Port boolean functions and tests

CONTRIBUTING.md

@@ -20,6 +20,42 @@ To put it simply, be kind to each other.
 - Clone the repository: ```git clone [email protected]:dartclub/turf_dart.git```
 - Navigate to project's folder in terminal & get its dependencies:  ```dart pub get```
 - Go through [Implementation Process](#implementation-process)
+- Import the library in your code and use it. For example:
+```dart
+import 'package:turf/helpers.dart';
+import 'package:turf/src/line_segment.dart';
+
+  Feature<Polygon> poly = Feature<Polygon>(
+    geometry: Polygon(coordinates: [
+      [
+        Position(0, 0),
+        Position(2, 2),
+        Position(0, 1),
+        Position(0, 0),
+      ],
+      [
+        Position(0, 0),
+        Position(1, 1),
+        Position(0, 1),
+        Position(0, 0),
+      ],
+    ]),
+  );
+
+var total = segmentReduce<int>(poly, (previousValue,
+        currentSegment,
+        initialValue,
+        featureIndex,
+        multiFeatureIndex,
+        geometryIndex,
+        segmentIndex) {
+      if (previousValue != null) {
+        previousValue++;
+      }
+      return previousValue;
+    }, 0, combineNestedGeometries: false);
+// total.length ==  6
+```
 
 ## Structure of modules
 ```
@@ -56,4 +92,4 @@ In order to add to this very documentation, please develop CONTRIBUTING.md in [d
 
 ## GeoJSON Object Model
 If you have not read our [README.md](https://github.com/dartclub/turf_dart/blob/main/README.md) this diagram will give you a lot of information. Please consider looking our [notable design decisions](https://github.com/dartclub/turf_dart/blob/main/README.md#notable-design-decisions).  
-![polymorphism](https://user-images.githubusercontent.com/10634693/159876354-f9da2f37-02b3-4546-b32a-c0f82c372272.png)
+![polymorphism](https://user-images.githubusercontent.com/10634693/159876354-f9da2f37-02b3-4546-b32a-c0f82c372272.png)

README.md

@@ -15,6 +15,7 @@ Most of the implementation is a direct translation from [turf.js](https://github
 - Get the [Dart tools](https://dart.dev/tools)
 - Install the library with `dart pub add turf`
 - Import the library in your code and use it. For example:
+
 ```dart
 import 'package:turf/helpers.dart';
 import 'package:turf/src/line_segment.dart';
@@ -36,7 +37,7 @@ Feature<Polygon> poly = Feature<Polygon>(
   ]),
 );
 
-main() {
+void main() {
   var total = segmentReduce<int>(
     poly,
     (previousValue, currentSegment, initialValue, featureIndex,
@@ -145,7 +146,7 @@ Any new benchmarks must be named `*_benchmark.dart` and reside in the
 - [ ] kinks
 - [ ] lineArc
 - [ ] lineChunk
-- [ ] lineIntersect
+- [ ] [lineIntersect](https://github.com/dartclub/turf_dart/blob/main/lib/src/line_intersect.dart)
 - [ ] lineOverlap
 - [x] [lineSegment](https://github.com/dartclub/turf_dart/blob/main/lib/src/line_segment.dart)
 - [ ] lineSlice
@@ -207,8 +208,6 @@ Any new benchmarks must be named `*_benchmark.dart` and reside in the
 - [x] [featureReduce](https://github.com/dartclub/turf_dart/blob/main/lib/src/meta/feature.dart)
 - [x] [flattenEach](https://github.com/dartclub/turf_dart/blob/main/lib/src/meta/flatten.dart)
 - [x] [flattenReduce](https://github.com/dartclub/turf_dart/blob/main/lib/src/meta/flatten.dart)
-- [x] [getCoord](https://github.com/dartclub/turf_dart/blob/main/lib/src/meta/coord.dart)
-- [x] [getCoords](https://github.com/dartclub/turf_dart/blob/main/lib/src/meta/coord.dart)
 - [x] [geomEach](https://github.com/dartclub/turf_dart/blob/main/lib/src/meta/geom.dart)
 - [x] [geomReduce](https://github.com/dartclub/turf_dart/blob/main/lib/src/meta/geom.dart)
 - [x] [propEach](https://github.com/dartclub/turf_dart/blob/main/lib/src/meta/prop.dart)
@@ -219,19 +218,25 @@ Any new benchmarks must be named `*_benchmark.dart` and reside in the
 - [x] [clusterEach](https://github.com/dartclub/turf_dart/blob/main/lib/src/meta/cluster.dart)
 - [x] [clusterReduce](https://github.com/dartclub/turf_dart/blob/main/lib/src/meta/cluster.dart)
 
