Allows some low level storage trait to specify error type

lib/src/error.rs

@@ -2,6 +2,7 @@ use crate::model::{BlankNodeIdParseError, IriParseError, LanguageTagParseError};
 use crate::sparql::SparqlParseError;
 use rio_turtle::TurtleError;
 use rio_xml::RdfXmlError;
+use std::convert::Infallible;
 use std::error;
 use std::fmt;
 use std::io;
@@ -71,6 +72,12 @@ enum ErrorKind {
     Other(Box<dyn error::Error + Send + Sync + 'static>),
 }
 
+impl From<Infallible> for Error {
+    fn from(error: Infallible) -> Self {
+        match error {}
+    }
+}
+
 impl From<io::Error> for Error {
     fn from(error: io::Error) -> Self {
         Self {
@@ -148,3 +155,21 @@ impl From<sled::Error> for Error {
         Self::wrap(error)
     }
 }
+
+/// Traits that allows unwrapping only infallible results
+pub(crate) trait UnwrapInfallible {
+    type Value;
+
+    fn unwrap_infallible(self) -> Self::Value;
+}
+
+impl<T> UnwrapInfallible for Result<T, Infallible> {
+    type Value = T;
+
+    fn unwrap_infallible(self) -> T {
+        match self {
+            Ok(value) => value,
+            Err(error) => match error {},
+        }
+    }
+}

lib/src/sparql/eval.rs

@@ -1652,7 +1652,7 @@ impl<'a, S: ReadableEncodedStore + 'a> SimpleEvaluator<S> {
                 put_variable_value(
                     variable,
                     variables,
-                    encoder.encode_term(term)?,
+                    encoder.encode_term(term).map_err(|e| e.into())?,
                     &mut encoded_terms,
                 )
             }

lib/src/sparql/plan.rs

@@ -1,3 +1,4 @@
+use crate::error::UnwrapInfallible;
 use crate::sparql::model::Variable;
 use crate::sparql::GraphPattern;
 use crate::store::numeric_encoder::{
@@ -617,8 +618,10 @@ impl<S: ReadableEncodedStore> DatasetView<S> {
 }
 
 impl<S: ReadableEncodedStore> StrLookup for DatasetView<S> {
-    fn get_str(&self, id: StrHash) -> Result<Option<String>> {
-        if let Some(value) = self.extra.borrow().get_str(id)? {
+    type Error = S::Error;
+
+    fn get_str(&self, id: StrHash) -> std::result::Result<Option<String>, Self::Error> {
+        if let Some(value) = self.extra.borrow().get_str(id).unwrap_infallible() {
             Ok(Some(value))
         } else {
             self.store.get_str(id)
@@ -632,9 +635,12 @@ struct DatasetViewStrContainer<'a, S: ReadableEncodedStore> {
 }
 
 impl<'a, S: ReadableEncodedStore> StrContainer for DatasetViewStrContainer<'a, S> {
-    fn insert_str(&mut self, key: StrHash, value: &str) -> Result<()> {
+    type Error = S::Error;
+
+    fn insert_str(&mut self, key: StrHash, value: &str) -> std::result::Result<(), Self::Error> {
         if self.store.get_str(key)?.is_none() {
-            self.extra.insert_str(key, value)
+            self.extra.insert_str(key, value).unwrap();
+            Ok(())
         } else {
             Ok(())
         }

