Colorize trace info when on a TTY

[fyc09]

Currently, I did not found any way to debug when my parser is broken (except console.log or read the auto-generated code), which is not intuitive enough. I wonder if we have a better way to see the process of parsing, maybe we can generate an log file to show the process. I can help implement that if necessary.
Or, further more, we can use chrome inspect to debug the source code, just like a node.js program.

[hildjj]

Using --trace often helps me. If you want to customize the output, you can pass a tracer object to the generated parse routine (only if you generated with --trace or trace: true if you are calling generate yourself):

import peggy from "peggy";

const { parse } = peggy.generate('foo = "a"+', { trace: true });
parse("aaa", {
  tracer: {
    trace({ type, rule, location }) {
      console.log(type, rule, location);
    },
  },
});

Open to suggestions for how we can make it better.

[fyc09]

Sorry, I didn't see this option. Now I have solved my problem.

By the way, the enter, fail, match doesn't look very clear. I think it will be better if we use different colors for different actions.

Here I made a test, it seems better:

[hildjj]

I'll take a PR for that, which checks process.stdout.isTTY to turn on color.