gstreamer-rs/gstreamer/src/value_serde.rs
2022-11-01 11:10:57 +02:00

674 lines
25 KiB
Rust

// Take a look at the license at the top of the repository in the LICENSE file.
#![allow(clippy::upper_case_acronyms)]
use glib::{Date, StaticType, ToValue};
use num_rational::Rational32;
use serde::de;
use serde::de::{Deserialize, Deserializer, SeqAccess, Visitor};
use serde::ser;
use serde::ser::{Serialize, SerializeTuple, Serializer};
use std::{fmt, mem};
use once_cell::sync::Lazy;
use crate::Buffer;
use crate::DateTime;
use crate::Sample;
use crate::Structure;
use crate::date_time_serde;
use crate::value::*;
pub(crate) static ARRAY_OTHER_TYPE_ID: Lazy<glib::Type> = Lazy::new(Array::static_type);
pub(crate) static BITMASK_OTHER_TYPE_ID: Lazy<glib::Type> = Lazy::new(Bitmask::static_type);
pub(crate) static DATE_OTHER_TYPE_ID: Lazy<glib::Type> = Lazy::new(Date::static_type);
pub(crate) static DATE_TIME_OTHER_TYPE_ID: Lazy<glib::Type> = Lazy::new(DateTime::static_type);
pub(crate) static FRACTION_OTHER_TYPE_ID: Lazy<glib::Type> = Lazy::new(Fraction::static_type);
pub(crate) static FRACTION_RANGE_OTHER_TYPE_ID: Lazy<glib::Type> =
Lazy::new(FractionRange::static_type);
pub(crate) static INT_RANGE_I32_OTHER_TYPE_ID: Lazy<glib::Type> =
Lazy::new(IntRange::<i32>::static_type);
pub(crate) static INT_RANGE_I64_OTHER_TYPE_ID: Lazy<glib::Type> =
Lazy::new(IntRange::<i64>::static_type);
pub(crate) static LIST_OTHER_TYPE_ID: Lazy<glib::Type> = Lazy::new(List::static_type);
pub(crate) static SAMPLE_OTHER_TYPE_ID: Lazy<glib::Type> = Lazy::new(Sample::static_type);
pub(crate) static BUFFER_OTHER_TYPE_ID: Lazy<glib::Type> = Lazy::new(Buffer::static_type);
pub(crate) static STRUCTURE_OTHER_TYPE_ID: Lazy<glib::Type> = Lazy::new(Structure::static_type);
impl Serialize for Fraction {
fn serialize<S: Serializer>(&self, serializer: S) -> Result<S::Ok, S::Error> {
self.0.serialize(serializer)
}
}
impl<'de> Deserialize<'de> for Fraction {
fn deserialize<D: Deserializer<'de>>(deserializer: D) -> Result<Self, D::Error> {
skip_assert_initialized!();
Rational32::deserialize(deserializer)
.map(|rational| Fraction::new(*rational.numer(), *rational.denom()))
}
}
macro_rules! ser_some_value (
($value:expr, $t:ty, $ser_closure:expr) => (
{
let value = $value.get::<$t>().expect("ser_some_value macro");
$ser_closure(stringify!($t), value)
}
);
);
macro_rules! ser_opt_value (
($value:expr, $t:ty, $ser_closure:expr) => (
{
let value = $value.get::<Option<$t>>().expect("ser_opt_value macro");
$ser_closure(stringify!($t), value)
}
);
);
macro_rules! ser_value (
($value:expr, $ser_closure:expr) => (
match $value.type_() {
glib::Type::I8 => ser_some_value!($value, i8, $ser_closure),
glib::Type::U8 => ser_some_value!($value, u8, $ser_closure),
glib::Type::BOOL => ser_some_value!($value, bool, $ser_closure),
glib::Type::I32 => ser_some_value!($value, i32, $ser_closure),
glib::Type::U32 => ser_some_value!($value, u32, $ser_closure),
glib::Type::I64 => ser_some_value!($value, i64, $ser_closure),
glib::Type::U64 => ser_some_value!($value, u64, $ser_closure),
glib::Type::F32 => ser_some_value!($value, f32, $ser_closure),
glib::Type::F64 => ser_some_value!($value, f64, $ser_closure),
glib::Type::STRING => ser_opt_value!($value, String, $ser_closure),
type_id => {