lib/src/sparql/plan_builder.rs

@@ -238,9 +238,9 @@ impl<E: Encoder> PlanBuilder<E> {
 
     fn build_for_path(&mut self, path: &PropertyPath) -> Result<PlanPropertyPath> {
         Ok(match path {
-            PropertyPath::PredicatePath(p) => {
-                PlanPropertyPath::PredicatePath(self.encoder.encode_named_node(p)?)
-            }
+            PropertyPath::PredicatePath(p) => PlanPropertyPath::PredicatePath(
+                self.encoder.encode_named_node(p).map_err(|e| e.into())?,
+            ),
             PropertyPath::InversePath(p) => {
                 PlanPropertyPath::InversePath(Box::new(self.build_for_path(p)?))
             }
@@ -263,7 +263,7 @@ impl<E: Encoder> PlanBuilder<E> {
             }
             PropertyPath::NegatedPropertySet(p) => PlanPropertyPath::NegatedPropertySet(
                 p.iter()
-                    .map(|p| self.encoder.encode_named_node(p))
+                    .map(|p| self.encoder.encode_named_node(p).map_err(|e| e.into()))
                     .collect::<Result<Vec<_>>>()?,
             ),
         })
@@ -276,10 +276,12 @@ impl<E: Encoder> PlanBuilder<E> {
         graph_name: PatternValue,
     ) -> Result<PlanExpression> {
         Ok(match expression {
-            Expression::NamedNode(node) => {
-                PlanExpression::Constant(self.encoder.encode_named_node(node)?)
+            Expression::NamedNode(node) => PlanExpression::Constant(
+                self.encoder.encode_named_node(node).map_err(|e| e.into())?,
+            ),
+            Expression::Literal(l) => {
+                PlanExpression::Constant(self.encoder.encode_literal(l).map_err(|e| e.into())?)
             }
-            Expression::Literal(l) => PlanExpression::Constant(self.encoder.encode_literal(l)?),
             Expression::Variable(v) => PlanExpression::Variable(variable_key(variables, v)),
             Expression::Or(a, b) => PlanExpression::Or(
                 Box::new(self.build_for_expression(a, variables, graph_name)?),
@@ -728,7 +730,9 @@ impl<E: Encoder> PlanBuilder<E> {
                 PatternValue::Variable(variable_key(variables, &Variable::new(bnode.as_str())))
                 //TODO: very bad hack to convert bnode to variable
             }
-            TermOrVariable::Term(term) => PatternValue::Constant(self.encoder.encode_term(term)?),
+            TermOrVariable::Term(term) => {
+                PatternValue::Constant(self.encoder.encode_term(term).map_err(|e| e.into())?)
+            }
         })
     }
 
@@ -738,9 +742,11 @@ impl<E: Encoder> PlanBuilder<E> {
         variables: &mut Vec<Variable>,
     ) -> Result<PatternValue> {
         Ok(match named_node_or_variable {
-            NamedNodeOrVariable::NamedNode(named_node) => {
-                PatternValue::Constant(self.encoder.encode_named_node(named_node)?)
-            }
+            NamedNodeOrVariable::NamedNode(named_node) => PatternValue::Constant(
+                self.encoder
+                    .encode_named_node(named_node)
+                    .map_err(|e| e.into())?,
+            ),
             NamedNodeOrVariable::Variable(variable) => {
                 PatternValue::Variable(variable_key(variables, variable))
             }
@@ -765,7 +771,7 @@ impl<E: Encoder> PlanBuilder<E> {
                     if let Some(term) = value {
                         result.set(
                             bindings_variables_keys[key],
-                            self.encoder.encode_term(term)?,
+                            self.encoder.encode_term(term).map_err(|e| e.into())?,
                         );
                     }
                 }
@@ -865,7 +871,7 @@ impl<E: Encoder> PlanBuilder<E> {
                 TripleTemplateValue::BlankNode(bnode_key(bnodes, bnode))
             }
             TermOrVariable::Term(term) => {
-                TripleTemplateValue::Constant(self.encoder.encode_term(term)?)
+                TripleTemplateValue::Constant(self.encoder.encode_term(term).map_err(|e| e.into())?)
             }
         })
     }
@@ -879,9 +885,9 @@ impl<E: Encoder> PlanBuilder<E> {
             NamedNodeOrVariable::Variable(variable) => {
                 TripleTemplateValue::Variable(variable_key(variables, variable))
             }
-            NamedNodeOrVariable::NamedNode(term) => {
-                TripleTemplateValue::Constant(self.encoder.encode_named_node(term)?)
-            }
+            NamedNodeOrVariable::NamedNode(term) => TripleTemplateValue::Constant(
+                self.encoder.encode_named_node(term).map_err(|e| e.into())?,
+            ),
         })
     }
 

lib/src/store/memory.rs

@@ -1,12 +1,15 @@
 //! In-memory store.
 
+use crate::error::UnwrapInfallible;
 use crate::model::*;
 use crate::sparql::{QueryOptions, QueryResult, SimplePreparedQuery};
 use crate::store::numeric_encoder::*;
 use crate::store::*;
-use crate::{DatasetSyntax, GraphSyntax, Result};
+use crate::Result;
+use crate::{DatasetSyntax, GraphSyntax};
 use std::collections::hash_map::DefaultHasher;
 use std::collections::{HashMap, HashSet};
+use std::convert::Infallible;
 use std::fmt;
 use std::hash::{BuildHasherDefault, Hash, Hasher};
 use std::io::BufRead;
@@ -75,7 +78,7 @@ impl MemoryStore {
         let mut new = Self {
             indexes: Arc::new(RwLock::default()),
         };
-        new.set_first_strings().unwrap();
+        new.set_first_strings().unwrap_infallible();
         new
     }
 
