contrast 0.1.1

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  • Example
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contrast

Build Status

Utilities for comparing (and contrasting) dart values:

  • Comparator combinators (by/compound/reverse/lexicographic/nullsFirst/nullsLast)
  • Comparison operator mixin (Quantity)(<, <=, ==, >, >=)
  • Find extrema of Comparables and Iterables (min/max/minOf/maxOf)
  • Test and obtain clamped comparables (clamp/between)
  • Test and obtain sorted iterables (sorted/isOrdered/isStrictlyOrdered)

#Example


import 'package:contrast/contrast.dart';
import 'dart:math' as math;

main() {
  
  // Easily define comparison operators (see Point class below).
  assert(Point.ZERO < Point.UNIT);
  assert(Point.UNIT >= Point.ZERO);
  assert(Point.ZERO == new Point(0, 0));

  // Find extrema of arbitrary comparables.
  // (dart:math's min/max only work with numbers)
  assert(min(Point.ZERO, Point.UNIT) == Point.ZERO);
  assert(max(Point.ZERO, Point.UNIT) == Point.UNIT);
  assert(clamp(new Point(1, 2), Point.ZERO, Point.UNIT) == Point.UNIT);
  assert(between(new Point(0.5, 0.5), Point.ZERO, Point.UNIT));
  
  // Find extrema of iterables.
  var points = [Point.UNIT, new Point(1, 2), Point.ZERO, new Point(0, 1)];
  assert(minOf(points) == Point.ZERO);
  assert(maxOf(points) == new Point(1, 2));
  
  // Sort into a new List easily ( vs. iterable.toList()..sort() ).
  var sortedPoints = sorted(points);
  
  // Check ordering of iterables.
  assert(isOrdered(sortedPoints));
  assert(isStrictlyOrdered(sortedPoints));

  // Define comparators using combinator helpers...
  
  // By key function
  var byMagnitude = by((point) => point.magnitude);
  assert(max(Point.ZERO, new Point(-1, -1), 
      compare: byMagnitude) == new Point(-1, -1));
  
  // Compound
  assert(max(Point.ZERO, new Point(-1, -1), 
      compare: compound([byMagnitude, Comparable.compare])) == new Point(-1, -1));
  
  // Reversed
  assert(max(Point.ZERO, Point.UNIT, compare: reverse()) == Point.ZERO);

  // Lexicographic
  assert(min([Point.ZERO, Point.UNIT], [Point.ZERO, new Point(2, 2)], 
      compare: lexicographic()).last == Point.UNIT);
  
  // Null safe
  var maybePoints = [Point.UNIT, null, Point.ZERO, null];
  assert(sorted(maybePoints, compare: nullsFirst()).first == null);
  assert(sorted(maybePoints, compare: nullsLast()).last == null);
}

// Mixin `Comparable`-based comparison operators with `Quantity`.
class Point extends Object with Quantity<Point> {
  
  static Point ZERO = new Point(0, 0);
  static Point UNIT = new Point(1, 1);
  
  final num x, y;
  
  num get magnitude => math.sqrt(x*x + y*y);
  
  Point(this.x, this.y);
  
  // Use comparator combinators`compound` and `by`.
  static final _comparator = compound([by((p) => p.x), by((p) => p.y)]);
  
  int compareTo(Point other) => _comparator(this, other);
  
  toString() => '($x, $y)';
}

example/example.dart

import 'package:contrast/contrast.dart';
import 'dart:math' as math;

main() {
  
  // Easily define comparison operators (see Point class below).
  assert(Point.ZERO < Point.UNIT);
  assert(Point.UNIT >= Point.ZERO);
  assert(Point.ZERO == new Point(0, 0));

  // Find extrema of arbitrary comparables.
  // (dart:math's min/max only work with numbers)
  assert(min(Point.ZERO, Point.UNIT) == Point.ZERO);
  assert(max(Point.ZERO, Point.UNIT) == Point.UNIT);
  assert(clamp(new Point(1, 2), Point.ZERO, Point.UNIT) == Point.UNIT);
  assert(between(new Point(0.5, 0.5), Point.ZERO, Point.UNIT));
  
  // Find extrema of iterables.
  var points = [Point.UNIT, new Point(1, 2), Point.ZERO, new Point(0, 1)];
  assert(minOf(points) == Point.ZERO);
  assert(maxOf(points) == new Point(1, 2));
  
  // Sort into a new List easily ( vs. iterable.toList()..sort() ).
  var sortedPoints = sorted(points);
  
  // Check ordering of iterables.
  assert(isOrdered(sortedPoints));
  assert(isStrictlyOrdered(sortedPoints));

  // Define comparators using combinator helpers...
  
  // By key function
  var byMagnitude = by((point) => point.magnitude);
  assert(max(Point.ZERO, new Point(-1, -1), 
      compare: byMagnitude) == new Point(-1, -1));
  
  // Compound
  assert(max(Point.ZERO, new Point(-1, -1), 
      compare: compound([byMagnitude, Comparable.compare])) == new Point(-1, -1));
  
  // Reversed
  assert(max(Point.ZERO, Point.UNIT, compare: reverse()) == Point.ZERO);

  // Lexicographic
  assert(min([Point.ZERO, Point.UNIT], [Point.ZERO, new Point(2, 2)], 
      compare: lexicographic()).last == Point.UNIT);
  
  // Null safe
  var maybePoints = [Point.UNIT, null, Point.ZERO, null];
  assert(sorted(maybePoints, compare: nullsFirst()).first == null);
  assert(sorted(maybePoints, compare: nullsLast()).last == null);
}

// Mixin `Comparable`-based comparison operators with `Quantity`.
class Point extends Object with Quantity<Point> {
  
  static Point ZERO = new Point(0, 0);
  static Point UNIT = new Point(1, 1);
  
  final num x, y;
  
  num get magnitude => math.sqrt(x*x + y*y);
  
  Point(this.x, this.y);
  
  // Use comparator combinators`compound` and `by`.
  static final _comparator = compound([by((p) => p.x), by((p) => p.y)]);
  
  int compareTo(Point other) => _comparator(this, other);
  
  toString() => '($x, $y)';
}

Use this package as a library

1. Depend on it

Add this to your package's pubspec.yaml file:


dependencies:
  contrast: ^0.1.1

2. Install it

You can install packages from the command line:

with pub:


$ pub get

Alternatively, your editor might support pub get. Check the docs for your editor to learn more.