if *ARRAY_OTHER_TYPE_ID == type_id {
ser_some_value!($value, Array, $ser_closure)
} else if *BITMASK_OTHER_TYPE_ID == type_id {
ser_some_value!($value, Bitmask, $ser_closure)
} else if *STRUCTURE_OTHER_TYPE_ID == type_id {
ser_some_value!($value, Structure, $ser_closure)
} else if *DATE_OTHER_TYPE_ID == type_id {
ser_opt_value!($value, Date, |type_, value: Option<Date>| {
// Need to wrap the `glib::Date` in new type `date_time_serde::Date` first
// See comment in `date_time_serde.rs`
$ser_closure(type_, value.map(date_time_serde::Date::from))
})
} else if *DATE_TIME_OTHER_TYPE_ID == type_id {
ser_opt_value!($value, DateTime, $ser_closure)
} else if *FRACTION_OTHER_TYPE_ID == type_id {
ser_some_value!($value, Fraction, $ser_closure)
} else if *FRACTION_RANGE_OTHER_TYPE_ID == type_id {
ser_some_value!($value, FractionRange, $ser_closure)
} else if *INT_RANGE_I32_OTHER_TYPE_ID == type_id {
ser_some_value!($value, IntRange<i32>, $ser_closure)
} else if *INT_RANGE_I64_OTHER_TYPE_ID == type_id {
ser_some_value!($value, IntRange<i64>, $ser_closure)
} else if *LIST_OTHER_TYPE_ID == type_id {
ser_some_value!($value, List, $ser_closure)
} else if *SAMPLE_OTHER_TYPE_ID == type_id {
ser_opt_value!($value, Sample, $ser_closure)
} else if *BUFFER_OTHER_TYPE_ID == type_id {
ser_opt_value!($value, Buffer, $ser_closure)
} else {
Err(
ser::Error::custom(
format!("unimplemented `Value` serialization for type {}",
type_id,
)
)
)
}
}
}
);
);
#[repr(transparent)]
pub(crate) struct SendValue(glib::SendValue);
impl SendValue {
pub(crate) fn from(send_value: glib::SendValue) -> Self {
skip_assert_initialized!();
SendValue(send_value)
}
}
impl From<SendValue> for glib::SendValue {
fn from(send_value: SendValue) -> Self {
skip_assert_initialized!();
send_value.0
}
}
impl Serialize for SendValue {
fn serialize<S: Serializer>(&self, serializer: S) -> Result<S::Ok, S::Error> {
ser_value!(self.0, |type_, value| {
let mut tup = serializer.serialize_tuple(2)?;
tup.serialize_element(type_)?;
tup.serialize_element(&value)?;
tup.end()
})
}
}
macro_rules! impl_ser_send_value_collection (
($t:ident) => (
impl Serialize for $t {
fn serialize<S: Serializer>(&self, serializer: S) -> Result<S::Ok, S::Error> {
let send_value_vec = unsafe {
&*(self.as_slice() as *const [glib::SendValue] as *const [SendValue])
};
send_value_vec.serialize(serializer)
}
}
);
);
impl_ser_send_value_collection!(Array);
impl_ser_send_value_collection!(List);
macro_rules! de_some_send_value(
($type_name:expr, $seq:expr, $t:ty) => (
de_some_send_value!("Value", $type_name, $seq, $t)
);
($outer_type:expr, $type_name:expr, $seq:expr, $t:ty) => (
de_send_value!($outer_type, $type_name, $seq, $t, $t)
);
);
macro_rules! de_opt_send_value(
($type_name:expr, $seq:expr, $t:ty) => (
de_opt_send_value!("Value", $type_name, $seq, $t)
);
($outer_type:expr, $type_name:expr, $seq:expr, $t:ty) => (
de_send_value!($outer_type, $type_name, $seq, Option<$t>, $t)
);
);
macro_rules! de_send_value(
($outer_type:expr, $type_name:expr, $seq:expr, $elem_t:ty, $t:ty) => (
Ok(match $seq.next_element::<$elem_t>()? {
Some(base_value) => {
Some(SendValue::from(base_value
.to_value()
.try_into_send_value::<$t>()
.map_err(|_|
de::Error::custom(format!(
"Failed to convert `{}` with type {:?} to `SendValue`",
$outer_type,
$type_name,
))
)?
