Structures Implementations

To provide an opportunity to interact with the compiler Genpay reserved list of special functions signatures. It allows user to implement basic operators and automatization for structures.

Reserved Functions

NOTE

Type notations in the functions below

• &self - Pointer of the structure to itself
• Self - Denotes the same type as the structure itself
• _ - Any type

• fn display(&self) *char - For output and format macros.

Example

struct Int {
  value: i32,

  fn display(&self) *char {
    return format!("{}", self.value);
  }
}

fn main() {
  let num = Int { .value = 10 };
  println!("Integer number is: {}", num);
}

Integer number is: 10

---

• fn drop(&self) - Data destructor. Calls on scope exit.

Example

struct Int {
  value: i32,

  fn drop(&self) {
    println!("Dropping value `{}`", self.value);
  }
}

fn main() {
  let num = Int { .value = 10 };
  println!("Hello!");
}

Hello!
Dropping value `10`

---

• fn iterate(&self) (_, bool) - Iterator function, used by for loop.
  Boolean flag in return type is used to know if value is something.

Example

struct Int {
  value: i32,
  iterator: i32,

  fn new(value: i32) Int {
    return Int { .value = value, .iterator = 0 };
  }

  fn iterate(&self) (i32, bool) {
    let output = self.iterator;

    if output >= self.value {
      self.iterator = 0;
      return (output, false);
    }

    self.iterator += 1;
    return (output, true);
  }
}

fn main() {
  let num = Int.new(5);

  for item = num {
    println!("{}", item);
  }
}

0
1
2
3
4

---

• fn binary(&self, other: *Self, operator: *char) Self - For binary operations on structures.

Example

struct Int {
  value: i32,

  fn new(value: i32) Int {
    return Int { .value = value };
  }

  fn binary(&self, other: *Int, operator: *char) Int {
    let value = self.value;

    if operator == "+" {
      value += other.value;
    } else if operator == "-" {
      value -= other.value;
    } else if operator == "*" {
      value *= other.value;
    } else {
      value /= other.value;
    }

    return Int.new(value);
  }

  fn display(&self) *char {
    return format!("{}", self.value);
  }
}

fn main() {
  let a = Int.new(10);
  let b = Int.new(5);

  println!("{}", a + b);
  println!("{}", a - b);
  println!("{}", a * b);
  println!("{}", a / b);
}

15
5
50
2

---

• fn unary(&self, operator: *char) Self - For unary operations on structures.

Example

struct Int {
  value: i32,

  fn new(value: i32) Int {
    return Int { .value = value };
  }

  fn unary(&self, operator: *char) Int {
    if operator == "!" {
      return Int.new(!self.value);
    } else {
      return Int.new(-self.value);
    }
  }

  fn display(&self) *char {
    return format!("{}", self.value);
  }
}

fn main() {
  let a = Int.new(10);

  println!("-a = {}", -a);
  println!("!a = {}", !a);
}

-a = -10
!a = -11

---

• fn compare(&self, other: *Self) i32 - For boolean operators on structs (-1 - left is greater; 0 - equal; 1 - right is greater).

Example

struct Int {
  value: i32,

  fn new(value: i32) Int {
    return Int { .value = value };
  }

  fn compare(&self, other: *Int) i32 {
    if self.value > other.value {
      return -1;
    } else if self.value < other.value {
      return 1;
    }

    return 0;
  }

}

fn main() {
  let a = Int.new(10);
  let b = Int.new(5);

  println!("{}", a > b);
  println!("{}", a => b);
  println!("{}", a < b);
  println!("{}", a <= b);
  println!("{}", a == b);
  println!("{}", a != b);
}

true
true
false
false
false
true

---

• fn deref(&self) _ - For the dereference operator.

Example

struct Int {
  value: i32,

  fn new(value: i32) Int {
    return Int { .value = value };
  }

  fn deref(&self) i32 {
    return self.value + 1;
  }

  fn display(&self) *char {
    return format!("{}", self.value);
  }
}

fn main() {
  let a = Int.new(10);

  println!("a: {}", a);
  println!("*a: {}", *a);
}

a: 10
*a: 11

---

• fn deref_assign(&self, value: _) - For the dereference assignment operator.

Example

struct Int {
  value: i32,

  fn new(value: i32) Int {
    return Int { .value = value };
  }

  fn deref_assign(&self, value: i32) {
    self.value = value + 1;
  }

  fn display(&self) *char {
    return format!("{}", self.value);
  }
}

fn main() {
  let a = Int.new(10);

  *a = 100;

  println!("{}", a);
}

101

---

• fn slice(&self, index: usize) _ - For the slice expression.

Example

struct Int {
  value: i32,

  fn new(value: i32) Int {
    return Int { .value = value };
  }

  fn slice(&self, index: usize) i32 {
    return self.value + cast!(index, i32);
  }

  fn display(&self) *char {
    return format!("{}", self.value);
  }
}

fn main() {
  let a = Int.new(10);

  println!("a: {}", a);
  println!("a[10]: {}", a[10]);
}

a: 10
a[10]: 20

---

• fn slice_assign(&self, index: usize, value: _) - For the slice assign statement.

Example

struct Int {
  value: i32,

  fn new(value: i32) Int {
    return Int { .value = value };
  }

  fn slice_assign(&self, index: usize, value: i32) {
    self.value = cast!(index, i32) + value;
  }

  fn display(&self) *char {
    return format!("{}", self.value);
  }
}

fn main() {
  let a = Int.new(10);

  a[10] = 10;

  println!("a: {}", a);
}

a: 20