@@ -288,15 +291,15 @@ impl MemoryStore {
     #[allow(clippy::needless_pass_by_value)]
     pub fn insert(&self, quad: Quad) {
         let mut store = self;
-        let quad = store.encode_quad(&quad).unwrap(); // Could never fail
-        store.insert_encoded(&quad).unwrap(); // Could never fail
+        let quad = store.encode_quad(&quad).unwrap_infallible();
+        store.insert_encoded(&quad).unwrap_infallible();
     }
 
     /// Removes a quad from this store.
     pub fn remove(&self, quad: &Quad) {
         let mut store = self;
         let quad = quad.into();
-        store.remove_encoded(&quad).unwrap(); // Could never fail
+        store.remove_encoded(&quad).unwrap_infallible();
     }
 
     /// Returns if the current dataset is [isomorphic](https://www.w3.org/TR/rdf11-concepts/#dfn-dataset-isomorphism) with another one.
@@ -595,33 +598,43 @@ impl MemoryStore {
 }
 
 impl StrLookup for MemoryStore {
-    fn get_str(&self, id: StrHash) -> Result<Option<String>> {
+    type Error = Infallible;
+
+    fn get_str(&self, id: StrHash) -> std::result::Result<Option<String>, Infallible> {
         //TODO: avoid copy by adding a lifetime limit to get_str
         self.indexes().get_str(id)
     }
 }
 
 impl StrLookup for MemoryStoreIndexes {
-    fn get_str(&self, id: StrHash) -> Result<Option<String>> {
+    type Error = Infallible;
+
+    fn get_str(&self, id: StrHash) -> std::result::Result<Option<String>, Infallible> {
         //TODO: avoid copy by adding a lifetime limit to get_str
         Ok(self.id2str.get(&id).cloned())
     }
 }
 
 impl StrContainer for MemoryStore {
-    fn insert_str(&mut self, key: StrHash, value: &str) -> Result<()> {
+    type Error = Infallible;
+
+    fn insert_str(&mut self, key: StrHash, value: &str) -> std::result::Result<(), Infallible> {
         self.indexes_mut().insert_str(key, value)
     }
 }
 
 impl<'a> StrContainer for &'a MemoryStore {
-    fn insert_str(&mut self, key: StrHash, value: &str) -> Result<()> {
+    type Error = Infallible;
+
+    fn insert_str(&mut self, key: StrHash, value: &str) -> std::result::Result<(), Infallible> {
         self.indexes_mut().insert_str(key, value)
     }
 }
 
 impl StrContainer for MemoryStoreIndexes {
-    fn insert_str(&mut self, key: StrHash, value: &str) -> Result<()> {
+    type Error = Infallible;
+
+    fn insert_str(&mut self, key: StrHash, value: &str) -> std::result::Result<(), Infallible> {
         self.id2str.entry(key).or_insert_with(|| value.to_owned());
         Ok(())
     }
@@ -644,27 +657,33 @@ impl<'a> ReadableEncodedStore for MemoryStore {
 }
 
 impl WritableEncodedStore for MemoryStore {
-    fn insert_encoded(&mut self, quad: &EncodedQuad) -> Result<()> {
+    type Error = Infallible;
+
+    fn insert_encoded(&mut self, quad: &EncodedQuad) -> std::result::Result<(), Infallible> {
         self.indexes_mut().insert_encoded(quad)
     }
 
-    fn remove_encoded(&mut self, quad: &EncodedQuad) -> Result<()> {
+    fn remove_encoded(&mut self, quad: &EncodedQuad) -> std::result::Result<(), Infallible> {
         self.indexes_mut().remove_encoded(quad)
     }
 }
 
 impl<'a> WritableEncodedStore for &'a MemoryStore {
-    fn insert_encoded(&mut self, quad: &EncodedQuad) -> Result<()> {
+    type Error = Infallible;
+
+    fn insert_encoded(&mut self, quad: &EncodedQuad) -> std::result::Result<(), Infallible> {
         self.indexes_mut().insert_encoded(quad)
     }
 
