odin-lang.Odin/misc/old_stuff/demo_backup.odin

import (
	"fmt.odin";
	"atomics.odin";
	"bits.odin";
	"decimal.odin";
	"hash.odin";
	"math.odin";
	"mem.odin";
	"opengl.odin";
	"os.odin";
	"raw.odin";
	"strconv.odin";
	"strings.odin";
	"sync.odin";
	"sort.odin";
	"types.odin";
	"utf8.odin";
	"utf16.odin";
/*
*/
)


general_stuff :: proc() {
	// Complex numbers
	a := 3 + 4i;
	b: complex64 = 3 + 4i;
	c: complex128 = 3 + 4i;
	d := complex(2, 3);

	e := a / conj(a);
	fmt.println("(3+4i)/(3-4i) =", e);
	fmt.println(real(e), "+", imag(e), "i");


	// C-style variadic procedures
	foreign __llvm_core {
		// The variadic part allows for extra type checking too which C does not provide
		c_printf :: proc(fmt: ^u8, #c_vararg args: ..any) -> i32 #link_name "printf" ---;
	}
	str := "%d\n\x00";
	// c_printf(&str[0], i32(789456123));


	Foo :: struct {
		x: int;
		y: f32;
		z: string;
	}
	foo := Foo{123, 0.513, "A string"};
	x, y, z := expand_to_tuple(foo);
	fmt.println(x, y, z);
	#assert(type_of(x) == int);
	#assert(type_of(y) == f32);
	#assert(type_of(z) == string);


	// By default, all variables are zeroed
	// This can be overridden with the "uninitialized value"
	// This is similar to `nil` but applied to everything
	undef_int: int = ---;


	// Context system is now implemented using Implicit Parameter Passing (IPP)
	// The previous implementation was Thread Local Storage (TLS)
	// IPP has the advantage that it works on systems without TLS and that you can
	// link the context to the stack frame and thus look at previous contexts
	//
	// It does mean that a pointer is implicitly passed procedures with the default
	// Odin calling convention (#cc_odin)
	// This can be overridden with something like #cc_contextless or #cc_c if performance
	// is worried about

}

foreign_blocks :: proc() {
	// See sys/windows.odin
}

default_arguments :: proc() {
	hello :: proc(a: int = 9, b: int = 9) do fmt.printf("a is %d; b is %d\n", a, b);
	fmt.println("\nTesting default arguments:");
	hello(1, 2);
	hello(1);
	hello();
}

named_arguments :: proc() {
	Colour :: enum {
		Red,
		Orange,
		Yellow,
		Green,
		Blue,
		Octarine,
	};
	using Colour;

	make_character :: proc(name, catch_phrase: string, favourite_colour, least_favourite_colour: Colour) {
		fmt.println();
		fmt.printf("My name is %v and I like %v.  %v\n", name, favourite_colour, catch_phrase);
	}

	make_character("Frank", "¡Ay, caramba!", Blue, Green);


	// As the procedures have more and more parameters, it is very easy
	// to get many of the arguments in the wrong order especialy if the
	// types are the same
	make_character("¡Ay, caramba!", "Frank", Green, Blue);

	// Named arguments help to disambiguate this problem
	make_character(catch_phrase = "¡Ay, caramba!", name = "Frank",
	               least_favourite_colour = Green, favourite_colour = Blue);


	// The named arguments can be specifed in any order.
	make_character(favourite_colour = Octarine, catch_phrase = "U wot m8!",
	               least_favourite_colour = Green, name = "Dennis");


	// NOTE: You cannot mix named arguments with normal values
	/*
	make_character("Dennis",
	               favourite_colour = Octarine, catch_phrase = "U wot m8!",
	               least_favourite_colour = Green);
	*/


	// Named arguments can also aid with default arguments
	numerous_things :: proc(s: string, a := 1, b := 2, c := 3.14,
	                        d := "The Best String!", e := false, f := 10.3/3.1, g := false) {
		g_str := g ? "true" : "false";
		fmt.printf("How many?! %s: %v\n", s, g_str);
	}

	numerous_things("First");
	numerous_things(s = "Second", g = true);


	// Default values can be placed anywhere, not just at the end like in other languages
	weird :: proc(pre: string, mid: int = 0, post: string) {
		fmt.println(pre, mid, post);
	}

	weird("How many things", 42, "huh?");
	weird(pre = "Prefix", post = "Pat");

}


default_return_values :: proc() {
	foo :: proc(x: int) -> (first: string = "Hellope", second := "world!") {
		match x {
		case 0: return;
		case 1: return "Goodbye";
		case 2: return "Goodbye", "cruel world..";
		case 3: return second = "cruel world..", first = "Goodbye";
		}

		return second = "my old friend.";
	}

	fmt.printf("%s %s\n", foo(0));
	fmt.printf("%s %s\n", foo(1));
	fmt.printf("%s %s\n", foo(2));
	fmt.printf("%s %s\n", foo(3));
	fmt.printf("%s %s\n", foo(4));
	fmt.println();


	// A more "real" example
	Error :: enum {
		None,
		WhyTheNumberThree,
		TenIsTooBig,
	};

	Entity :: struct {
		name: string;
		id:   u32;
	}

	some_thing :: proc(input: int) -> (result: ^Entity = nil, err := Error.None) {
		match {
		case input == 3:  return err = Error.WhyTheNumberThree;
		case input >= 10: return err = Error.TenIsTooBig;
		}

		e := new(Entity);
		e.id = u32(input);

		return result = e;
	}
}

call_location :: proc() {
	amazing :: proc(n: int, using loc := #caller_location) {
		fmt.printf("%s(%d:%d) just asked to do something amazing.\n",
				   fully_pathed_filename, line, column);
		fmt.printf("Normal -> %d\n", n);
		fmt.printf("Amazing -> %d\n", n+1);
		fmt.println();
	}

	loc := #location(main);
	fmt.println("`main` is located at", loc);

	fmt.println("This line is located at", #location());
	fmt.println();

	amazing(3);
	amazing(4, #location(call_location));

