Refactoring: split up the projector crate. No other code changes.

query-projector/src/aggregates.rs

@@ -0,0 +1,216 @@
+// Copyright 2018 Mozilla
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may not use
+// this file except in compliance with the License. You may obtain a copy of the
+// License at http://www.apache.org/licenses/LICENSE-2.0
+// Unless required by applicable law or agreed to in writing, software distributed
+// under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
+// CONDITIONS OF ANY KIND, either express or implied. See the License for the
+// specific language governing permissions and limitations under the License.
+
+use mentat_core::{
+    ValueType,
+    ValueTypeSet,
+};
+
+use mentat_query::{
+    Aggregate,
+    QueryFunction,
+    Variable,
+};
+
+use mentat_query_algebrizer::{
+    ColumnName,
+    ConjoiningClauses,
+    VariableColumn,
+};
+
+use mentat_query_sql::{
+    ColumnOrExpression,
+    Expression,
+    Name,
+    ProjectedColumn,
+};
+
+use errors::{
+    ErrorKind,
+    Result,
+};
+
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+pub enum SimpleAggregationOp {
+    Avg,
+    Count,
+    Max,
+    Min,
+    Sum,
+}
+
+impl SimpleAggregationOp {
+    pub(crate) fn to_sql(&self) -> &'static str {
+        use self::SimpleAggregationOp::*;
+        match self {
+            &Avg => "avg",
+            &Count => "count",
+            &Max => "max",
+            &Min => "min",
+            &Sum => "sum",
+        }
+    }
+
+    fn for_function(function: &QueryFunction) -> Option<SimpleAggregationOp> {
+        match function.0.plain_name() {
+            "avg" => Some(SimpleAggregationOp::Avg),
+            "count" => Some(SimpleAggregationOp::Count),
+            "max" => Some(SimpleAggregationOp::Max),
+            "min" => Some(SimpleAggregationOp::Min),
+            "sum" => Some(SimpleAggregationOp::Sum),
+            _ => None,
+        }
+    }
+
+    /// With knowledge of the types to which a variable might be bound,
+    /// return a `Result` to determine whether this aggregation is suitable.
+    /// For example, it's valid to take the `Avg` of `{Double, Long}`, invalid
+    /// to take `Sum` of `{Instant}`, valid to take (lexicographic) `Max` of `{String}`,
+    /// but invalid to take `Max` of `{Uuid, String}`.
+    ///
+    /// The returned type is the type of the result of the aggregation.
+    pub(crate) fn is_applicable_to_types(&self, possibilities: ValueTypeSet) -> Result<ValueType> {
+        use self::SimpleAggregationOp::*;
+        if possibilities.is_empty() {
+            bail!(ErrorKind::CannotProjectImpossibleBinding(*self))
+        }
+
+        match self {
+            // One can always count results.
+            &Count => Ok(ValueType::Long),
+
+            // Only numeric types can be averaged or summed.
+            &Avg => {
+                if possibilities.is_only_numeric() {
+                    // The mean of a set of numeric values will always, for our purposes, be a double.
+                    Ok(ValueType::Double)
+                } else {
+                    bail!(ErrorKind::CannotApplyAggregateOperationToTypes(*self, possibilities))
+                }
+            },
+            &Sum => {
+                if possibilities.is_only_numeric() {
+                    if possibilities.contains(ValueType::Double) {
+                        Ok(ValueType::Double)
+                    } else {
+                        // TODO: BigInt.
+                        Ok(ValueType::Long)
+                    }
+                } else {
+                    bail!(ErrorKind::CannotApplyAggregateOperationToTypes(*self, possibilities))
+                }
+            },
+
+            &Max | &Min => {
+                if possibilities.is_unit() {
+                    use ValueType::*;
+                    let the_type = possibilities.exemplar().expect("a type");
+                    match the_type {
+                        // These types are numerically ordered.
+                        Double | Long | Instant => Ok(the_type),
+
+                        // Boolean: false < true.
+                        Boolean => Ok(the_type),
+
+                        // String: lexicographic order.
+                        String => Ok(the_type),
+
+                        // These types are unordered.
+                        Keyword | Ref | Uuid => {
+                            bail!(ErrorKind::CannotApplyAggregateOperationToTypes(*self, possibilities))
+                        },
+                    }
+                } else {
+                    // It cannot be empty -- we checked.
+                    // The only types that are valid to compare cross-type are numbers.
+                    if possibilities.is_only_numeric() {
+                        // Note that if the max/min is a Long, it will be returned as a Double!
+                        if possibilities.contains(ValueType::Double) {
+                            Ok(ValueType::Double)
+                        } else {
+                            // TODO: BigInt.
+                            Ok(ValueType::Long)
+                        }
+                    } else {
+                        bail!(ErrorKind::CannotApplyAggregateOperationToTypes(*self, possibilities))
+                    }
+                }
+            },
+        }
+    }
+}
+
+pub(crate) struct SimpleAggregate {
+    pub op: SimpleAggregationOp,
+    pub var: Variable,
+}
+
+impl SimpleAggregate {
+    pub(crate) fn column_name(&self) -> Name {
+        format!("({} {})", self.op.to_sql(), self.var.name())
+    }
+
+    pub(crate) fn use_static_value(&self) -> bool {
+        use self::SimpleAggregationOp::*;
+        match self.op {
+            Avg | Max | Min => true,
+            Count | Sum => false,
+        }
+    }
+}
+
+pub(crate) trait SimpleAggregation {
+    fn to_simple(&self) -> Option<SimpleAggregate>;
+}
+
+impl SimpleAggregation for Aggregate {
+    fn to_simple(&self) -> Option<SimpleAggregate> {
+        if self.args.len() != 1 {
+            return None;
+        }
+        self.args[0]
+            .as_variable()
+            .and_then(|v| SimpleAggregationOp::for_function(&self.func)
+                              .map(|op| SimpleAggregate { op, var: v.clone(), }))
+    }
+}
+
+/// Returns two values:
+/// - The `ColumnOrExpression` to use in the query. This will always refer to other
+///   variables by name; never to a datoms column.
+/// - The known type of that value.
+pub(crate) fn projected_column_for_simple_aggregate(simple: &SimpleAggregate, cc: &ConjoiningClauses) -> Result<(ProjectedColumn, ValueType)> {
+    let known_types = cc.known_type_set(&simple.var);
+    let return_type = simple.op.is_applicable_to_types(known_types)?;
+    let projected_column_or_expression =
+        if let Some(value) = cc.bound_value(&simple.var) {
+            // Oh, we already know the value!
+            if simple.use_static_value() {
+                // We can statically compute the aggregate result for some operators -- not count or
+                // sum, but avg/max/min are OK.
+                ColumnOrExpression::Value(value)
+            } else {
+                let expression = Expression::Unary {
+                    sql_op: simple.op.to_sql(),
+                    arg: ColumnOrExpression::Value(value),
+                };
+                ColumnOrExpression::Expression(Box::new(expression), return_type)
+            }
+        } else {
+            // The common case: the values are bound during execution.
+            let name = VariableColumn::Variable(simple.var.clone()).column_name();
+            let expression = Expression::Unary {
+                sql_op: simple.op.to_sql(),
+                arg: ColumnOrExpression::ExistingColumn(name),
+            };
+            ColumnOrExpression::Expression(Box::new(expression), return_type)
+        };
+    Ok((ProjectedColumn(projected_column_or_expression, simple.column_name()), return_type))
+}