-    fn remove_encoded(&mut self, quad: &EncodedQuad) -> Result<()> {
+    fn remove_encoded(&mut self, quad: &EncodedQuad) -> std::result::Result<(), Infallible> {
         self.indexes_mut().remove_encoded(quad)
     }
 }
 
 impl WritableEncodedStore for MemoryStoreIndexes {
-    fn insert_encoded(&mut self, quad: &EncodedQuad) -> Result<()> {
+    type Error = Infallible;
+
+    fn insert_encoded(&mut self, quad: &EncodedQuad) -> std::result::Result<(), Infallible> {
         insert_into_quad_map(
             &mut self.gosp,
             quad.graph_name,
@@ -710,7 +729,7 @@ impl WritableEncodedStore for MemoryStoreIndexes {
         Ok(())
     }
 
-    fn remove_encoded(&mut self, quad: &EncodedQuad) -> Result<()> {
+    fn remove_encoded(&mut self, quad: &EncodedQuad) -> std::result::Result<(), Infallible> {
         remove_from_quad_map(
             &mut self.gosp,
             &quad.graph_name,
@@ -921,14 +940,14 @@ impl<'a> MemoryTransaction<'a> {
     /// Adds a quad to this store during the transaction.
     #[allow(clippy::needless_pass_by_value)]
     pub fn insert(&mut self, quad: Quad) {
-        let quad = self.encode_quad(&quad).unwrap(); // Could never fail
-        self.insert_encoded(&quad).unwrap(); // Could never fail
+        let quad = self.encode_quad(&quad).unwrap_infallible();
+        self.insert_encoded(&quad).unwrap_infallible();
     }
 
     /// Removes a quad from this store during the transaction.
     pub fn remove(&mut self, quad: &Quad) {
         let quad = quad.into();
-        self.remove_encoded(&quad).unwrap(); // Could never fail
+        self.remove_encoded(&quad).unwrap_infallible();
     }
 
     fn commit(self) -> Result<()> {
@@ -945,19 +964,23 @@ impl<'a> MemoryTransaction<'a> {
 }
 
 impl StrContainer for MemoryTransaction<'_> {
-    fn insert_str(&mut self, key: StrHash, value: &str) -> Result<()> {
+    type Error = Infallible;
+
+    fn insert_str(&mut self, key: StrHash, value: &str) -> std::result::Result<(), Infallible> {
         self.strings.push((key, value.to_owned()));
         Ok(())
     }
 }
 
 impl WritableEncodedStore for MemoryTransaction<'_> {
-    fn insert_encoded(&mut self, quad: &EncodedQuad) -> Result<()> {
+    type Error = Infallible;
+
+    fn insert_encoded(&mut self, quad: &EncodedQuad) -> std::result::Result<(), Infallible> {
         self.ops.push(TransactionOp::Insert(*quad));
         Ok(())
     }
 
-    fn remove_encoded(&mut self, quad: &EncodedQuad) -> Result<()> {
+    fn remove_encoded(&mut self, quad: &EncodedQuad) -> std::result::Result<(), Infallible> {
         self.ops.push(TransactionOp::Delete(*quad));
         Ok(())
     }

lib/src/store/mod.rs

@@ -38,9 +38,17 @@ pub(crate) trait ReadableEncodedStore: StrLookup {
 }
 
 pub(crate) trait WritableEncodedStore: StrContainer {
-    fn insert_encoded(&mut self, quad: &EncodedQuad) -> Result<()>;
+    type Error: From<<Self as StrContainer>::Error> + std::error::Error + Into<Error>;
 
-    fn remove_encoded(&mut self, quad: &EncodedQuad) -> Result<()>;
+    fn insert_encoded(
+        &mut self,
+        quad: &EncodedQuad,
+    ) -> std::result::Result<(), <Self as WritableEncodedStore>::Error>;
+
+    fn remove_encoded(
+        &mut self,
+        quad: &EncodedQuad,
+    ) -> std::result::Result<(), <Self as WritableEncodedStore>::Error>;
 }
 
 fn load_graph<S: WritableEncodedStore>(
@@ -73,10 +81,14 @@ where
     Error: From<P::Error>,
 {
     let mut bnode_map = HashMap::default();
-    let to_graph_name = store.encode_graph_name(to_graph_name)?;
+    let to_graph_name = store
+        .encode_graph_name(to_graph_name)
+        .map_err(|e| e.into())?;
     parser.parse_all(&mut move |t| {
-        let quad = store.encode_rio_triple_in_graph(t, to_graph_name, &mut bnode_map)?;
-        store.insert_encoded(&quad)
+        let quad = store
+            .encode_rio_triple_in_graph(t, to_graph_name, &mut bnode_map)
+            .map_err(|e| e.into())?;
+        store.insert_encoded(&quad).map_err(|e| e.into())
     })
 }
 
