RUST-1406 Convert serde errors to standard error type (#562)

Author: isabelatkinson

src/bson.rs

@@ -911,6 +911,36 @@ impl Bson {
                 .collect(),
         )
     }
+
+    /// Method for converting a given [`Bson`] value to a [`serde::de::Unexpected`] for error
+    /// reporting.
+    #[cfg(feature = "serde")]
+    pub(crate) fn as_unexpected(&self) -> serde::de::Unexpected {
+        use serde::de::Unexpected;
+        match self {
+            Bson::Array(_) => Unexpected::Seq,
+            Bson::Binary(b) => Unexpected::Bytes(b.bytes.as_slice()),
+            Bson::Boolean(b) => Unexpected::Bool(*b),
+            Bson::DbPointer(_) => Unexpected::Other("dbpointer"),
+            Bson::Document(_) => Unexpected::Map,
+            Bson::Double(f) => Unexpected::Float(*f),
+            Bson::Int32(i) => Unexpected::Signed(*i as i64),
+            Bson::Int64(i) => Unexpected::Signed(*i),
+            Bson::JavaScriptCode(_) => Unexpected::Other("javascript code"),
+            Bson::JavaScriptCodeWithScope(_) => Unexpected::Other("javascript code with scope"),
+            Bson::MaxKey => Unexpected::Other("maxkey"),
+            Bson::MinKey => Unexpected::Other("minkey"),
+            Bson::Null => Unexpected::Unit,
+            Bson::Undefined => Unexpected::Other("undefined"),
+            Bson::ObjectId(_) => Unexpected::Other("objectid"),
+            Bson::RegularExpression(_) => Unexpected::Other("regex"),
+            Bson::String(s) => Unexpected::Str(s.as_str()),
+            Bson::Symbol(_) => Unexpected::Other("symbol"),
+            Bson::Timestamp(_) => Unexpected::Other("timestamp"),
+            Bson::DateTime(_) => Unexpected::Other("datetime"),
+            Bson::Decimal128(_) => Unexpected::Other("decimal128"),
+        }
+    }
 }
 
 /// Value helpers

src/datetime.rs

@@ -70,7 +70,7 @@ use crate::error::{Error, Result};
 ///     chrono_datetime: chrono::DateTime<chrono::Utc>,
 /// }
 ///
-/// # fn main() -> bson::ser::Result<()> {
+/// # fn main() -> bson::error::Result<()> {
 /// let f = Foo { date_time: bson::DateTime::now(), chrono_datetime: chrono::Utc::now() };
 /// println!("{:?}", bson::serialize_to_document(&f)?);
 /// # Ok(())

src/de.rs

@@ -21,19 +21,16 @@
 
 //! Deserializer
 
-mod error;
 mod raw;
 mod serde;
 
-pub use self::{
-    error::{Error, Result},
-    serde::Deserializer,
-};
+pub use self::serde::Deserializer;
 
 use std::io::Read;
 
 use crate::{
     bson::{Bson, Document},
+    error::{Error, Result},
     raw::reader_to_vec,
     spec::BinarySubtype,
 };

src/de/error.rs

@@ -61,7 +61,7 @@ impl<'de> Deserializer<'de> {
     }
 
     fn value(&self) -> Result<RawBsonRef<'de>> {
-        Ok(self.element.value()?)
+        self.element.value()
     }
 
     /// Deserialize the element, using the type of the element along with the
@@ -419,7 +419,7 @@ impl<'de> serde::de::EnumAccess<'de> for DocumentAccess<'de> {
         self.advance()?;
         let elem = match &self.elem {
             Some(e) => e,
-            None => return Err(Error::EndOfStream),
+            None => return Err(Error::end_of_stream()),
         };
         let de: BorrowedStrDeserializer<'_, Error> = BorrowedStrDeserializer::new(elem.key());
         let key = seed.deserialize(de)?;
@@ -1077,7 +1077,7 @@ impl<'de> serde::de::MapAccess<'de> for CodeWithScopeAccess<'de> {
         self.stage = match self.stage {
             CodeWithScopeDeserializationStage::Code => CodeWithScopeDeserializationStage::Scope,
             CodeWithScopeDeserializationStage::Scope => CodeWithScopeDeserializationStage::Done,
-            CodeWithScopeDeserializationStage::Done => return Err(Error::EndOfStream),
+            CodeWithScopeDeserializationStage::Done => return Err(Error::end_of_stream()),
         };
         Ok(value)
     }
@@ -1105,7 +1105,7 @@ impl<'de> serde::de::Deserializer<'de> for &CodeWithScopeAccess<'de> {
                     _ => visitor.visit_map(DocumentAccess::new(scope, self.options.clone())?),
                 }
             }
-            CodeWithScopeDeserializationStage::Done => Err(Error::EndOfStream),
+            CodeWithScopeDeserializationStage::Done => Err(Error::end_of_stream()),
         }
     }