2008/06/26/01.02.53
A Ruby readline-like method for AS3
I’ve missed the readline method from Ruby, so here’s a stab at a readline that returns an array of all the lines you might want from a given file.
These examples of using this method assume some var f in scope that might look like:
var f : File = File.applicationDirectory.resolvePath("temp.txt");
You’d call this method in one of several ways. The simplest would return an array of all the lines in a file.
var lines : Array = readLines( f );
The rest of the examples assume some var r in scope that might look like:
var r : RegExp = new RegExp(/enabled/);
A slightly more complex way would use the filter property to select specific lines out of the file. In this case, lines that returned true for the regex /enabled/.
var lines : Array = readLines( f, r );
You could also flip the filter_accepts parameter to false, and get an array of all the lines that don’t match the regex.
var lines : Array = readLines( f, r, false );
Finally, you could find the first line, after skipping the first two lines, that didn’t match the regex.
var lines : Array = readLines( f, r, false, 1, 2 );
So, after all those wonderfully fun samples, here’s the code:
/**
* @param … If you supply one extra param it’ll be the number of lines possible.
* If you supply two extra params the first’ll be the same and the second’ll be an offset by lines.
* Anything past the first two params is ignored.
*/
private function readLines( f : File, line_filter : RegExp = null, filter_accepts : Boolean = true, … params ) : Array {
var line_offset : Number;
var lines_possible : Number;
switch( params.length ){
case 0: lines_possible = Number.MAX_VALUE; line_offset = 0; break;
case 1: lines_possible = params[0]; line_offset = 0; break;
default: lines_possible = params[0]; line_offset = params[1];
}
var total_lines_to_be_seen : Number = line_offset + lines_possible;
var lines : Array = [];
if( f.size > 0 ){
var fileStream : FileStream = new FileStream();
fileStream.open( f, FileMode.READ );
var char : String;
var line : String;
var lines_seen : Number = 0;
// Read either to the EOF or until we have enough lines
while( fileStream.bytesAvailable > 0 && lines_seen < total_lines_to_be_seen ){
line = "";
char = fileStream.readUTFBytes(1);
// Keep adding to the line until an EOL
while( !(char == File.lineEnding) ){
line += char;
char = fileStream.readUTFBytes(1);
}
// If we’ve hit an EOL and we’re past the offset, then see if it passes the filter.
if( lines_seen >= line_offset ){
if( line_filter == null ){
lines.push(line);
}else{
if( line_filter.test(line) == filter_accepts ){
lines.push(line);
}else{
lines_seen -= 1;
}
}
}
lines_seen += 1;
}
fileStream.close();
}
return lines;
}
Original post by richard.lyman and software by Elliott Back