Merge pull request #26 from eZioPan/negative-byte-offset

allow negative byte offset

src/transform/modify_byte_offset.rs

@@ -5,19 +5,53 @@ use crate::ir::*;
 
 #[derive(Debug, Serialize, Deserialize)]
 pub struct ModifyByteOffset {
-    pub block: String,
-    pub add_offset: u32,
+    pub blocks: String,
+    pub exclude_items: Option<String>,
+    pub add_offset: i32,
+    pub strict: Option<bool>, // if this value is false, bypass overflowed/underflowed modification
 }
 
 impl ModifyByteOffset {
     pub fn run(&self, ir: &mut IR) -> anyhow::Result<()> {
-        let path_re = make_regex(&self.block)?;
+        let path_re = make_regex(&self.blocks)?;
+        let ex_re = if let Some(exclude_items) = &self.exclude_items {
+            make_regex(exclude_items)?
+        } else {
+            make_regex("")?
+        };
+
+        let strict = self.strict.unwrap_or_default();
+
+        let mut err_names = Vec::new();
+
         for id in match_all(ir.blocks.keys().cloned(), &path_re) {
             let b = ir.blocks.get_mut(&id).unwrap();
             for i in &mut b.items {
-                i.byte_offset += self.add_offset;
+                if ex_re.is_match(&i.name) {
+                    continue;
+                }
+
+                match i.byte_offset.checked_add_signed(self.add_offset) {
+                    Some(new_offset) => i.byte_offset = new_offset,
+                    None if strict => err_names.push((id.clone(), i.name.clone())),
+                    None => (),
+                };
+            }
+        }
+
+        if !err_names.is_empty() {
+            let mut err_msg = String::new();
+
+            for e_name in err_names {
+                err_msg.push_str(&format!(
+                    "Block: {} Item: {}: byte_offset out of range after modify\n",
+                    e_name.0, e_name.1
+                ));
             }
+
+            panic!("{err_msg}")
         }
+
         Ok(())
     }
 }