How to parse text in Groovy - parsing

Question

I need to parse a text (output from a svn command) in order to retrieve a number (svn revision).
This is my code. Note that I need to retrieve all the output stream as a text to do other operations.
def proc = cmdLine.execute() // Call *execute* on the strin
proc.waitFor() // Wait for the command to finish
def output = proc.in.text
//other stuff happening here
output.eachLine {
line ->
def revisionPrefix = "Last Changed Rev: "
if (line.startsWith(revisionPrefix)) res = new Integer(line.substring(revisionPrefix.length()).trim())
}
This code is working fine, but since I'm still a novice in Groovy, I'm wondering if there were a better idiomatic way to avoid the ugly if...
Example of svn output (but of course the problem is more general)
Path: .
Working Copy Root Path: /svn
URL: svn+ssh://svn.company.com/opt/svnserve/repos/project/trunk
Repository Root: svn+ssh://svn.company.com/opt/svnserve/repos
Repository UUID: 516c549e-805d-4d3d-bafa-98aea39579ae
Revision: 25447
Node Kind: directory
Schedule: normal
Last Changed Author: ubi
Last Changed Rev: 25362
Last Changed Date: 2012-11-22 10:27:00 +0000 (Thu, 22 Nov 2012)
I've got inspiration from the answer below and I solved using find(). My solution is:
def revisionPrefix = "Last Changed Rev: "
def line = output.readLines().find { line -> line.startsWith(revisionPrefix) }
def res = new Integer(line?.substring(revisionPrefix.length())?.trim()?:"0")
3 lines, no if, very clean

Answer 1

One possible alternative is:
def output = cmdLine.execute().text
Integer res = output.readLines().findResult { line ->
(line =~ /^Last Changed Rev: (\d+)$/).with { m ->
if( m.matches() ) {
m[ 0 ][ 1 ] as Integer
}
}
}
Not sure it's better or not. I'm sure others will have different alternatives
Edit:
Also, beware of using proc.text. if your proc outputs a lot of stuff, then you could end up blocking when the inputstream gets full...
Here is a heavily commented alternative, using consumeProcessOutput:
// Run the command
String output = cmdLine.execute().with { proc ->
// Then, with a StringWriter
new StringWriter().with { sw ->
// Consume the output of the process
proc.consumeProcessOutput( sw, System.err )
// Make sure we worked
assert proc.waitFor() == 0
// Return the output (goes into `output` var)
sw.toString()
}
}
// Extract the version from by looking through all the lines
Integer version = output.readLines().findResult { line ->
// Pass the line through a regular expression
(line =~ /Last Changed Rev: (\d+)/).with { m ->
// And if it matches
if( m.matches() ) {
// Return the \d+ part as an Integer
m[ 0 ][ 1 ] as Integer
}
}
}