如何使用clojure.edn / read获取文件中的对象序列？ [英] How to use clojure.edn/read to get a sequence of objects in a file?

问题描述

Clojure 1.5引入了 clojure.edn ，其中包含一个读取函数，需要 PushbackReader 。

如果我想读取前五个对象，我可以这样做：

  with-open [infile（java.io.PushbackReader。（clojure.java.io/readerfoo.txt））] 
（binding [* in * infile] 
（let [edn-seq （重复clojure.edn / read）] 
（dorun（take 5（map println edn-seq））））））
  

我如何打印出所有的对象？考虑到其中一些可能是nil，它似乎需要检查EOF，或类似的东西。我想要一个类似于 line-seq 的对象序列。

解决方案

使用：eof键

http://clojure.github.com/clojure/clojure.edn-api.html

opts是映射可以包括以下键：：eof - value到
在文件结束时返回。当不提供时，eof会抛出异常。

编辑：对不起，这不够详细！这里y'go：

 （with-open [java.io.PushbackReader。（clojure.java.io/reader foo.txt））] 
（let [edn-seq（repeated（partial edn / read {：eof：theend} in））] 
（dorun not =：theend）edn-seq）））））
  

Clojure 1.5 introduced clojure.edn, which includes a read function that requires a PushbackReader.

If I want to read the first five objects, I can do:

(with-open [infile (java.io.PushbackReader. (clojure.java.io/reader "foo.txt"))]
  (binding [*in* infile]
    (let [edn-seq (repeatedly clojure.edn/read)]
      (dorun (take 5 (map println edn-seq))))))

How can I instead print out all of the objects? Considering that some of them may be nils, it seems like I need to check for the EOF, or something similar. I want to have a sequence of objects similar to what I would get from line-seq.

解决方案

Use :eof key

http://clojure.github.com/clojure/clojure.edn-api.html

opts is a map that can include the following keys: :eof - value to return on end-of-file. When not supplied, eof throws an exception.

edit: sorry, that wasn't enough detail! here y'go:

(with-open [in (java.io.PushbackReader. (clojure.java.io/reader "foo.txt"))]
  (let [edn-seq (repeatedly (partial edn/read {:eof :theend} in))]
    (dorun (map println (take-while (partial not= :theend) edn-seq)))))

that should do it

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