css2mongo.js

/**
    var css2mongo = require('css2mongo');

    css2mongo('.foo.bar[xxx="yyy"], #AAA');

    {
      "$or": [
        {
          "$and": [
            {
              "classes": {
                "$all": [
                  "bar",
                  "foo"
                ]
              }
            },
            {
              "xxx": "yyy"
            }
          ]
        },
        {
          "id": "AAA"
        }
      ]
    }

*/

var slick = require('slick');

function cssToMongoQuery(css) {
  if (typeof css === 'string') {
    css = slick.parse(css);
  }

  if (css.length === 1) {
    return exprToMongoQuery(css[0]);
  }

  var or = [];
  for (var i=0; i<css.length; i++) {
    or.push(exprToMongoQuery(css[i]));
  }
  return {'$or': or};
}

function exprToMongoQuery(expr) {
  if (expr.length !== 1) {
    throw "ERROR: Multiple parts in an expressions doesn't make sense";
  }

  var part = expr[0];

  var and = [];

  if (part.id) {
    and.push(idToMongoQuery(part.id));
  }

  if (part.tag !== '*') {
    and.push(tagToMongoQuery(part.tag));
  }

  if (part.classList) {
    and.push(classesToMongoQuery(part.classList));
  }

  if (part.attributes) {
    and.push(attributesToMongoQuery(part.attributes));
  }

  // TODO: pseudo classes

  if (and.length === 1) {
    return and[0];
  }
  return {$and: and};
}

function classesToMongoQuery(classes) {
  if (classes.length === 1) {
    return { classes: classes[0] };
  }
  return {classes: {$all: classes}};
}

function idToMongoQuery(id) {
  return {id: id};
}

function tagToMongoQuery(tag) {
  return {type: tag};
}

function attributesToMongoQuery(attrs) {
  if (attrs.length === 1) {
    return attrToMongoQuery(attrs[0]);
  }
  return {$and: attrs.map(attrToMongoQuery)};
}

function attrToMongoQuery(attr) {
  var q = {};
  var op = attr.operator;
  if (op === '=') {
    q[attr.name] = attr.value;
  }
  else {
    // TODO: other operators
    throw "Unknown operator: " + attr.operator;
  }
  return q;
}

module.exports = cssToMongoQuery;