luaur-rt 0.1.3

//! `serde::Serialize` implementations for [`Value`] and [`Table`], plus the
//! [`SerializableValue`] / [`SerializableTable`] wrappers that let callers tune
//! serialization options (`sort_keys`, `deny_recursive_tables`, ...).
//!
//! Mirrors the `#[cfg(feature = "serde")]` blocks in mlua's `value.rs`/
//! `table.rs`. Kept in the serde module so the base `value.rs`/`table.rs` are
//! unchanged.

use std::cell::RefCell;
use std::collections::HashSet;
use std::ffi::c_void;
use std::rc::Rc;
use std::result::Result as StdResult;

use serde::ser::{self, Serialize, SerializeMap, SerializeSeq, Serializer};

use super::de::{check_value_for_skip, encode_as_array, MapPairs, Options, RecursionGuard};
use crate::table::Table;
use crate::value::Value;

type Visited = Rc<RefCell<HashSet<*const c_void>>>;

/// A wrapped [`Value`] with customized serialization behavior. Mirrors
/// `mlua::SerializableValue`.
pub struct SerializableValue<'a> {
    value: &'a Value,
    options: Options,
    // Only needed for tables; left `None` otherwise to avoid an allocation.
    visited: Option<Visited>,
}

impl Value {
    /// Wraps a reference to this [`Value`] into a [`SerializableValue`], allowing
    /// serialization behavior to be customized via serde. Mirrors
    /// `mlua::Value::to_serializable`.
    pub fn to_serializable(&self) -> SerializableValue<'_> {
        SerializableValue::new(self, Options::default(), None)
    }
}

impl Serialize for Value {
    #[inline]
    fn serialize<S: Serializer>(&self, serializer: S) -> StdResult<S::Ok, S::Error> {
        SerializableValue::new(self, Options::default(), None).serialize(serializer)
    }
}

impl<'a> SerializableValue<'a> {
    #[inline]
    pub(crate) fn new(value: &'a Value, options: Options, visited: Option<&Visited>) -> Self {
        if let Value::Table(_) = value {
            return Self {
                value,
                options,
                visited: visited.cloned().or_else(|| Some(Default::default())),
            };
        }
        Self {
            value,
            options,
            visited: None,
        }
    }

    /// See [`DeserializeOptions::deny_unsupported_types`](super::DeserializeOptions).
    #[must_use]
    pub fn deny_unsupported_types(mut self, enabled: bool) -> Self {
        self.options.deny_unsupported_types = enabled;
        self
    }

    /// See [`DeserializeOptions::deny_recursive_tables`](super::DeserializeOptions).
    #[must_use]
    pub fn deny_recursive_tables(mut self, enabled: bool) -> Self {
        self.options.deny_recursive_tables = enabled;
        self
    }

    /// See [`DeserializeOptions::sort_keys`](super::DeserializeOptions).
    #[must_use]
    pub fn sort_keys(mut self, enabled: bool) -> Self {
        self.options.sort_keys = enabled;
        self
    }

    /// See [`DeserializeOptions::encode_empty_tables_as_array`](super::DeserializeOptions).
    #[must_use]
    pub fn encode_empty_tables_as_array(mut self, enabled: bool) -> Self {
        self.options.encode_empty_tables_as_array = enabled;
        self
    }

    /// See [`DeserializeOptions::detect_mixed_tables`](super::DeserializeOptions).
    #[must_use]
    pub fn detect_mixed_tables(mut self, enabled: bool) -> Self {
        self.options.detect_mixed_tables = enabled;
        self
    }
}

