From 6ff4eeb237aa1f4f0f2ed20520a0ed3cb3dece0f Mon Sep 17 00:00:00 2001
From: tyshko-rostyslav <122977916+tyshko-rostyslav@users.noreply.github.com>
Date: Wed, 29 Mar 2023 15:16:36 +0200
Subject: [PATCH] Macro to call functions with an error message (#140)

abstract out calls

---------

Co-authored-by: tyshkor <tyshko1@gmail.com>
---
 .gitignore          |   1 +
 rln-wasm/src/lib.rs | 103 +++++++++++++++++++++++++++++++++-----------
 2 files changed, 78 insertions(+), 26 deletions(-)

diff --git a/.gitignore b/.gitignore
index c51faaa..201b119 100644
--- a/.gitignore
+++ b/.gitignore
@@ -8,6 +8,7 @@ rln/pmtree_db
 # will have compiled files and executables
 debug/
 target/
+wabt/
 
 # These are backup files generated by rustfmt
 **/*.rs.bk
diff --git a/rln-wasm/src/lib.rs b/rln-wasm/src/lib.rs
index 27c8e25..e6f031c 100644
--- a/rln-wasm/src/lib.rs
+++ b/rln-wasm/src/lib.rs
@@ -20,6 +20,64 @@ pub struct RLNWrapper {
     instance: RLN<'static>,
 }
 
+// Macro to call_with_error_msg methods with arbitrary amount of arguments,
+// First argument to the macro is context,
+// second is the actual method on `RLNWrapper`
+// rest are all other arguments to the method
+macro_rules! call_with_error_msg {
+    ($instance:expr, $method:ident, $error_msg:expr $(, $arg:expr)*) => {
+        {
+            let new_instance: &mut RLNWrapper = $instance.process();
+            if let Err(err) = new_instance.instance.$method($($arg.process()),*) {
+                Err(format!("Msg: {:#?}, Error: {:#?}", $error_msg, err))
+            } else {
+                Ok(())
+            }
+
+        }
+    }
+}
+
+trait ProcessArg {
+    type ReturnType;
+    fn process(self) -> Self::ReturnType;
+}
+
+impl ProcessArg for usize {
+    type ReturnType = usize;
+    fn process(self) -> Self::ReturnType {
+        self
+    }
+}
+
+impl<'a> ProcessArg for *const RLN<'a> {
+    type ReturnType = &'a RLN<'a>;
+    fn process(self) -> Self::ReturnType {
+        unsafe { &*self }
+    }
+}
+
+trait ProcessArgRef {
+    type ReturnType;
+    fn process(self) -> Self::ReturnType;
+}
+
+impl ProcessArgRef for *mut RLNWrapper {
+    type ReturnType = &'static mut RLNWrapper;
+
+    fn process(self) -> Self::ReturnType {
+        unsafe { &mut *self }
+    }
+}
+
+impl<'a> ProcessArgRef for &'a [u8] {
+    type ReturnType = &'a [u8];
+
+    fn process(self) -> Self::ReturnType {
+        self
+    }
+}
+
 #[allow(clippy::not_unsafe_ptr_arg_deref)]
 #[wasm_bindgen(js_name = newRLN)]
 pub fn wasm_new(
@@ -51,12 +109,12 @@ pub fn wasm_get_serialized_rln_witness(
 #[allow(clippy::not_unsafe_ptr_arg_deref)]
 #[wasm_bindgen(js_name = insertMember)]
 pub fn wasm_set_next_leaf(ctx: *mut RLNWrapper, input: Uint8Array) -> Result<(), String> {
-    let wrapper = unsafe { &mut *ctx };
-    if wrapper.instance.set_next_leaf(&input.to_vec()[..]).is_ok() {
-        Ok(())
-    } else {
-        Err("could not insert member into merkle tree".into())
-    }
+    call_with_error_msg!(
+        ctx,
+        set_next_leaf,
+        "could not insert member into merkle tree".to_string(),
+        &input.to_vec()[..]
+    )
 }
 
 #[allow(clippy::not_unsafe_ptr_arg_deref)]
@@ -66,31 +124,24 @@ pub fn wasm_set_leaves_from(
     index: usize,
     input: Uint8Array,
 ) -> Result<(), String> {
-    let wrapper = unsafe { &mut *ctx };
-    if wrapper
-        .instance
-        .set_leaves_from(index as usize, &input.to_vec()[..])
-        .is_ok()
-    {
-        Ok(())
-    } else {
-        Err("could not set multiple leaves".into())
-    }
+    call_with_error_msg!(
+        ctx,
+        set_leaves_from,
+        "could not set multiple leaves".to_string(),
+        index,
+        &*input.to_vec()
+    )
 }
 
 #[allow(clippy::not_unsafe_ptr_arg_deref)]
 #[wasm_bindgen(js_name = initTreeWithLeaves)]
 pub fn wasm_init_tree_with_leaves(ctx: *mut RLNWrapper, input: Uint8Array) -> Result<(), String> {
-    let wrapper = unsafe { &mut *ctx };
-    if wrapper
-        .instance
-        .init_tree_with_leaves(&input.to_vec()[..])
-        .is_ok()
-    {
-        Ok(())
-    } else {
-        Err("could not init merkle tree".into())
-    }
+    call_with_error_msg!(
+        ctx,
+        init_tree_with_leaves,
+        "could not init merkle tree".to_string(),
+        &*input.to_vec()
+    )
 }
 
 #[allow(clippy::not_unsafe_ptr_arg_deref)]