))
}
None => None
})
);
($type_name:expr, $seq:expr) => (
match $type_name.as_str() {
"i8" => de_some_send_value!($type_name, $seq, i8),
"u8" => de_some_send_value!($type_name, $seq, u8),
"bool" => de_some_send_value!($type_name, $seq, bool),
"i32" => de_some_send_value!($type_name, $seq, i32),
"u32" => de_some_send_value!($type_name, $seq, u32),
"i64" => de_some_send_value!($type_name, $seq, i64),
"u64" => de_some_send_value!($type_name, $seq, u64),
"f32" => de_some_send_value!($type_name, $seq, f32),
"f64" => de_some_send_value!($type_name, $seq, f64),
"String" => de_opt_send_value!($type_name, $seq, String),
"Array" => de_some_send_value!($type_name, $seq, Array),
"Bitmask" => de_some_send_value!($type_name, $seq, Bitmask),
"Structure" => de_some_send_value!($type_name, $seq, Structure),
"Date" => {
// Need to deserialize as `date_time_serde::Date` new type
// See comment in `date_time_serde.rs`
de_send_value!(
"Value",
$type_name,
$seq,
Option<date_time_serde::Date>,
Date
)
}
"DateTime" => de_opt_send_value!($type_name, $seq, DateTime),
"Fraction" => de_some_send_value!($type_name, $seq, Fraction),
"FractionRange" => de_some_send_value!($type_name, $seq, FractionRange),
"IntRange<i32>" => de_some_send_value!($type_name, $seq, IntRange<i32>),
"IntRange<i64>" => de_some_send_value!($type_name, $seq, IntRange<i64>),
"Sample" => de_opt_send_value!($type_name, $seq, Sample),
"Buffer" => de_opt_send_value!($type_name, $seq, Buffer),
_ => return Err(
de::Error::custom(
format!(
"unimplemented deserialization for `Value` with type `{}`",
$type_name,
),
)
),
}
);
);
struct SendValueVisitor;
impl<'de> Visitor<'de> for SendValueVisitor {
type Value = SendValue;
fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
formatter.write_str("a tuple: (name, value)")
}
fn visit_seq<A: SeqAccess<'de>>(self, mut seq: A) -> Result<Self::Value, A::Error> {
let type_name = seq
.next_element::<String>()?
.ok_or_else(|| de::Error::custom("Expected a value for `Value` type"))?;
let send_value = de_send_value!(type_name, seq)?
.ok_or_else(|| de::Error::custom("Expected a value for `Value`"))?;
Ok(send_value)
}
}
impl<'de> Deserialize<'de> for SendValue {
fn deserialize<D: Deserializer<'de>>(deserializer: D) -> Result<Self, D::Error> {
skip_assert_initialized!();
deserializer.deserialize_tuple(2, SendValueVisitor {})
}
}
macro_rules! impl_de_send_value_collection (
($t:ident) => {
impl<'de> Deserialize<'de> for $t {
fn deserialize<D: Deserializer<'de>>(deserializer: D) -> Result<Self, D::Error> {
skip_assert_initialized!();
let send_value_vec = Vec::<SendValue>::deserialize(deserializer)?;
Ok($t::from_values(unsafe{
mem::transmute::<Vec<SendValue>, Vec<glib::SendValue>>(send_value_vec)
}))
}
}
}
);
impl_de_send_value_collection!(Array);
impl_de_send_value_collection!(List);
#[cfg(test)]
mod tests {
use crate::Array;
use crate::Bitmask;
use crate::DateTime;
use crate::Fraction;
use crate::FractionRange;
use crate::IntRange;
use crate::List;
use crate::Structure;
use glib::{Date, DateMonth};
#[test]
fn test_serialize_simple() {
crate::init().unwrap();
let pretty_config = ron::ser::PrettyConfig::new().new_line("".to_string());
// Fraction
let fraction = Fraction::new(1, 3);
let res = ron::ser::to_string_pretty(&fraction, pretty_config.clone());
assert_eq!(Ok("(1, 3)".to_owned()), res);
let res = serde_json::to_string(&fraction).unwrap();
assert_eq!("[1,3]".to_owned(), res);
