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src/passes/field_deleter.rs

@@ -0,0 +1,81 @@
+use quote::ToTokens;
+use syn::{visit_mut::VisitMut, Fields};
+
+use crate::processor::{tracking, Pass, PassController, ProcessState, SourceFile};
+
+struct Visitor<'a> {
+    current_path: Vec<String>,
+    checker: &'a mut PassController,
+    process_state: ProcessState,
+}
+
+impl<'a> Visitor<'a> {
+    fn new(checker: &'a mut PassController) -> Self {
+        Self {
+            current_path: Vec::new(),
+            checker,
+            process_state: ProcessState::NoChange,
+        }
+    }
+
+    fn consider_deleting_field(&mut self, name: String) -> bool {
+        self.current_path.push(name);
+        let can_process = self.checker.can_process(&self.current_path);
+        if can_process {
+            self.process_state = ProcessState::Changed;
+        }
+        self.current_path.pop();
+        !can_process
+    }
+}
+
+impl VisitMut for Visitor<'_> {
+    fn visit_fields_mut(&mut self, fields: &mut syn::Fields) {
+        match fields {
+            Fields::Named(named) => {
+                named.named = named
+                    .named
+                    .clone()
+                    .into_pairs()
+                    .filter(|pair| {
+                        let field = pair.value();
+                        self.consider_deleting_field(field.ident.as_ref().unwrap().to_string())
+                    })
+                    .collect();
+            }
+            Fields::Unnamed(unnamed) => {
+                unnamed.unnamed = unnamed
+                    .unnamed
+                    .clone()
+                    .into_pairs()
+                    .enumerate()
+                    .filter(|(i, _)| self.consider_deleting_field(i.to_string()))
+                    .map(|(_, f)| f)
+                    .collect();
+            }
+            Fields::Unit => {}
+        }
+    }
+
+    tracking!();
+}
+
+#[derive(Default)]
+pub struct FieldDeleter;
+
+impl Pass for FieldDeleter {
+    fn process_file(
+        &mut self,
+        krate: &mut syn::File,
+        _: &SourceFile,
+        checker: &mut PassController,
+    ) -> ProcessState {
+        let mut visitor = Visitor::new(checker);
+        visitor.visit_file_mut(krate);
+        visitor.process_state
+    }
+
+    fn name(&self) -> &'static str {
+        "field-deleter"
+    }
+}

src/passes/mod.rs

@@ -1,5 +1,9 @@
 mod everybody_loops;
+mod field_deleter;
 mod item_deleter;
 mod privatize;
 
-pub use self::{everybody_loops::EverybodyLoops, item_deleter::ItemDeleter, privatize::Privatize};
+pub use self::{
+    everybody_loops::EverybodyLoops, field_deleter::FieldDeleter, item_deleter::ItemDeleter,
+    privatize::Privatize,
+};