query-projector/src/errors.rs

@@ -0,0 +1,72 @@
+// Copyright 2018 Mozilla
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may not use
+// this file except in compliance with the License. You may obtain a copy of the
+// License at http://www.apache.org/licenses/LICENSE-2.0
+// Unless required by applicable law or agreed to in writing, software distributed
+// under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
+// CONDITIONS OF ANY KIND, either express or implied. See the License for the
+// specific language governing permissions and limitations under the License.
+
+use rusqlite;
+
+use mentat_core::{
+    ValueTypeSet,
+};
+
+use mentat_db;
+
+use mentat_query::{
+    PlainSymbol,
+};
+
+use aggregates::{
+    SimpleAggregationOp,
+};
+
+error_chain! {
+    types {
+        Error, ErrorKind, ResultExt, Result;
+    }
+
+    errors {
+        /// We're just not done yet.  Message that the feature is recognized but not yet
+        /// implemented.
+        NotYetImplemented(t: String) {
+            description("not yet implemented")
+            display("not yet implemented: {}", t)
+        }
+        CannotProjectImpossibleBinding(op: SimpleAggregationOp) {
+            description("no possible types for variable in projection list")
+            display("no possible types for value provided to {:?}", op)
+        }
+        CannotApplyAggregateOperationToTypes(op: SimpleAggregationOp, types: ValueTypeSet) {
+            description("cannot apply projection operation to types")
+            display("cannot apply projection operation {:?} to types {:?}", op, types)
+        }
+        UnboundVariable(var: PlainSymbol) {
+            description("cannot project unbound variable")
+            display("cannot project unbound variable {:?}", var)
+        }
+        NoTypeAvailableForVariable(var: PlainSymbol) {
+            description("cannot find type for variable")
+            display("cannot find type for variable {:?}", var)
+        }
+        UnexpectedResultsType(actual: &'static str, expected: &'static str) {
+            description("unexpected query results type")
+            display("expected {}, got {}", expected, actual)
+        }
+        AmbiguousAggregates(min_max_count: usize, corresponding_count: usize) {
+            description("ambiguous aggregates")
+            display("min/max expressions: {} (max 1), corresponding: {}", min_max_count, corresponding_count)
+        }
+    }
+
+    foreign_links {
+        Rusqlite(rusqlite::Error);
+    }
+
+    links {
+        DbError(mentat_db::Error, mentat_db::ErrorKind);
+    }
+}

query-projector/src/lib.rs

@@ -28,21 +28,14 @@ use std::iter;
 
 use std::rc::Rc;
 
-use indexmap::{
-    IndexSet,
-};
-
 use rusqlite::{
     Row,
     Rows,
 };
 
 use mentat_core::{
-    SQLValueType,
-    SQLValueTypeSet,
     TypedValue,
     ValueType,
-    ValueTypeSet,
     ValueTypeTag,
 };
 
@@ -55,79 +48,43 @@ use mentat_db::{
 };
 
 use mentat_query::{
-    Aggregate,
     Element,
     FindSpec,
     Limit,
-    PlainSymbol,
-    QueryFunction,
     Variable,
 };
 
 use mentat_query_algebrizer::{
     AlgebraicQuery,
-    ColumnName,
-    ConjoiningClauses,
-    QualifiedAlias,
     VariableBindings,
-    VariableColumn,
 };
 
 use mentat_query_sql::{
-    ColumnOrExpression,
-    Expression,
     GroupBy,
-    Name,
     Projection,
-    ProjectedColumn,
 };
 
-error_chain! {
+mod aggregates;
-    types {
+mod project;
-        Error, ErrorKind, ResultExt, Result;
+pub mod errors;
-    }
 
-    errors {
+pub use aggregates::{
-        /// We're just not done yet.  Message that the feature is recognized but not yet
+    SimpleAggregationOp,
-        /// implemented.
+};
-        NotYetImplemented(t: String) {
-            description("not yet implemented")
-            display("not yet implemented: {}", t)
-        }
-        CannotProjectImpossibleBinding(op: SimpleAggregationOp) {
-            description("no possible types for variable in projection list")
-            display("no possible types for value provided to {:?}", op)
-        }
-        CannotApplyAggregateOperationToTypes(op: SimpleAggregationOp, types: ValueTypeSet) {
-            description("cannot apply projection operation to types")
-            display("cannot apply projection operation {:?} to types {:?}", op, types)
-        }
-        UnboundVariable(var: PlainSymbol) {
-            description("cannot project unbound variable")
-            display("cannot project unbound variable {:?}", var)
-        }
-        NoTypeAvailableForVariable(var: PlainSymbol) {
-            description("cannot find type for variable")
-            display("cannot find type for variable {:?}", var)
-        }
-        UnexpectedResultsType(actual: &'static str, expected: &'static str) {
-            description("unexpected query results type")
-            display("expected {}, got {}", expected, actual)
-        }
-        AmbiguousAggregates(min_max_count: usize, corresponding_count: usize) {
-            description("ambiguous aggregates")
-            display("min/max expressions: {} (max 1), corresponding: {}", min_max_count, corresponding_count)
-        }
-    }
 
-    foreign_links {
+use project::{
-        Rusqlite(rusqlite::Error);
+    ProjectedElements,
-    }
+    project_elements,
+};
 
