Hasher on a Source delete contents

[yaghmr]

How I can do something like:

val src = Source.fromFile("data.csv")
val currentHash = Hasher(src).crc32.hex

without empty my source iterator?. What's the correct way to calculate a Source's hash?

[Nycto]

In this case, the hash is generated from the content of your file, so it makes sense that it consumes the Source object. The file has to be read to build a hash.

You have two other options:

1. Reset the Source object after you're done generating the hash
2. Use a Tap instead of directly building the hash. This allows the digest to be constructed passively as some other piece of code reads your source. Like this:

val source = Algo.crc32.tap( Source.fromFile("data.csv") )

source.getLines.foreach( line => {
    // Application logic to process each line
    println(line)
})

println( "Hash: " + source.hash )

[Nycto]

As a follow up, I added a section to the Readme about this:

https://github.com/Nycto/Hasher/commit/76447dd93585a229ca2be797301d08fd29159bd8