Adds beggining of SPARQL FILTER evaluation

src/model/literal.rs

@@ -119,6 +119,34 @@ impl Literal {
             _ => false,
         }
     }
+
+    /// Checks if the literal has the datatype [xsd:string](http://www.w3.org/2001/XMLSchema#string) and is valid
+    pub fn is_string(&self) -> bool {
+        match self.0 {
+            LiteralContent::String(_) => true,
+            _ => false,
+        }
+    }
+
+    /// Checks if the literal has the datatype [xsd:boolean](http://www.w3.org/2001/XMLSchema#string) and is valid
+    pub fn is_boolean(&self) -> bool {
+        match self.0 {
+            LiteralContent::Boolean(_) => true,
+            _ => false,
+        }
+    }
+
+    /// Returns the [effective boolean value](https://www.w3.org/TR/sparql11-query/#ebv) of the literal if it exists
+    pub fn to_bool(&self) -> Option<bool> {
+        //TODO: numeric literals
+        match self.0 {
+            LiteralContent::SimpleLiteral(ref value) => Some(!value.is_empty()),
+            LiteralContent::String(ref value) => Some(!value.is_empty()),
+            LiteralContent::LanguageTaggedString { .. } => None,
+            LiteralContent::Boolean(value) => Some(value),
+            LiteralContent::TypedLiteral { .. } => None,
+        }
+    }
 }
 
 impl fmt::Display for Literal {

src/model/triple.rs

@@ -80,6 +80,14 @@ impl Term {
             Term::Literal(_) => true,
         }
     }
+
+    /// Returns the [effective boolean value](https://www.w3.org/TR/sparql11-query/#ebv) of the term if it exists
+    pub fn to_bool(&self) -> Option<bool> {
+        match self {
+            Term::Literal(literal) => literal.to_bool(),
+            _ => None,
+        }
+    }
 }
 
 impl fmt::Display for Term {

src/sparql/algebra.rs

@@ -522,8 +522,8 @@ impl fmt::Display for Expression {
             Expression::IRIFunctionCall(e) => write!(f, "IRI({})", e),
             Expression::BNodeFunctionCall(v) => v
                 .as_ref()
-                .map(|id| write!(f, "BOUND({})", id))
-                .unwrap_or_else(|| write!(f, "BOUND()")),
+                .map(|id| write!(f, "BNODE({})", id))
+                .unwrap_or_else(|| write!(f, "BNODE()")),
             Expression::RandFunctionCall() => write!(f, "RAND()"),
             Expression::AbsFunctionCall(e) => write!(f, "ABS({})", e),
             Expression::CeilFunctionCall(e) => write!(f, "CEIL({})", e),

src/store/numeric_encoder.rs

@@ -7,6 +7,7 @@ use std::str;
 use std::str::FromStr;
 use url::Url;
 use uuid::Uuid;
+use Error;
 use Result;
 
 pub trait BytesStore {
@@ -22,6 +23,9 @@ const TYPE_BLANK_NODE_ID: u8 = 2;
 const TYPE_SIMPLE_LITERAL_ID: u8 = 3;
 const TYPE_LANG_STRING_LITERAL_ID: u8 = 4;
 const TYPE_TYPED_LITERAL_ID: u8 = 5;
+const TYPE_STRING_LITERAL: u8 = 6;
+const TYPE_BOOLEAN_LITERAL_TRUE: u8 = 6;
+const TYPE_BOOLEAN_LITERAL_FALSE: u8 = 7;
 
 pub static ENCODED_DEFAULT_GRAPH: EncodedTerm = EncodedTerm::DefaultGraph {};
 
