Re: Creating InputRanges from strings, files etc.
On Thursday, 8 November 2018 at 16:41:50 UTC, Steven Schveighoffer wrote: I did this in a run.dlang.org playground: pragma(msg, ElementType!(typeof(b))); pragma(msg, ElementType!(typeof(d))); I get: immutable(ubyte) ubyte Which means they aren't the same type, and they don't define the same interface (InputRange!(ubyte) is not the same as InputRange!(immutable(ubyte)) ). Other than simply using compile-time functions, and dropping the object interface as Alex suggests, the easiest thing I can recommend is wrapping representation into a casting input range such as map: auto b = inputRangeObject(a.representation.map!(b => ubyte(b))); You can see all this here: https://run.dlang.io/is/1E6Uqj -Steve Thanks, guys, those are helpful pointers.
Re: Creating InputRanges from strings, files etc.
On 11/8/18 11:15 AM, Vinay Sajip wrote:
On Thursday, 8 November 2018 at 14:38:37 UTC, Paul Backus wrote:
To pass these ranges around using the `InputRange` interface, use
`inputRangeObject` to wrap them:
InputRange!ubyte r3 = inputRangeObject(r1);
InputRange!(immutable(ubyte)) r4 = inputRangeObject(r2);
I did a bit more digging, and it seems to work for strings but not for
files: The program
import std.algorithm.iteration;
import std.format;
import std.range;
import std.stdio;
import std.string;
void somefn(InputRange!(immutable(ubyte)) r) {
writeln(format!"%s"(r));
}
void main()
{
auto a = "Hello, world!";
auto b = inputRangeObject(a.representation);
somefn(b);
auto c = stdin.byChunk(1024).joiner;
auto d = inputRangeObject(c);
//somefn(d);
}
compiles as given above, but if the somefn(d) line is uncommented, I get
an error:
function onlineapp.somefn(InputRange!(immutable(ubyte)) r) is not
callable using argument types (InputRangeObject!(Result))
onlineapp.d(18): cannot pass argument d of type
std.range.interfaces.InputRangeObject!(Result) to parameter
InputRange!(immutable(ubyte)) r
Do I need to do an explicit cast? If so, can someone tell me the precise
incantation? How come it doesn't figure out that the underlying range is
a ubyte range, or is it to do with immutability, or something else
altogether?
A cool feature of D is to have it tell you something about your code at
compile time.
I did this in a run.dlang.org playground:
pragma(msg, ElementType!(typeof(b)));
pragma(msg, ElementType!(typeof(d)));
I get:
immutable(ubyte)
ubyte
Which means they aren't the same type, and they don't define the same
interface (InputRange!(ubyte) is not the same as
InputRange!(immutable(ubyte)) ).
Other than simply using compile-time functions, and dropping the object
interface as Alex suggests, the easiest thing I can recommend is
wrapping representation into a casting input range such as map:
auto b = inputRangeObject(a.representation.map!(b => ubyte(b)));
You can see all this here:
https://run.dlang.io/is/1E6Uqj
-Steve
Re: Creating InputRanges from strings, files etc.
On Thursday, 8 November 2018 at 16:15:25 UTC, Vinay Sajip wrote:
On Thursday, 8 November 2018 at 14:38:37 UTC, Paul Backus wrote:
To pass these ranges around using the `InputRange` interface,
use `inputRangeObject` to wrap them:
InputRange!ubyte r3 = inputRangeObject(r1);
InputRange!(immutable(ubyte)) r4 = inputRangeObject(r2);
I did a bit more digging, and it seems to work for strings but
not for files: The program
import std.algorithm.iteration;
import std.format;
import std.range;
import std.stdio;
import std.string;
void somefn(InputRange!(immutable(ubyte)) r) {
writeln(format!"%s"(r));
}
void main()
{
auto a = "Hello, world!";
auto b = inputRangeObject(a.representation);
somefn(b);
auto c = stdin.byChunk(1024).joiner;
auto d = inputRangeObject(c);
//somefn(d);
}
compiles as given above, but if the somefn(d) line is
uncommented, I get an error:
function onlineapp.somefn(InputRange!(immutable(ubyte)) r) is
not callable using argument types (InputRangeObject!(Result))
onlineapp.d(18):cannot pass argument d of type
std.range.interfaces.InputRangeObject!(Result) to parameter
InputRange!(immutable(ubyte)) r
Do I need to do an explicit cast? If so, can someone tell me
the precise incantation? How come it doesn't figure out that
the underlying range is a ubyte range, or is it to do with
immutability, or something else altogether?
you could use a template for somefn definition:
´´´
void somefn(T)(T r) {
writeln(format!"%s"(r));
}
´´´
Re: Creating InputRanges from strings, files etc.
