从扫描仪转换为io.Reader的惯用方式

问题描述：

I recently ran into this issue of how to read from a CSV file, apply some transformation to every line and write to a HTTP request.

The problem I was faced with was how to convert from a line-by-line reader which returns an arbitrary number of bytes (like a Scanner) to a byte reader, which returns a fixed amount of bytes at every call to Read().

The best solution I came up with is to build a custom io.Reader that would read from the Scanner and buffer bytes locally if they wouldn't fit. Then the buffered bytes would be returned on the next call to Read().

This is what I came up with: https://gist.github.com/paulsc/6a0bf30a2a8d898f7a8086aedf6af1e1

Intuitively, this feels like the wrong solution, because the code seems like a fairly low-level solution that might already be in the standard library.

Is there a better way, more idiomatic to do this with standard go components ?

我最近遇到了这样一个问题：如何从CSV文件读取，对每行进行一些转换并写入一个HTTP请求。 p>

我面临的问题是如何从逐行读取器（该扫描器返回任意数量的字节（如扫描仪））转换为字节读取器，该读取器返回一个固定值每次调用Read（）时的字节数。 p>

我想到的最好的解决方案是构建一个自定义io.Reader，该io.Reader将从Scanner读取并在本地缓存字节（如果可以）不适合。然后，在下次调用Read（）时将返回缓冲的字节。 p>

这是我想到的： https://gist.github.com/paulsc/6a0bf30a2a8d898f7a8086aedf6af1e1 p>

很直观，因为代码似乎是一个相当底层的解决方案，可能已经在标准库中了。 p>

是否有更好的方法，更惯用的标准go组件？ p> div>

答

A simple method is using io.Pipe.

func ScannerToReader(scanner *bufio.Scanner) io.Reader {
    reader, writer := io.Pipe()


    go func() {
        defer writer.Close()
        for scanner.Scan() {
            writer.Write(scanner.Bytes())
        }
    }()

    return reader
}

从扫描仪转换为io.Reader的惯用方式

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