// FractionRange
let fraction_range = FractionRange::new(Fraction::new(1, 3), Fraction::new(1, 2));
let res = ron::ser::to_string_pretty(&fraction_range, pretty_config.clone());
assert_eq!(Ok("( min: (1, 3), max: (1, 2),)".to_owned()), res);
let res = serde_json::to_string(&fraction_range).unwrap();
assert_eq!(r#"{"min":[1,3],"max":[1,2]}"#.to_owned(), res);
// IntRange
let int_range = IntRange::with_step(0, 42, 21);
let res = ron::ser::to_string_pretty(&int_range, pretty_config.clone());
assert_eq!(Ok("( min: 0, max: 42, step: 21,)".to_owned()), res,);
let res = serde_json::to_string(&int_range).unwrap();
assert_eq!(r#"{"min":0,"max":42,"step":21}"#.to_owned(), res);
// Bitmask
let bitmask = Bitmask::new(1024 + 128 + 32);
let res = ron::ser::to_string_pretty(&bitmask, pretty_config.clone());
assert_eq!(Ok("(1184)".to_owned()), res);
let res = serde_json::to_string(&bitmask).unwrap();
assert_eq!("1184".to_owned(), res);
// Nested structure
let s = Structure::builder("foobar")
.field("foo", 42)
.field("baz", Structure::builder("baz").field("foo", 43).build())
.build();
let res = ron::ser::to_string_pretty(&s, pretty_config);
assert_eq!(
Ok(r#"("foobar", [ ("foo", "i32", 42), ("baz", "Structure", ("baz", [ ("foo", "i32", 43), ])),])"#.to_owned()),
res
);
let res = serde_json::to_string(&s).unwrap();
assert_eq!(
r#"["foobar",[["foo","i32",42],["baz","Structure",["baz",[["foo","i32",43]]]]]]"#
.to_owned(),
res
);
}
#[test]
fn test_serialize_collections() {
crate::init().unwrap();
let pretty_config = ron::ser::PrettyConfig::new().new_line("".to_string());
// Array
let value_13 = Fraction::new(1, 3);
let value_12 = Fraction::new(1, 2);
let array = Array::new([value_13, value_12]);
let res = ron::ser::to_string_pretty(&array, pretty_config.clone());
assert_eq!(
Ok(concat!(
r#"["#,
r#" ("Fraction", (1, 3)),"#,
r#" ("Fraction", (1, 2)),"#,
r#"]"#
)
.to_owned()),
res,
);
let res = serde_json::to_string(&array).unwrap();
assert_eq!(r#"[["Fraction",[1,3]],["Fraction",[1,2]]]"#.to_owned(), res);
// List
let value_12 = Fraction::new(1, 2);
let list = List::new([value_12]);
let res = ron::ser::to_string_pretty(&list, pretty_config);
assert_eq!(
Ok(concat!(r#"["#, r#" ("Fraction", (1, 2)),"#, r#"]"#).to_owned()),
res,
);
}
#[test]
fn test_deserialize_simple() {
crate::init().unwrap();
// Fraction
let fraction_ron = "(1, 3)";
let fraction: Fraction = ron::de::from_str(fraction_ron).unwrap();
assert_eq!(fraction.0.numer(), &1);
assert_eq!(fraction.0.denom(), &3);
let fraction_json = "[1,3]";
let fraction: Fraction = serde_json::from_str(fraction_json).unwrap();
assert_eq!(fraction.0.numer(), &1);
assert_eq!(fraction.0.denom(), &3);
// FractionRange
let fraction_range_ron = "(min: (1, 3), max: (1, 2))";
let fraction_range: FractionRange = ron::de::from_str(fraction_range_ron).unwrap();
assert_eq!(fraction_range.min().0.denom(), &3);
assert_eq!(fraction_range.max().0.denom(), &2);
let fraction_range_json = r#"{"min":[1,3],"max":[1,2]}"#;
let fraction_range: FractionRange = serde_json::from_str(fraction_range_json).unwrap();
assert_eq!(fraction_range.min().0.denom(), &3);
assert_eq!(fraction_range.max().0.denom(), &2);
// IntRange
let int_range_ron = "(min: 0, max: 42, step: 21)";
let int_range: IntRange<i32> = ron::de::from_str(int_range_ron).unwrap();
assert_eq!(int_range.min(), 0);
assert_eq!(int_range.max(), 42);
assert_eq!(int_range.step(), 21);