-    links {
+pub use project::{
-        DbError(mentat_db::Error, mentat_db::ErrorKind);
+    projected_column_for_var,
-    }
+};
-}
+
+use errors::{
+    ErrorKind,
+    Result,
+};
 
 #[derive(Debug, PartialEq, Eq)]
 pub struct QueryOutput {
@@ -353,525 +310,6 @@ impl TypedIndex {
     }
 }
 
-fn cc_column(cc: &ConjoiningClauses, var: &Variable) -> Result<QualifiedAlias> {
-    cc.column_bindings
-      .get(var)
-      .and_then(|cols| cols.get(0).cloned())
-      .ok_or_else(|| ErrorKind::UnboundVariable(var.name()).into())
-}
-
-fn candidate_column(cc: &ConjoiningClauses, var: &Variable) -> Result<(ColumnOrExpression, Name)> {
-    // Every variable should be bound by the top-level CC to at least
-    // one column in the query. If that constraint is violated it's a
-    // bug in our code, so it's appropriate to panic here.
-    cc_column(cc, var)
-        .map(|qa| {
-            let name = VariableColumn::Variable(var.clone()).column_name();
-            (ColumnOrExpression::Column(qa), name)
-        })
-}
-
-fn candidate_type_column(cc: &ConjoiningClauses, var: &Variable) -> Result<(ColumnOrExpression, Name)> {
-    cc.extracted_types
-      .get(var)
-      .cloned()
-      .map(|alias| {
-          let type_name = VariableColumn::VariableTypeTag(var.clone()).column_name();
-          (ColumnOrExpression::Column(alias), type_name)
-      })
-      .ok_or_else(|| ErrorKind::UnboundVariable(var.name()).into())
-}
-
-/// Return the projected column -- that is, a value or SQL column and an associated name -- for a
-/// given variable. Also return the type.
-/// Callers are expected to determine whether to project a type tag as an additional SQL column.
-pub fn projected_column_for_var(var: &Variable, cc: &ConjoiningClauses) -> Result<(ProjectedColumn, ValueTypeSet)> {
-    if let Some(value) = cc.bound_value(&var) {
-        // If we already know the value, then our lives are easy.
-        let tag = value.value_type();
-        let name = VariableColumn::Variable(var.clone()).column_name();
-        Ok((ProjectedColumn(ColumnOrExpression::Value(value.clone()), name), ValueTypeSet::of_one(tag)))
-    } else {
-        // If we don't, then the CC *must* have bound the variable.
-        let (column, name) = candidate_column(cc, var)?;
-        Ok((ProjectedColumn(column, name), cc.known_type_set(var)))
-    }
-}
-
-/// Returns two values:
-/// - The `ColumnOrExpression` to use in the query. This will always refer to other
-///   variables by name; never to a datoms column.
-/// - The known type of that value.
-fn projected_column_for_simple_aggregate(simple: &SimpleAggregate, cc: &ConjoiningClauses) -> Result<(ProjectedColumn, ValueType)> {
-    let known_types = cc.known_type_set(&simple.var);
-    let return_type = simple.op.is_applicable_to_types(known_types)?;
-    let projected_column_or_expression =
-        if let Some(value) = cc.bound_value(&simple.var) {
-            // Oh, we already know the value!
-            if simple.use_static_value() {
-                // We can statically compute the aggregate result for some operators -- not count or
-                // sum, but avg/max/min are OK.
-                ColumnOrExpression::Value(value)
-            } else {
-                let expression = Expression::Unary {
-                    sql_op: simple.op.to_sql(),
-                    arg: ColumnOrExpression::Value(value),
-                };
-                ColumnOrExpression::Expression(Box::new(expression), return_type)
-            }
-        } else {
-            // The common case: the values are bound during execution.
-            let name = VariableColumn::Variable(simple.var.clone()).column_name();
-            let expression = Expression::Unary {
-                sql_op: simple.op.to_sql(),
-                arg: ColumnOrExpression::ExistingColumn(name),
-            };
-            ColumnOrExpression::Expression(Box::new(expression), return_type)
-        };
-    Ok((ProjectedColumn(projected_column_or_expression, simple.column_name()), return_type))
-}
-
-#[derive(Clone, Copy, Debug, Eq, PartialEq)]
-pub enum SimpleAggregationOp {
-    Avg,
-    Count,
-    Max,
-    Min,
-    Sum,
-}
-
-impl SimpleAggregationOp {
-    fn to_sql(&self) -> &'static str {
-        use SimpleAggregationOp::*;
-        match self {
-            &Avg => "avg",
-            &Count => "count",
-            &Max => "max",
-            &Min => "min",
-            &Sum => "sum",
-        }
-    }
-
-    fn for_function(function: &QueryFunction) -> Option<SimpleAggregationOp> {
-        match function.0.plain_name() {
-            "avg" => Some(SimpleAggregationOp::Avg),
-            "count" => Some(SimpleAggregationOp::Count),
-            "max" => Some(SimpleAggregationOp::Max),
-            "min" => Some(SimpleAggregationOp::Min),
-            "sum" => Some(SimpleAggregationOp::Sum),
-            _ => None,
-        }
-    }
-
-    /// With knowledge of the types to which a variable might be bound,
-    /// return a `Result` to determine whether this aggregation is suitable.
-    /// For example, it's valid to take the `Avg` of `{Double, Long}`, invalid
-    /// to take `Sum` of `{Instant}`, valid to take (lexicographic) `Max` of `{String}`,
-    /// but invalid to take `Max` of `{Uuid, String}`.
-    ///
-    /// The returned type is the type of the result of the aggregation.
-    fn is_applicable_to_types(&self, possibilities: ValueTypeSet) -> Result<ValueType> {
-        use SimpleAggregationOp::*;
-        if possibilities.is_empty() {
-            bail!(ErrorKind::CannotProjectImpossibleBinding(*self))
-        }
-
-        match self {
-            // One can always count results.
-            &Count => Ok(ValueType::Long),
-
-            // Only numeric types can be averaged or summed.
-            &Avg => {
-                if possibilities.is_only_numeric() {
-                    // The mean of a set of numeric values will always, for our purposes, be a double.
-                    Ok(ValueType::Double)
-                } else {
-                    bail!(ErrorKind::CannotApplyAggregateOperationToTypes(*self, possibilities))
-                }
-            },
-            &Sum => {
-                if possibilities.is_only_numeric() {
-                    if possibilities.contains(ValueType::Double) {
-                        Ok(ValueType::Double)
-                    } else {
-                        // TODO: BigInt.
-                        Ok(ValueType::Long)
-                    }
-                } else {
-                    bail!(ErrorKind::CannotApplyAggregateOperationToTypes(*self, possibilities))
-                }
-            },
-
-            &Max | &Min => {
-                if possibilities.is_unit() {
-                    use ValueType::*;
-                    let the_type = possibilities.exemplar().expect("a type");
-                    match the_type {
-                        // These types are numerically ordered.
-                        Double | Long | Instant => Ok(the_type),
-
-                        // Boolean: false < true.
-                        Boolean => Ok(the_type),
-
-                        // String: lexicographic order.
-                        String => Ok(the_type),
-
-                        // These types are unordered.
-                        Keyword | Ref | Uuid => {
-                            bail!(ErrorKind::CannotApplyAggregateOperationToTypes(*self, possibilities))
