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digitalmars.D.learn - how do you append arrays?

reply asdf <a b.c> writes:
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();
     }
}
Feb 25 2016
next sibling parent reply Nicholas Wilson <iamthewilsonator hotmail.com> writes:
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
Feb 25 2016
next sibling parent asdf <a b.c> writes:
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...
Feb 25 2016
prev sibling parent reply cym13 <cpicard openmailbox.org> writes:
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.
Feb 25 2016
parent reply asdf <a b.c> writes:
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/l
c/arrayinit.d(151): overlapping array copy
Feb 25 2016
next sibling parent reply Nicholas Wilson <iamthewilsonator hotmail.com> writes:
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/l
c/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
Feb 25 2016
parent reply ag0aep6g <anonymous example.com> writes:
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.
Feb 25 2016
parent Nicholas Wilson <iamthewilsonator hotmail.com> writes:
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.
Feb 25 2016
prev sibling parent reply Steven Schveighoffer <schveiguy yahoo.com> writes:
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
Feb 25 2016
parent reply Steven Schveighoffer <schveiguy yahoo.com> writes:
On 2/25/16 2:12 PM, Steven Schveighoffer wrote:

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


Heh, or of course use memmove :)

-Steve
Feb 25 2016
parent reply asdf <a b.c> writes:
On Thursday, 25 February 2016 at 19:21:31 UTC, Steven 
Schveighoffer wrote:

 On 2/25/16 2:12 PM, Steven Schveighoffer wrote:

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


 Heh, or of course use memmove :)

 -Steve


I got the history list working this morning but probably not very 
efficient. You can see:
---- cut ----
debug = 0;
import std.stdio;
import std.string;

void main() {
     string line;
     string[] history;
     char cmd = '/',
          sep = ';',
          dot = '.',
          bak = '\\';

     line = readln().chomp;
     foreach(int i; 0..100) history ~= "";
     debug(1) { stderr.writeln(history); }

     while(!stdin.eof) {
         string[] emit = line.split(sep);
         foreach(string e; emit) {

             /* how to do proper prefix and/or leading word? */
             if(e[0] == cmd) { /* ... */ }
             else if(e[0] == dot) { /* ... */ }
             else if(e[0] == bak) { /* ... */ }
             else writeln(e);
         }

         if(line != "" && line != history[0]) {
             string[] x = [line];
             foreach(string i; history[0..99]) x ~= i;
             history = x;
         }
         debug(1) { stderr.writeln(history); }

         line = readln().chomp;
     }
}
---- cut ----

Is there a good way to pick out matching prefixes of a string? 
Picking out the first word without disrupting whitespace after 
the second word would be nice =)

How do you read chars without waiting for a newline? That would 
be needed to respond to the ANSI esapes for arrow keys...
Feb 25 2016
parent reply Steven Schveighoffer <schveiguy yahoo.com> writes:
On 2/25/16 4:39 PM, asdf wrote:


          if(line != "" && line != history[0]) {
              string[] x = [line];
              foreach(string i; history[0..99]) x ~= i;
              history = x;
          }


ugh!

history = line ~ history[0 .. $ - 1];

What you may want to consider is making history backwards referenced. 
That is, history[0] is the oldest line.

Then you could do:
history = history[1 .. $];
history ~= line;


 Is there a good way to pick out matching prefixes of a string? Picking
 out the first word without disrupting whitespace after the second word
 would be nice =)

 How do you read chars without waiting for a newline? That would be
 needed to respond to the ANSI esapes for arrow keys...


If you are only getting characters after a newline, then you aren't 
interacting directly with the terminal (which requires some terminal 
access library). The terminal is letting the user edit the line, then 
when he hits return, it sends the whole line to your program. You won't 
get arrow key codes.

