From 22451a60321ac1a8ffb42cb7d5767b62b307cd75 Mon Sep 17 00:00:00 2001
From: poppingmoon <63451158+poppingmoon@users.noreply.github.com>
Date: Wed, 10 Jul 2024 22:21:49 +0900
Subject: [PATCH] add arr.at

---
 src/interpreter/primitive_props.rs |  20 +++++
 tests/test.rs                      | 114 +++++++++++++++++++++++++++++
 2 files changed, 134 insertions(+)

diff --git a/src/interpreter/primitive_props.rs b/src/interpreter/primitive_props.rs
index fc7e866..560440d 100644
--- a/src/interpreter/primitive_props.rs
+++ b/src/interpreter/primitive_props.rs
@@ -878,6 +878,26 @@ pub fn get_prim_prop(target: Value, name: String) -> Result<Value, AiScriptError
                 }
                 .boxed()
             }),
+            "at" => Value::fn_native(move |args, _| {
+                let target = target.clone();
+                let target_len = target.read().unwrap().len();
+                async move {
+                    let mut args = args.into_iter();
+                    let idx = f64::try_from(args.next().unwrap_or_default())? as isize;
+                    let index = if idx < 0 {
+                        target_len as isize + idx
+                    } else {
+                        idx
+                    };
+                    Ok(if index < 0 {
+                        None
+                    } else {
+                        target.read().unwrap().get(index as usize).cloned()
+                    }
+                    .unwrap_or_else(|| args.next().unwrap_or_default()))
+                }
+                .boxed()
+            }),
             _ => Err(AiScriptRuntimeError::Runtime(format!(
                 "No such prop ({name}) in string."
             )))?,
diff --git a/tests/test.rs b/tests/test.rs
index ff38a22..54a7d49 100644
--- a/tests/test.rs
+++ b/tests/test.rs
@@ -4897,6 +4897,120 @@ mod primitive_props {
             .await
             .unwrap();
         }
+
+        #[tokio::test]
+        async fn at_without_default_value() {
+            test(
+                r#"
+                let arr1 = [10, 20, 30]
+				<: [
+					arr1
+					arr1.at(0), arr1.at(1), arr1.at(2)
+					arr1.at(-3), arr1.at(-2), arr1.at(-1)
+					arr1.at(3), arr1.at(4), arr1.at(5)
+					arr1.at(-6), arr1.at(-5), arr1.at(-4)
+				]
+                "#,
+                |res| {
+                    assert_eq!(
+                        res,
+                        arr([
+                            arr([num(10), num(20), num(30)]),
+                            num(10),
+                            num(20),
+                            num(30),
+                            num(10),
+                            num(20),
+                            num(30),
+                            null(),
+                            null(),
+                            null(),
+                            null(),
+                            null(),
+                            null(),
+                        ])
+                    )
+                },
+            )
+            .await
+            .unwrap();
+        }
+
+        #[tokio::test]
+        async fn at_with_default_value() {
+            test(
+                r#"
+                let arr1 = [10, 20, 30]
+				<: [
+					arr1
+					arr1.at(0, 100), arr1.at(1, 100), arr1.at(2, 100)
+					arr1.at(-3, 100), arr1.at(-2, 100), arr1.at(-1, 100)
+					arr1.at(3, 100), arr1.at(4, 100), arr1.at(5, 100)
+					arr1.at(-6, 100), arr1.at(-5, 100), arr1.at(-4, 100)
+				]
+                "#,
+                |res| {
+                    assert_eq!(
+                        res,
+                        arr([
+                            arr([num(10), num(20), num(30)]),
+                            num(10),
+                            num(20),
+                            num(30),
+                            num(10),
+                            num(20),
+                            num(30),
+                            num(100),
+                            num(100),
+                            num(100),
+                            num(100),
+                            num(100),
+                            num(100),
+                        ])
+                    )
+                },
+            )
+            .await
+            .unwrap();
+        }
+
+        #[tokio::test]
+        async fn at_fraction() {
+            test(
+                r#"
+                let arr1 = [10, 20, 30]
+				<: [
+					arr1
+					arr1.at(0.1), arr1.at(1.4), arr1.at(2.5)
+					arr1.at(-3.1), arr1.at(-2.4), arr1.at(-1.5)
+					arr1.at(3.1), arr1.at(4.4), arr1.at(5.5)
+					arr1.at(-6.1), arr1.at(-5.4), arr1.at(-4.5)
+				]
+                "#,
+                |res| {
+                    assert_eq!(
+                        res,
+                        arr([
+                            arr([num(10), num(20), num(30)]),
+                            num(10),
+                            num(20),
+                            num(30),
+                            num(10),
+                            num(20),
+                            num(30),
+                            null(),
+                            null(),
+                            null(),
+                            null(),
+                            null(),
+                            null(),
+                        ])
+                    )
+                },
+            )
+            .await
+            .unwrap();
+        }
     }
 }