add -P:sxr:output-class:<class> option

[ezh]

Dear Mark,
Thank you very much for 'browse'. I slightly modify your code by adding new option. I try to preserve all punctuation, tabs, \r\n. I hope that addition look like original code. This new option allow add external class writer for sxr.

For example
somewhere at build.sbt or like one:
scalacOptions += "-Xplugin:other.package.jar"
scalacOptions <+= (scalaSource in Compile) map { (source) => { "-P:sxr:output-class:other.package.CustomWriter" }

Our custom writer

package other.package

import java.io.File
import sxr.OutputWriter
import sxr.Token
import sxr.OutputWriterContext

class CustomWriter(context: OutputWriterContext) extends OutputWriter {
/** Generates initial content. */
def writeStart() {
}

/** Generates content for a given source file. */
def writeUnit(source: File, relativeSourcePath: String, tokenList: List[Token]) {
println("--- " + source.toString)
...
withReader(source, context.encoding) { input =>
withWriter(destination) { output =>
tokenList.foreach( ... custom code ...))
}
}
}

/** Generates final content. */
def writeEnd() {
}
}

It's work surprisingly well. I hope that you accept this addition. If i need it modify, please tell me about.

King regards,
Alexey

[harrah]

I apologize for the long delay in looking at this. I like the idea. If you still happen to be interested, please rebase onto master and it will get merged.

[jsuereth]

Hey @ezh If you have the opportunity, can you rebase this patch on master over here: https://github.com/sbt/sxr.

Thanks!