tree - V code

tree.v

struct TNode {
pub mut:
        id      int
        children []*TNode
}

struct Record{
pub:
        id      int
        parent  int
}

fn compare_records(a, b *Record) int {
	// println('sorting a.id:$a.id b.id$b.id')

	if a.id < b.id {
		return -1
	}
	if a.id > b.id {
		return 1
	}
	return 0
}

fn build(records []Record) *TNode{

	// sort incoming records on IDs
	mut records_sorted := records.clone()
	records_sorted.sort_with_compare(compare_records)
	println('length of records_sorted:${records_sorted.len}')

        mut result :=  [TNode{}; records_sorted.len]

        for _, rec in records_sorted{
                if rec.id != 0 {
                        mut parent := rec.parent // avoid  `rec` is immutable (can't <<)
                        result[parent].children << &result[rec.id]  //add REFERENENCE to existing node
                }
                result[rec.id] = TNode{id: rec.id}
        }
        return result[0]
}


fn main(){
	records := [
		Record{id: 5, parent: 1},
		Record{id: 3, parent: 2},
		Record{id: 2, parent: 0},
		Record{id: 4, parent: 1},
		Record{id: 1, parent: 0},
		Record{id: 0}, 
		Record{id: 6, parent: 2}
	]


	res := build(records) or {
		println('err:$err')
		return
	}
	println(res.id)
}

// Output:
// bad arr array_TNode*
// bad arr array_TNode*
// .tree.c:155:1: error: unknown type name 'array_TNode'
// array_TNode* children;
// ^
// .tree.c:3534:1: error: use of undeclared identifier 'array_TNode'; did you mean 'array_clone'?
// array_TNode result= array_repeat(&tmp2,  records_sorted .len , sizeof(TNode) ) ;
// ^~~~~~~~~~~
// array_clone
// .tree.c:613:24: note: 'array_clone' declared here
//  /* returns 0 */ array array_clone(array a) {
//                        ^
// .tree.c:3534:12: error: expected ';' after expression
// array_TNode result= array_repeat(&tmp2,  records_sorted .len , sizeof(TNode) ) ;
//            ^
//            ;
// .tree.c:3534:13: error: use of undeclared identifier 'result'
// array_TNode result= array_repeat(&tmp2,  records_sorted .len , sizeof(TNode) ) ;
//             ^
// .tree.c:3546:101: error: use of undeclared identifier 'result'
// _PUSH( ( *(TNode*) array__get( result , parent) ) .children , ( & /*vvar*/  ( *(TNode*) array__get( result , rec .id) ) ), tmp8, TNode*) ;
//                                                                                                     ^
// .tree.c:3546:32: error: use of undeclared identifier 'result'
// _PUSH( ( *(TNode*) array__get( result , parent) ) .children , ( & /*vvar*/  ( *(TNode*) array__get( result , rec .id) ) ), tmp8, TNode*) ;
//                                ^
// .tree.c:3553:18: error: use of undeclared identifier 'result'
// array_set(&/*q*/ result , rec .id , & tmp11) ;
//                  ^
// .tree.c:3558:33: error: use of undeclared identifier 'result'
// return  ( *(TNode*) array__get( result , 0) ) ;
//                                 ^
// .tree.c:3568:13: error: member reference type 'TNode *' (aka 'struct TNode *') is a pointer; did you mean to use '->'?
//  if (!tmp15 .ok) {
//       ~~~~~ ^
//             ->
// .tree.c:3568:14: error: no member named 'ok' in 'struct TNode'
//  if (!tmp15 .ok) {
//       ~~~~~  ^
// .tree.c:3569:21: error: member reference type 'TNode *' (aka 'struct TNode *') is a pointer; did you mean to use '->'?
//  string err = tmp15 . error;
//               ~~~~~ ^
//                     ->
// .tree.c:3569:23: error: no member named 'error' in 'struct TNode'
//  string err = tmp15 . error;
//               ~~~~~   ^
// .tree.c:3576:32: error: member reference type 'TNode *' (aka 'struct TNode *') is a pointer; did you mean to use '->'?
//  TNode* res = *(TNode**) tmp15 . data;
//                          ~~~~~ ^
//                                ->
// .tree.c:3576:34: error: no member named 'data' in 'struct TNode'
//  TNode* res = *(TNode**) tmp15 . data;
//                          ~~~~~   ^
// 14 errors generated.