UNPKG

mingo

Version:

MongoDB query language for in-memory objects

108 lines (107 loc) 2.74 kB
import { getOperator, initOptions, OperatorType } from "./core"; import { Cursor } from "./cursor"; import { assert, inArray, isObject, isOperator, MingoError, normalize } from "./util"; class Query { constructor(condition, options) { this.condition = condition; this.options = initOptions(options); this.compiled = []; this.compile(); } compile() { assert( isObject(this.condition), `query criteria must be an object: ${JSON.stringify(this.condition)}` ); const whereOperator = {}; for (const [field, expr] of Object.entries(this.condition)) { if ("$where" === field) { Object.assign(whereOperator, { field, expr }); } else if (inArray(["$and", "$or", "$nor", "$expr", "$jsonSchema"], field)) { this.processOperator(field, field, expr); } else { assert(!isOperator(field), `unknown top level operator: ${field}`); for (const [operator, val] of Object.entries( normalize(expr) )) { this.processOperator(field, operator, val); } } if (whereOperator.field) { this.processOperator( whereOperator.field, whereOperator.field, whereOperator.expr ); } } } processOperator(field, operator, value) { const call = getOperator( OperatorType.QUERY, operator, this.options ); if (!call) { throw new MingoError(`unknown query operator ${operator}`); } const fn = call(field, value, this.options); this.compiled.push(fn); } /** * Checks if the object passes the query criteria. Returns true if so, false otherwise. * * @param obj The object to test * @returns {boolean} True or false */ test(obj) { for (let i = 0, len = this.compiled.length; i < len; i++) { if (!this.compiled[i](obj)) { return false; } } return true; } /** * Returns a cursor to select matching documents from the input source. * * @param source A source providing a sequence of documents * @param projection An optional projection criteria * @returns {Cursor} A Cursor for iterating over the results */ find(collection, projection) { return new Cursor( collection, (x) => this.test(x), projection || {}, this.options ); } /** * Remove matched documents from the collection returning the remainder * * @param collection An array of documents * @returns {Array} A new array with matching elements removed */ remove(collection) { return collection.reduce((acc, obj) => { if (!this.test(obj)) acc.push(obj); return acc; }, []); } } export { Query };