add iko

iko/.gitignore

@@ -0,0 +1 @@
+/target/

iko/Cargo.toml

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+[package]
+name = "iko"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

iko/README.md

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+# iko

iko/src/lib.rs

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+#[cfg(test)]
+mod tests {
+    #[test]
+    fn test() {
+        trait Migration {
+            fn migrate(&self);
+            fn version(&self) -> u32;
+        }
+
+        struct Migration1 {}
+        impl Migration for Migration1 {
+            fn migrate(&self) {
+                println!("migrate1");
+            }
+
+            fn version(&self) -> u32 {
+                1
+            }
+        }
+
+        struct Migration2 {}
+        impl Migration for Migration2 {
+            fn migrate(&self) {
+                println!("migrate2");
+            }
+
+            fn version(&self) -> u32 {
+                2
+            }
+        }
+
+        let mut current_version = 0;
+        let migrations: Vec<Box<dyn Migration>> =
+            vec![Box::new(Migration1 {}), Box::new(Migration2 {})];
+        for migration in migrations {
+            // load_and_lock_current_version()
+            if current_version + 1 != migration.version() {
+                continue;
+            }
+
+            migration.migrate();
+
+            // save_and_unlock_current_version()
+            current_version += 1;
+        }
+    }
+}