genData

genData

A normalization pattern to build, query, and manipulate everything.

(4/20/12) version 1.2.1 by Bemi Faison

DESCRIPTION

genData is a recursive, depth-first iterator and generic parser, for querying objects. genData lets you control iteration and parsing behavior, along with the returned dataset.

FILES

• gendata-min.js - genData source file (minified with UglifyJS )
• LICENSE - The legal terms and conditions under which this software may be used
• README.md - This readme file
• src/ - Directory containing the source code
• test/ - Directory containing Qunit test files

INSTALL

Within web browsers, reference the gendata-min.js, as you would any external JavaScript file.

  <script type="text/javascript" src="somepath/gendata-min.js"></script>
  <script type="text/javascript">
    // Your code that uses genData...
  </script>

For Node, install genData source files manually, or via npm (recommended).

  npm install genData

Then, for commonJS environments (like Node), require the genData module, and reference the exported genData function.

  var genData = require('genData').genData;

  // Your code that uses genData...

USAGE

Warning: genData scans objects recursively!! Make sure to check for previously inspected objects, or avoid passing self-referencing structures!

Normalize

genData translates anything into a dataset. A dataset is an array of objects with a common structure. By default, genData assigns a name and value member to dataset objects. The examples below, demonstrate how genData normalizes data, the first argument.

Use genData to normalize an object...

  genData({hello: "world"});

  /*
  returns this array...
    [
      {
       name: '',
       value: {hello: 'world', pie: "sky"}
      },
      {
        name: 'hello',
        value: 'world'
      },
      {
        name: 'pie',
        value: 'sky'
      }
    ]
  */

Use genData to normalize an array...

  genData([9276, {ping: "pong"}, "foo"]);

  /*
  returns this array...
    [
      {
       name: '',
       value: [9276, {ping: "pong"}, "foo"]
      },
      {
        name: '0',
        value: 9276
      },
      {
        name: '1',
        value: {ping: "pong"}
      },
      {
        name: 'ping',
        value: 'pong'
      },
      {
        name: '2',
        value: 'foo'
      }
    ]
  */

Use genData to normalize nothing...

  genData();

  /*
  returns this array...
    [
      {
       name: '',
       value: undefined
      }
    ]
  */

Build

The second argument may be a function or array of functions, called parsers.

Use genData with a parser that manipulates members of each data object in the dataset...

  genData(
    [{hello: 'world', pie: "sky"}],
    function () {
      this.randId = Math.random();
      delete this.name;
    }
  );
  /*
  returns this array...
    [
      {
       value: {hello: 'world', pie: "sky"},
       randId: 0.9093414132948965
      },
      {
        value: 'world',
        randId: 0.20426166336983442
      },
      {
        value: 'sky',
        randId: 0.5697704532649368
      }
    ]
  */

Query & Parse

Parsers also control what genData iterates and returns, by performing logic and setting iteration flags from the following function signature.

• name - String, The original name of this data object.
• value - Mixed, The original value of this data object.
• parent - Data, The data object that was scanned in order to create this data object.
• dataset - Array, The array that will be returned when genData completes iterating.
• flags - Object, A collection of keys used to for controlling genData.

• parent: The object to be scanned next, in order to create subsequent data objects.
• omit: When truthy, the current data object is excluded from the final dataset.
• scan: When falsy, the current data object will not be scanned by genData.
• exit: When truthy, genData will abort all parsing and iteration queues.

• shared - Object, An (initially) empty object that is preserved between parsers invocations, until genData completes all iterations.

Use genData to query the numeric values of an object...

  genData(
    [10, ["echo", {top: 20}], true, 30, "charlie"],
    function (name, value, parent, dataset, flags) {
      flags.omit = typeof value !== 'number';
    }
  );
  /*
  returns this array...
    [
      {
        name: '0',
        value: 10
      },
      {
        name: 'top',
        value: 20
      },
      {
        name: '3',
        value: 50
      }
    ]
  */

Use genData to capture all strings of an object...

  genData(
    [10, ["echo", {top: 20}], true, 30, "charlie"],
    function (name, value, parent, dataset, flags) {
      flags.omit = 1;
      if (typeof value === 'string') {
        dataset.push(value);
      }
    }
  );
  /*
  returns this array...
    [
      'echo',
      'charlie'
    ]
  */

Generators

Generators are functions that capture and extend complex parsing logic.

For example, this generator returns all found functions.

  var extractFncs = new genData(
      function (name, value, parent, dataset, flags) {
        flags.omit = 1;
        if (typeof value === 'function') {
          dataset.push(value);
        }
      }
    );

You can then pass anything to the @extractFncs@ generator, and it will call genData as if you included the parsers manually.

var foundFncs = extractFns(aBigConfigObject);

You can also spawn new generators and pass (additional) parser functions to any generator. Below, we'll spawn a generator from our @extractFncs@ generator, to further exclude functions that have a length greater than 2.

  var extractFncsLessThan3 = new extractFncs(
      function (name, value, parent, dataset) {
        if (typeof value === 'function' && value.length > 2) {
          dataset.pop();
        }
      }
    );

Prototyping

genData, along with each generator, supplies a prototype chain to each data object. Below, we define an @.isArray()@ method to the genData prototype, then access this method through a generator.

  genData.prototype.isArray = function () {
    return !!~{}.toString.call(this.value).indexOf('y');
  };

  var extractArrays = new genData(
      function (name, value, parent, dataset, flags) {
        flags.omit = !this.isArray();
      }
    );

You may also pass a third parameter to genData (or a generator), an object or function, to serve as the prototype for the returned data objects.

  var dataset = genData(
      stuff,
      [], // this could also be "falsy"
      {
        myFamiliarMethod: function () {
          // "this" will be the data object
        }
      }
    );

  dataset[0].myFamiliarMethod();

Note: Generators only branch/extend the genData prototype chain.

LICENSE

genData is available under the terms of the MIT-License.

Copyright 2011, Bemi Faison