Move PyObject serialization to its own file

Author: coolreader18

vm/src/lib.rs

@@ -55,6 +55,7 @@ pub mod import;
 pub mod obj;
 mod pyhash;
 pub mod pyobject;
+pub mod ser_de;
 pub mod stdlib;
 mod sysmodule;
 mod traceback;

vm/src/ser_de.rs

@@ -0,0 +1,199 @@
+use std::fmt;
+
+use serde;
+use serde::de::Visitor;
+use serde::ser::{SerializeMap, SerializeSeq};
+
+use crate::obj::{
+    objbool,
+    objdict::PyDictRef,
+    objfloat, objint, objsequence,
+    objstr::{self, PyString},
+    objtype,
+};
+use crate::pyobject::{IdProtocol, ItemProtocol, PyObjectRef, TypeProtocol};
+use crate::VirtualMachine;
+use num_traits::cast::ToPrimitive;
+
+// We need to have a VM available to serialise a PyObject based on its subclass, so we implement
+// PyObject serialisation via a proxy object which holds a reference to a VM
+pub struct PyObjectSerializer<'s> {
+    pyobject: &'s PyObjectRef,
+    vm: &'s VirtualMachine,
+}
+
+impl<'s> PyObjectSerializer<'s> {
+    pub fn new(vm: &'s VirtualMachine, pyobject: &'s PyObjectRef) -> Self {
+        PyObjectSerializer { pyobject, vm }
+    }
+
+    fn clone_with_object(&self, pyobject: &'s PyObjectRef) -> PyObjectSerializer {
+        PyObjectSerializer {
+            pyobject,
+            vm: self.vm,
+        }
+    }
+}
+
+impl<'s> serde::Serialize for PyObjectSerializer<'s> {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: serde::Serializer,
+    {
+        let serialize_seq_elements =
+            |serializer: S, elements: &Vec<PyObjectRef>| -> Result<S::Ok, S::Error> {
+                let mut seq = serializer.serialize_seq(Some(elements.len()))?;
+                for e in elements.iter() {
+                    seq.serialize_element(&self.clone_with_object(e))?;
+                }
+                seq.end()
+            };
+        if objtype::isinstance(self.pyobject, &self.vm.ctx.str_type()) {
+            serializer.serialize_str(&objstr::get_value(&self.pyobject))
+        } else if objtype::isinstance(self.pyobject, &self.vm.ctx.float_type()) {
+            serializer.serialize_f64(objfloat::get_value(self.pyobject))
+        } else if objtype::isinstance(self.pyobject, &self.vm.ctx.bool_type()) {
+            serializer.serialize_bool(objbool::get_value(self.pyobject))
+        } else if objtype::isinstance(self.pyobject, &self.vm.ctx.int_type()) {
+            let v = objint::get_value(self.pyobject);
+            serializer.serialize_i64(v.to_i64().unwrap())
+        // Although this may seem nice, it does not give the right result:
+        // v.serialize(serializer)
+        } else if objtype::isinstance(self.pyobject, &self.vm.ctx.list_type()) {
+            let elements = objsequence::get_elements_list(self.pyobject);
+            serialize_seq_elements(serializer, &elements)
+        } else if objtype::isinstance(self.pyobject, &self.vm.ctx.tuple_type()) {
+            let elements = objsequence::get_elements_tuple(self.pyobject);
+            serialize_seq_elements(serializer, &elements)
+        } else if objtype::isinstance(self.pyobject, &self.vm.ctx.dict_type()) {
+            let dict: PyDictRef = self.pyobject.clone().downcast().unwrap();
+            let pairs: Vec<_> = dict.into_iter().collect();
+            let mut map = serializer.serialize_map(Some(pairs.len()))?;
+            for (key, e) in pairs.iter() {
+                map.serialize_entry(&self.clone_with_object(key), &self.clone_with_object(&e))?;
+            }
+            map.end()
+        } else if self.pyobject.is(&self.vm.get_none()) {
+            serializer.serialize_none()
+        } else {