3. Import it

Now in your Dart code, you can use:


import 'package:contrast/contrast.dart';
  
Version Uploaded Documentation Archive
0.1.1 Sep 23, 2014 Go to the documentation of contrast 0.1.1 Download contrast 0.1.1 archive
0.1.0 Sep 19, 2014 Go to the documentation of contrast 0.1.0 Download contrast 0.1.0 archive
Popularity:
Describes how popular the package is relative to other packages. [more]
17
Health:
Code health derived from static analysis. [more]
1
Maintenance:
Reflects how tidy and up-to-date the package is. [more]
0
Overall:
Weighted score of the above. [more]
9
Learn more about scoring.

We analyzed this package on Sep 18, 2018, and provided a score, details, and suggestions below. Analysis was completed with status completed using:

  • Dart: 2.0.0
  • pana: 0.12.3

Platforms

Detected platforms: unsure

Low code quality prevents platform classification.

Issues and suggestions

Fix platform conflicts.

Low code quality prevents platform classification.

Fix lib/src/comparators.dart.

Analysis of lib/src/comparators.dart failed with 5 errors:

line 14 col 27: The method tear-off 'compare' has type '(Comparable<dynamic>, Comparable<dynamic>) → int' that isn't of expected type '(dynamic, dynamic) → int'. This means its parameter or return type does not match what is expected.

line 45 col 27: The method tear-off 'compare' has type '(Comparable<dynamic>, Comparable<dynamic>) → int' that isn't of expected type '(dynamic, dynamic) → int'. This means its parameter or return type does not match what is expected.

line 58 col 27: The method tear-off 'compare' has type '(Comparable<dynamic>, Comparable<dynamic>) → int' that isn't of expected type '(dynamic, dynamic) → int'. This means its parameter or return type does not match what is expected.

line 80 col 45: The method tear-off 'compare' has type '(Comparable<dynamic>, Comparable<dynamic>) → int' that isn't of expected type '(dynamic, dynamic) → int'. This means its parameter or return type does not match what is expected.

line 93 col 44: The method tear-off 'compare' has type '(Comparable<dynamic>, Comparable<dynamic>) → int' that isn't of expected type '(dynamic, dynamic) → int'. This means its parameter or return type does not match what is expected.

Fix lib/src/extrema.dart.

Analysis of lib/src/extrema.dart failed with 6 errors, including:

line 8 col 41: The method tear-off 'compare' has type '(Comparable<dynamic>, Comparable<dynamic>) → int' that isn't of expected type '(dynamic, dynamic) → int'. This means its parameter or return type does not match what is expected.

line 15 col 41: The method tear-off 'compare' has type '(Comparable<dynamic>, Comparable<dynamic>) → int' that isn't of expected type '(dynamic, dynamic) → int'. This means its parameter or return type does not match what is expected.

line 25 col 58: The method tear-off 'compare' has type '(Comparable<dynamic>, Comparable<dynamic>) → int' that isn't of expected type '(dynamic, dynamic) → int'. This means its parameter or return type does not match what is expected.

line 33 col 57: The method tear-off 'compare' has type '(Comparable<dynamic>, Comparable<dynamic>) → int' that isn't of expected type '(dynamic, dynamic) → int'. This means its parameter or return type does not match what is expected.

line 47 col 27: The method tear-off 'compare' has type '(Comparable<dynamic>, Comparable<dynamic>) → int' that isn't of expected type '(dynamic, dynamic) → int'. This means its parameter or return type does not match what is expected.

Fix lib/src/ordered.dart.

Analysis of lib/src/ordered.dart failed with 2 errors:

line 9 col 27: The method tear-off 'compare' has type '(Comparable<dynamic>, Comparable<dynamic>) → int' that isn't of expected type '(dynamic, dynamic) → int'. This means its parameter or return type does not match what is expected.

line 17 col 27: The method tear-off 'compare' has type '(Comparable<dynamic>, Comparable<dynamic>) → int' that isn't of expected type '(dynamic, dynamic) → int'. This means its parameter or return type does not match what is expected.

Fix additional 3 files with analysis or formatting issues.

Additional issues in the following files:

  • lib/src/quantity.dart (1 error, 1 hint)
  • lib/src/sorted.dart (1 error)
  • lib/contrast.dart (Run dartfmt to format lib/contrast.dart.)

Package is too old.

The package was released more than two years ago.

Maintain CHANGELOG.md.

Changelog entries help clients to follow the progress in your code.

Add SDK constraint in pubspec.yaml.

For information about setting SDK constraint, please see https://www.dartlang.org/tools/pub/pubspec#sdk-constraints.

The description is too short.

Add more detail about the package, what it does and what is its target use case. Try to write at least 60 characters.

Dependencies

Package Constraint Resolved Available
Dev dependencies
quiver >=0.18.2 <0.20.0
unittest >=0.11.0+2 <0.12.0