start implementing field

androscalpel_serializer/src/file_reader.rs

@@ -143,6 +143,27 @@ impl<'a> DexFileReader<'a> {
             })
     }
 
+    /// Return a [`&TypeIdItem`] from its idx.
+    pub fn get_type_id(&self, idx: usize) -> Result<&TypeIdItem> {
+        self.type_ids
+            .get(idx)
+            .ok_or(Error::InconsistantStruct(format!(
+                "type idx {} out of bound of type_ids (|type_ids| = {})",
+                idx,
+                self.type_ids.len()
+            )))
+    }
+
+    /// Return a [`&FieldIdItem`] from its idx.
+    pub fn get_field_id(&self, idx: usize) -> Result<&FieldIdItem> {
+        self.field_ids
+            .get(idx)
+            .ok_or(Error::InconsistantStruct(format!(
+                "field idx {idx} is out of bound (|field_ids|={})",
+                self.field_ids.len()
+            )))
+    }
+
     fn sanity_check(&self) -> Result<()> {
         if self.header.magic.version != [0x30, 0x33, 0x39] {
             warn!(