Code to accompany "Parsing files using Groovy closures" on my blog.

Gather.groovy

package com.octodecillion

import java.nio.file.Files;

/**
 * Simple folder walker and file parser.
 * <p>
 * Dev with Groovy 2.1.6, Java 7, Eclipse 4.3
 * 
 * @author jbetancourt
 *
 */
class Gather {
    
	/** test file name with filter, if true, iterate lines
	 * and collect data via strainer.
	 * <p>
	 * @param file the file
	 * @param filter file name filter
	 * @param strainer  line strainer
	 * @return  List<List<Object>>
	 */
	static gather(File file, Closure strainer) {		
		def all = []
			
		file.eachLine{ line ->
			def list = strainer(line)
			if(list.size){
				all << list
			}
		}						
		
		return all  
	}
	
	/** Gather files in a folder */
	static gather(File folder, Closure filter, Closure strainer) {
		def all = []
		
		folder.eachFile { file ->		
			if(filter(file)){				
				all << gather(file, strainer)							
			}		
		}
		
		return all  
	}
	
	/** Gather files in a folder */
	static gatherRecurse(File folder, Closure filter, Closure strainer) {
		def all = []
		
		folder.eachFileRecurse {		
			if(filter(file)){				
				file.eachLine{ line ->
					def list = strainer(line)
					if(list.size){
						all << list
					}
				}
			}			
		}
		
		return all  
	}

	/** a test */
	static main(args) {			
		def folder= Files.createTempDirectory("tempFolder")
		folder.toFile().deleteOnExit()
		def f = Files.createTempFile(folder, "test", ".log")
		f.toFile().deleteOnExit()
		
		f.toFile().text = 
		'''
			# test data			
			20120817 Foo.java			
			# 2 20120817 Foo.java
			2013        Fee.java
		'''				
		def list = Gather.gather(folder.toFile(), { file -> 
			file.name.matches(/.*\.log/) }) { line ->
				def m = line ==~ /^\s*\d{8}\s+\S+\.java.*/ 
				if(m){
					return [line]
				}
				
				return []			
		}
		
	        assert list.size == 1    // has [[[            20120817 Foo.java]]]
	        def result =  list[0][0] // [            20120817 Foo.java]
	        assert result[0] == '            20120817 Foo.java'
	}	
}