-                        },
-                    }
-                } else {
-                    // It cannot be empty -- we checked.
-                    // The only types that are valid to compare cross-type are numbers.
-                    if possibilities.is_only_numeric() {
-                        // Note that if the max/min is a Long, it will be returned as a Double!
-                        if possibilities.contains(ValueType::Double) {
-                            Ok(ValueType::Double)
-                        } else {
-                            // TODO: BigInt.
-                            Ok(ValueType::Long)
-                        }
-                    } else {
-                        bail!(ErrorKind::CannotApplyAggregateOperationToTypes(*self, possibilities))
-                    }
-                }
-            },
-        }
-    }
-}
-
-struct SimpleAggregate {
-    op: SimpleAggregationOp,
-    var: Variable,
-}
-
-impl SimpleAggregate {
-    fn column_name(&self) -> Name {
-        format!("({} {})", self.op.to_sql(), self.var.name())
-    }
-
-    fn use_static_value(&self) -> bool {
-        use SimpleAggregationOp::*;
-        match self.op {
-            Avg | Max | Min => true,
-            Count | Sum => false,
-        }
-    }
-}
-
-trait SimpleAggregation {
-    fn to_simple(&self) -> Option<SimpleAggregate>;
-}
-
-impl SimpleAggregation for Aggregate {
-    fn to_simple(&self) -> Option<SimpleAggregate> {
-        if self.args.len() != 1 {
-            return None;
-        }
-        self.args[0]
-            .as_variable()
-            .and_then(|v| SimpleAggregationOp::for_function(&self.func)
-                              .map(|op| SimpleAggregate { op, var: v.clone(), }))
-    }
-}
-
-/// An internal temporary struct to pass between the projection 'walk' and the
-/// resultant projector.
-/// Projection accumulates four things:
-/// - Two SQL projection lists. We need two because aggregate queries are nested
-///   in order to apply DISTINCT to values prior to aggregation.
-/// - A collection of templates for the projector to use to extract values.
-/// - A list of columns to use for grouping. Grouping is a property of the projection!
-struct ProjectedElements {
-    sql_projection: Projection,
-    pre_aggregate_projection: Option<Projection>,
-    templates: Vec<TypedIndex>,
-    group_by: Vec<GroupBy>,
-}
-
-/// Walk an iterator of `Element`s, collecting projector templates and columns.
-///
-/// Returns a `ProjectedElements`, which combines SQL projections
-/// and a `Vec` of `TypedIndex` 'keys' to use when looking up values.
-///
-/// Callers must ensure that every `Element` is distinct -- a query like
-///
-/// ```edn
-/// [:find ?x ?x :where [?x _ _]]
-/// ```
-///
-/// should fail to parse. See #358.
-fn project_elements<'a, I: IntoIterator<Item = &'a Element>>(
-    count: usize,
-    elements: I,
-    query: &AlgebraicQuery) -> Result<ProjectedElements> {
-
-    // Give a little padding for type tags.
-    let mut inner_projection = Vec::with_capacity(count + 2);
-
-    // Everything in the outer query will _either_ be an aggregate operation
-    // _or_ a reference to a name projected from the inner.
-    // We'll expand them later.
-    let mut outer_projection: Vec<Either<Name, ProjectedColumn>> = Vec::with_capacity(count + 2);
-
-    let mut i: i32 = 0;
-    let mut min_max_count: usize = 0;
-    let mut corresponding_count: usize = 0;
-    let mut templates = vec![];
-
-    let mut aggregates = false;
-
-    // Any variable that appears intact in the :find clause, not inside an aggregate expression.
-    // "Query variables not in aggregate expressions will group the results and appear intact
-    // in the result."
-    // We use an ordered set here so that we group in the correct order.
-    let mut outer_variables = IndexSet::new();
-
-    // Any variable that we are projecting from the inner query.
-    let mut inner_variables = BTreeSet::new();
-
-    for e in elements {
-        if let &Element::Corresponding(_) = e {
-            corresponding_count += 1;
-        }
-
-        match e {
-            // Each time we come across a variable, we push a SQL column
-            // into the SQL projection, aliased to the name of the variable,
-            // and we push an annotated index into the projector.
-            &Element::Variable(ref var) |
-            &Element::Corresponding(ref var) => {
-                if outer_variables.contains(var) {
-                    eprintln!("Warning: duplicate variable {} in query.", var);
-                }
-
-                // TODO: it's an error to have `[:find ?x (the ?x) …]`.
-                outer_variables.insert(var.clone());
-                inner_variables.insert(var.clone());
-
-                let (projected_column, type_set) = projected_column_for_var(&var, &query.cc)?;
-                outer_projection.push(Either::Left(projected_column.1.clone()));
-                inner_projection.push(projected_column);
-
-                if let Some(tag) = type_set.unique_type_tag() {
-                    templates.push(TypedIndex::Known(i, tag));
-                    i += 1;     // We used one SQL column.
-                } else {
-                    templates.push(TypedIndex::Unknown(i, i + 1));
-                    i += 2;     // We used two SQL columns.
-
-                    // Also project the type from the SQL query.
-                    let (type_column, type_name) = candidate_type_column(&query.cc, &var)?;
-                    inner_projection.push(ProjectedColumn(type_column, type_name.clone()));
-                    outer_projection.push(Either::Left(type_name));
-                }
-            },
-            &Element::Aggregate(ref a) => {
-                if let Some(simple) = a.to_simple() {
-                    aggregates = true;
-
-                    use SimpleAggregationOp::*;
-                    match simple.op {
-                        Max | Min => {
-                            min_max_count += 1;
-                        },
-                        Avg | Count | Sum => (),
-                    }
-
-                    // When we encounter a simple aggregate -- one in which the aggregation can be
-                    // implemented in SQL, on a single variable -- we just push the SQL aggregation op.
-                    // We must ensure the following:
-                    // - There's a column for the var.
-                    // - The type of the var is known to be restricted to a sensible input set
-                    //   (not necessarily a single type, but e.g., all vals must be Double or Long).
-                    // - The type set must be appropriate for the operation. E.g., `Sum` is not a
-                    //   meaningful operation on instants.
-
-                    let (projected_column, return_type) = projected_column_for_simple_aggregate(&simple, &query.cc)?;
-                    outer_projection.push(Either::Right(projected_column));
-
-                    if !inner_variables.contains(&simple.var) {
-                        inner_variables.insert(simple.var.clone());
-                        let (projected_column, _type_set) = projected_column_for_var(&simple.var, &query.cc)?;
-                        inner_projection.push(projected_column);
-                        if query.cc.known_type_set(&simple.var).unique_type_tag().is_none() {