@@ -33,6 +37,8 @@ pub enum EncodedTerm {
     SimpleLiteral { value_id: u64 },
     LangStringLiteral { value_id: u64, language_id: u64 },
     TypedLiteral { value_id: u64, datatype_id: u64 },
+    StringLiteral { value_id: u64 },
+    BooleanLiteral(bool),
 }
 
 impl EncodedTerm {
@@ -44,10 +50,19 @@ impl EncodedTerm {
             EncodedTerm::SimpleLiteral { .. } => TYPE_SIMPLE_LITERAL_ID,
             EncodedTerm::LangStringLiteral { .. } => TYPE_LANG_STRING_LITERAL_ID,
             EncodedTerm::TypedLiteral { .. } => TYPE_TYPED_LITERAL_ID,
+            EncodedTerm::StringLiteral { .. } => TYPE_STRING_LITERAL,
+            EncodedTerm::BooleanLiteral(true) => TYPE_BOOLEAN_LITERAL_TRUE,
+            EncodedTerm::BooleanLiteral(false) => TYPE_BOOLEAN_LITERAL_FALSE,
         }
     }
 }
 
+impl From<bool> for EncodedTerm {
+    fn from(val: bool) -> Self {
+        EncodedTerm::BooleanLiteral(val)
+    }
+}
+
 #[derive(Eq, PartialEq, Ord, PartialOrd, Debug, Clone, Hash)]
 pub struct EncodedQuad {
     pub subject: EncodedTerm,
@@ -102,6 +117,11 @@ impl<R: Read> TermReader for R {
                 datatype_id: self.read_u64::<NetworkEndian>()?,
                 value_id: self.read_u64::<NetworkEndian>()?,
             }),
+            TYPE_STRING_LITERAL => Ok(EncodedTerm::SimpleLiteral {
+                value_id: self.read_u64::<NetworkEndian>()?,
+            }),
+            TYPE_BOOLEAN_LITERAL_TRUE => Ok(EncodedTerm::BooleanLiteral(true)),
+            TYPE_BOOLEAN_LITERAL_FALSE => Ok(EncodedTerm::BooleanLiteral(false)),
             _ => Err("the term buffer has an invalid type id".into()),
         }
     }
@@ -177,6 +197,11 @@ impl<R: Write> TermWriter for R {
                 self.write_u64::<NetworkEndian>(datatype_id)?;
                 self.write_u64::<NetworkEndian>(value_id)?;
             }
+
+            EncodedTerm::StringLiteral { value_id } => {
+                self.write_u64::<NetworkEndian>(value_id)?;
+            }
+            EncodedTerm::BooleanLiteral(_) => {}
         }
         Ok(())
     }
@@ -237,6 +262,16 @@ impl<S: BytesStore> Encoder<S> {
                     value_id: self.encode_str_value(&literal.value())?,
                 }
             }
+        } else if literal.is_string() {
+            EncodedTerm::StringLiteral {
+                value_id: self.encode_str_value(&literal.value())?,
+            }
+        } else if literal.is_boolean() {
+            EncodedTerm::BooleanLiteral(
+                literal
+                    .to_bool()
+                    .ok_or_else(|| Error::from("boolean literal without boolean value"))?,
+            )
         } else {
             EncodedTerm::TypedLiteral {
                 value_id: self.encode_str_value(&literal.value())?,
@@ -309,6 +344,10 @@ impl<S: BytesStore> Encoder<S> {
                 self.decode_str_value(value_id)?,
                 NamedNode::from(self.decode_url_value(datatype_id)?),
             ).into()),
+            EncodedTerm::StringLiteral { value_id } => {
+                Ok(Literal::from(self.decode_str_value(value_id)?).into())
+            }
+            EncodedTerm::BooleanLiteral(value) => Ok(Literal::from(value).into()),
         }
     }
 

src/store/sparql.rs

@@ -124,7 +124,7 @@ impl EncodedBindingsIterator {
                 iter: Box::new(oks.clone().into_iter().map(Ok)),
             },
             EncodedBindingsIterator {
-                variables: variables,
+                variables,
                 iter: Box::new(errors.into_iter().map(Err).chain(oks.into_iter().map(Ok))),
             },
         )
@@ -149,6 +149,7 @@ fn slice_key<T: Eq>(slice: &[T], element: &T) -> Option<usize> {
     None
 }
 