+### Invariants
+
+- [x] [getCoord](https://github.com/dartclub/turf_dart/blob/main/lib/src/meta/coord.dart)
+- [x] [getCoords](https://github.com/dartclub/turf_dart/blob/main/lib/src/invariant.dart)
+- [x] [getGeom](https://github.com/dartclub/turf_dart/blob/main/lib/src/invariant.dart)
+
 ### Booleans
 
-- [ ] booleanClockwise
-- [ ] booleanConcave
-- [ ] booleanContains
-- [ ] booleanCrosses
-- [ ] booleanDisjoint
-- [ ] booleanEqual
-- [ ] booleanIntersects
+- [x] [booleanClockwise](https://github.com/dartclub/turf_dart/blob/main/lib/src/booleans/boolean_clockwise.dart)
+- [x] [booleanConcave](https://github.com/dartclub/turf_dart/blob/main/lib/src/booleans/boolean_concave.dart)
+- [x] [booleanContains](https://github.com/dartclub/turf_dart/blob/main/lib/src/booleans/boolean_contains.dart)
+- [x] [booleanCrosses](https://github.com/dartclub/turf_dart/blob/main/lib/src/booleans/boolean_crosses.dart)
+- [x] [booleanDisjoint](https://github.com/dartclub/turf_dart/blob/main/lib/src/booleans/boolean_disjoint.dart)
+- [x] [booleanEqual](https://github.com/dartclub/turf_dart/blob/main/lib/src/booleans/boolean_equal.dart)
+- [x] [booleanIntersects](https://github.com/dartclub/turf_dart/blob/main/lib/src/booleans/boolean_intersect.dart)
 - [ ] booleanOverlap
-- [ ] booleanParallel
-- [ ] booleanPointInPolygon
-- [ ] booleanPointOnLine
+- [x] [booleanParallel](https://github.com/dartclub/turf_dart/blob/main/lib/src/booleans/boolean_parallel.dart)
+- [x] [booleanPointInPolygon](https://github.com/dartclub/turf_dart/blob/main/lib/src/booleans/boolean_point_in_polygon.dart)
+- [x] [booleanPointOnLine](https://github.com/dartclub/turf_dart/blob/main/lib/src/booleans/boolean_point_on_line.dart)
 - [ ] booleanWithin
 
 ### Unit Conversion

analysis_options.yaml

@@ -2,4 +2,4 @@ include: package:dartclub_lint/dart.yaml
 
 analyzer:
   errors:
-    prefer_generic_function_type_aliases: error
+    prefer_generic_function_type_aliases: error

benchmark/area_benchmark.dart

@@ -16,7 +16,7 @@ Feature<Polygon> poly = Feature<Polygon>(
   ]),
 );
 
-main() {
+void main() {
   group('area', () {
     benchmark('simple', () {
       area(poly);

benchmark/explode_benchmark.dart

@@ -12,7 +12,7 @@ var poly = Polygon(coordinates: [
   ],
 ]);
 