let int_range_json = r#"{"min":0,"max":42,"step":21}"#;
let int_range: IntRange<i32> = serde_json::from_str(int_range_json).unwrap();
assert_eq!(int_range.min(), 0);
assert_eq!(int_range.max(), 42);
assert_eq!(int_range.step(), 21);
// Bitmask
let bitmask_ref = Bitmask::new(1024 + 128 + 32);
let bitmask_ron = "(1184)";
let bitmask: Bitmask = ron::de::from_str(bitmask_ron).unwrap();
assert_eq!(bitmask_ref, bitmask);
let bitmask_json = "1184";
let bitmask: Bitmask = serde_json::from_str(bitmask_json).unwrap();
assert_eq!(bitmask_ref, bitmask);
// Nested structure
let s_ref = Structure::builder("foobar")
.field("foo", 42)
.field("baz", Structure::builder("baz").field("foo", 43).build())
.build();
let s_ron = r#"("foobar", [ ("foo", "i32", 42), ("baz", "Structure", ("baz", [ ("foo", "i32", 43), ])),])"#;
let s: Structure = ron::de::from_str(s_ron).unwrap();
assert_eq!(s_ref, s);
let s_json =
r#"["foobar",[["foo","i32",42],["baz","Structure",["baz",[["foo","i32",43]]]]]]"#;
let s: Structure = serde_json::from_str(s_json).unwrap();
assert_eq!(s_ref, s);
}
#[test]
fn test_serde_roundtrip_simple() {
crate::init().unwrap();
// Fraction
let fraction = Fraction::new(1, 3);
let fraction_ser = ron::ser::to_string(&fraction).unwrap();
let fraction_de: Fraction = ron::de::from_str(fraction_ser.as_str()).unwrap();
assert_eq!(fraction_de.0.numer(), fraction.0.numer());
assert_eq!(fraction_de.0.denom(), fraction.0.denom());
// FractionRange
let fraction_range = FractionRange::new(Fraction::new(1, 3), Fraction::new(1, 2));
let fraction_range_ser = ron::ser::to_string(&fraction_range).unwrap();
let fraction_range_de: FractionRange =
ron::de::from_str(fraction_range_ser.as_str()).unwrap();
assert_eq!(
fraction_range_de.min().0.denom(),
fraction_range.min().0.denom()
);
assert_eq!(
fraction_range_de.max().0.denom(),
fraction_range.max().0.denom()
);
// IntRange
let int_range = IntRange::with_step(0, 42, 21);
let int_range_ser = ron::ser::to_string(&int_range).unwrap();
let int_range_de: IntRange<i32> = ron::de::from_str(int_range_ser.as_str()).unwrap();
assert_eq!(int_range_de.min(), int_range.min());
assert_eq!(int_range_de.max(), int_range.max());
assert_eq!(int_range_de.step(), int_range.step());
// Bitmask
let bitmask = Bitmask::new(1024 + 128 + 32);
let bitmask_ser = ron::ser::to_string(&bitmask).unwrap();
let bitmask_de: Bitmask = ron::de::from_str(bitmask_ser.as_str()).unwrap();
assert_eq!(bitmask_de, bitmask);
// Nested structure
let s = Structure::builder("foobar")
.field("foo", 42)
.field("baz", Structure::builder("baz").field("foo", 43).build())
.build();
let s_ser = ron::ser::to_string(&s).unwrap();
let s_de: Structure = ron::de::from_str(s_ser.as_str()).unwrap();
assert_eq!(s_de, s);
}
#[allow(clippy::cognitive_complexity)]
#[test]
fn test_deserialize_collections() {
crate::init().unwrap();
// Array
let array_ron = r#"[
("Fraction", (1, 3)),
("Fraction", (1, 2)),
("String", Some("test str")),
("String", None),
("Date", Some(YMD(2019, 8, 19))),
("Date", None),
]"#;
let array: Array = ron::de::from_str(array_ron).unwrap();
let slice = array.as_slice();
assert_eq!(6, slice.len());
let fraction = slice[0].get::<Fraction>().expect("slice[0]");
assert_eq!(fraction.0.numer(), &1);
assert_eq!(fraction.0.denom(), &3);
let fraction = slice[1].get::<Fraction>().expect("slice[1]");
assert_eq!(fraction.0.numer(), &1);
assert_eq!(fraction.0.denom(), &2);
assert_eq!(
"test str".to_owned(),
