CSV Parser - Airbnb

Buttercola: Airbnb: CSV Parser
/*

John,Smith,john.smith@gmail.com,Los Angeles,1
Jane,Roberts,janer@msn.com,"San Francisco, CA",0
"Alexandra ""Alex""",Menendez,alex.menendez@gmail.com,Miami,1
"""Alexandra Alex"""

John|Smith|john.smith@gmail.com|Los Angeles|1
Jane|Roberts|janer@msn.com|San Francisco, CA|0
Alexandra "Alex"|Menendez|alex.menendez@gmail.com|Miami|1
"Alexandra Alex"
*/

Understand the problem:
For this problem, there are several cases need to consider:
1. For comma, transform to |
2. If comma is inside a quote, don't treat the comma as separated. Remove the comma and print the entire token. e.g. "San Francisco, CA" => San Francisco, CA
3. If there are double quotes, remove one. e.g. "Alexandra ""Alex""" => Alexandra "Alex". 
Note that """Alexandra Alex""" becomes "Alexandra Alex" because we first remove the outer-most quote, and then remove one quote of the double quote.

It's very complex to build a real csv parser - need consider white space etc

  public static String parseCSV(String s) {

    List<String> result = new ArrayList<>();

    if (s == null || s.length() == 0) {

      return "";

    }

     

    boolean inQuote = false;

    StringBuffer sb = new StringBuffer();

     

    for (int i = 0; i < s.length(); i++) {

      if (inQuote) {

        if (s.charAt(i) == '"') {

          if (i == s.length() - 1) {

            result.add(sb.toString()); // change the 2 lines to break

            return printStr(result); //

          } else if (s.charAt(i + 1) == '"') {

            sb.append('"');

            i++;

          } else {

            result.add(sb.toString());

            sb.setLength(0);

            inQuote = false;

            i++;

          }

        } else {

          sb.append(s.charAt(i));

        }

      } else {

        if (s.charAt(i) == '"') {

          inQuote = true;

        } else if (s.charAt(i) == ',') {

          result.add(sb.toString());

          sb.setLength(0);

        } else {

          sb.append(s.charAt(i));

        }

      }

    }

     

    if (sb.length() > 0) {

      result.add(sb.toString());

    }

     

    return printStr(result);

  }

   

  private static String printStr(List<String> input) {

    if (input == null || input.size() == 0) {

      return "";

    }

     

    StringBuffer sb = new StringBuffer();

    for (int i = 0; i < input.size(); i++) {

      sb.append(input.get(i));

      if (i == input.size() - 1) {

        break;

      }

      sb.append("|");

    }

     

    return sb.toString();

  }

airbnb面试题汇总
给定一个CSV文件，格式是 “some_name|some_address|some_phone|some_job”
要求输出Json format “{name:some_name, address:some_addres,phone:some_phone, job:some_job}”
输入内容中有些特殊符号要注意处理

vector<string> parseCSV(string s) {
    vector<string> ans;
    bool inQuote = false;
    string tmp = "";
    for(int i = 0; i < s.length(); ++i) {
        if(inQuote) {
            if(s[i] == '"') {
                if(i == s.length() - 1) {
                    ans.push_back(tmp);
                    return ans;
                } else if(s[i + 1] == '"') {
                    tmp += '"';
                    ++i;
                } else {
                    ans.push_back(tmp);
                    tmp = "";
                    inQuote = false;
                    i++;
                }
            } else tmp += s[i];
        } else {
            if(s[i] == '"')
                inQuote = true;
            else if(s[i] == ',') {
                ans.push_back(tmp);
                tmp = "";
            } else tmp += s[i];
        }
    }
    if(!tmp.empty()) ans.push_back(tmp);
    return ans;
}

int main() {
    string ss[] = {"John,Smith,john.smith@gmail.com,Los Angeles,1", "\"Alexandra \"\"Alex\"\"\",Menendez,alex.menendez@gmail.com,Miami,1"};
    for(auto s : ss) {
        auto parsed = parseCSV(s);
        for (int i = 0; i < parsed.size() - 1; ++i)
            cout << parsed[i] << "|";
        cout<<parsed[parsed.size() - 1]<<endl;
    }
    return 0;
}

https://github.com/allaboutjst/airbnb/blob/master/src/main/java/csv_parser/CSVParser.java

        public String parseCSV(String str) {
            List<String> res = new ArrayList<>();
            boolean inQuote = false;
            StringBuilder sb = new StringBuilder();
            for (int i = 0; i < str.length(); i++) {
                if (inQuote) {
                    if (str.charAt(i) == '\"') {
                        if (i < str.length() - 1 && str.charAt(i + 1) == '\"') {
                            sb.append("\"");
                            i++;
                        } else {
                            inQuote = false;
                        }
                    } else {
                        sb.append(str.charAt(i));
                    }
                } else {
                    if (str.charAt(i) == '\"') {
                        inQuote = true;
                    } else if (str.charAt(i) == ',') {
                        res.add(sb.toString());
                        sb.setLength(0);
                    } else {
                        sb.append(str.charAt(i));
                    }
                }
            }

            if (sb.length() > 0) {
                res.add(sb.toString());
            }
            return String.join("|", res);
        }