@@ -102,7 +114,9 @@ where
 {
     let mut bnode_map = HashMap::default();
     parser.parse_all(&mut move |q| {
-        let quad = store.encode_rio_quad(q, &mut bnode_map)?;
-        store.insert_encoded(&quad)
+        let quad = store
+            .encode_rio_quad(q, &mut bnode_map)
+            .map_err(|e| e.into())?;
+        store.insert_encoded(&quad).map_err(|e| e.into())
     })
 }

lib/src/store/numeric_encoder.rs

@@ -1,15 +1,17 @@
 #![allow(clippy::unreadable_literal)]
 
+use crate::error::UnwrapInfallible;
 use crate::model::vocab::rdf;
 use crate::model::vocab::xsd;
 use crate::model::xsd::*;
 use crate::model::*;
-use crate::Error;
-use crate::Result;
+use crate::{Error as OxError, Result as OxResult};
 use rand::random;
 use rio_api::model as rio;
 use siphasher::sip128::{Hasher128, SipHasher24};
 use std::collections::HashMap;
+use std::convert::Infallible;
+use std::error::Error;
 use std::hash::Hash;
 use std::hash::Hasher;
 use std::io::{Cursor, Error as IoError, ErrorKind, Read, Result as IoResult};
@@ -923,14 +925,18 @@ impl QuadEncoding {
 }
 
 pub trait StrLookup {
-    fn get_str(&self, id: StrHash) -> Result<Option<String>>;
+    type Error: Error + Into<OxError>;
+
+    fn get_str(&self, id: StrHash) -> Result<Option<String>, Self::Error>;
 }
 
 pub trait StrContainer {
-    fn insert_str(&mut self, key: StrHash, value: &str) -> Result<()>;
+    type Error: Error + Into<OxError>;
+
+    fn insert_str(&mut self, key: StrHash, value: &str) -> Result<(), Self::Error>;
 
     /// Should be called when the bytes store is created
-    fn set_first_strings(&mut self) -> Result<()> {
+    fn set_first_strings(&mut self) -> Result<(), Self::Error> {
         self.insert_str(EMPTY_STRING_ID, "")?;
         self.insert_str(RDF_LANG_STRING_ID, rdf::LANG_STRING.as_str())?;
         self.insert_str(XSD_STRING_ID, xsd::STRING.as_str())?;
@@ -961,44 +967,53 @@ impl Default for MemoryStrStore {
         let mut new = Self {
             id2str: HashMap::default(),
         };
-        new.set_first_strings().unwrap();
+        new.set_first_strings().unwrap_infallible();
         new
     }
 }
 
 impl StrLookup for MemoryStrStore {
-    fn get_str(&self, id: StrHash) -> Result<Option<String>> {
+    type Error = Infallible;
+
+    fn get_str(&self, id: StrHash) -> Result<Option<String>, Infallible> {
         //TODO: avoid copy by adding a lifetime limit to get_str
         Ok(self.id2str.get(&id).cloned())
     }
 }
 
 impl StrContainer for MemoryStrStore {
-    fn insert_str(&mut self, key: StrHash, value: &str) -> Result<()> {
+    type Error = Infallible;
+
+    fn insert_str(&mut self, key: StrHash, value: &str) -> Result<(), Infallible> {
         self.id2str.entry(key).or_insert_with(|| value.to_owned());
         Ok(())
     }
 }
 
 pub trait Encoder {
-    fn encode_named_node(&mut self, named_node: &NamedNode) -> Result<EncodedTerm> {
+    type Error: Error + Into<OxError>;
+
+    fn encode_named_node(&mut self, named_node: &NamedNode) -> Result<EncodedTerm, Self::Error> {
         self.encode_rio_named_node(named_node.into())
     }
 
-    fn encode_blank_node(&mut self, blank_node: &BlankNode) -> Result<EncodedTerm>;
+    fn encode_blank_node(&mut self, blank_node: &BlankNode) -> Result<EncodedTerm, Self::Error>;
 
-    fn encode_literal(&mut self, literal: &Literal) -> Result<EncodedTerm> {
+    fn encode_literal(&mut self, literal: &Literal) -> Result<EncodedTerm, Self::Error> {
         self.encode_rio_literal(literal.into())
     }
 
