Make air public inputs deserializable (#1648)

* Derive deserialize for AirPublicInput

* Add test

* Add more test cases

* Add Changelog entry

* Clippy

* Fix import

* Fix import

* fmt

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 #### Upcoming Changes
 
+* feat: Make air public inputs deserializable [#1648](https://github.com/lambdaclass/cairo-vm/pull/1648)
+
 * feat: Show only layout builtins in air private input [#1651](https://github.com/lambdaclass/cairo-vm/pull/1651)
 
 * feat: Sort builtin segment info upon serialization for Cairo PIE [#1654](https://github.com/lambdaclass/cairo-vm/pull/1654)

vm/src/air_public_input.rs

@@ -1,5 +1,5 @@
 use crate::Felt252;
-use serde::Serialize;
+use serde::{Deserialize, Serialize};
 use thiserror_no_std::Error;
 
 use crate::{
@@ -14,18 +14,21 @@ use crate::{
     },
 };
 
-#[derive(Serialize, Debug)]
+#[derive(Serialize, Deserialize, Debug, PartialEq)]
 pub struct PublicMemoryEntry {
     pub address: usize,
     #[serde(serialize_with = "mem_value_serde::serialize")]
+    #[serde(deserialize_with = "mem_value_serde::deserialize")]
     pub value: Option<Felt252>,
     pub page: usize,
 }
 
 mod mem_value_serde {
+    use core::fmt;
+
     use super::*;
 
-    use serde::Serializer;
+    use serde::{de, Deserializer, Serializer};
 
     pub(crate) fn serialize<S: Serializer>(
         value: &Option<Felt252>,
@@ -37,9 +40,41 @@ mod mem_value_serde {
             serializer.serialize_none()
         }
     }
+
+    pub(crate) fn deserialize<'de, D: Deserializer<'de>>(
+        d: D,
+    ) -> Result<Option<Felt252>, D::Error> {
+        d.deserialize_str(Felt252OptionVisitor)
+    }
+
+    struct Felt252OptionVisitor;
+
+    impl<'de> de::Visitor<'de> for Felt252OptionVisitor {
+        type Value = Option<Felt252>;
+
+        fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+            formatter.write_str("Could not deserialize hexadecimal string")
+        }
+
+        fn visit_none<E>(self) -> Result<Self::Value, E>
+        where
+            E: de::Error,
+        {
+            Ok(None)
+        }
+
+        fn visit_str<E>(self, value: &str) -> Result<Self::Value, E>
+        where
+            E: de::Error,
+        {
+            Felt252::from_hex(value)
+                .map_err(de::Error::custom)
+                .map(Some)
+        }
+    }
 }
 
-#[derive(Serialize, Debug)]
+#[derive(Serialize, Deserialize, Debug, PartialEq)]
 pub struct MemorySegmentAddresses {
     pub begin_addr: usize,
     pub stop_ptr: usize,
@@ -55,7 +90,7 @@ impl From<(usize, usize)> for MemorySegmentAddresses {
     }
 }
 
-#[derive(Serialize, Debug)]
+#[derive(Serialize, Deserialize, Debug)]
 pub struct PublicInput<'a> {
     pub layout: &'a str,
     pub rc_min: isize,
@@ -64,6 +99,7 @@ pub struct PublicInput<'a> {
     pub memory_segments: HashMap<&'a str, MemorySegmentAddresses>,
     pub public_memory: Vec<PublicMemoryEntry>,
     #[serde(rename = "dynamic_params")]
+    #[serde(skip_deserializing)] // This is set to None by default so we can skip it
     layout_params: Option<&'a CairoLayout>,
 }
 
@@ -139,3 +175,52 @@ pub enum PublicInputError {
     #[error(transparent)]
     Trace(#[from] TraceError),
 }
+#[cfg(test)]
+mod tests {
+    #[cfg(feature = "std")]
+    use super::*;
+    #[cfg(feature = "std")]
+    use rstest::rstest;
+
+    #[cfg(feature = "std")]
+    #[rstest]
+    #[case(include_bytes!("../../cairo_programs/proof_programs/fibonacci.json"))]
+    #[case(include_bytes!("../../cairo_programs/proof_programs/bitwise_output.json"))]
+    #[case(include_bytes!("../../cairo_programs/proof_programs/keccak_builtin.json"))]
+    #[case(include_bytes!("../../cairo_programs/proof_programs/poseidon_builtin.json"))]
+    #[case(include_bytes!("../../cairo_programs/proof_programs/relocate_temporary_segment_append.json"))]
+    #[case(include_bytes!("../../cairo_programs/proof_programs/pedersen_test.json"))]
+    #[case(include_bytes!("../../cairo_programs/proof_programs/ec_op.json"))]
+    fn serialize_and_deserialize_air_public_input(#[case] program_content: &[u8]) {
+        let config = crate::cairo_run::CairoRunConfig {
+            proof_mode: true,
+            relocate_mem: true,
+            trace_enabled: true,
+            layout: "all_cairo",
+            ..Default::default()
+        };
+        let (runner, vm) = crate::cairo_run::cairo_run(program_content, &config, &mut crate::hint_processor::builtin_hint_processor::builtin_hint_processor_definition::BuiltinHintProcessor::new_empty()).unwrap();
+        let public_input = runner.get_air_public_input(&vm).unwrap();
+        // We already know serialization works as expected due to the comparison against python VM
+        let serialized_public_input = public_input.serialize_json().unwrap();
+        let deserialized_public_input: PublicInput =
+            serde_json::from_str(&serialized_public_input).unwrap();
+        // Check that the deserialized public input is equal to the one we obtained from the vm first
+        assert_eq!(public_input.layout, deserialized_public_input.layout);
+        assert_eq!(public_input.rc_max, deserialized_public_input.rc_max);
+        assert_eq!(public_input.rc_min, deserialized_public_input.rc_min);
+        assert_eq!(public_input.n_steps, deserialized_public_input.n_steps);
+        assert_eq!(
+            public_input.memory_segments,
+            deserialized_public_input.memory_segments
+        );
+        assert_eq!(
+            public_input.public_memory,
+            deserialized_public_input.public_memory
+        );
+        assert!(
+            public_input.layout_params.is_none()
+                && deserialized_public_input.layout_params.is_none()
+        );
+    }
+}