-                            // Also project the type from the SQL query.
-                            let (type_column, type_name) = candidate_type_column(&query.cc, &simple.var)?;
-                            inner_projection.push(ProjectedColumn(type_column, type_name.clone()));
-                        }
-                    }
-
-                    // We might regret using the type tag here instead of the `ValueType`.
-                    templates.push(TypedIndex::Known(i, return_type.value_type_tag()));
-                    i += 1;
-                } else {
-                    // TODO: complex aggregates.
-                    bail!(ErrorKind::NotYetImplemented("complex aggregates".into()));
-                }
-            },
-        }
-    }
-
-    match (min_max_count, corresponding_count) {
-        (0, 0) | (_, 0) => {},
-        (0, _) => {
-            eprintln!("Warning: used `(the ?var)` without `min` or `max`.");
-        },
-        (1, _) => {
-            // This is the success case!
-        },
-        (n, c) => {
-            bail!(ErrorKind::AmbiguousAggregates(n, c));
-        },
-    }
-
-    // Anything used in ORDER BY (which we're given in `named_projection`)
-    // needs to be in the SQL column list so we can refer to it by name.
-    //
-    // They don't affect projection.
-    //
-    // If a variable is of a non-fixed type, also project the type tag column, so we don't
-    // accidentally unify across types when considering uniqueness!
-    for var in query.named_projection.iter() {
-        if outer_variables.contains(var) {
-            continue;
-        }
-
-        // If it's a fixed value, we need do nothing further.
-        if query.cc.is_value_bound(&var) {
-            continue;
-        }
-
-        let already_inner = inner_variables.contains(&var);
-        let (column, name) = candidate_column(&query.cc, &var)?;
-        if !already_inner {
-            inner_projection.push(ProjectedColumn(column, name.clone()));
-            inner_variables.insert(var.clone());
-        }
-
-        outer_projection.push(Either::Left(name));
-        outer_variables.insert(var.clone());
-
-        // We don't care if a column has a single _type_, we care if it has a single type _tag_,
-        // because that's what we'll use if we're projecting. E.g., Long and Double.
-        // Single type implies single type tag, and is cheaper, so we check that first.
-        let types = query.cc.known_type_set(&var);
-        if !types.has_unique_type_tag() {
-            let (type_column, type_name) = candidate_type_column(&query.cc, &var)?;
-            if !already_inner {
-                inner_projection.push(ProjectedColumn(type_column, type_name.clone()));
-            }
-
-            outer_projection.push(Either::Left(type_name));
-        }
-    }
-
-    if !aggregates {
-        // We're done -- we never need to group unless we're aggregating.
-        return Ok(ProjectedElements {
-                      sql_projection: Projection::Columns(inner_projection),
-                      pre_aggregate_projection: None,
-                      templates,
-                      group_by: vec![],
-                  });
-    }
-
-    // OK, on to aggregates.
-    // We need to produce two SQL projection lists: one for an inner query and one for the outer.
-    //
-    // The inner serves these purposes:
-    // - Projecting variables to avoid duplicates being elided. (:with)
-    // - Making bindings available to the outermost query for projection, ordering, and grouping.
-    //
-    // The outer is consumed by the projector.
-    //
-    // We will also be producing:
-    // - A GROUP BY list to group the output of the inner query by non-aggregate variables
-    //   so that it can be correctly aggregated.
-
-    // Turn this collection of vars into a collection of columns from the query.
-    // We don't allow grouping on anything but a variable bound in the query.
-    // We group by tag if necessary.
-    let mut group_by = Vec::with_capacity(outer_variables.len() + 2);
-    for var in outer_variables.into_iter() {
-        if query.cc.is_value_bound(&var) {
-            continue;
-        }
-
-        // The GROUP BY goes outside, but it needs every variable and type tag to be
-        // projected from inside. Collect in both directions here.
-        let name = VariableColumn::Variable(var.clone()).column_name();
-        group_by.push(GroupBy::ProjectedColumn(name));
-
-        let needs_type_projection = !query.cc.known_type_set(&var).has_unique_type_tag();
-
-        let already_inner = inner_variables.contains(&var);
-        if !already_inner {
-            let (column, name) = candidate_column(&query.cc, &var)?;
-            inner_projection.push(ProjectedColumn(column, name.clone()));
-        }
-
-        if needs_type_projection {
-            let type_name = VariableColumn::VariableTypeTag(var.clone()).column_name();
-            if !already_inner {
-                let type_col = query.cc
-                                    .extracted_types
-                                    .get(&var)
-                                    .cloned()
-                                    .ok_or_else(|| ErrorKind::NoTypeAvailableForVariable(var.name().clone()))?;
-                inner_projection.push(ProjectedColumn(ColumnOrExpression::Column(type_col), type_name.clone()));
-            }
-            group_by.push(GroupBy::ProjectedColumn(type_name));
-        };
-    }
-
-    for var in query.with.iter() {
-        // We never need to project a constant.
-        if query.cc.is_value_bound(&var) {
-            continue;
-        }
-
-        // We don't need to add inner projections for :with if they are already there.
-        if !inner_variables.contains(&var) {
-            let (projected_column, type_set) = projected_column_for_var(&var, &query.cc)?;
-            inner_projection.push(projected_column);
-
-            if type_set.unique_type_tag().is_none() {
-                // Also project the type from the SQL query.
-                let (type_column, type_name) = candidate_type_column(&query.cc, &var)?;
-                inner_projection.push(ProjectedColumn(type_column, type_name.clone()));
-            }
-        }
-    }
-
-    // At this point we know we have a double-layer projection. Collect the outer.
-    //
-    // If we have an inner and outer layer, the inner layer will name its
-    // variables, and the outer will re-project them.
-    // If we only have one layer, then the outer will do the naming.
-    // (We could try to not use names in the inner query, but then what would we do for
-    // `ground` and known values?)
-    // Walk the projection, switching the outer columns to use the inner names.
-
-    let outer_projection = outer_projection.into_iter().map(|c| {
-        match c {
-            Either::Left(name) => {
-                ProjectedColumn(ColumnOrExpression::ExistingColumn(name.clone()),
-                                name)
-            },
-            Either::Right(pc) => pc,
-        }
-    }).collect();
-
-    Ok(ProjectedElements {
-        sql_projection: Projection::Columns(outer_projection),
-        pre_aggregate_projection: Some(Projection::Columns(inner_projection)),
-        templates,
-        group_by,
-    })
-}
-
 pub trait Projector {
     fn project<'stmt>(&self, rows: Rows<'stmt>) -> Result<QueryOutput>;
     fn columns<'s>(&'s self) -> Box<Iterator<Item=&Element> + 's>;