-    fn encode_named_or_blank_node(&mut self, term: &NamedOrBlankNode) -> Result<EncodedTerm> {
+    fn encode_named_or_blank_node(
+        &mut self,
+        term: &NamedOrBlankNode,
+    ) -> Result<EncodedTerm, Self::Error> {
         match term {
             NamedOrBlankNode::NamedNode(named_node) => self.encode_named_node(named_node),
             NamedOrBlankNode::BlankNode(blank_node) => self.encode_blank_node(blank_node),
         }
     }
 
-    fn encode_term(&mut self, term: &Term) -> Result<EncodedTerm> {
+    fn encode_term(&mut self, term: &Term) -> Result<EncodedTerm, Self::Error> {
         match term {
             Term::NamedNode(named_node) => self.encode_named_node(named_node),
             Term::BlankNode(blank_node) => self.encode_blank_node(blank_node),
@@ -1006,7 +1021,7 @@ pub trait Encoder {
         }
     }
 
-    fn encode_graph_name(&mut self, name: &GraphName) -> Result<EncodedTerm> {
+    fn encode_graph_name(&mut self, name: &GraphName) -> Result<EncodedTerm, Self::Error> {
         match name {
             GraphName::NamedNode(named_node) => self.encode_named_node(named_node),
             GraphName::BlankNode(blank_node) => self.encode_blank_node(blank_node),
@@ -1014,7 +1029,7 @@ pub trait Encoder {
         }
     }
 
-    fn encode_quad(&mut self, quad: &Quad) -> Result<EncodedQuad> {
+    fn encode_quad(&mut self, quad: &Quad) -> Result<EncodedQuad, Self::Error> {
         Ok(EncodedQuad {
             subject: self.encode_named_or_blank_node(&quad.subject)?,
             predicate: self.encode_named_node(&quad.predicate)?,
@@ -1027,7 +1042,7 @@ pub trait Encoder {
         &mut self,
         triple: &Triple,
         graph_name: EncodedTerm,
-    ) -> Result<EncodedQuad> {
+    ) -> Result<EncodedQuad, Self::Error> {
         Ok(EncodedQuad {
             subject: self.encode_named_or_blank_node(&triple.subject)?,
             predicate: self.encode_named_node(&triple.predicate)?,
@@ -1036,21 +1051,25 @@ pub trait Encoder {
         })
     }
 
-    fn encode_rio_named_node(&mut self, named_node: rio::NamedNode<'_>) -> Result<EncodedTerm>;
+    fn encode_rio_named_node(
+        &mut self,
+        named_node: rio::NamedNode<'_>,
+    ) -> Result<EncodedTerm, Self::Error>;
 
     fn encode_rio_blank_node(
         &mut self,
         blank_node: rio::BlankNode<'_>,
         bnodes_map: &mut HashMap<String, u128>,
-    ) -> Result<EncodedTerm>;
+    ) -> Result<EncodedTerm, Self::Error>;
 
-    fn encode_rio_literal(&mut self, literal: rio::Literal<'_>) -> Result<EncodedTerm>;
+    fn encode_rio_literal(&mut self, literal: rio::Literal<'_>)
+        -> Result<EncodedTerm, Self::Error>;
 
     fn encode_rio_named_or_blank_node(
         &mut self,
         term: rio::NamedOrBlankNode<'_>,
         bnodes_map: &mut HashMap<String, u128>,
-    ) -> Result<EncodedTerm> {
+    ) -> Result<EncodedTerm, Self::Error> {
         match term {
             rio::NamedOrBlankNode::NamedNode(named_node) => self.encode_rio_named_node(named_node),
             rio::NamedOrBlankNode::BlankNode(blank_node) => {
@@ -1063,7 +1082,7 @@ pub trait Encoder {
         &mut self,
         term: rio::Term<'_>,
         bnodes_map: &mut HashMap<String, u128>,
-    ) -> Result<EncodedTerm> {
+    ) -> Result<EncodedTerm, Self::Error> {
         match term {
             rio::Term::NamedNode(named_node) => self.encode_rio_named_node(named_node),
             rio::Term::BlankNode(blank_node) => self.encode_rio_blank_node(blank_node, bnodes_map),
@@ -1075,7 +1094,7 @@ pub trait Encoder {
         &mut self,
         quad: rio::Quad<'_>,
         bnodes_map: &mut HashMap<String, u128>,
-    ) -> Result<EncodedQuad> {
+    ) -> Result<EncodedQuad, Self::Error> {
         Ok(EncodedQuad {
             subject: self.encode_rio_named_or_blank_node(quad.subject, bnodes_map)?,
             predicate: self.encode_rio_named_node(quad.predicate)?,
@@ -1092,7 +1111,7 @@ pub trait Encoder {
         triple: rio::Triple<'_>,
         graph_name: EncodedTerm,
         bnodes_map: &mut HashMap<String, u128>,
-    ) -> Result<EncodedQuad> {
+    ) -> Result<EncodedQuad, Self::Error> {
         Ok(EncodedQuad {
             subject: self.encode_rio_named_or_blank_node(triple.subject, bnodes_map)?,
             predicate: self.encode_rio_named_node(triple.predicate)?,
@@ -1103,13 +1122,18 @@ pub trait Encoder {
 }
 