-Steve
Feb 25 2016
parent reply asdf <a b.c> writes:
On Friday, 26 February 2016 at 00:40:40 UTC, Steven Schveighoffer 
wrote:

 ugh!

 history = line ~ history[0 .. $ - 1];


That works alot better =)

Trying to uncook the terminal failed however. It can't recognize 
struct tag-declarations I think:


/*
    copy-paste code from:
    http://tldp.org/HOWTO/Serial-Programming-HOWTO/x115.html
*/

import core.sys.linux.termios;

// struct termios oldterm;
// struct termios newterm;
termios.termios oldterm;
termios.termios newterm;

void uncook_term() {
     tcgetattr(stdin.fileno, &oldterm);
     newterm = oldterm;

     newterm.c_cflag = BAUDRATE | CRTSCTS | CS8 | CLOCAL | CREAD;
     newterm.c_iflag = IGNPAR;
     newterm.c_oflag = 0;
     newterm.c_lflag = 0;
     tcflush(stdin.fileno, TCIFLUSH);
     tcsetattr(stdin.fileno, TCSANOW, &newterm);
}

void restore_term() {
     tcsetattr(stdin.fileno, TCSANOW, &oldterm);
}

void main() {
     uncook_term();

     char ch = read();
     while(ch != 'q' && !stdin.eof) {
         write(ch);
         ch = read();
     }

     restore_term();
}
Feb 26 2016
parent reply =?UTF-8?Q?Ali_=c3=87ehreli?= <acehreli yahoo.com> writes:
On 02/26/2016 12:47 AM, asdf wrote:


 Trying to uncook the terminal failed however. It can't recognize struct
 tag-declarations I think:


The following compiles and seems to work. I've marked my changes with // 
Ali:

/*
    copy-paste code from:
    http://tldp.org/HOWTO/Serial-Programming-HOWTO/x115.html
*/

import std.stdio;    // Ali
import core.sys.linux.termios;

// struct termios oldterm;
// struct termios newterm;
termios oldterm;    // Ali
termios newterm;    // Ali

void uncook_term() {
     tcgetattr(stdin.fileno, &oldterm);
     newterm = oldterm;

     newterm.c_cflag = /*BAUDRATE | Ali */ CRTSCTS | CS8 | CLOCAL | CREAD;
     newterm.c_iflag = IGNPAR;
     newterm.c_oflag = 0;
     newterm.c_lflag = 0;
     tcflush(stdin.fileno, TCIFLUSH);
     tcsetattr(stdin.fileno, TCSANOW, &newterm);
}

void restore_term() {
     tcsetattr(stdin.fileno, TCSANOW, &oldterm);
}

void main() {
     uncook_term();

     int ch = fgetc(core.stdc.stdio.stdin); //read();  Ali
     while(ch != 'q' && !stdin.eof) {
         write(ch);
         ch = fgetc(core.stdc.stdio.stdin); //read(); Ali
     }

     restore_term();
}

Ali
Feb 26 2016
parent =?UTF-8?Q?Ali_=c3=87ehreli?= <acehreli yahoo.com> writes:
On 02/26/2016 01:01 AM, Ali Çehreli wrote:

 On 02/26/2016 12:47 AM, asdf wrote:


 Trying to uncook the terminal failed however. It can't recognize struct
 tag-declarations I think:




I've just found the following code among my collection of D snippets, 
which uses a different method and supports Ctrl-D:

import std.stdio : writef, writeln;
import core.stdc.stdio;
import core.sys.posix.termios;

/* The declaration of cfmakeraw, which is missing from standard D 
modules. */
extern(C) void cfmakeraw(termios *termios_p);

void main()
{
     /* Saving the existing state of tty. */
     termios oldState;
     tcgetattr(1, &oldState);

     /* Ensuring that it will be restored upon exit. */
     scope (exit) tcsetattr(1, TCSADRAIN, &oldState);

     /* Make a new state and set it to raw mode. */
     termios  newState;
     tcgetattr(1, &newState);
     cfmakeraw(&newState);

     /* Use the new state in this terminal. */
     tcsetattr(1, TCSADRAIN, &newState);

     /*
      * We are ready to read characters in this raw mode...
      */

     /* This is Ctrl-D, the EOF character under Linux. */
     enum endOfFile = '\4';

     for (char c; c != endOfFile; ) {
         c = cast(char)fgetc(stdin);
         writef("%02x ", c);
     }

     writeln();
}

Ali
Feb 26 2016
prev sibling parent Nicholas Wilson <iamthewilsonator hotmail.com> writes:
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
Feb 25 2016