-main() {
+void main() {
   group('explode', () {
     benchmark('simple', () {
       explode(poly);

benchmark/polygon_smooth_benchmark.dart

@@ -5,7 +5,7 @@ import 'package:benchmark/benchmark.dart';
 import 'package:turf/polygon_smooth.dart';
 import 'package:turf/turf.dart';
 
-main() {
+void main() {
   group("turf-polygon-smooth", () {
     var inDir = Directory('./test/examples/polygonSmooth/in');
     for (var file in inDir.listSync(recursive: true)) {

example/main.dart

@@ -18,7 +18,7 @@ Feature<Polygon> poly = Feature<Polygon>(
   ]),
 );
 
-main() {
+void main() {
   var total = segmentReduce<int>(
     poly,
     (previousValue, currentSegment, initialValue, featureIndex,

lib/src/booleans/boolean_clockwise.dart

@@ -0,0 +1,47 @@
+import 'package:turf/src/invariant.dart';
+
+import '../../helpers.dart';
+
+/// Takes a ring and return [true] or [false] whether or not the ring is clockwise
+/// or counter-clockwise.
+/// Takes a [Feature<LineString>] or[LineString] or a [List<Position>] to be
+/// evaluated.
+/// example:
+/// ```dart
+/// var clockwiseRing = LineString(
+///   coordinates: [
+///     Position.of([0, 0]),
+///     Position.of([1, 1]),
+///     Position.of([1, 0]),
+///     Position.of([0, 0])
+///   ],
+/// );
+/// var counterClockwiseRing = LineString(
+///   coordinates: [
+///     Position.of([0, 0]),
+///     Position.of([1, 0]),
+///     Position.of([1, 1]),
+///     Position.of([0, 0])
+///   ],
+/// );
+///
+/// booleanClockwise(clockwiseRing);
+/// //=true
+/// booleanClockwise(counterClockwiseRing);
+/// //=false
+/// ```
+bool booleanClockwise(LineString line) {
+  var ring = getCoords(line) as List<Position>;
+  num sum = 0;
+  int i = 1;
+  Position prev;
+  Position? cur;
+
+  while (i < ring.length) {
+    prev = cur ?? ring[0];
+    cur = ring[i];
+    sum += (cur[0]! - prev[0]!) * (cur[1]! + prev[1]!);
+    i++;
+  }
+  return sum > 0;
+}

lib/src/booleans/boolean_concave.dart

@@ -0,0 +1,42 @@
+import 'package:turf/helpers.dart';
+
+/// Takes a [Polygon] and returns [true] or [false] as to whether it is concave
+/// or not.
+/// example:
+/// ```dart
+/// var convexPolygon = Polygon(coordinates: [
+///   [
+///     Position.of([0, 0]),
+///     Position.of([0, 1]),
+///     Position.of([1, 1]),
+///     Position.of([1, 0]),
+///     Position.of([0, 0])
+///   ]
+/// ]);
+/// booleanConcave(convexPolygon);
+/// //=false
+/// ```
+bool booleanConcave(Polygon polygon) {
+  // Taken from https://stackoverflow.com/a/1881201 & https://stackoverflow.com/a/25304159
+  List<List<Position>> coords = polygon.coordinates;
+
+  if (coords[0].length <= 4) {
+    return false;
+  }
+
+  var sign = false;
+  var n = coords[0].length - 1;
+  for (var i = 0; i < n; i++) {
+    var dx1 = coords[0][(i + 2) % n][0]! - coords[0][(i + 1) % n][0]!;
+    var dy1 = coords[0][(i + 2) % n][1]! - coords[0][(i + 1) % n][1]!;
+    var dx2 = coords[0][i][0]! - coords[0][(i + 1) % n][0]!;
+    var dy2 = coords[0][i][1]! - coords[0][(i + 1) % n][1]!;
+    var zcrossproduct = dx1 * dy2 - dy1 * dx2;
+    if (i == 0) {
+      sign = zcrossproduct > 0;
+    } else if (sign != zcrossproduct > 0) {
+      return true;
+    }
+  }
+  return false;
+}