impl Serialize for SerializableValue<'_> {
    fn serialize<S>(&self, serializer: S) -> StdResult<S::Ok, S::Error>
    where
        S: Serializer,
    {
        // The `null` sentinel serializes as `none`.
        if super::is_null(self.value) {
            return serializer.serialize_none();
        }
        match self.value {
            Value::Nil => serializer.serialize_unit(),
            Value::Boolean(b) => serializer.serialize_bool(*b),
            Value::Integer(i) => serializer.serialize_i64(*i),
            Value::Number(n) => serializer.serialize_f64(*n),
            Value::Vector(v) => {
                use ser::SerializeTupleStruct;
                let mut ts = serializer.serialize_tuple_struct("Vector", crate::Vector::SIZE)?;
                ts.serialize_field(&v.x())?;
                ts.serialize_field(&v.y())?;
                ts.serialize_field(&v.z())?;
                ts.end()
            }
            Value::String(s) => serialize_lua_string(s, serializer),
            Value::Table(t) => {
                let visited = self.visited.as_ref().unwrap().clone();
                SerializableTable::new(t, self.options, visited).serialize(serializer)
            }
            Value::Buffer(buf) => serializer.serialize_bytes(buf.as_slice()),
            Value::Function(_)
            | Value::Thread(_)
            | Value::LightUserData(_)
            | Value::UserData(_)
            | Value::Error(_) => {
                if self.options.deny_unsupported_types {
                    let msg = format!("cannot serialize <{}>", self.value.type_name());
                    Err(ser::Error::custom(msg))
                } else {
                    serializer.serialize_unit()
                }
            }
        }
    }
}

fn serialize_lua_string<S>(s: &crate::LuaString, serializer: S) -> StdResult<S::Ok, S::Error>
where
    S: Serializer,
{
    match s.to_str() {
        Ok(s) => serializer.serialize_str(&s),
        Err(_) => serializer.serialize_bytes(&s.as_bytes()),
    }
}

/// A wrapped [`Table`] with customized serialization behavior. Mirrors mlua's
/// `SerializableTable`.
pub struct SerializableTable<'a> {
    table: &'a Table,
    options: Options,
    visited: Visited,
}

impl Serialize for Table {
    #[inline]
    fn serialize<S: Serializer>(&self, serializer: S) -> StdResult<S::Ok, S::Error> {
        SerializableTable::new(self, Options::default(), Default::default()).serialize(serializer)
    }
}

impl<'a> SerializableTable<'a> {
    #[inline]
    pub(crate) fn new(table: &'a Table, options: Options, visited: Visited) -> Self {
        Self {
            table,
            options,
            visited,
        }
    }
}

impl Serialize for SerializableTable<'_> {
    fn serialize<S>(&self, serializer: S) -> StdResult<S::Ok, S::Error>
    where
        S: Serializer,
    {
        let options = self.options;
        let visited = &self.visited;
        let _guard = RecursionGuard::new(self.table, visited);

        // Array
        if let Some(len) = encode_as_array(self.table, self.options) {
            let mut seq = serializer.serialize_seq(Some(len))?;
            let mut idx = 1usize;
            while idx <= len {
                let value: Value = self
                    .table
                    .raw_get(idx as i64)
                    .map_err(serde::ser::Error::custom)?;
                let skip = check_value_for_skip(&value, options, visited)
                    .map_err(serde::ser::Error::custom)?;
                if !skip {
                    seq.serialize_element(&SerializableValue::new(&value, options, Some(visited)))?;
                }
                idx += 1;
            }
            return seq.end();
        }

        // Map
        let mut map = serializer.serialize_map(None)?;
        let pairs =
            MapPairs::new(self.table, options.sort_keys).map_err(serde::ser::Error::custom)?;
        for kv in pairs {
            let (key, value) = kv.map_err(serde::ser::Error::custom)?;
            let skip_key =
                check_value_for_skip(&key, options, visited).map_err(serde::ser::Error::custom)?;
            let skip_value = check_value_for_skip(&value, options, visited)
                .map_err(serde::ser::Error::custom)?;
            if skip_key || skip_value {
                continue;
            }
            map.serialize_entry(
                &SerializableValue::new(&key, options, Some(visited)),
                &SerializableValue::new(&value, options, Some(visited)),
            )?;
        }
        map.end()
    }
}