wild csv parse function

wild-csv-parse.ts

const DELIMITER = ","
const GROUP_QUOTES = ['"', "'"]

function parse(input: string) {
  const rows = input.trim().split(/\r?\n/)
  return rows.map((row, rowIndex) => {
    let [start, cursor, end] = [0, 0, row.length - 1]

    const fields: string[] = []

    while (start <= end) {
      const char = row.charAt(start)

      const quote_char_index = GROUP_QUOTES.indexOf(char)
      // 当前字符为单引号/双引号
      if (quote_char_index >= 0 && cursor === start) {
        const quote_char = GROUP_QUOTES[quote_char_index]
        // 查找下一个引号+分隔符的位置, 默认引号后没有空格
        const next_quote_char_index = row.indexOf(`${quote_char}${DELIMITER}`, start)
        // 没有找到
        if (next_quote_char_index < 0) {
          // 可能是因为最后一个field后没有分隔符，判断一下最后一个字符能否匹配上引号
          if (row.charAt(end) === quote_char) {
            fields.push(row.slice(start))
            break // 本行已经遍历结束
          } else {
            // throw new Error(`括号无法匹配 ${rowIndex}: ${row}`)
            fields.push(row.slice(start))
            break
          }
        } else {
          // 找到了对应的字符
          fields.push(row.slice(start, next_quote_char_index + 1))
          cursor = start = next_quote_char_index + 2
        }
      } else if (char === DELIMITER) {
        if (start === end) { 
            fields.push(row.slice(start, start))
            break
        }
        fields.push(row.slice(cursor, start))
        cursor = start = start + 1
      } else {
        start += 1
      }

      if (start === end) {
        const regexp = new RegExp(`${DELIMITER}$`)
        fields.push(row.slice(cursor).replace(regexp, ""))
      }
    }

    return fields
  })
}

const csv_input = `
line_1, column_2
line_2, "column_2,2"
line_3, "column_\"3,2\""
line_4, column_2,a
line_5, 'column_2',a
line_6, "column_2"2",a
line_7,"column_3'3',a
line_8,"column_3'3',a'
line_9,‘1，2，3’
line_10,'1,2,3'
line_11,'content,a,b'
line_12,"content,a,b"
line_13,"name:'sy'",3
line_14,"name:'sy',age:18",4
awdwa, "adwadwd","dawdaw"
colum12,colum2,colum3
"content,a",1,
‘1，2，3’,2,
"name:'sy'",3,
"name:'sy',age:18",4,
colum12,colum2,colum3,
"content,a",1,,
‘1，2，3’,2,,
"name:'sy'",3,,,
"name:'sy',age:18",4,,,5,6,
`

console.log(JSON.stringify(parse(csv_input), null, 2))