firebase-rule-pretty-printer.js

// This is just a toy. I used this to experient before adding more advanced functionality into Targaryen.

const esprima = require('esprima');

var expr = "data.val() == null && auth != null && (auth.isWorker == true || (newData.parent().child('chatType').val() == 'oneToOne' && $chatID.contains(auth.uid) == true || newData.parent().child('chatType').val() == 'group' && newData.parent().child('users').val() != null && newData.parent().child('users').child(auth.uid).val() != null || newData.parent().child('chatType').val() == 'org' && (auth.officialCounselorAt == null && $chatID.contains(auth.uid) == true || newData.parent().child('orgID').val() != null && auth.officialCounselorAt != null && auth.officialCounselorAt[newData.parent().child('orgID').val() + ''] == true))) || data.val() != null && newData.val() != null && auth != null && auth.isWorker == true || data.val() != null && newData.val() == null && auth != null && auth.isWorker == true";

var tree = esprima.parse(expr);

// BinaryExpression
// CallExpression
// ExpressionStatement
// Identifier
// Literal
// LogicalExpression
// MemberExpression
// Program


var indentLevel = 0;

function indent() {
  indentLevel++;
}
function dedent() {
  indentLevel--;
}

function ws() {
  var ws = '';
  for (var i = 0; i < indentLevel; i++) {
    ws += '  ';
  }
  return ws;
}

function printNode(node) {
  if (printers[node.type] != null) {
    return printers[node.type](node);
  }
  return '-------';
}

var printers = {
  BinaryExpression(node) {
    return printNode(node.left) + " " + node.operator + " " + printNode(node.right);
  },

  CallExpression(node) {
    var args = node.arguments.map((n) => printNode(n));
    return printNode(node.callee) + "(" + args.join(', ') + ")";
  },

  ExpressionStatement(node) {
    var str = ws() + "(\n";

    indent();
    str += ws() + printNode(node.expression) + "\n";
    dedent();

    str += ws() + ")";

    return str;
  },

  Identifier(node) {
    return node.name;
  },

  Literal(node) {
    return node.raw;
  },

  LogicalExpression(node) {
    var str = "(\n";

    indent();

    str += ws() + printNode(node.left) + "\n";
    str += ws() + node.operator + "\n";
    str += ws() + printNode(node.right) + "\n";

    dedent();

    str += ws() + ")";
    return str
  },

  MemberExpression(node) {
    if (node.property.type === 'Identifier') {
      return printNode(node.object) + '.' + printNode(node.property);
    } else {
      return printNode(node.object) + '[' + printNode(node.property) + ']';
    }
  },

  Program(node) {
    return printNode(node.body[0]);
  },
};

console.log(printNode(tree));