refactor: use RangeDetacher for Range inference to reduce redundant l…

…ogic and avoid more potential bugs (#151)

src/execution/volcano/dql/index_scan.rs

@@ -1,6 +1,6 @@
 use crate::errors::DatabaseError;
 use crate::execution::volcano::{BoxedExecutor, ReadExecutor};
-use crate::expression::simplify::ConstantBinary;
+use crate::expression::range_detacher::Range;
 use crate::planner::operator::scan::ScanOperator;
 use crate::storage::{Iter, Transaction};
 use crate::types::index::IndexMetaRef;
@@ -10,11 +10,16 @@ use futures_async_stream::try_stream;
 pub(crate) struct IndexScan {
     op: ScanOperator,
     index_by: IndexMetaRef,
-    ranges: Vec<ConstantBinary>,
+    ranges: Vec<Range>,
 }
 
-impl From<(ScanOperator, IndexMetaRef, Vec<ConstantBinary>)> for IndexScan {
-    fn from((op, index_by, ranges): (ScanOperator, IndexMetaRef, Vec<ConstantBinary>)) -> Self {
+impl From<(ScanOperator, IndexMetaRef, Range)> for IndexScan {
+    fn from((op, index_by, range): (ScanOperator, IndexMetaRef, Range)) -> Self {
+        let ranges = match range {
+            Range::SortedRanges(ranges) => ranges,
+            range => vec![range],
+        };
+
         IndexScan {
             op,
             index_by,

src/execution/volcano/mod.rs

@@ -84,10 +84,10 @@ pub fn build_read<T: Transaction>(plan: LogicalPlan, transaction: &T) -> BoxedEx
         Operator::Scan(op) => {
             if let Some(PhysicalOption::IndexScan(IndexInfo {
                 meta,
-                ranges: Some(ranges),
+                range: Some(range),
             })) = plan.physical_option
             {
-                IndexScan::from((op, meta, ranges)).execute(transaction)
+                IndexScan::from((op, meta, range)).execute(transaction)
             } else {
                 SeqScan::from(op).execute(transaction)
             }

src/expression/mod.rs

@@ -16,6 +16,7 @@ use crate::types::LogicalType;
 pub mod agg;
 mod evaluator;
 pub mod function;
+pub mod range_detacher;
 pub mod simplify;
 pub mod value_compute;