I'm trying to make a terminal input preprocessor with alias/shortcuts and history.


import std.stdio;

void main() {
    string line;
    string[] history;

    line = readln();
    foreach(int i; 0..100) history = history + [""]; // XXX

    while(!stdin.eof) {
        writeln(line);
        if(line != history[0]) {
            history[1..100] = history[0..99];
            history[0] = line;
        }
        line = readln();
    }
}

On Thursday, 25 February 2016 at 12:53:37 UTC, asdf wrote:
> I'm trying to make a terminal input preprocessor with alias/shortcuts and history.
>
>
> import std.stdio;
>
> void main() {
>     string line;
>     string[] history;
>
>     line = readln();
>     foreach(int i; 0..100) history = history + [""]; // XXX
>
>     while(!stdin.eof) {
>         writeln(line);
>         if(line != history[0]) {
>             history[1..100] = history[0..99];
>             history[0] = line;
>         }
>         line = readln();
>     }
> }

In D the binary operator "~"  is used to concatenate both strings (arrays of characters) and arrays. (also the ~= operator is equivalent to lhs = lhs ~ rhs

Nic

On Thursday, 25 February 2016 at 12:53:37 UTC, asdf wrote:
> I'm trying to make a terminal input preprocessor with alias/shortcuts and history.
>
>
> import std.stdio;
>
> void main() {
>     string line;
>     string[] history;
>
>     line = readln();
>     foreach(int i; 0..100) history = history + [""]; // XXX
>
>     while(!stdin.eof) {
>         writeln(line);
>         if(line != history[0]) {
>             history[1..100] = history[0..99];
>             history[0] = line;
>         }
>         line = readln();
>     }
> }

Also for this kind of thing you probably want to use a circular buffer. I'm sure there is an implementation of one somewhere. see std.range.cycle

On Thursday, 25 February 2016 at 12:58:54 UTC, Nicholas Wilson wrote:
>
> In D the binary operator "~"  is used to concatenate both strings (arrays of characters) and arrays. (also the ~= operator is equivalent to lhs = lhs ~ rhs
>
> Nic

It worked! A link from someone else's question suggested `new string[101]` also. Now on to other problems, it never ends...

On Thursday, 25 February 2016 at 12:58:54 UTC, Nicholas Wilson wrote:
> On Thursday, 25 February 2016 at 12:53:37 UTC, asdf wrote:
>> I'm trying to make a terminal input preprocessor with alias/shortcuts and history.
>>
>>
>> import std.stdio;
>>
>> void main() {
>>     string line;
>>     string[] history;
>>
>>     line = readln();
>>     foreach(int i; 0..100) history = history + [""]; // XXX
>>
>>     while(!stdin.eof) {
>>         writeln(line);
>>         if(line != history[0]) {
>>             history[1..100] = history[0..99];
>>             history[0] = line;
>>         }
>>         line = readln();
>>     }
>> }
>
> In D the binary operator "~"  is used to concatenate both strings (arrays of characters) and arrays. (also the ~= operator is equivalent to lhs = lhs ~ rhs
>
> Nic

Just a precision:  "lhs ~= rhs" isn't exactly equivalent to "lhs = lhs ~ rhs", those are two distinct operators that may deal with memory etc in different ways. For arrays doing "lhs = lhs ~ rhs" will first create (and allocate) the array corresponding  to "lhs ~ rhs" and then assign this new array to lhs. On the other hand "lhs ~= rhs" realises in-place append.

On Thursday, 25 February 2016 at 13:06:10 UTC, cym13 wrote:
>>
>> In D the binary operator "~"  is used to concatenate both strings (arrays of characters) and arrays. (also the ~= operator is equivalent to lhs = lhs ~ rhs
>>
>> Nic
>
> Just a precision:  "lhs ~= rhs" isn't exactly equivalent to "lhs = lhs ~ rhs", those are two distinct operators that may deal with memory etc in different ways. For arrays doing "lhs = lhs ~ rhs" will first create (and allocate) the array corresponding  to "lhs ~ rhs" and then assign this new array to lhs. On the other hand "lhs ~= rhs" realises in-place append.

I tried both, the error this time is:
object.Exception@/data/data/com.termux/files/home/ldc/runtime/druntime/src/ldc/arrayinit.d(151): overlapping array copy

On Thursday, 25 February 2016 at 13:24:09 UTC, asdf wrote:
> On Thursday, 25 February 2016 at 13:06:10 UTC, cym13 wrote:
>>>
>>> In D the binary operator "~"  is used to concatenate both strings (arrays of characters) and arrays. (also the ~= operator is equivalent to lhs = lhs ~ rhs
>>>
>>> Nic
>>
>> Just a precision:  "lhs ~= rhs" isn't exactly equivalent to "lhs = lhs ~ rhs", those are two distinct operators that may deal with memory etc in different ways. For arrays doing "lhs = lhs ~ rhs" will first create (and allocate) the array corresponding  to "lhs ~ rhs" and then assign this new array to lhs. On the other hand "lhs ~= rhs" realises in-place append.
>
> I tried both, the error this time is:
> object.Exception@/data/data/com.termux/files/home/ldc/runtime/druntime/src/ldc/arrayinit.d(151): overlapping array copy

so you will have to make a copy and then move it

Im assuming
 history[1..100] = history[0..99];
this is the line causing your problem.
Note that D has zero based array indexing
so assuming your array has 100 elements history[1..100]
is going one past the end of the array.

also using a circular buffer here will solve this problem.

Nic

On 25.02.2016 14:33, Nicholas Wilson wrote:
> Note that D has zero based array indexing
> so assuming your array has 100 elements history[1..100]
> is going one past the end of the array.

No, that's fine. `history[1..100]` gives you 99 elements starting at index 1, i.e. all except the first one.

On Thursday, 25 February 2016 at 13:38:56 UTC, ag0aep6g wrote:
> On 25.02.2016 14:33, Nicholas Wilson wrote:
>> Note that D has zero based array indexing
>> so assuming your array has 100 elements history[1..100]
>> is going one past the end of the array.
>
> No, that's fine. `history[1..100]` gives you 99 elements starting at index 1, i.e. all except the first one.

Derp. You are correct, I was thinking about the first index.

On 2/25/16 8:24 AM, asdf wrote:
> On Thursday, 25 February 2016 at 13:06:10 UTC, cym13 wrote:
>>>
>>> In D the binary operator "~"  is used to concatenate both strings
>>> (arrays of characters) and arrays. (also the ~= operator is
>>> equivalent to lhs = lhs ~ rhs
>>>
>>> Nic
>>
>> Just a precision:  "lhs ~= rhs" isn't exactly equivalent to "lhs = lhs
>> ~ rhs", those are two distinct operators that may deal with memory etc
>> in different ways. For arrays doing "lhs = lhs ~ rhs" will first
>> create (and allocate) the array corresponding  to "lhs ~ rhs" and then
>> assign this new array to lhs. On the other hand "lhs ~= rhs" realises
>> in-place append.
>
> I tried both, the error this time is:
> object.Exception@/data/data/com.termux/files/home/ldc/runtime/druntime/src/ldc/arrayinit.d(151):
> overlapping array copy

overlapping copies are not supported.

In this case especially, the copying has to be done backwards.

I believe you could use std.algorithm.copy, but probably need to do it with retro as well.

-Steve