ref: Move the filter operator in new file

README.md

@@ -42,7 +42,7 @@ SELECT @arr[1], @arr[2], @arr[3], ARRAY_LENGTH(@arr);
 SELECT @arr[1:2], @arr[2:], @arr[:2];
 
 SELECT DISTINCT title AS tt FROM commits
-SELECT name, COUNT(name) AS commit_num FROM commits GROUP BY name, author_email ORDER BY commit_num DESC LIMIT 10
+SELECT author_name, COUNT(author_name) AS commit_num FROM commits GROUP BY author_name, author_email ORDER BY commit_num DESC LIMIT 10
 SELECT commit_count FROM branches WHERE commit_count BETWEEN 0 .. 10
 
 SELECT * FROM refs WHERE type = "branch"

crates/gitql-engine/src/engine_executor.rs

@@ -23,11 +23,11 @@ use gitql_ast::statement::WhereStatement;
 use gitql_core::environment::Environment;
 use gitql_core::object::GitQLObject;
 use gitql_core::object::Group;
-use gitql_core::object::Row;
 use gitql_core::value::Value;
 
 use crate::data_provider::DataProvider;
 use crate::engine_evaluator::evaluate_expression;
+use crate::engine_filter::filter_rows_by_condition;
 
 #[allow(clippy::borrowed_box)]
 pub fn execute_statement(
@@ -169,31 +169,12 @@ fn execute_where_statement(
     statement: &WhereStatement,
     gitql_object: &mut GitQLObject,
 ) -> Result<(), String> {
-    if gitql_object.is_empty() {
-        return Ok(());
-    }
-
     // Perform where command only on the first group
     // because group by command not executed yet
-    let mut filtered_group: Group = Group { rows: vec![] };
-    let first_group = gitql_object.groups.first().unwrap().rows.iter();
-    for object in first_group {
-        let eval_result = evaluate_expression(
-            env,
-            &statement.condition,
-            &gitql_object.titles,
-            &object.values,
-        );
-        if eval_result.is_err() {
-            return Err(eval_result.err().unwrap());
-        }
-
-        if eval_result.ok().unwrap().as_bool() {
-            filtered_group.rows.push(Row {
-                values: object.values.clone(),
-            });
-        }
-    }
+    let condition = &statement.condition;
+    let main_group = &gitql_object.groups.first().unwrap().rows;
+    let rows = filter_rows_by_condition(env, condition, &gitql_object.titles, main_group)?;
+    let filtered_group: Group = Group { rows };
 
     // Update the main group with the filtered data
     gitql_object.groups.remove(0);
@@ -216,26 +197,11 @@ fn execute_having_statement(
     }
 
     // Perform where command only on the first group
-    // because groups are already merged
-    let mut filtered_group: Group = Group { rows: vec![] };
-    let first_group = gitql_object.groups.first().unwrap().rows.iter();
-    for object in first_group {
-        let eval_result = evaluate_expression(
-            env,
-            &statement.condition,
-            &gitql_object.titles,
-            &object.values,
-        );
-        if eval_result.is_err() {
-            return Err(eval_result.err().unwrap());
-        }
-
-        if eval_result.ok().unwrap().as_bool() {
-            filtered_group.rows.push(Row {
-                values: object.values.clone(),
-            });
-        }
-    }
+    // because group by command not executed yet
+    let condition = &statement.condition;
+    let main_group = &gitql_object.groups.first().unwrap().rows;
+    let rows = filter_rows_by_condition(env, condition, &gitql_object.titles, main_group)?;
+    let filtered_group: Group = Group { rows };
 
     // Update the main group with the filtered data
     gitql_object.groups.remove(0);

crates/gitql-engine/src/engine_filter.rs

@@ -0,0 +1,26 @@
+use gitql_ast::expression::Expression;
+use gitql_core::environment::Environment;
+use gitql_core::object::Row;
+
+use crate::engine_evaluator::evaluate_expression;
+
+#[inline(always)]
+#[allow(clippy::borrowed_box)]
+pub fn filter_rows_by_condition(
+    env: &mut Environment,
+    condition: &Box<dyn Expression>,
+    titles: &[String],
+    objects: &Vec<Row>,
+) -> Result<Vec<Row>, String> {
+    let mut rows: Vec<Row> = vec![];
+
+    for object in objects {
+        if evaluate_expression(env, condition, titles, &object.values)?.as_bool() {
+            rows.push(Row {
+                values: object.values.clone(),
+            });
+        }
+    }
+
+    Ok(rows)
+}

crates/gitql-engine/src/lib.rs

@@ -3,3 +3,4 @@ pub mod engine;
 pub mod engine_distinct;
 pub mod engine_evaluator;
 pub mod engine_executor;
+pub mod engine_filter;