Add Bunyan source metadata at compile-time without the performance hit

readme.md

AST Explorer In:

log.info('hi')
log.info(test)
app.get('test', function () { log.info({ req, res }, 'hi') })

Out:

log.info({
  src: {
    file: "unknown",
    line: 1
  }
}, 'hi')
log.info({
  src: {
    file: "unknown",
    line: 2
  }
}, test)
app.get('test', function () { log.info({
  src: {
    file: "unknown",
    line: 3
  },

  req,
  res
}, 'hi') })

babel-plugin-add-bunyan-metadata.js

export default function (babel) {
  const { types: t } = babel;
  
  return {
    visitor: {
      CallExpression(path) {
        if (!t.isMemberExpression(path.node.callee)
         || path.node.callee.object.name !== 'log') {
          return
        }
        if (!t.isObjectExpression(path.node.arguments[0])) {
          path.node.arguments.unshift(t.objectExpression([]))
        }
        const file = t.objectProperty(
          t.identifier('file'),
          t.stringLiteral(this.file.opts.filename)
        )
        const line = t.objectProperty(
          t.identifier('line'),
          t.numericLiteral(path.node.loc.start.line)
        )
        path.node.arguments[0].properties.unshift(t.objectProperty(
          t.identifier('src'),
          t.objectExpression([
            file,
            line,
          ])
        ))
      }
    }
  };
}