	// See _preload.odin for the implementations of `assert` and `panic`

}


explicit_parametric_polymorphic_procedures :: proc() {
	// This is how `new` is actually implemented, see _preload.odin
	alloc_type :: proc(T: type) -> ^T do return cast(^T)alloc(size_of(T), align_of(T));

	int_ptr := alloc_type(int);
	defer free(int_ptr);
	int_ptr^ = 137;
	fmt.println(int_ptr, int_ptr^);

	// Named arguments work too!
	another_ptr := alloc_type(T = f32);
	defer free(another_ptr);


	add :: proc(T: type, args: ..T) -> T {
		res: T;
		for arg in args do res += arg;
		return res;
	}

	fmt.println("add =", add(int, 1, 2, 3, 4, 5, 6));

	swap :: proc(T: type, a, b: ^T) {
		tmp := a^;
		a^ = b^;
		b^ = tmp;
	}

	a, b: int = 3, 4;
	fmt.println("Pre-swap:", a, b);
	swap(int, &a, &b);
	fmt.println("Post-swap:", a, b);
	a, b = b, a; // Or use this syntax for this silly example case


	Vector2 :: struct {x, y: f32;};
	{
		// A more complicated example using subtyping
		// Something like this could be used in a game

		Entity :: struct {
			using position: Vector2;
			flags:          u64;
			id:             u64;
			derived:        any;
		}

		Rock :: struct {
			using entity: Entity;
			heavy: bool;
		}
		Door :: struct {
			using entity: Entity;
			open:         bool;
		}
		Monster :: struct {
			using entity: Entity;
			is_robot:     bool;
			is_zombie:    bool;
		}

		new_entity :: proc(T: type, x, y: f32) -> ^T {
			result := new(T);
			result.derived = result^;
			result.x = x;
			result.y = y;

			return result;
		}

		entities: [dynamic]^Entity;

		rock := new_entity(Rock, 3, 5);

		// Named arguments work too!
		door := new_entity(T = Door, x = 3, y = 6);

		// And named arguments can be any order
		monster := new_entity(
			y = 1,
			x = 2,
			T = Monster,
		);

		append(&entities, rock, door, monster);

		fmt.println("Subtyping");
		for entity in entities {
			match e in entity.derived {
			case Rock:    fmt.println("Rock",    e.x, e.y);
			case Door:    fmt.println("Door",    e.x, e.y);
			case Monster: fmt.println("Monster", e.x, e.y);
			}
		}
	}
	{
		Entity :: struct {
			using position: Vector2;
			flags:          u64;
			id:             u64;
			variant: union { Rock, Door, Monster };
		}

		Rock :: struct {
			using entity: ^Entity;
			heavy: bool;
		}
		Door :: struct {
			using entity: ^Entity;
			open:         bool;
		}
		Monster :: struct {
			using entity: ^Entity;
			is_robot:     bool;
			is_zombie:    bool;
		}

		new_entity :: proc(T: type, x, y: f32) -> ^T {
			result := new(Entity);
			result.variant = T{entity = result};
			result.x = x;
			result.y = y;

			return cast(^T)&result.variant;
		}

		entities: [dynamic]^Entity;

		rock := new_entity(Rock, 3, 5);

		// Named arguments work too!
		door := new_entity(T = Door, x = 3, y = 6);

		// And named arguments can be any order
		monster := new_entity(
			y = 1,
			x = 2,
			T = Monster,
		);

		append(&entities, rock, door, monster);

		fmt.println("Union");
		for entity in entities {
			match e in entity.variant {
			case Rock:    fmt.println("Rock",    e.x, e.y);
			case Door:    fmt.println("Door",    e.x, e.y);
			case Monster: fmt.println("Monster", e.x, e.y);
			}
		}
	}
}


implicit_polymorphic_assignment :: proc() {
	yep :: proc(p: proc(x: int)) {
		p(123);
	}

	frank :: proc(x: $T)    do fmt.println("frank ->", x);
	tim   :: proc(x, y: $T) do fmt.println("tim ->", x, y);
	yep(frank);
	// yep(tim);
}




main :: proc() {
/*
	foo :: proc(x: i64,  y: f32) do fmt.println("#1", x, y);
	foo :: proc(x: type, y: f32) do fmt.println("#2", type_info(x), y);
	foo :: proc(x: type)         do fmt.println("#3", type_info(x));

	f :: foo;

	f(y = 3785.1546, x = 123);
	f(x = int, y = 897.513);
	f(x = f32);

	general_stuff();
	foreign_blocks();
	default_arguments();
	named_arguments();
	default_return_values();
	call_location();
	explicit_parametric_polymorphic_procedures();
	implicit_polymorphic_assignment();


	// Command line argument(s)!
	// -opt=0,1,2,3
*/
/*
	program := "+ + * - /";
	accumulator := 0;

	for token in program {
		match token {
		case '+': accumulator += 1;
		case '-': accumulator -= 1;
		case '*': accumulator *= 2;
		case '/': accumulator /= 2;
		case: // Ignore everything else
		}
	}

	fmt.printf("The program \"%s\" calculates the value %d\n",
			   program, accumulator);
*/
}