2 files changed, 41 insertions, 0 deletions
diff --git a/crates/shirabe-metadata-minifier/src/lib.rs b/crates/shirabe-metadata-minifier/src/lib.rs
new file mode 100644
index 0000000..342786f
--- /dev/null
+++ b/crates/shirabe-metadata-minifier/src/lib.rs
@@ -0,0 +1,3 @@
+mod metadata_minifier;
+
+pub use metadata_minifier::*;
diff --git a/crates/shirabe-metadata-minifier/src/metadata_minifier.rs b/crates/shirabe-metadata-minifier/src/metadata_minifier.rs
new file mode 100644
index 0000000..3f1a4fc
--- /dev/null
+++ b/crates/shirabe-metadata-minifier/src/metadata_minifier.rs
@@ -0,0 +1,38 @@
+//! ref: composer/vendor/composer/metadata-minifier/src/MetadataMinifier.php
+
+use indexmap::IndexMap;
+use shirabe_php_shim::PhpMixed;
+
+#[derive(Debug)]
+pub struct MetadataMinifier;
+
+impl MetadataMinifier {
+    pub fn expand(versions: Vec<IndexMap<String, PhpMixed>>) -> Vec<IndexMap<String, PhpMixed>> {
+        let mut expanded: Vec<IndexMap<String, PhpMixed>> = Vec::new();
+        let mut expanded_version: Option<IndexMap<String, PhpMixed>> = None;
+        for version_data in versions {
+            if expanded_version.as_ref().is_none_or(|ev| ev.is_empty()) {
+                expanded.push(version_data.clone());
+                expanded_version = Some(version_data);
+                continue;
+            }
+
+            // add any changes from the previous version to the expanded one
+            let ev = expanded_version.as_mut().unwrap();
+            for (key, val) in version_data {
+                if matches!(&val, PhpMixed::String(s) if s == "__unset") {
+                    ev.shift_remove(&key);
+                } else {
+                    ev.insert(key, val);
+                }
+            }
+
+            expanded.push(ev.clone());
+        }
+
+        expanded
+    }
+
+    // MetadataMinifier::minify() is not ported because it is not used in Composer itself.
+    // The function is mainly for package repositories.
+}