serde: Move string-related helpers into a new module

ruma-serde/src/lib.rs

@@ -1,15 +1,5 @@
 //! De-/serialization helpers for other ruma crates
 
-use js_int::Int;
-use serde::{
-    de::{Error, IntoDeserializer},
-    Deserialize,
-};
-use std::{
-    collections::BTreeMap,
-    convert::{TryFrom, TryInto},
-};
-
 pub mod can_be_empty;
 mod canonical_json;
 mod cow;
@@ -17,6 +7,7 @@ pub mod duration;
 pub mod empty;
 pub mod json_string;
 pub mod single_element_seq;
+mod strings;
 pub mod test;
 pub mod time;
 pub mod urlencoded;
@@ -29,6 +20,9 @@ pub use canonical_json::{
 };
 pub use cow::deserialize_cow_str;
 pub use empty::vec_as_map_of_empty;
+pub use strings::{
+    btreemap_int_or_string_to_int_values, empty_string_as_none, int_or_string_to_int,
+};
 
 /// Check whether a value is equal to its default value.
 pub fn is_default<T: Default + PartialEq>(val: &T) -> bool {
@@ -49,73 +43,3 @@ pub fn default_true() -> bool {
 pub fn is_true(b: &bool) -> bool {
     *b
 }
-
-/// Serde deserialization decorator to map empty Strings to None,
-/// and forward non-empty Strings to the Deserialize implementation for T.
-/// Useful for the typical
-/// "A room with an X event with an absent, null, or empty Y field
-/// should be treated the same as a room with no such event."
-/// formulation in the spec.
-///
-/// To be used like this:
-/// `#[serde(deserialize_with = "empty_string_as_none")]`
-/// Relevant serde issue: <https://github.com/serde-rs/serde/issues/1425>
-pub fn empty_string_as_none<'de, D, T>(de: D) -> Result<Option<T>, D::Error>
-where
-    D: serde::Deserializer<'de>,
-    T: serde::Deserialize<'de>,
-{
-    let opt = Option::<String>::deserialize(de)?;
-    match opt.as_deref() {
-        None | Some("") => Ok(None),
-        // If T = String, like in m.room.name, the second deserialize is actually superfluous.
-        // TODO: optimize that somehow?
-        Some(s) => T::deserialize(s.into_deserializer()).map(Some),
-    }
-}
-
-// Helper type for deserialize_int_or_string_to_int
-#[derive(Deserialize)]
-#[serde(untagged)]
-enum IntOrString<'a> {
-    Num(Int),
-    Str(&'a str),
-}
-
-impl TryFrom<IntOrString<'_>> for Int {
-    type Error = js_int::ParseIntError;
-
-    fn try_from(input: IntOrString) -> Result<Self, Self::Error> {
-        match input {
-            IntOrString::Num(n) => Ok(n),
-            IntOrString::Str(string) => string.parse(),
-        }
-    }
-}
-
-/// Take either an integer number or a string and deserialize to an integer number.
-///
-/// To be used like this:
-/// `#[serde(deserialize_with = "int_or_string_to_int")]`
-pub fn int_or_string_to_int<'de, D>(de: D) -> Result<Int, D::Error>
-where
-    D: serde::Deserializer<'de>,
-{
-    IntOrString::deserialize(de)?.try_into().map_err(D::Error::custom)
-}
-
-/// Take a BTreeMap with values of either an integer number or a string and deserialize
-/// those to integer numbers.
-///
-/// To be used like this:
-/// `#[serde(deserialize_with = "btreemap_int_or_string_to_int_values")]`
-pub fn btreemap_int_or_string_to_int_values<'de, D, T>(de: D) -> Result<BTreeMap<T, Int>, D::Error>
-where
-    D: serde::Deserializer<'de>,
-    T: serde::Deserialize<'de> + Ord,
-{
-    BTreeMap::<T, IntOrString>::deserialize(de)?
-        .into_iter()
-        .map(|(k, v)| v.try_into().map(|n| (k, n)).map_err(D::Error::custom))
-        .collect()
-}

ruma-serde/src/strings.rs

@@ -0,0 +1,80 @@
+use std::{
+    collections::BTreeMap,
+    convert::{TryFrom, TryInto},
+};
+
+use js_int::Int;
+use serde::{
+    de::{Deserializer, Error as _, IntoDeserializer as _},
+    Deserialize,
+};
+
+/// Serde deserialization decorator to map empty Strings to None,
+/// and forward non-empty Strings to the Deserialize implementation for T.
+/// Useful for the typical
+/// "A room with an X event with an absent, null, or empty Y field
+/// should be treated the same as a room with no such event."
+/// formulation in the spec.
+///
+/// To be used like this:
+/// `#[serde(deserialize_with = "empty_string_as_none")]`
+/// Relevant serde issue: <https://github.com/serde-rs/serde/issues/1425>
+pub fn empty_string_as_none<'de, D, T>(de: D) -> Result<Option<T>, D::Error>
+where
+    D: Deserializer<'de>,
+    T: Deserialize<'de>,
+{
+    let opt = Option::<String>::deserialize(de)?;
+    match opt.as_deref() {
+        None | Some("") => Ok(None),
+        // If T = String, like in m.room.name, the second deserialize is actually superfluous.
+        // TODO: optimize that somehow?
+        Some(s) => T::deserialize(s.into_deserializer()).map(Some),
+    }
+}
+
+// Helper type for deserialize_int_or_string_to_int
+#[derive(Deserialize)]
+#[serde(untagged)]
+enum IntOrString<'a> {
+    Num(Int),
+    Str(&'a str),
+}
+
+impl TryFrom<IntOrString<'_>> for Int {
+    type Error = js_int::ParseIntError;
+
+    fn try_from(input: IntOrString) -> Result<Self, Self::Error> {
+        match input {
+            IntOrString::Num(n) => Ok(n),
+            IntOrString::Str(string) => string.parse(),
+        }
+    }
+}
+
+/// Take either an integer number or a string and deserialize to an integer number.
+///
+/// To be used like this:
+/// `#[serde(deserialize_with = "int_or_string_to_int")]`
+pub fn int_or_string_to_int<'de, D>(de: D) -> Result<Int, D::Error>
+where
+    D: Deserializer<'de>,
+{
+    IntOrString::deserialize(de)?.try_into().map_err(D::Error::custom)
+}
+
+/// Take a BTreeMap with values of either an integer number or a string and deserialize
+/// those to integer numbers.
+///
+/// To be used like this:
+/// `#[serde(deserialize_with = "btreemap_int_or_string_to_int_values")]`
+pub fn btreemap_int_or_string_to_int_values<'de, D, T>(de: D) -> Result<BTreeMap<T, Int>, D::Error>
+where
+    D: Deserializer<'de>,
+    T: Deserialize<'de> + Ord,
+{
+    BTreeMap::<T, IntOrString>::deserialize(de)?
+        .into_iter()
+        .map(|(k, v)| v.try_into().map(|n| (k, n)).map_err(D::Error::custom))
+        .collect()
+}