CSV解析嵌入式双引号 [英] CSV parsing for embedded double quotes

问题描述

我写了一个简单的CSV文件解析器。但在查看 CSV格式的wiki页面后，我注意到了一些基本的扩展格式。通过双引号特别嵌入逗号。我已经设法解析这些，但是有第二个问题：嵌入式双引号。

I've written a simple CSV file parser. But after looking at the wiki page on CSV formats I noticed some "extensions" to the basic format. Specifically embedded comma via double quotes. I've managed to parse those, however there is a second issue: embedded double quotes.

示例：

12345，ABC，IJKXYZ - > [1234]和[ABC，IJKXYZ]

12345,"ABC, ""IJK"" XYZ" -> [1234] and [ABC, "IJK" XYZ]

正确的方式来区分封闭的双引号和无。所以我的问题是什么是正确的方法/算法来解析CVS格式，如上面的那样？

I can't seem to find the correct way to distinguish between an enclosed double quote and none. So my question is what is the correct way/algorithm to parse CVS formats such as the one above?

推荐答案

认为这基本上是将引用的值看作一个单引号，非引号的值或一个双引号值序列，形成一个用引号括起来的值。也就是

The way I normally think about this is basically to look at the quoted value as a single, unquoted value or a sequence of double quoted values that form a value joined by quotes. That is,

• 来解析行中的下一个原子：
  
  
  
  • 到第一个非空白字符
  
  
  • 如果当前字符不是引号：
    
    
    
    • 标记当前位置
    
    
    • 读取下一个逗号或换行符
    
    
    • 返回标记和逗号之前的字符之间的文本（如果适用，条形空格）
    
    
    • to parse the next atom in the row:
      • read up to the first non whitespace character
      • if the current character is not a quote:
        • mark the current spot
        • read up to the next comma or newline
        • return the text between the mark and the character before the comma (strip spaces if appropriate)
        
        
        • 创建空字符串缓冲区
        
        
        • 当前字符不是引号
          
          
          
          • 标记当前位置+1（跳过引号字符）
          
          
          • 读取下一个报价
          
          
          • 如果缓冲区不为空，则向其附加引号
          
          
          
          
          
          
          • 读取下一个逗号或换行符
          
          
          • 返回缓冲区
          
          
          • create an empty string buffer
          • while the current character is not a quote
            • mark the current position +1 (skip the quote character)
            • read up to the next quote
            • if the buffer is not empty, append a quote to it
            • append to the buffer the text between the mark and the character before the current position (to strip both quotes)
            • advance one character (past the just read quote)

            本质上，将引用字符串的每个双引号段分开，然后用引号括起来。因此：ABC，IJKXYZ变为 ABC，， IJK ，  XYZ ，后者又变成 ABC，IJK  XYZ

            essentially, split each double quoted segment of the quoted string and then catenate them together with quotes. thus: "ABC, ""IJK"" XYZ" becomes ABC, , IJK,  XYZ, which in turn becomes ABC, "IJK" XYZ

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