Hi everybody!
I'm new to D and trying to wrap my head around ranges.
For a start I'm trying to take a input string and transform it, group
it, etc.
After each step I inspect the result.
It works fine until step 3 where all of a sudden, after write(ln)ing the
result, "step3" holds an array of empty arrays.
What gives? Program and output are attached below.
My question is why are "step3"'s contents before and after the writeln
(1) different?
If I remove this line at (1) the foreach loops print the contents as I'd
expect and the following writeln (2) prints the contents as expected, too.
However the writeln (3) prints empty arrays again.
I don't understand this behavior and I'd really like to know what's
going on.
Your help and time is much appreciated!
I'm using an unmodified local build of dmd, druntime, and phobos from
github updated and recompiled today.
[code]
import std.range;
import std.stdio;
import std.algorithm;
void main() {
string test = "@\r node1\n nodea\r\n key:val\n\n node2\n
nodea\n";
writeln(test);
writeln("---");
auto step1 = test.replace("\r\n", "\n")
.replace(" ", "\t")
.splitter!"a == 10 || a == 13"()
;
writeln("Step 1:", step1);
writeln("---");
writeln(" type: ", typeid(step1));
writeln("---");
import std.typecons: Tuple;
string[][] step2;
foreach(a; step1) {
auto e = findSplitAfter(a, "\t").array;
step2 ~= e;
}
writeln("Step 2:", step2);
writeln("---");
writeln(" type: ", typeid(step2));
writeln("---");
auto step3 = step2.chunkBy!((a,b) => a[0]==b[0]).array;
writeln("Step 3:", step3); // (1)
writeln("---");
writeln(" type: ", typeid(step3));
writeln("-+-");
foreach(x; step3) {
writeln("x:",typeid(x),x);
foreach(y; x)
writeln(" y:",typeid(y),y);
}
writeln("--",step3); // (2)
writeln("--",step3); // (3)
writeln("the end");
}
[/code]
Output:
[code]
node1
nodea
key:val
node2
nodea
---
Step 1:["@", "\tnode1", "\t\tnodea", "\t\tkey:val", "", "\tnode2",
"\t\tnodea", ""]
---
type: std.algorithm.iteration.SplitterResult!(unaryFun,
string).SplitterResult
---
Step 2:[["", "@"], ["\t", "node1"], ["\t", "\tnodea"], ["\t",
"\tkey:val"], ["", ""], ["\t", "node2"], ["\t", "\tnodea"], ["", ""]]
---
type: immutable(char)[][][]
---
Step 3:[[["", "@"]], [["\t", "node1"], ["\t", "\tnodea"], ["\t",
"\tkey:val"]], [["", ""]], [["\t", "node2"], ["\t", "\tnodea"]], [["",
""]]]
---
type: app.main.ChunkByImpl!(__lambda1, string[][]).ChunkByImpl.Group[]
-+-
x:app.main.ChunkByImpl!(__lambda1, string[][]).ChunkByImpl.Group[]
x:app.main.ChunkByImpl!(__lambda1, string[][]).ChunkByImpl.Group[]
x:app.main.ChunkByImpl!(__lambda1, string[][]).ChunkByImpl.Group[]
x:app.main.ChunkByImpl!(__lambda1, string[][]).ChunkByImpl.Group[]
x:app.main.ChunkByImpl!(__lambda1, string[][]).ChunkByImpl.Group[]
--[[], [], [], [], []]
the end
[/code]
