git-blame by PR #

git-blame-pr.js

const { spawn, spawnSync } = require('child_process');
const readline = require('readline');

const blame = spawn('git', ['blame', '--first-parent', process.argv[2]]);
const lines = readline.createInterface({ input: blame.stdout });

const lookup = hash => {
    const ret = spawnSync('git', ['show', '--oneline', hash]);
    const msg = /Merge\s+(?:pull\s+request|pr)\s+\#?(\d+)\s/i;
    const matcher = msg.exec(ret.stdout.toString());
    if (matcher) {
        return `PR #${matcher[1]}`;
    }
    return hash;
};
const cache = new Map();
const get = hash => {
    const val = cache.get(hash);
    if (val) {
        return val;
    } else {
        const no = lookup(hash).padEnd(8, ' ');
        cache.set(hash, no);
        return no;
    }
};
lines.on('line', (input) => {
    const [hash, content] = input.split(/ .*?\) /);
    console.log(get(hash), content);
});