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use std::fmt;
use serde::{Serialize, Serializer, Deserialize, Deserializer};
use serde::de::{Visitor, SeqAccess, MapAccess, DeserializeOwned};
use serde_json;
use serde_json::value::from_value;
use super::{Value, Error};
#[derive(Debug, PartialEq, Clone)]
pub enum Params {
Array(Vec<Value>),
Map(serde_json::Map<String, Value>),
None
}
impl Params {
pub fn parse<D>(self) -> Result<D, Error> where D: DeserializeOwned {
let value = match self {
Params::Array(vec) => Value::Array(vec),
Params::Map(map) => Value::Object(map),
Params::None => Value::Null
};
from_value(value).map_err(|e| {
Error::invalid_params(format!("Invalid params: {}.", e))
})
}
}
impl Serialize for Params {
fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
where S: Serializer {
match *self {
Params::Array(ref vec) => vec.serialize(serializer),
Params::Map(ref map) => map.serialize(serializer),
Params::None => ([0u8; 0]).serialize(serializer)
}
}
}
struct ParamsVisitor;
impl<'a> Deserialize<'a> for Params {
fn deserialize<D>(deserializer: D) -> Result<Params, D::Error>
where D: Deserializer<'a> {
deserializer.deserialize_identifier(ParamsVisitor)
}
}
impl<'a> Visitor<'a> for ParamsVisitor {
type Value = Params;
fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
formatter.write_str("a map or sequence")
}
fn visit_seq<V>(self, mut visitor: V) -> Result<Self::Value, V::Error>
where V: SeqAccess<'a> {
let mut values = Vec::new();
while let Some(value) = visitor.next_element()? {
values.push(value);
}
if values.is_empty() {
Ok(Params::None)
} else {
Ok(Params::Array(values))
}
}
fn visit_map<V>(self, mut visitor: V) -> Result<Self::Value, V::Error>
where V: MapAccess<'a> {
let mut values = serde_json::Map::new();
while let Some((key, value)) = visitor.next_entry()? {
values.insert(key, value);
}
Ok(if values.is_empty() { Params::None } else { Params::Map(values) })
}
}
#[cfg(test)]
mod tests {
use serde_json;
use super::Params;
use types::{Value, Error, ErrorCode};
#[test]
fn params_deserialization() {
let s = r#"[null, true, -1, 4, 2.3, "hello", [0], {"key": "value"}]"#;
let deserialized: Params = serde_json::from_str(s).unwrap();
let mut map = serde_json::Map::new();
map.insert("key".to_string(), Value::String("value".to_string()));
assert_eq!(Params::Array(vec![
Value::Null, Value::Bool(true), Value::from(-1), Value::from(4),
Value::from(2.3), Value::String("hello".to_string()),
Value::Array(vec![Value::from(0)]), Value::Object(map)]), deserialized);
}
#[test]
fn should_return_meaningful_error_when_deserialization_fails() {
let s = r#"[1, true]"#;
let params = || serde_json::from_str::<Params>(s).unwrap();
let v1: Result<(Option<u8>, String), Error> = params().parse();
let v2: Result<(u8, bool, String), Error> = params().parse();
let err1 = v1.unwrap_err();
let err2 = v2.unwrap_err();
assert_eq!(err1.code, ErrorCode::InvalidParams);
assert_eq!(err1.message, "Invalid params: invalid type: boolean `true`, expected a string.");
assert_eq!(err1.data, None);
assert_eq!(err2.code, ErrorCode::InvalidParams);
assert_eq!(err2.message, "Invalid params: invalid length 2, expected a tuple of size 3.");
assert_eq!(err2.data, None);
}
}