Parsr is a project mainly written in Java, it's free.
simple java framework for ragel based parsers
The buildr buildfile contains to rake tasks for generating ragel parsers and cleaning up the generated ragel parsers: buildr ragel : generate ragel parsers buildr ragel_clean : remove generated ragel parsers
Remember to call buildr ragel_clean before you do a commit.
The parsr projekt is a framework for event based parsing using the ragel parser generation framework. You can write your parser definition in ragel and use the framework for generating and processing parsing events.
Parsing events are thrown as user actions in the ragel machine definition, (see chapter 3 of the ragel user guide) and are processed by the ContentHandler which is implemented by you.
To create a Parser you have to create a file with the following contents and the ending .rl for ragel. The filename should match the class name and the folder should match the package. In the example the filename would be SomeParser and the package com.foo.bar.
%% machine someparser;
package com.foo.bar;
import de.entwicklerland.parsr.Parser;
public class SomeParser extends Parser {
%% write data;
%% write init;
public void parse(char[] data) {
int pe = data.length;
%% write exec;
%%{
# machine definition
action anyChar {
write();
}
# machine instantiation
main := any $anyChar;
}%%
}
}
After that call buildr ragel to generate the parser class from the parsr definition. You may now modify the maschine definition.
To process the input stream you may use the following methods of the parser:
Parser.write() to write the current processed character to the outputstream, which is a sort of echo back the input stream to the output stream.
Parser.beginMatch("eventname") to start matching a region
Parser.endMatch("eventname") to end matching a region, calling endMatch generates an event for the content handler.
Parser.shrink(int) method to shrink the buffer of the buffered input stream
the data sink is filled by the content handler
// create data sink
ByteArrayOutputStream output = new ByteArrayOutputStream();
// instantiate parser
Parser parser = new SomeParser();
// create content handler implementation
ContentHandler handler = new ContentHandler() {
@Override
public void process(Match match, StringBuilder buffer, OutputStream output) throws IOException {
String content = match.getContent(buffer);
String event = match.getEvent();
// write event and content to output, separated by a colon
output.write(content.getBytes());
output.write(':');
output.write(event.getBytes());
}
};
// register content handler to all parsing events
parser.registerToAll(handler);
// process input
parser.parse(input, output);
You may use the ParserValidator.java class to validate the parsing behaviour. Have a look at the existing tests on how to use the ParserValidator.java.
An endLastMatch() that is executed before a beginMatch() will result in an an IllegalStateException. You may want to use the logMark() method to debug such a case.