 impl<S: StrContainer> Encoder for S {
-    fn encode_rio_named_node(&mut self, named_node: rio::NamedNode<'_>) -> Result<EncodedTerm> {
+    type Error = S::Error;
+
+    fn encode_rio_named_node(
+        &mut self,
+        named_node: rio::NamedNode<'_>,
+    ) -> Result<EncodedTerm, Self::Error> {
         let iri_id = StrHash::new(named_node.iri);
         self.insert_str(iri_id, named_node.iri)?;
         Ok(EncodedTerm::NamedNode { iri_id })
     }
 
-    fn encode_blank_node(&mut self, blank_node: &BlankNode) -> Result<EncodedTerm> {
+    fn encode_blank_node(&mut self, blank_node: &BlankNode) -> Result<EncodedTerm, Self::Error> {
         if let Some(id) = blank_node.id() {
             Ok(EncodedTerm::InlineBlankNode { id })
         } else {
@@ -1124,7 +1148,7 @@ impl<S: StrContainer> Encoder for S {
         &mut self,
         blank_node: rio::BlankNode<'_>,
         bnodes_map: &mut HashMap<String, u128>,
-    ) -> Result<EncodedTerm> {
+    ) -> Result<EncodedTerm, Self::Error> {
         Ok(if let Some(id) = bnodes_map.get(blank_node.id) {
             EncodedTerm::InlineBlankNode { id: *id }
         } else {
@@ -1134,7 +1158,10 @@ impl<S: StrContainer> Encoder for S {
         })
     }
 
-    fn encode_rio_literal(&mut self, literal: rio::Literal<'_>) -> Result<EncodedTerm> {
+    fn encode_rio_literal(
+        &mut self,
+        literal: rio::Literal<'_>,
+    ) -> Result<EncodedTerm, Self::Error> {
         Ok(match literal {
             rio::Literal::Simple { value } => {
                 let value_id = StrHash::new(value);
@@ -1261,31 +1288,31 @@ pub fn parse_day_time_duration_str(value: &str) -> Option<EncodedTerm> {
 }
 
 pub trait Decoder {
-    fn decode_term(&self, encoded: EncodedTerm) -> Result<Term>;
+    fn decode_term(&self, encoded: EncodedTerm) -> OxResult<Term>;
 
-    fn decode_named_or_blank_node(&self, encoded: EncodedTerm) -> Result<NamedOrBlankNode> {
+    fn decode_named_or_blank_node(&self, encoded: EncodedTerm) -> OxResult<NamedOrBlankNode> {
         match self.decode_term(encoded)? {
             Term::NamedNode(named_node) => Ok(named_node.into()),
             Term::BlankNode(blank_node) => Ok(blank_node.into()),
-            Term::Literal(_) => Err(Error::msg(
+            Term::Literal(_) => Err(OxError::msg(
                 "A literal has ben found instead of a named node",
             )),
         }
     }
 
-    fn decode_named_node(&self, encoded: EncodedTerm) -> Result<NamedNode> {
+    fn decode_named_node(&self, encoded: EncodedTerm) -> OxResult<NamedNode> {
         match self.decode_term(encoded)? {
             Term::NamedNode(named_node) => Ok(named_node),
-            Term::BlankNode(_) => Err(Error::msg(
+            Term::BlankNode(_) => Err(OxError::msg(
                 "A blank node has been found instead of a named node",
             )),
-            Term::Literal(_) => Err(Error::msg(
+            Term::Literal(_) => Err(OxError::msg(
                 "A literal has ben found instead of a named node",
             )),
         }
     }
 
-    fn decode_triple(&self, encoded: &EncodedQuad) -> Result<Triple> {
+    fn decode_triple(&self, encoded: &EncodedQuad) -> OxResult<Triple> {
         Ok(Triple::new(
             self.decode_named_or_blank_node(encoded.subject)?,
             self.decode_named_node(encoded.predicate)?,
@@ -1293,7 +1320,7 @@ pub trait Decoder {
         ))
     }
 
