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dss:laboratoare:04 [2019/06/21 15:10] razvan.nitu1305 |
dss:laboratoare:04 [2021/07/12 18:58] (current) razvan.nitu1305 [5. Ranges] |
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| - | ==== Nogc Function ==== | + | ==== Nogc Functions ==== |
| D is a garbage collected language. Many data structures and algorithms in most D programs take advantage of dynamic memory blocks that are managed by the garbage collector (GC). Such memory blocks are reclaimed again by the GC by an algorithm called garbage collection. | D is a garbage collected language. Many data structures and algorithms in most D programs take advantage of dynamic memory blocks that are managed by the garbage collector (GC). Such memory blocks are reclaimed again by the GC by an algorithm called garbage collection. | ||
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| For an extensive list of operations forbidden in **@nogc** code, check this [[https://dlang.org/spec/function.html#nogc-functions|link]] | For an extensive list of operations forbidden in **@nogc** code, check this [[https://dlang.org/spec/function.html#nogc-functions|link]] | ||
| + | |||
| + | ==== Ranges ==== | ||
| + | |||
| + | Any object which fulfills the following interface is called a **range** (or more specific **InputRange**) and is thus a type that can be iterated over: | ||
| + | |||
| + | <code D> | ||
| + | interface InputRange(E) | ||
| + | { | ||
| + | bool empty(); | ||
| + | E front(); | ||
| + | void popFront(); | ||
| + | } | ||
| + | </code> | ||
| + | |||
| + | Check this [[https://tour.dlang.org/tour/en/basics/ranges|link]] for an example of a Fibonaci range implementation. | ||
| + | |||
| + | Besides the dumbest form of range, the **InputRange**, the are other forms of ranges: | ||
| + | |||
| + | * **ForwardRange** is an **InputRange** and additionally requires the **save** method that saves the state of the range. | ||
| + | * **BidirectionalRange** is a **ForwardRange** and additionally requires the **back** and **popBack** methods. | ||
| + | * **RandomAccessRange** is a **BidirectionalRange** and additionally requires the **[]** operator (and another property depending whether the range is finite or infinite) | ||
| + | |||
| + | For more informations on ranges, you can read the outstanding [[http://ddili.org/ders/d.en/ranges.html|description]] in Ali's book. | ||
| + | |||
| + | ===== Exercises ===== | ||
| + | |||
| + | The lab can be found at this [[https://github.com/RazvanN7/D-Summer-School/tree/master/lab-04|link]]. | ||
| + | |||
| + | ==== 1. Complex numbers ==== | ||
| + | |||
| + | Implement a struct that will emulate a [[https://en.wikipedia.org/wiki/Complex_number|complex number]]. The operations that need to be implemented on complex numbers are: assignment, addition, subtraction, multiply and division. Write a unittest to assure the validity of the implementation. | ||
| + | |||
| + | <note> | ||
| + | What happens if you comment the assignment operator? | ||
| + | </note> | ||
| + | |||
| + | ==== 2. Alias ==== | ||
| + | |||
| + | Navigate to the ''2-alias'' directory. Inspect the two source files. Compile de code: | ||
| + | |||
| + | <code bash> | ||
| + | dmd main.d func.d | ||
| + | </code> | ||
| + | |||
| + | What happens? Why? Before invoking function **fun**, add the line: | ||
| + | |||
| + | <code D> | ||
| + | alias fun = func.fun; | ||
| + | </code> | ||
| + | |||
| + | What happens? Why? | ||
| + | |||
| + | ==== 3. Nullable ==== | ||
| + | |||
| + | Implement a [[https://dlang.org/library/std/typecons/nullable.html#2|Nullable]] object. In D, there are certain types that cannot be null (such as int, struct objects etc.), also there are algorithms that work only for types that can be in the null state; for those algorithms to work with non-nullable types, an abstraction is considered in the form of a Nullable object. | ||
| + | |||
| + | * Implement the Nullable(T) struct by having a templated field which is the value and a boolean that keeps track whether the value is null or not; the Nullable object is considered null if the field holds the **.init** value | ||
| + | * Implement the methods: | ||
| + | - get: returns the value of the object if not null; if null, halts execution raising an assert error with the appropriate message; | ||
| + | - opAssign: a Nullable!T object can be assigned a value of type T; | ||
| + | - a constructor that takes a value of type T; | ||
| + | |||
| + | What is the problem with this implementation? | ||
| + | |||
| + | ==== 4. Alias this ==== | ||
| + | |||
| + | Solve the problem of the previous **Nullable!T** implementation by forwarding unknown operations to the T object contained. Test the new implementation by adding instances of **Nullable** with int, struct and class. | ||
| + | |||
| + | ==== 5. Ranges ==== | ||
| + | |||
| + | Implement a stack that respects the range interface. | ||
| + | |||
| + | - Implement the stack as an input range (you may use builtin arrays as the underlying data structure); | ||
| + | - Improve the stack by adding support for forward range methods; | ||
| + | - Improve the stack by adding support for bidirectional range methods; | ||
| + | - Improve the stack by adding support for random access range methods; | ||
| + | |||
| + | To test your implementation you can use these [[https://dlang.org/phobos/std_range_primitives.html|range primitives]] | ||