+#[derive(Clone)]
 pub struct SparqlEvaluator<S: EncodedQuadsStore> {
     store: Arc<S>,
 }
@@ -218,7 +219,26 @@ impl<S: EncodedQuadsStore> SparqlEvaluator<S> {
                 self.eval_multi_set_pattern(b, self.eval_multi_set_pattern(a, from)?)
             }
             MultiSetPattern::LeftJoin(a, b, e) => unimplemented!(),
-            MultiSetPattern::Filter(e, p) => unimplemented!(),
+            MultiSetPattern::Filter(e, p) => {
+                let EncodedBindingsIterator { variables, iter } =
+                    self.eval_multi_set_pattern(p, from)?;
+                let expression = e.clone();
+                let evaluator = Self {
+                    store: self.store.clone(),
+                };
+                Ok(EncodedBindingsIterator {
+                    variables: variables.clone(),
+                    iter: Box::new(iter.filter(move |val| match val {
+                        Ok(binding) => {
+                            match evaluator.eval_expression(&expression, binding, &variables) {
+                                Ok(Some(term)) => true,
+                                _ => false,
+                            }
+                        }
+                        Err(_) => true,
+                    })),
+                })
+            }
             MultiSetPattern::Union(a, b) => {
                 let (from1, from2) = from.duplicate();
                 Ok(self
@@ -314,6 +334,56 @@ impl<S: EncodedQuadsStore> SparqlEvaluator<S> {
         unimplemented!()
     }
 
+    fn eval_expression(
+        &self,
+        expr: &Expression,
+        binding: &[Option<EncodedTerm>],
+        variables: &[Variable],
+    ) -> Result<Option<EncodedTerm>> {
+        match expr {
+            Expression::ConstantExpression(TermOrVariable::Term(t)) => {
+                Ok(Some(self.store.encoder().encode_term(t)?))
+            }
+            Expression::ConstantExpression(TermOrVariable::Variable(v)) => {
+                Ok(slice_key(variables, v).and_then(|key| binding[key]))
+            }
+            Expression::OrExpression(a, b) => Ok(match self
+                .to_bool(self.eval_expression(a, binding, variables)?)?
+            {
+                Some(true) => Some(true.into()),
+                Some(false) => self.eval_expression(b, binding, variables)?,
+                None => match self.to_bool(self.eval_expression(b, binding, variables)?)? {
+                    Some(true) => Some(true.into()),
+                    _ => None,
+                },
+            }),
+            Expression::AndExpression(a, b) => Ok(match self
+                .to_bool(self.eval_expression(a, binding, variables)?)?
+            {
+                Some(true) => self.eval_expression(b, binding, variables)?,
+                Some(false) => Some(false.into()),
+                None => match self.to_bool(self.eval_expression(b, binding, variables)?)? {
+                    Some(false) => Some(false.into()),
+                    _ => None,
+                },
+            }),
+            Expression::UnaryNotExpression(e) => Ok(self
+                .to_bool(self.eval_expression(e, binding, variables)?)?
+                .map(|v| (!v).into())),
+            e => Err(format!("Evaluation of expression {} is not implemented yet", e).into()),
+        }
+    }
+
+    fn to_bool(&self, term: Option<EncodedTerm>) -> Result<Option<bool>> {
+        Ok(match term {
+            Some(EncodedTerm::BooleanLiteral(value)) => Some(value),
+            Some(EncodedTerm::NamedNode { .. }) => None,
+            Some(EncodedTerm::BlankNode(_)) => None,
+            Some(term) => self.store.encoder().decode_term(term)?.to_bool(),
+            None => None,
+        })
+    }
+
     fn binding_value_lookup_from_term_or_variable(
         &self,
         term_or_variable: &TermOrVariable,