Re: Adding item to a rbtree with a custom binaryFun

[Steven Schveighoffer via Digitalmars-d-learn]

On 4/13/20 7:59 PM, Adnan wrote:
I want to keep an ordered set of records and the standard provides me 
with RedBlackTree. The record is of type Tuple!(string, uint). Here's 
what it looks like:

import std.json : parseJSON;

     uint[string] wordTable;
     import std.datetime.stopwatch : StopWatch, AutoStart;

     auto sw = StopWatch(AutoStart.yes);
     const auto j = parseJSON(get(link));
     const long downloadTime = sw.peek.total!"msecs";

     import std.typecons : Tuple, tuple;
     import std.container.rbtree : RedBlackTree;
     import std.functional : binaryFun;


// instead of this:

     RedBlackTree!(Tuple!(string, uint), binaryFun!("a[1] > b[1]")) 
records;

// do this: (note you don't need binaryFun)
       auto records = new RedBlackTree!(Tuple!(String, uint), "a[1] > 
b[1]");


     foreach (node; j["posts"].array()) {
         import std.stdio : writeln;
         import std.utf : decode;

         if ("com" in node) {
             import std.algorithm : splitter;

             foreach (word; getStr(node["com"].str()).splitter(' ')) {
                 import std.string : strip;

                 if (word.strip().length > 0)
                     wordTable.require(word, 0)++;

                 records ~= (tuple(word, wordTable[word])); // error
             }
         }
     }

Now primarily I used `insert()` method to add a record to the records 
but it causes segfault in runtime.

Because RedBlackTree is a class, so you need to initialize it with a 
call to new.

So I decided to use ~= to see what's 
going on. Here's what the compiler says:

Error: cannot append type Tuple!(string, uint) to type 
std.container.rbtree.RedBlackTree!(Tuple!(string, uint), binaryFun, false)

Because RedBlackTree doesn't overload appending.

-Steve