Simplify select_all and delete_all

minisql/src/interpreter.rs

@@ -86,7 +86,7 @@ impl State {
             Delete(table_name, maybe_condition) => {
                 let table: &mut Table = self.table_from_name_mut(&table_name)?;
 
-                let rows_affected = table.delete_where(maybe_condition)?;
+                let rows_affected = table.delete_rows_where(maybe_condition)?;
                 Ok(Response::Deleted(rows_affected))
             },
             CreateTable(table_name, table_schema) => {

minisql/src/table.rs

@@ -17,16 +17,13 @@ pub struct Table {
 }
 
 
-// Use `ColumnPosition` as index
-pub type Row = Vec<DbValue>;
-
 pub type Rows =
     // TODO: This should be some sort of an interface to a dictionary
     // s.t. in the background it may modify stuff in memory or talk to the disk
     BTreeMap<UUID, Row>;
 
-    // interface
+// Use `ColumnPosition` as index
-    // insert(id, value)
+pub type Row = Vec<DbValue>;
 
 fn restrict_columns(row: &Row, columns: &Vec<ColumnPosition>) -> Row {
     // If the index from `columns` is non-existant in `row`, it will just ignore it.
@@ -51,10 +48,7 @@ impl Table {
         }
     }
 
-    pub fn attach_index(&mut self, column_position: ColumnPosition, column_index: ColumnIndex) {
+    // ======Selection======
-        self.indexes.insert(column_position, column_index);
-    }
-
     fn get_row_by_id(&self, id: UUID) -> Option<Row> {
         self.rows.get(&id).cloned()
     }
@@ -72,6 +66,61 @@ impl Table {
             .collect()
     }
 
+    fn select_all_rows(&self, selected_column_positions: &Vec<ColumnPosition>) -> Vec<Row> {
+        self.rows.values().map(|row| restrict_columns(row, &selected_column_positions)).collect()
+    }
+
+    fn select_rows_where_eq(&self, selected_column_positions: &Vec<ColumnPosition>, column_position: ColumnPosition, value: DbValue) -> DbResult<Vec<Row>> {
+        match value {
+            DbValue::Indexable(value) => {
+                match self.fetch_ids_from_index(column_position, &value)? {
+                    Some(ids) =>
+                        Ok(self.get_rows_by_ids(ids).iter().map(|row| restrict_columns(row, &selected_column_positions)).collect()),
+                    None =>
+                        Ok(self.get_rows_by_value(column_position, &DbValue::Indexable(value)).iter().map(|row| restrict_columns(row, &selected_column_positions)).collect())
+                }
+            },
+            _ => {
+                Ok(self.get_rows_by_value(column_position, &value).iter().map(|row| restrict_columns(row, &selected_column_positions)).collect())
+            }
+        }
+    }
+
+    pub fn select_where(&self, column_selection: ColumnSelection, condition: Option<Condition>) -> DbResult<Vec<Row>> {
+        let selected_column_positions: Vec<ColumnPosition> = self.schema.column_positions_from_column_selection(&column_selection)?;
+        match condition {
+            None => Ok(self.select_all_rows(&selected_column_positions)),
+
+            Some(Condition::Eq(eq_column_name, value)) => {
+                let eq_column_position = self.schema.column_position_from_column_name(&eq_column_name)?;
+                self.select_rows_where_eq(&selected_column_positions, eq_column_position, value)
+            }
+        }
+    }
+
+    // ======Insertion======
+    pub fn insert(&mut self, values: InsertionValues) -> DbResult<()> {
+        let (id, row) = self.schema.row_from_insertion_values(values)?;
+
+        if self.rows.get(&id).is_some() {
+            return Err(Error::AttemptingToInsertAlreadyPresentId(self.schema.table_name.clone(), id))
+        }
+
+        for (column_position, column_index) in &mut self.indexes {
+            match row.get(*column_position) {
+                Some(DbValue::Indexable(val)) => {
+                    column_index.add(val.clone(), id)
+                },
+                Some(_) => {},
+                None => return Err(Error::ColumnPositionDoesNotExist(self.schema.table_name.clone(), *column_position))
+            }
+        }
+
+        let _ = self.rows.insert(id, row);
+        Ok(())
+    }
+
+    // ======Deletion======
     fn delete_row_by_id(&mut self, id: UUID) -> usize {
         match self.rows.remove(&id) {
             Some(row) => {
@@ -101,80 +150,41 @@ impl Table {
         self.delete_rows_by_ids(matched_ids)
     }
 