query-projector/src/project.rs

@@ -0,0 +1,403 @@
+// Copyright 2018 Mozilla
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may not use
+// this file except in compliance with the License. You may obtain a copy of the
+// License at http://www.apache.org/licenses/LICENSE-2.0
+// Unless required by applicable law or agreed to in writing, software distributed
+// under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
+// CONDITIONS OF ANY KIND, either express or implied. See the License for the
+// specific language governing permissions and limitations under the License.
+
+use std::collections::{
+    BTreeSet,
+};
+
+use indexmap::{
+    IndexSet,
+};
+
+use mentat_core::{
+    SQLValueType,
+    SQLValueTypeSet,
+    ValueTypeSet,
+};
+
+use mentat_core::util::{
+    Either,
+};
+
+use mentat_query::{
+    Element,
+    Variable,
+};
+
+use mentat_query_algebrizer::{
+    AlgebraicQuery,
+    ColumnName,
+    ConjoiningClauses,
+    QualifiedAlias,
+    VariableColumn,
+};
+
+
+use mentat_query_sql::{
+    ColumnOrExpression,
+    GroupBy,
+    Name,
+    Projection,
+    ProjectedColumn,
+};
+
+use aggregates::{
+    SimpleAggregation,
+    projected_column_for_simple_aggregate,
+};
+
+use errors::{
+    ErrorKind,
+    Result,
+};
+
+use super::{
+    TypedIndex,
+};
+
+/// An internal temporary struct to pass between the projection 'walk' and the
+/// resultant projector.
+/// Projection accumulates four things:
+/// - Two SQL projection lists. We need two because aggregate queries are nested
+///   in order to apply DISTINCT to values prior to aggregation.
+/// - A collection of templates for the projector to use to extract values.
+/// - A list of columns to use for grouping. Grouping is a property of the projection!
+pub(crate) struct ProjectedElements {
+    pub sql_projection: Projection,
+    pub pre_aggregate_projection: Option<Projection>,
+    pub templates: Vec<TypedIndex>,
+    pub group_by: Vec<GroupBy>,
+}
+
+fn candidate_type_column(cc: &ConjoiningClauses, var: &Variable) -> Result<(ColumnOrExpression, Name)> {
+    cc.extracted_types
+      .get(var)
+      .cloned()
+      .map(|alias| {
+          let type_name = VariableColumn::VariableTypeTag(var.clone()).column_name();
+          (ColumnOrExpression::Column(alias), type_name)
+      })
+      .ok_or_else(|| ErrorKind::UnboundVariable(var.name()).into())
+}
+
+fn cc_column(cc: &ConjoiningClauses, var: &Variable) -> Result<QualifiedAlias> {
+    cc.column_bindings
+      .get(var)
+      .and_then(|cols| cols.get(0).cloned())
+      .ok_or_else(|| ErrorKind::UnboundVariable(var.name()).into())
+}
+
+fn candidate_column(cc: &ConjoiningClauses, var: &Variable) -> Result<(ColumnOrExpression, Name)> {
+    // Every variable should be bound by the top-level CC to at least
+    // one column in the query. If that constraint is violated it's a
+    // bug in our code, so it's appropriate to panic here.
+    cc_column(cc, var)
+        .map(|qa| {
+            let name = VariableColumn::Variable(var.clone()).column_name();
+            (ColumnOrExpression::Column(qa), name)
+        })
+}
+
+/// Return the projected column -- that is, a value or SQL column and an associated name -- for a
+/// given variable. Also return the type.
+/// Callers are expected to determine whether to project a type tag as an additional SQL column.
+pub fn projected_column_for_var(var: &Variable, cc: &ConjoiningClauses) -> Result<(ProjectedColumn, ValueTypeSet)> {
+    if let Some(value) = cc.bound_value(&var) {
+        // If we already know the value, then our lives are easy.
+        let tag = value.value_type();
+        let name = VariableColumn::Variable(var.clone()).column_name();
+        Ok((ProjectedColumn(ColumnOrExpression::Value(value.clone()), name), ValueTypeSet::of_one(tag)))
+    } else {
+        // If we don't, then the CC *must* have bound the variable.
+        let (column, name) = candidate_column(cc, var)?;
+        Ok((ProjectedColumn(column, name), cc.known_type_set(var)))
+    }
+}
+/// Walk an iterator of `Element`s, collecting projector templates and columns.
+///
+/// Returns a `ProjectedElements`, which combines SQL projections
+/// and a `Vec` of `TypedIndex` 'keys' to use when looking up values.
+///
+/// Callers must ensure that every `Element` is distinct -- a query like
+///
+/// ```edn
+/// [:find ?x ?x :where [?x _ _]]
+/// ```
+///
+/// should fail to parse. See #358.
+pub(crate) fn project_elements<'a, I: IntoIterator<Item = &'a Element>>(
+    count: usize,
+    elements: I,
+    query: &AlgebraicQuery) -> Result<ProjectedElements> {
+
+    // Give a little padding for type tags.
+    let mut inner_projection = Vec::with_capacity(count + 2);
+
+    // Everything in the outer query will _either_ be an aggregate operation
+    // _or_ a reference to a name projected from the inner.
+    // We'll expand them later.
+    let mut outer_projection: Vec<Either<Name, ProjectedColumn>> = Vec::with_capacity(count + 2);
+
+    let mut i: i32 = 0;
+    let mut min_max_count: usize = 0;
+    let mut corresponding_count: usize = 0;
+    let mut templates = vec![];
+
+    let mut aggregates = false;
+
+    // Any variable that appears intact in the :find clause, not inside an aggregate expression.
+    // "Query variables not in aggregate expressions will group the results and appear intact
+    // in the result."
+    // We use an ordered set here so that we group in the correct order.
+    let mut outer_variables = IndexSet::new();
+
+    // Any variable that we are projecting from the inner query.
+    let mut inner_variables = BTreeSet::new();
+
+    for e in elements {
+        if let &Element::Corresponding(_) = e {
+            corresponding_count += 1;
+        }
+
+        match e {
+            // Each time we come across a variable, we push a SQL column
+            // into the SQL projection, aliased to the name of the variable,
+            // and we push an annotated index into the projector.
+            &Element::Variable(ref var) |
+            &Element::Corresponding(ref var) => {
+                if outer_variables.contains(var) {
+                    eprintln!("Warning: duplicate variable {} in query.", var);
+                }
+
+                // TODO: it's an error to have `[:find ?x (the ?x) …]`.
+                outer_variables.insert(var.clone());
+                inner_variables.insert(var.clone());
+
+                let (projected_column, type_set) = projected_column_for_var(&var, &query.cc)?;
+                outer_projection.push(Either::Left(projected_column.1.clone()));
+                inner_projection.push(projected_column);
+
+                if let Some(tag) = type_set.unique_type_tag() {
+                    templates.push(TypedIndex::Known(i, tag));
+                    i += 1;     // We used one SQL column.
+                } else {
+                    templates.push(TypedIndex::Unknown(i, i + 1));
+                    i += 2;     // We used two SQL columns.
+
+                    // Also project the type from the SQL query.
+                    let (type_column, type_name) = candidate_type_column(&query.cc, &var)?;
+                    inner_projection.push(ProjectedColumn(type_column, type_name.clone()));
+                    outer_projection.push(Either::Left(type_name));
+                }
+            },
+            &Element::Aggregate(ref a) => {
+                if let Some(simple) = a.to_simple() {
+                    aggregates = true;
+
+                    use aggregates::SimpleAggregationOp::*;
+                    match simple.op {
+                        Max | Min => {
+                            min_max_count += 1;
+                        },
+                        Avg | Count | Sum => (),
+                    }
+
+                    // When we encounter a simple aggregate -- one in which the aggregation can be
+                    // implemented in SQL, on a single variable -- we just push the SQL aggregation op.
+                    // We must ensure the following:
+                    // - There's a column for the var.
+                    // - The type of the var is known to be restricted to a sensible input set
