reading from file

[Ali Çehreli via Digitalmars-d-learn]

On 12/15/2016 10:47 PM, KaattuPoochi wrote:
 > On Tuesday, 13 December 2016 at 21:13:26 UTC, Ali wrote:
 >>
 >> And extending Ali's solution you can actually get the data in
 >> to a two dimentional array at compile time and have it in static
 >> memory with a small adjustment:
 >>
 >> static immutable matrix = import("data.txt")
 >>     .split("\n")
 >>     .map!(a => a.split(",").map!(to!int).array)
 >>     .array;
 >>
 >> void main() {
 >>     writeln(matrix);
 >> }
 >
 > 1. For any non-trivial matrices (with 500 lines) runs DMD 2.072.1 out of
 > memory (2GB). Not sure if this is a known bug. Works fine with LDC 1.0.0.

Just to note, there are 501 arrays generated at compile. You can reduce 
that number to 1 if you know the width and the height of the matrix. The 
following solution reads everything into a single array and then uses it 
as an int[N][]:

import std.algorithm;
import std.conv;
import std.array;
import std.stdio;

static immutable buffer = import("deneme.txt")
                           .splitter
                           .map!(a => a.splitter(',').map!(to!int))
                           .joiner
                           .array;

// Assume these are known or are calculated at compile time:
enum width = 4;
enum height = 3;

immutable int[width][] matrix;

shared static this() {
     matrix = (cast(immutable(int[width])*)buffer.ptr)[0..height];

     // Make sure we did not copy into matrix
     assert(cast(void*)matrix.ptr == cast(void*)buffer.ptr);
}

void main() {
     writeln(matrix);
}

 > 2. The EOL on the last line results in an empty row in the end. Is there
 > a way to overcome this?

As an added bonus, the solution above does not suffer from empty lines.

Ali