+            Err(serde::ser::Error::custom(format!(
+                "Object of type '{:?}' is not serializable",
+                self.pyobject.class()
+            )))
+        }
+    }
+}
+
+// This object is used as the seed for deserialization so we have access to the PyContext for type
+// creation
+#[derive(Clone)]
+pub struct PyObjectDeserializer<'c> {
+    vm: &'c VirtualMachine,
+}
+
+impl<'c> PyObjectDeserializer<'c> {
+    pub fn new(vm: &'c VirtualMachine) -> Self {
+        PyObjectDeserializer { vm }
+    }
+}
+
+impl<'de> serde::de::DeserializeSeed<'de> for PyObjectDeserializer<'de> {
+    type Value = PyObjectRef;
+
+    fn deserialize<D>(self, deserializer: D) -> Result<Self::Value, D::Error>
+    where
+        D: serde::Deserializer<'de>,
+    {
+        deserializer.deserialize_any(self.clone())
+    }
+}
+
+impl<'de> Visitor<'de> for PyObjectDeserializer<'de> {
+    type Value = PyObjectRef;
+
+    fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.write_str("a type that can deserialise in Python")
+    }
+
+    fn visit_str<E>(self, value: &str) -> Result<Self::Value, E>
+    where
+        E: serde::de::Error,
+    {
+        Ok(self.vm.ctx.new_str(value.to_string()))
+    }
+
+    fn visit_string<E>(self, value: String) -> Result<Self::Value, E>
+    where
+        E: serde::de::Error,
+    {
+        Ok(self.vm.ctx.new_str(value))
+    }
+
+    fn visit_i64<E>(self, value: i64) -> Result<Self::Value, E>
+    where
+        E: serde::de::Error,
+    {
+        // The JSON deserializer always uses the i64/u64 deserializers, so we only need to
+        // implement those for now
+        Ok(self.vm.ctx.new_int(value))
+    }
+
+    fn visit_u64<E>(self, value: u64) -> Result<Self::Value, E>
+    where
+        E: serde::de::Error,
+    {
+        // The JSON deserializer always uses the i64/u64 deserializers, so we only need to
+        // implement those for now
+        Ok(self.vm.ctx.new_int(value))
+    }
+
+    fn visit_f64<E>(self, value: f64) -> Result<Self::Value, E>
+    where
+        E: serde::de::Error,
+    {
+        Ok(self.vm.ctx.new_float(value))
+    }
+
+    fn visit_bool<E>(self, value: bool) -> Result<Self::Value, E>
+    where
+        E: serde::de::Error,
+    {
+        Ok(self.vm.ctx.new_bool(value))
+    }
+
+    fn visit_seq<A>(self, mut access: A) -> Result<Self::Value, A::Error>
+    where
+        A: serde::de::SeqAccess<'de>,
+    {
+        let mut seq = Vec::with_capacity(access.size_hint().unwrap_or(0));
+        while let Some(value) = access.next_element_seed(self.clone())? {
+            seq.push(value);
+        }
+        Ok(self.vm.ctx.new_list(seq))
+    }
+
+    fn visit_map<M>(self, mut access: M) -> Result<Self::Value, M::Error>
+    where
+        M: serde::de::MapAccess<'de>,
+    {
+        let dict = self.vm.ctx.new_dict();
+        // TODO: Given keys must be strings, we can probably do something more efficient
+        // than wrapping the given object up and then unwrapping it to determine whether or
+        // not it is a string
+        while let Some((key_obj, value)) = access.next_entry_seed(self.clone(), self.clone())? {
+            let key: String = match key_obj.payload::<PyString>() {
+                Some(PyString { ref value }) => value.clone(),
+                _ => unimplemented!("map keys must be strings"),
+            };
+            dict.set_item(&key, value, self.vm).unwrap();
+        }
+        Ok(dict.into_object())
+    }
+
+    fn visit_unit<E>(self) -> Result<Self::Value, E>
+    where
+        E: serde::de::Error,
+    {
+        Ok(self.vm.get_none())
+    }
+}