+                    //   (not necessarily a single type, but e.g., all vals must be Double or Long).
+                    // - The type set must be appropriate for the operation. E.g., `Sum` is not a
+                    //   meaningful operation on instants.
+
+                    let (projected_column, return_type) = projected_column_for_simple_aggregate(&simple, &query.cc)?;
+                    outer_projection.push(Either::Right(projected_column));
+
+                    if !inner_variables.contains(&simple.var) {
+                        inner_variables.insert(simple.var.clone());
+                        let (projected_column, _type_set) = projected_column_for_var(&simple.var, &query.cc)?;
+                        inner_projection.push(projected_column);
+                        if query.cc.known_type_set(&simple.var).unique_type_tag().is_none() {
+                            // Also project the type from the SQL query.
+                            let (type_column, type_name) = candidate_type_column(&query.cc, &simple.var)?;
+                            inner_projection.push(ProjectedColumn(type_column, type_name.clone()));
+                        }
+                    }
+
+                    // We might regret using the type tag here instead of the `ValueType`.
+                    templates.push(TypedIndex::Known(i, return_type.value_type_tag()));
+                    i += 1;
+                } else {
+                    // TODO: complex aggregates.
+                    bail!(ErrorKind::NotYetImplemented("complex aggregates".into()));
+                }
+            },
+        }
+    }
+
+    match (min_max_count, corresponding_count) {
+        (0, 0) | (_, 0) => {},
+        (0, _) => {
+            eprintln!("Warning: used `(the ?var)` without `min` or `max`.");
+        },
+        (1, _) => {
+            // This is the success case!
+        },
+        (n, c) => {
+            bail!(ErrorKind::AmbiguousAggregates(n, c));
+        },
+    }
+
+    // Anything used in ORDER BY (which we're given in `named_projection`)
+    // needs to be in the SQL column list so we can refer to it by name.
+    //
+    // They don't affect projection.
+    //
+    // If a variable is of a non-fixed type, also project the type tag column, so we don't
+    // accidentally unify across types when considering uniqueness!
+    for var in query.named_projection.iter() {
+        if outer_variables.contains(var) {
+            continue;
+        }
+
+        // If it's a fixed value, we need do nothing further.
+        if query.cc.is_value_bound(&var) {
+            continue;
+        }
+
+        let already_inner = inner_variables.contains(&var);
+        let (column, name) = candidate_column(&query.cc, &var)?;
+        if !already_inner {
+            inner_projection.push(ProjectedColumn(column, name.clone()));
+            inner_variables.insert(var.clone());
+        }
+
+        outer_projection.push(Either::Left(name));
+        outer_variables.insert(var.clone());
+
+        // We don't care if a column has a single _type_, we care if it has a single type _tag_,
+        // because that's what we'll use if we're projecting. E.g., Long and Double.
+        // Single type implies single type tag, and is cheaper, so we check that first.
+        let types = query.cc.known_type_set(&var);
+        if !types.has_unique_type_tag() {
+            let (type_column, type_name) = candidate_type_column(&query.cc, &var)?;
+            if !already_inner {
+                inner_projection.push(ProjectedColumn(type_column, type_name.clone()));
+            }
+
+            outer_projection.push(Either::Left(type_name));
+        }
+    }
+
+    if !aggregates {
+        // We're done -- we never need to group unless we're aggregating.
+        return Ok(ProjectedElements {
+                      sql_projection: Projection::Columns(inner_projection),
+                      pre_aggregate_projection: None,
+                      templates,
+                      group_by: vec![],
+                  });
+    }
+
+    // OK, on to aggregates.
+    // We need to produce two SQL projection lists: one for an inner query and one for the outer.
+    //
+    // The inner serves these purposes:
+    // - Projecting variables to avoid duplicates being elided. (:with)
+    // - Making bindings available to the outermost query for projection, ordering, and grouping.
+    //
+    // The outer is consumed by the projector.
+    //
+    // We will also be producing:
+    // - A GROUP BY list to group the output of the inner query by non-aggregate variables
+    //   so that it can be correctly aggregated.
+
+    // Turn this collection of vars into a collection of columns from the query.
+    // We don't allow grouping on anything but a variable bound in the query.
+    // We group by tag if necessary.
+    let mut group_by = Vec::with_capacity(outer_variables.len() + 2);
+    for var in outer_variables.into_iter() {
+        if query.cc.is_value_bound(&var) {
+            continue;
+        }
+
+        // The GROUP BY goes outside, but it needs every variable and type tag to be
+        // projected from inside. Collect in both directions here.
+        let name = VariableColumn::Variable(var.clone()).column_name();
+        group_by.push(GroupBy::ProjectedColumn(name));
+
+        let needs_type_projection = !query.cc.known_type_set(&var).has_unique_type_tag();
+
+        let already_inner = inner_variables.contains(&var);
+        if !already_inner {
+            let (column, name) = candidate_column(&query.cc, &var)?;
+            inner_projection.push(ProjectedColumn(column, name.clone()));
+        }
+
+        if needs_type_projection {
+            let type_name = VariableColumn::VariableTypeTag(var.clone()).column_name();
+            if !already_inner {
+                let type_col = query.cc
+                                    .extracted_types
+                                    .get(&var)
+                                    .cloned()
+                                    .ok_or_else(|| ErrorKind::NoTypeAvailableForVariable(var.name().clone()))?;
+                inner_projection.push(ProjectedColumn(ColumnOrExpression::Column(type_col), type_name.clone()));
+            }
+            group_by.push(GroupBy::ProjectedColumn(type_name));
+        };
+    }
+
+    for var in query.with.iter() {
+        // We never need to project a constant.
+        if query.cc.is_value_bound(&var) {
+            continue;
+        }
+
+        // We don't need to add inner projections for :with if they are already there.
+        if !inner_variables.contains(&var) {
+            let (projected_column, type_set) = projected_column_for_var(&var, &query.cc)?;
+            inner_projection.push(projected_column);
+
+            if type_set.unique_type_tag().is_none() {
+                // Also project the type from the SQL query.
+                let (type_column, type_name) = candidate_type_column(&query.cc, &var)?;
+                inner_projection.push(ProjectedColumn(type_column, type_name.clone()));
+            }
+        }
+    }
+
+    // At this point we know we have a double-layer projection. Collect the outer.
+    //
+    // If we have an inner and outer layer, the inner layer will name its
+    // variables, and the outer will re-project them.
+    // If we only have one layer, then the outer will do the naming.
+    // (We could try to not use names in the inner query, but then what would we do for
+    // `ground` and known values?)
+    // Walk the projection, switching the outer columns to use the inner names.
+
+    let outer_projection = outer_projection.into_iter().map(|c| {
+        match c {
+            Either::Left(name) => {
+                ProjectedColumn(ColumnOrExpression::ExistingColumn(name.clone()),
+                                name)
+            },
+            Either::Right(pc) => pc,
+        }
+    }).collect();
+
+    Ok(ProjectedElements {
+        sql_projection: Projection::Columns(outer_projection),
+        pre_aggregate_projection: Some(Projection::Columns(inner_projection)),
+        templates,
+        group_by,
+    })
+}

