Shapes example¶

package shapes;

/// Centimeters encoded in 32-bit floats.
quantity<f32, cm> Centimeters;

/// Degrees encoded in 32-bit floats.
quantity<f32, deg> Degrees;

/// A color enumeration.
enum Color : u8 { red, green, blue }

// Specification of a triangle.
struct Triangle { side : Centimeters }

// Specification of a rectangle.
struct Rectangle { width : Centimeters, height : Centimeters }

// Specification of a circle.
struct Circle { radius : Centimeters }

// A 2-D 32 bit vector
struct Vec2 { x : Centimeters, y : Centimeters }

// The geometry of a shape.
variant Geometry { Triangle,  Rectangle,  Circle }

// The wall that we might collide with.
enum Wall : u8 { top, bottom, left, right }

// A shape.
class Shape
{
  var geometry : Geometry [static];   // Shape's geometry.
  var frozen   : bool     [writable]; // True if the shape should move.
  var color    : Color    [writable]; // Shape's color.
  var position : Vec2;                // Shape's center.

  // Emitted when the shape collides with a wall.
  //
  // @param wall the wall that we collided with.
  event collidedWithWall(wall : Wall);
}

import "shapes.stl"

package shapes;

// An distance interval
struct DistanceInterval
{
  min : Centimeters,
  max : Centimeters
}

// A color or nothing
optional<Color> MaybeColor;

// An interval or nothing
optional<DistanceInterval> MaybeInterval;

// A list of names
sequence<string> NameList;

// Base class for listening to various shapes
class ShapeListener
{
  // Number of shapes being tracked
  var detectedShapesCount: u32;

  // Number of active queries
  var queryCount: u32;

  // Start listening for shapes that fulfil certain conditions.
  // Returns the name of the query that was created.
  //
  // @param bus the bus where to find the shapes.
  // @param color if present, the color that the shape must have.
  // @param xRange if present, the interval along the x axis where the shape should be.
  // @param yRange if present, the interval along the y axis where the shape should be.
  fn startListeningTo(bus : string, color : MaybeColor, xRange : MaybeInterval, yRange : MaybeInterval) -> string;

  // Deletes a previously created query.
  //
  // @param queryName the name of the query (the one returned by calls to startListeningTo)
  fn stopListeningTo(queryName : string);

  // Deletes all previously created queries.
  fn stopListening();

  // Get the names of all the detected shapes
  fn getAllDetectedShapes() -> NameList;
}