refactor: refactor index by generics

[G-XD]

Related: #403 (comment)

[codecov]

Codecov Report

Merging #462 (2449e75) into master (46226a2) will increase coverage by 0.37%.
The diff coverage is 88.07%.

@@            Coverage Diff             @@
##           master     #462      +/-   ##
==========================================
+ Coverage   72.61%   72.99%   +0.37%     
==========================================
  Files          31       31              
  Lines        4189     4184       -5     
==========================================
+ Hits         3042     3054      +12     
+ Misses        881      865      -16     
+ Partials      266      265       -1     

Files Changed	Coverage Δ
db.go	66.90% <66.66%> (-0.51%)	⬇️
tx_zset.go	48.69% <73.33%> (ø)
merge.go	70.17% <80.00%> (ø)
tx_bucket.go	83.87% <86.66%> (+15.75%)	⬆️
tx_set.go	63.89% <92.30%> (ø)
index.go	87.50% <92.85%> (+19.75%)	⬆️
iterator.go	69.69% <100.00%> (ø)
tx.go	80.18% <100.00%> (-0.14%)	⬇️
tx_btree.go	72.65% <100.00%> (ø)
tx_list.go	72.15% <100.00%> (ø)

[G-XD]

Raw Output:
index.go:57:25: func (*defaultOp[T]).rangeIdx is unused (unused)
func (op *defaultOp[T]) rangeIdx(f func(elem *T)) {

db.go中的checkListExpired()有调用到此函数，这个问题怎么解决呢？

[bigboss2063]

Raw Output:
index.go:57:25: func (*defaultOp[T]).rangeIdx is unused (unused)
func (op *defaultOp[T]) rangeIdx(f func(elem *T)) {

db.go中的checkListExpired()有调用到此函数，这个问题怎么解决呢？

可能是由于 checkListExpired 这个方法没有使用到导致它检测出现的问题

[bigboss2063]

可以试一下给checkListExpired加个测试用例看看

[elliotchenzichang]

Amizing!

[bigboss2063]

LGTM!