ducky

Ducky — [duckyjs.com](http://duckyjs.com/) ================================================ **Duck-Typed Value Handling for JavaScript** <img src="https://nodei.co/npm/ducky.png?downloads=true&stars=true" alt=""/> <img src="https://david-dm.org/rse/ducky.png" alt=""/> Abstract -------- Ducky is a small Open-Source JavaScript library, providing Duck-Typed Value Validation, Value Selection and Flexible Function Parameter Handling. It can be used in [Node.js](http://nodejs.org/) based server and browser based client environments. Getting Ducky ---------------- You can conveniently get Ducky in various ways: - NPM: install as server component via the Node Package Manager: `$ npm install ducky` - Git: directly clone the official repository: `$ git clone https://github.com/rse/ducky.git` - cURL: download only the main file from the repository: `$ curl -O https://raw.github.com/rse/ducky/master/lib/ducky.browser.js` API --- Ducky provides the following API: #### ducky.version = { major: Number, minor: Number, micro: Number, date: Number } The version of Ducky, provided as a tuple of separate pieces, for easy comparison. if (!(ducky.version.major >= 2 && ducky.version.minor >= 0)) throw new Error("need at least Ducky 2.0.0"); #### ducky.register(name: String, type: Function): void Register under `name` an additional host or application type, represented by the constructor function `type`. This allows `ducky.validate()` and `ducky.params()` to validate objects which are instances of the type. var Foo = function () { ... }; ducky.register("app.Foo", Foo); ducky.validate(new Foo(), "app.Foo"); The following host types are pre-registered by default (if actually existing in the particular native or "polyfilled" host environment): `Object`, `Boolean`, `Number`, `String`, `Function`, `RegExp`, `Array`, `Date`, `Error`, `Set`, `Map`, `WeakMap`, `Promise`, `Proxy` and `Iterator`. #### ducky.unregister(name: String): void Unregisters the additional host or application type, which was previously registered under `name` with `ducky.register()`. ducky.unregister("app.Foo"); #### ducky.select(object: Object, path: String, value?: Object): Object Dereference into (and this way subset) `object` according to the `path` specification and either return the dereferenced value or set a new `value`. Object has to be a hash or array object. The `path` argument has to follow the following grammar (which is a direct JavaScript dereferencing syntax): LHS | | RHS ------------ | --- | ----------------------------- path | ::= | segment segment\* segment | ::= | bybareword | bykey bybareword | ::= | `"."`? identifier bykey | ::= | `"["` key `"]"` identifier | ::= | `/[_a-zA-Z$][_a-zA-Z$0-9]*>/` key | ::= | number | squote | dquote number | ::= | `/[0-9]+/` dquote | ::= | `/"(?:\\"|.)*?"/` squote | ::= | `/'(?:\\'|.)*?'/` Setting the `value` to `undefined` effectively removes the dereferenced value. If the dereferenced parent object is a hash, this means the value is `delete`'ed from it. If the dereferenced parent object is an array, this means the value is `splice`'ed out of it. ducky.select({ foo: { bar: { baz: [ 42, 7, "Quux" ] } } }, "foo['bar'].baz[2]") // → "Quux" In case caching of the internally compiled Abstract Syntax Tree (AST) is not wishes, you can perform the compile and execute steps of `ducky.select` individually: ##### ducky.select.compile(path: String): Object Compile the selection specification `path` into an AST. ##### ducky.select.execute(object: Object, ast: Object, value?: Object): Object Select from `object` a value via `ast` and either return it or set it to the new value `value`. #### ducky.validate(object: Object, spec: String, errors?: String[]): Boolean Validate an arbitrary nested JavaScript object `object` against the specification `spec`. The specification `spec` has to be a string following the following grammar (which is a mixture of JSON-like structure and RegExp-like quantifiers): LHS | | RHS ------------ | --- | ----------------------------- spec | ::= | not | alt | hash | array | any | regexp | primary | class not | ::= | `"!"