-    fn decode_quad(&self, encoded: &EncodedQuad) -> Result<Quad> {
+    fn decode_quad(&self, encoded: &EncodedQuad) -> OxResult<Quad> {
         Ok(Quad::new(
             self.decode_named_or_blank_node(encoded.subject)?,
             self.decode_named_node(encoded.predicate)?,
@@ -1307,10 +1334,10 @@ pub trait Decoder {
 }
 
 impl<S: StrLookup> Decoder for S {
-    fn decode_term(&self, encoded: EncodedTerm) -> Result<Term> {
+    fn decode_term(&self, encoded: EncodedTerm) -> OxResult<Term> {
         match encoded {
             EncodedTerm::DefaultGraph => {
-                Err(Error::msg("The default graph tag is not a valid term"))
+                Err(OxError::msg("The default graph tag is not a valid term"))
             }
             EncodedTerm::NamedNode { iri_id } => {
                 Ok(NamedNode::new_unchecked(get_required_str(self, iri_id)?).into())
@@ -1353,9 +1380,9 @@ impl<S: StrLookup> Decoder for S {
     }
 }
 
-fn get_required_str(lookup: &impl StrLookup, id: StrHash) -> Result<String> {
-    lookup.get_str(id)?.ok_or_else(|| {
-        Error::msg(format!(
+fn get_required_str(lookup: &impl StrLookup, id: StrHash) -> OxResult<String> {
+    lookup.get_str(id).map_err(|e| e.into())?.ok_or_else(|| {
+        OxError::msg(format!(
             "Not able to find the string with id {:?} in the string store",
             id
         ))

lib/src/store/rocksdb.rs

@@ -260,6 +260,8 @@ impl fmt::Display for RocksDbStore {
 }
 
 impl StrLookup for RocksDbStore {
+    type Error = crate::Error;
+
     fn get_str(&self, id: StrHash) -> Result<Option<String>> {
         Ok(self
             .db
@@ -534,6 +536,8 @@ pub struct RocksDbTransaction<'a> {
 }
 
 impl StrContainer for RocksDbTransaction<'_> {
+    type Error = crate::Error;
+
     fn insert_str(&mut self, key: StrHash, value: &str) -> Result<()> {
         self.inner.insert_str(key, value);
         Ok(())
@@ -541,6 +545,8 @@ impl StrContainer for RocksDbTransaction<'_> {
 }
 
 impl WritableEncodedStore for RocksDbTransaction<'_> {
+    type Error = crate::Error;
+
     fn insert_encoded(&mut self, quad: &EncodedQuad) -> Result<()> {
         self.inner.insert(quad)
     }
@@ -606,6 +612,8 @@ struct RocksDbAutoTransaction<'a> {
 }
 
 impl StrContainer for RocksDbAutoTransaction<'_> {
+    type Error = crate::Error;
+
     fn insert_str(&mut self, key: StrHash, value: &str) -> Result<()> {
         self.inner.insert_str(key, value);
         Ok(())
@@ -613,6 +621,8 @@ impl StrContainer for RocksDbAutoTransaction<'_> {
 }
 
 impl WritableEncodedStore for RocksDbAutoTransaction<'_> {
+    type Error = crate::Error;
+
     fn insert_encoded(&mut self, quad: &EncodedQuad) -> Result<()> {
         self.inner.insert(quad)?;
         self.commit_if_big()

lib/src/store/sled.rs

@@ -414,6 +414,8 @@ impl fmt::Display for SledStore {
 }
 
 impl StrLookup for SledStore {
+    type Error = Error;
+
     fn get_str(&self, id: StrHash) -> Result<Option<String>> {
         Ok(self
             .id2str
@@ -436,6 +438,8 @@ impl ReadableEncodedStore for SledStore {
 }
 
 impl<'a> StrContainer for &'a SledStore {
+    type Error = Error;
+
     fn insert_str(&mut self, key: StrHash, value: &str) -> Result<()> {
         self.id2str.insert(key.to_be_bytes(), value)?;
         Ok(())
@@ -443,6 +447,8 @@ impl<'a> StrContainer for &'a SledStore {
 }
 
 impl<'a> WritableEncodedStore for &'a SledStore {
+    type Error = Error;
+
     fn insert_encoded(&mut self, quad: &EncodedQuad) -> Result<()> {
         //TODO: atomicity
         let mut buffer = Vec::with_capacity(4 * WRITTEN_TERM_MAX_SIZE);