-    pub fn select_where(&self, column_selection: ColumnSelection, condition: Option<Condition>) -> DbResult<Vec<Row>> {
+    fn delete_all_rows(&mut self) -> usize {
-        let selected_column_positions = self.schema.column_positions_from_column_selection(&column_selection)?;
-        match condition {
-            None =>
-                // select all
-                Ok(self.rows.values().map(|row| restrict_columns(row, &selected_column_positions)).collect()),
-
-            Some(Condition::Eq(eq_column_name, value)) => {
-                let eq_column_position = self.schema.column_position_from_column_name(&eq_column_name)?;
-                match value {
-                    DbValue::Indexable(value) => {
-                        match self.fetch_ids_from_index(eq_column_position, &value)? {
-                            Some(ids) =>
-                                Ok(self.get_rows_by_ids(ids).iter().map(|row| restrict_columns(row, &selected_column_positions)).collect()),
-                            None =>
-                                Ok(self.get_rows_by_value(eq_column_position, &DbValue::Indexable(value)).iter().map(|row| restrict_columns(row, &selected_column_positions)).collect())
-                        }
-                    },
-                    _ => {
-                        Ok(self.get_rows_by_value(eq_column_position, &value).iter().map(|row| restrict_columns(row, &selected_column_positions)).collect())
-                    }
-                }
-            }
-        }
-    }
-
-    pub fn insert(&mut self, values: InsertionValues) -> DbResult<()> {
-        let (id, row) = self.schema.row_from_insertion_values(values)?;
-
-        if self.rows.get(&id).is_some() {
-            return Err(Error::AttemptingToInsertAlreadyPresentId(self.schema.table_name.clone(), id))
-        }
-
-        for (column_position, column_index) in &mut self.indexes {
-            match row.get(*column_position) {
-                Some(DbValue::Indexable(val)) => {
-                    column_index.add(val.clone(), id)
-                },
-                Some(_) => {},
-                None => return Err(Error::ColumnPositionDoesNotExist(self.schema.table_name.clone(), *column_position))
-            }
-        }
-
-        let _ = self.rows.insert(id, row);
-        Ok(())
-    }
-
-    // TODO: Split into delete all and delete_where(condition)
-    pub fn delete_where(&mut self, maybe_condition: Option<Condition>) -> DbResult<usize> {
-        match maybe_condition {
-            None => {
-                // delete all
         let number_of_rows = self.rows.len();
         self.rows = BTreeMap::new();
         self.indexes = HashMap::new();
-                Ok(number_of_rows)
+        number_of_rows
-            },
+    }
 
-            Some(Condition::Eq(eq_column_name, value)) => {
+    fn delete_rows_where_eq(&mut self, column_position: ColumnPosition, value: DbValue) -> DbResult<usize> {
-                let eq_column_position = self.schema.column_position_from_column_name(&eq_column_name)?;
         match value {
             DbValue::Indexable(value) => {
-                        match self.fetch_ids_from_index(eq_column_position, &value)? {
+                match self.fetch_ids_from_index(column_position, &value)? {
                     Some(ids) =>
                         Ok(self.delete_rows_by_ids(ids)),
                     None =>
-                                Ok(self.delete_rows_by_value(eq_column_position, &DbValue::Indexable(value)))
+                        Ok(self.delete_rows_by_value(column_position, &DbValue::Indexable(value)))
                 }
             },
             _ =>
-                        Ok(self.delete_rows_by_value(eq_column_position, &value))
+                Ok(self.delete_rows_by_value(column_position, &value))
+        }
+    }
+
+    pub fn delete_rows_where(&mut self, maybe_condition: Option<Condition>) -> DbResult<usize> {
+        match maybe_condition {
+            None => Ok(self.delete_all_rows()),
+            Some(Condition::Eq(eq_column_name, value)) => {
+                let eq_column_position = self.schema.column_position_from_column_name(&eq_column_name)?;
+                self.delete_rows_where_eq(eq_column_position, value)
             }
         }
     }
+
+    // ======Indexing======
+    pub fn attach_index(&mut self, column_position: ColumnPosition, column_index: ColumnIndex) {
+        self.indexes.insert(column_position, column_index);
     }
 
     fn fetch_ids_from_index(&self, column_position: ColumnPosition, value: &IndexableDbValue) -> DbResult<Option<HashSet<UUID>>> {