` spec alt | ::= | `"("` spec (`"`|`"` spec)\* `")"` hash | ::= | `"{"` (key arity? `":"` spec (`","` key arity? `":"` spec)\*)? `"}"` array | ::= | `"["` (spec arity? (`","` spec arity?)\*)? `"]"` arity | ::= | `"?"` | `"*"` | `"+"` | `"{"` number `","` (number | `"oo"`) `"}"` number | ::= | `/^[0-9]+$/` key | ::= | `/^[_a-zA-Z$][_a-zA-Z$0-9]*$/` | `"@"` any | ::= | `"any"` regexp | ::= | `/^\/(?:\\\/|.)*\/$/` primary | ::= | `/^(?:null|undefined|boolean|number|string|function|object)$/` class | ::= | `/^[_a-zA-Z$][_a-zA-Z$0-9]\*(?:\.[_a-zA-Z$][_a-zA-Z$0-9]\*)\*$/` The special key `@` can be used to match an arbitrary hash element key. ducky.validate({ foo: "Foo", bar: "Bar", baz: [ 42, 7, "Quux" ] }, "{ foo: string, bar: any, baz: [ number+, string* ], quux?: any }") // &arr; true If an empty `errors` array is given, use it to assemble detailed error messages in case of a validation failure. In case caching of the internally compiled Abstract Syntax Tree (AST) is not wishes, you can perform the compile and execute steps of `ducky.validate` individually: ##### ducky.validate.compile(spec: String): Object Compile the validation specification `spec` into an AST. ##### ducky.validate.execute(object: Object, ast: Object, errors?: String[]): Boolean Validate `object` against `ast` and return `true` in case it validates. If an empty `errors` array is given, use it to assemble detailed error messages in case of a validation failure. #### ducky.params(name: String, args: Object[], spec: Object): Object Handle positional and named function parameters by processing a function's `arguments` array. Parameter `name` is the name of the function for use in exceptions in case of invalid parameters. Parameter `args` usually is the JavaScript `arguments` pseudo-array of a function. Parameter `spec` is the parameter specification: each key is the name of a parameter and the value has to be an `Object` with the following possible fields: `pos` for the optional position in case of positional usage, `def` for the default value (of not required and hence optional parameters), `req` to indicate whether the parameter is required and `valid` for type validation (a validation specification string accepted by the `validate>()` method). function config () { var params = ducky.params("config", arguments, { scope: { pos: 0, req: true, valid: "boolean" }, key: { pos: 1, req: true, valid: /^[a-z][a-z0-9_]*$/ }, value: { pos: 2, def: undefined, valid: "object" }, force: { def: false, valid: "boolean" } }); var result = cfg_get(params.scope, params.key); if (typeof params.value !== "undefined") cfg_set(params.scope, params.key, params.value, params.force); return result; } var value = config("foo", "bar"); config("foo", "bar", "quux"); config({ scope: "foo", key: "bar", value: "quux", force: true }); #### ducky.options(spec: Object, options?: Object): Object Manage configuration option objects. Parameter `spec` is the option object specification: each key is the name of a parameter (or a sub-path) and the value has to be an `Array` with a type specification accepted by the `validate()` method as its first element and optionally a default value as the second element. If no default value is given for an option, it has to exist on initial value merging. Value merging is performed either when the `options` parameter is given or method `merge(options: Object): Object` is called on the resulting option object. function config (options) { var options = ducky.options({ foo: [ "string" ], bar: [ "boolean", false ], quux: [ "number", 1.2 ], sub: { foo: [ "string", "dummy" ], bar: [ "boolean", false ], quux: [ "number", 2.4 ] } }); options.merge({ foo: "bar", sub: { bar: true } }) options.merge({ sub: { quux: 4.8 } }) } License ------- Copyright (c) 2010-2023 Dr. Ralf S. Engelschall (http://engelschall.com/) Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.