gistfile1.js

var test = require('tape');
var bytewise = require('bytewise');
var encode = bytewise.encode;
var MIN = bytewise.MIN;
var MAX = bytewise.MAX;

test('tuple queries', function (t) {
  var yearly = tuples('reports', 'yearly');

  // component keys of the tuple space query are available by index
  t.equal(yearly[0], 'reports');
  t.equal(yearly[1], 'yearly');

  // the underlying array can be retrieved with the `valueOf` method
  t.deepEqual(yearly.valueOf(), [ 'reports', 'yearly' ]);

  // the tuple space query can be used as an explicit key value
  // the `key` accessor is available to compute and memoize bytewise-encoded key
  t.equal(yearly.key, encode([ 'reports', 'yearly' ]));

  // the `range` accessor can be used to create a query stream config object
  t.deepEqual(yearly.range, {
    gt: encode([ 'reports', 'yearly', MIN ]),
    lt: encode([ 'reports', 'yearly', MAX ])
  });

  // a tuple space query ranges over all child tuples spaces by default
  // this can be constrained by clamping a query's range
  var since2010 = yearly.clamp({ gte: 2010 });
  t.deepEqual(since2010.range, {
    gte: encode([ 'reports', 'yearly', 2010 ]),
    lt: encode([ 'reports', 'yearly', MAX ])
  });

  // a clamped query can be narrowed further
  var from2010to2020 = since2010.clamp({ lte: 2020 });
  t.deepEqual(from2010to2020.range, {
    gte: encode([ 'reports', 'yearly', 2010 ]),
    lte: encode([ 'reports', 'yearly', 2020 ])
  });

  // and further
  var from2010to2020exclusive = from2010to2020.clamp({ lt: 2020 });
  t.deepEqual(from2010to2020exclusive.range, {
    gte: encode([ 'reports', 'yearly', 2010 ]),
    lt: encode([ 'reports', 'yearly', 2020 ])
  });

  // but a query's range is not automatically widened
  var from2010to2020_ = from2010to2020.clamp({ gte: 2000 });
  t.deepEqual(from2010to2020_.range, from2010to2020.range);

  // a query may be constrained by restricting to a specific subspace
  var in2015 = yearly.subspace(2015);
  t.equal(in2015.key, encode([ 'reports', 'yearly', 2015 ]));
  t.deepEqual(in2015.range, {
    gt: encode([ 'reports', 'yearly', 2015, MIN ]),
    lt: encode([ 'reports', 'yearly', 2015, MAX ])
  });

  // any query range can be restricted to a subspace in this way
  var in2015_ = from2010to2020.subspace(2015);
  t.deepEqual(in2015, in2015_);

  // however the subspace key provided must exist within the range
  t.equal(from2010to2020.subspace(2000), tuples.EMPTY);

  // multiple subspace keys can be provided at once
  var tpsReports2015 = yearly.subspace(2015, 'tps');
  t.deepEqual(tpsReports2015.range, {
    gt: encode([ 'reports', 'yearly', 2015, 'tps', MIN ]),
    lt: encode([ 'reports', 'yearly', 2015, 'tps', MAX ])
  });
  t.deepEqual(tpsReports2015, in2015.subspace('tps'));

  t.end();
});