review: refactor inner join fragment creation using template and helper function

01.workspace/heave/src/fun/sqlite_build_statement.rs

@@ -1,21 +1,31 @@
 use crate::*;
 
 const BASE_SELECT: &str = r#"SELECT * FROM entity"#;
+const INNER_JOIN_FRAGMENT: &str = r#"
+    INNER JOIN attribute
+    ON entity.id = attribute.entity_id
+    AND attribute.id = '{attribute_id}'
+    AND {field} {op} ?{index}
+"#;
+
+fn compose_fragment(name: &str, field: &str, op: &str, index: usize) -> String {
+    INNER_JOIN_FRAGMENT
+        .replace("{attribute_id}", name)
+        .replace("{field}", field)
+        .replace("{op}", op)
+        .replace("{index}", &index.to_string())
+}
 
 pub fn run(filter: &Filter) -> Result<String, FailedTo> {
     let mut statement = String::from(BASE_SELECT);
-    for (i, (name, _comparison, condition)) in filter.conditions().enumerate() {
+    for (i, (name, comparison, condition)) in filter.conditions().enumerate() {
-        let fragment = match (_comparison, condition) {
+        let fragment = match (comparison, condition) {
-            (_, Condition::Bool(_)) => format!(
+            (Comparison::Equal, Condition::Bool(_)) => {
-                " INNER JOIN attribute ON entity.id = attribute.entity_id AND attribute.id = '{}' AND value_bool = ?{}",
+                compose_fragment(name, "value_bool", "=", i + 1)
-                name,
+            }
-                i + 1
+            (Comparison::Equal, Condition::SignedInt(_)) => {
-            ),
+                compose_fragment(name, "value_int", "=", i + 1)
-            (Comparison::Equal, Condition::SignedInt(_)) => format!(
+            }
-                " INNER JOIN attribute ON entity.id = attribute.entity_id AND attribute.id = '{}' AND value_int = ?{}",
-                name,
-                i + 1
-            ),
             _ => todo!(),
         };
         statement.push_str(&fragment);