query-translator/src/lib.rs

@@ -38,6 +38,6 @@ error_chain! {
     }
 
     links {
-        ProjectorError(mentat_query_projector::Error, mentat_query_projector::ErrorKind);
+        ProjectorError(mentat_query_projector::errors::Error, mentat_query_projector::errors::ErrorKind);
     }
 }

src/errors.rs

@@ -47,7 +47,7 @@ error_chain! {
         DbError(mentat_db::Error, mentat_db::ErrorKind);
         QueryError(mentat_query_algebrizer::Error, mentat_query_algebrizer::ErrorKind);   // Let's not leak the term 'algebrizer'.
         QueryParseError(mentat_query_parser::Error, mentat_query_parser::ErrorKind);
-        ProjectorError(mentat_query_projector::Error, mentat_query_projector::ErrorKind);
+        ProjectorError(mentat_query_projector::errors::Error, mentat_query_projector::errors::ErrorKind);
         TranslatorError(mentat_query_translator::Error, mentat_query_translator::ErrorKind);
         SqlError(mentat_sql::Error, mentat_sql::ErrorKind);
         TxParseError(mentat_tx_parser::Error, mentat_tx_parser::ErrorKind);

tests/query.rs

@@ -584,7 +584,7 @@ fn test_aggregates_type_handling() {
             Error(
                 ErrorKind::TranslatorError(
                     ::mentat_query_translator::ErrorKind::ProjectorError(
-                        ::mentat_query_projector::ErrorKind::CannotApplyAggregateOperationToTypes(
+                        ::mentat_query_projector::errors::ErrorKind::CannotApplyAggregateOperationToTypes(
                             SimpleAggregationOp::Sum,
                             types
                         ),
@@ -605,7 +605,7 @@ fn test_aggregates_type_handling() {
             Error(
                 ErrorKind::TranslatorError(
                     ::mentat_query_translator::ErrorKind::ProjectorError(
-                        ::mentat_query_projector::ErrorKind::CannotApplyAggregateOperationToTypes(
+                        ::mentat_query_projector::errors::ErrorKind::CannotApplyAggregateOperationToTypes(
                             SimpleAggregationOp::Sum,
                             types
                         ),
@@ -1173,7 +1173,7 @@ fn test_aggregation_implicit_grouping() {
             Error(
                 ErrorKind::TranslatorError(
                     ::mentat_query_translator::ErrorKind::ProjectorError(
-                        ::mentat_query_projector::ErrorKind::AmbiguousAggregates(mmc, cc)
+                        ::mentat_query_projector::errors::ErrorKind::AmbiguousAggregates(mmc, cc)
                     )
             ), _)) => {
             assert_eq!(mmc, 2);