On Thursday, 8 November 2018 at 14:38:37 UTC, Paul Backus wrote:
To pass these ranges around using the `InputRange` interface,
use `inputRangeObject` to wrap them:
InputRange!ubyte r3 = inputRangeObject(r1);
InputRange!(immutable(ubyte)) r4 = inputRangeObject(r2);
I did a bit more digging, and it seems to work for strings but
not for files: The program
import std.algorithm.iteration;
import std.format;
import std.range;
import std.stdio;
import std.string;
void somefn(InputRange!(immutable(ubyte)) r) {
writeln(format!"%s"(r));
}
void main()
{
auto a = "Hello, world!";
auto b = inputRangeObject(a.representation);
somefn(b);
auto c = stdin.byChunk(1024).joiner;
auto d = inputRangeObject(c);
//somefn(d);
}
compiles as given above, but if the somefn(d) line is
uncommented, I get an error:
function onlineapp.somefn(InputRange!(immutable(ubyte)) r) is not
callable using argument types (InputRangeObject!(Result))
onlineapp.d(18):cannot pass argument d of type
std.range.interfaces.InputRangeObject!(Result) to parameter
InputRange!(immutable(ubyte)) r
Do I need to do an explicit cast? If so, can someone tell me the
precise incantation? How come it doesn't figure out that the
underlying range is a ubyte range, or is it to do with
immutability, or something else altogether?
Re: Creating InputRanges from strings, files etc.
On Thursday, 8 November 2018 at 14:38:37 UTC, Paul Backus wrote: You can iterate through a file one ubyte at a time using `byChunk` and `joiner`: auto r1 = stdin.byChunk(1024).joiner; assert(is(typeof(r1.front) == ubyte)); You can iterate through a string one ubyte at a time using `representation`: auto r2 = "To be or not to be".representation; assert(is(typeof(r2.front) == immutable(ubyte))); To pass these ranges around using the `InputRange` interface, use `inputRangeObject` to wrap them: InputRange!ubyte r3 = inputRangeObject(r1); InputRange!(immutable(ubyte)) r4 = inputRangeObject(r2); Aha - inputRangeObject was the thing I was missing. Thanks!
Re: Creating InputRanges from strings, files etc.
On Thursday, 8 November 2018 at 13:58:55 UTC, Vinay Sajip wrote: Excuse my ignorance, but from looking at the documentation on std.range and a quick skim of the guides mentioned there near the top, I can't see what the simple way is of creating an InputRange!(ubyte) from strings, files etc. I would have expected to find something in the DLang Tour about this, but couldn't find anything. Please can someone tell me how to do it? Just to be clear, I want to create an object which is an InputRange!(ubyte) and pass that around, rather than e.g. iterate over a string or a file. You can iterate through a file one ubyte at a time using `byChunk` and `joiner`: auto r1 = stdin.byChunk(1024).joiner; assert(is(typeof(r1.front) == ubyte)); You can iterate through a string one ubyte at a time using `representation`: auto r2 = "To be or not to be".representation; assert(is(typeof(r2.front) == immutable(ubyte))); To pass these ranges around using the `InputRange` interface, use `inputRangeObject` to wrap them: InputRange!ubyte r3 = inputRangeObject(r1); InputRange!(immutable(ubyte)) r4 = inputRangeObject(r2);
Re: Creating InputRanges from strings, files etc.
On 09/11/2018 2:58 AM, Vinay Sajip wrote:
Excuse my ignorance, but from looking at the documentation on std.range
and a quick skim of the guides mentioned there near the top, I can't see
what the simple way is of creating an InputRange!(ubyte) from strings,
files etc. I would have expected to find something in the DLang Tour
about this, but couldn't find anything. Please can someone tell me how
to do it? Just to be clear, I want to create an object which is an
InputRange!(ubyte) and pass that around, rather than e.g. iterate over a
string or a file.
TLDR of how to write an input range:
struct MyInputRange {
ubyte[] input;
@property {
ubyte front() {
return this.input[0];
}
bool empty() {
return this.input.length == 0;
}
}
void popFront() {
this.input = this.input[1 .. $];
}
}
import std.stdio;
void main() {
foreach(b; MyInputRange([1, 2, 3])) {
writeln(b);
}
}
Creating InputRanges from strings, files etc.
Excuse my ignorance, but from looking at the documentation on std.range and a quick skim of the guides mentioned there near the top, I can't see what the simple way is of creating an InputRange!(ubyte) from strings, files etc. I would have expected to find something in the DLang Tour about this, but couldn't find anything. Please can someone tell me how to do it? Just to be clear, I want to create an object which is an InputRange!(ubyte) and pass that around, rather than e.g. iterate over a string or a file.
