Move index update into attach_index

minisql/src/internals/table.rs

@@ -171,8 +171,11 @@ impl Table {
     }
 
     // ======Indexing======
-    pub fn attach_index(&mut self, column_position: ColumnPosition, column_index: ColumnIndex) {
+    pub fn attach_index(&mut self, column_position: ColumnPosition) -> DbResult<()> {
+        let mut column_index: ColumnIndex = ColumnIndex::new();
+        update_index_from_table(&mut column_index, self, column_position)?;
         self.indexes.insert(column_position, column_index);
+        Ok(())
     }
 
     fn fetch_ids_from_index(
@@ -207,3 +210,34 @@ impl Table {
         }
     }
 }
+
+// Should be used in the case when an index is created after the table has existed for a
+// while. In such a case you need to build the index from the already existing rows.
+fn update_index_from_table(
+    column_index: &mut ColumnIndex,
+    table: &Table,
+    column_position: ColumnPosition,
+) -> DbResult<()> {
+    for (id, row) in &table.rows {
+        let value = match row.get(column_position) {
+            Some(Value::Indexable(value)) => value.clone(),
+            Some(_) => {
+                let column_name: ColumnName = table
+                    .schema
+                    .column_name_from_column_position(column_position)?;
+                return Err(Error::AttemptToIndexNonIndexableColumn(
+                    table.schema.table_name.to_string(),
+                    column_name,
+                ));
+            }
+            None => {
+                return Err(Error::ColumnPositionDoesNotExist(
+                    table.schema.table_name.to_string(),
+                    column_position,
+                ))
+            }
+        };
+        column_index.add(value, *id)
+    }
+    Ok(())
+}

minisql/src/interpreter.rs

@@ -1,5 +1,4 @@
 use crate::error::Error;
-use crate::internals::column_index::ColumnIndex;
 use crate::internals::row::{ColumnPosition, Row};
 use crate::internals::schema::{ColumnName, TableName, TableSchema};
 use crate::internals::table::Table;
@@ -134,47 +133,13 @@ impl State {
                     .schema
                     .column_position_from_column_name(&column_name)?;
 
-                let mut index: ColumnIndex = ColumnIndex::new();
+                table.attach_index(column_position)?;
-                update_index_from_table(&mut index, table, column_position)?;
-
-                table.attach_index(column_position, index);
                 Ok(Response::IndexCreated)
             }
         }
     }
 }
 
-// Should be used in the case when an index is created after the table has existed for a
-// while. In such a case you need to build the index from the already existing rows.
-fn update_index_from_table(
-    column_index: &mut ColumnIndex,
-    table: &Table,
-    column_position: ColumnPosition,
-) -> DbResult<()> {
-    for (id, row) in &table.rows {
-        let value = match row.get(column_position) {
-            Some(Value::Indexable(value)) => value.clone(),
-            Some(_) => {
-                let column_name: ColumnName = table
-                    .schema
-                    .column_name_from_column_position(column_position)?;
-                return Err(Error::AttemptToIndexNonIndexableColumn(
-                    table.schema.table_name.to_string(),
-                    column_name,
-                ));
-            }
-            None => {
-                return Err(Error::ColumnPositionDoesNotExist(
-                    table.schema.table_name.to_string(),
-                    column_position,
-                ))
-            }
-        };
-        column_index.add(value, *id)
-    }
-    Ok(())
-}
-
 // TODO: Give a better name to something that you can respond to with rows
 trait SqlResponseConsumer {
     // TODO:
@@ -494,7 +459,9 @@ mod tests {
             .interpret(CreateTable(users.clone(), users_schema))
             .unwrap();
 
-        state.interpret(CreateIndex(users.clone(), "name".to_string())).unwrap();
+        state
+            .interpret(CreateIndex(users.clone(), "name".to_string()))
+            .unwrap();
 
         let (id0, name0, age0) = (
             Indexable(Uuid(0)),