }
                                    return;
                                case '\r':
                                case '\n': //end of line.
                                    if (inquote) {
                                        append(ch);
                                    } else {
                                        end();
                                        state = READY;
                                        return;
                                    }
                                    break;
                                case ',': //comma
                                    if (inquote) {
                                        append(ch);
                                    } else {
                                        end_part();
                                        break;
                                    }
                                    break;
                                case '"': //quote.
                                    inquote = !inquote;
                                    break;
                            }
                        }
                    }

                    @Override
                    public boolean hasNext() {
                        if (state == UNCALCULATED) {
                            try {
                                calculate();
                            } catch (IOException ex) {
                            }
                        }
                        return state == READY;
                    }

                    @Override
                    public String[] next() {
                        if (state == UNCALCULATED) {
                            try {
                                calculate();
                            } catch (IOException ex) {
                            }
                        }
                        state = UNCALCULATED;
                        return return_value;
                    }
                };
            }
        };
    }