Converting a file to a stream

[Félix López]

Hi there,

Is it possible to convert a file to a stream?

I have this code:

(def stoken (gloss/string :utf-8 :delimiters "«"))
(defcodec record-codec [stoken stoken])

(defn read-from-file [offset]
(let [raf (RandomAccessFile. (:db_file conf) "r")
buf (byte-array 4096)
_ (.seek raf offset)
n (.read raf buf)]
(.close raf)
(decode record-codec (java.nio.ByteBuffer/wrap buf) false)))

This method has the problem that I'm only reading 4096, I'm going to change
this method to read the file one byte a at time until I reach the
delimiters and I'm wondering if it would be possible to convert the file to
a stream
and then use decode-stream.

Thanks, Félix

[Félix López]

I have a working version but without gloss:

(defn char-seq
[^java.io.RandomAccessFile rdr]
(let [chr (.read rdr)]
(if (> chr 0)
(cons chr (lazy-seq (char-seq rdr))))))

(defn parse-key-value [bytes-buffer]
(str/split (String. bytes-buffer) #"«"))

(defn read-from-file [offset]
(let [raf (RandomAccessFile. (:db_file conf) "r")
_ (.seek raf offset)
buf (char-seq raf)
data (parse-key-value (byte-array buf))]
(.close raf)
data))

Post by Félix López
Hi there,
Is it possible to convert a file to a stream?
(def stoken (gloss/string :utf-8 :delimiters "«"))
(defcodec record-codec [stoken stoken])
(defn read-from-file [offset]
(let [raf (RandomAccessFile. (:db_file conf) "r")
buf (byte-array 4096)
_ (.seek raf offset)
n (.read raf buf)]
(.close raf)
(decode record-codec (java.nio.ByteBuffer/wrap buf) false)))
This method has the problem that I'm only reading 4096, I'm going to
change this method to read the file one byte a at time until I reach the
delimiters and I'm wondering if it would be possible to convert the file to
a stream
and then use decode-stream.
Thanks, Félix

[Zach Tellman]

You can just call `(decode-all frame (java.io.File. path))`, and it should
do what you want.

Post by Félix López
(defn char-seq
[^java.io.RandomAccessFile rdr]
(let [chr (.read rdr)]
(if (> chr 0)
(cons chr (lazy-seq (char-seq rdr))))))
(defn parse-key-value [bytes-buffer]
(str/split (String. bytes-buffer) #"«"))
(defn read-from-file [offset]
(let [raf (RandomAccessFile. (:db_file conf) "r")
_ (.seek raf offset)
buf (char-seq raf)
data (parse-key-value (byte-array buf))]
(.close raf)
data))

Post by Félix López
Hi there,
Is it possible to convert a file to a stream?
(def stoken (gloss/string :utf-8 :delimiters "«"))
(defcodec record-codec [stoken stoken])
(defn read-from-file [offset]
(let [raf (RandomAccessFile. (:db_file conf) "r")
buf (byte-array 4096)
_ (.seek raf offset)
n (.read raf buf)]
(.close raf)
(decode record-codec (java.nio.ByteBuffer/wrap buf) false)))
This method has the problem that I'm only reading 4096, I'm going to
change this method to read the file one byte a at time until I reach the
delimiters and I'm wondering if it would be possible to convert the file to
a stream
and then use decode-stream.
Thanks, Félix

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[Félix López]

thanks!

Post by Zach Tellman
You can just call `(decode-all frame (java.io.File. path))`, and it should
do what you want.

Post by Félix López
(defn char-seq
[^java.io.RandomAccessFile rdr]
(let [chr (.read rdr)]
(if (> chr 0)
(cons chr (lazy-seq (char-seq rdr))))))
(defn parse-key-value [bytes-buffer]
(str/split (String. bytes-buffer) #"«"))
(defn read-from-file [offset]
(let [raf (RandomAccessFile. (:db_file conf) "r")
_ (.seek raf offset)
buf (char-seq raf)
data (parse-key-value (byte-array buf))]
(.close raf)
data))

Post by Félix López
Hi there,
Is it possible to convert a file to a stream?
(def stoken (gloss/string :utf-8 :delimiters "«"))
(defcodec record-codec [stoken stoken])
(defn read-from-file [offset]
(let [raf (RandomAccessFile. (:db_file conf) "r")
buf (byte-array 4096)
_ (.seek raf offset)
n (.read raf buf)]
(.close raf)
(decode record-codec (java.nio.ByteBuffer/wrap buf) false)))
This method has the problem that I'm only reading 4096, I'm going to
change this method to read the file one byte a at time until I reach the
delimiters and I'm wondering if it would be possible to convert the file to
a stream
and then use decode-stream.
Thanks, Félix

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