slice[2].get::<String>().expect("slice[2]")
);
assert!(slice[3]
.get::<Option<String>>()
.expect("slice[3]")
.is_none());
assert_eq!(
Date::from_dmy(19, DateMonth::August, 2019).unwrap(),
slice[4].get::<Date>().expect("slice[4]")
);
assert!(slice[5].get::<Option<Date>>().expect("slice[5]").is_none());
let array_json = r#"[["Fraction",[1,3]],["Fraction",[1,2]],["String","test str"],["String",null],["Date",{"YMD":[2019,8,19]}],["Date",null]]"#;
let array: Array = serde_json::from_str(array_json).unwrap();
let slice = array.as_slice();
assert_eq!(6, slice.len());
let fraction = slice[0].get::<Fraction>().expect("slice[0]");
assert_eq!(fraction.0.numer(), &1);
assert_eq!(fraction.0.denom(), &3);
let fraction = slice[1].get::<Fraction>().expect("slice[1]");
assert_eq!(fraction.0.numer(), &1);
assert_eq!(fraction.0.denom(), &2);
assert_eq!(
"test str".to_owned(),
slice[2].get::<String>().expect("slice[2]")
);
assert!(slice[3]
.get::<Option<String>>()
.expect("slice[3]")
.is_none());
assert_eq!(
Date::from_dmy(19, DateMonth::August, 2019).unwrap(),
slice[4].get::<Date>().expect("slice[4]")
);
assert!(slice[5].get::<Option<Date>>().expect("slice[5]").is_none());
// List
let list_ron = r#"[
("Fraction", (1, 2)),
("String", Some("test str")),
("String", None),
("DateTime", Some(YMDhmsTz(2019, 8, 19, 13, 34, 42, 2))),
("DateTime", None),
]"#;
let list: List = ron::de::from_str(list_ron).unwrap();
let slice = list.as_slice();
assert_eq!(5, slice.len());
let fraction = slice[0].get::<Fraction>().expect("slice[0]");
assert_eq!(fraction.0.numer(), &1);
assert_eq!(fraction.0.denom(), &2);
assert_eq!(
"test str".to_owned(),
slice[1].get::<String>().expect("slice[1]")
);
assert!(slice[2]
.get::<Option<String>>()
.expect("slice[2]")
.is_none());
assert_eq!(
DateTime::new(2f32, 2019, 8, 19, 13, 34, 42f64).unwrap(),
slice[3].get::<DateTime>().expect("slice[3]")
);
assert!(slice[4]
.get::<Option<DateTime>>()
.expect("slice[4]")
.is_none());
}
#[test]
fn test_serde_roundtrip_collection() {
crate::init().unwrap();
// Array
let value_13 = Fraction::new(1, 3);
let value_12 = Fraction::new(1, 2);
let array = Array::new([value_13, value_12]);
let array_ser = ron::ser::to_string(&array).unwrap();
let array_de: Array = ron::de::from_str(array_ser.as_str()).unwrap();
let slice_de = array_de.as_slice();
let slice = array.as_slice();
assert_eq!(slice_de.len(), slice.len());
let fraction_de = slice_de[0].get::<Fraction>().expect("slice_de[0]");
let fraction = slice[0].get::<Fraction>().expect("slice[0]");
assert_eq!(fraction_de.0.numer(), fraction.0.numer());
assert_eq!(fraction_de.0.denom(), fraction.0.denom());
let fraction_de = slice_de[1].get::<Fraction>().expect("slice_de[1]");
let fraction = slice[1].get::<Fraction>().expect("slice[1]");
assert_eq!(fraction_de.0.numer(), fraction.0.numer());
assert_eq!(fraction.0.denom(), fraction.0.denom());
// List
let value_12 = Fraction::new(1, 2);
let list = List::new([value_12]);
let list_ser = ron::ser::to_string(&list).unwrap();
let list_de: List = ron::de::from_str(list_ser.as_str()).unwrap();
let slice_de = list_de.as_slice();
let slice = list.as_slice();
assert_eq!(slice_de.len(), slice.len());
let fraction_de = slice_de[0].get::<Fraction>().expect("slice_de[0]");
let fraction = slice[0].get::<Fraction>().expect("slice[0]");
assert_eq!(fraction_de.0.numer(), fraction.0.numer());
assert_eq!(fraction_de.0.denom(), fraction.0.denom());
}
}