greg/mentat
1
0
Fork 0
Code Issues 294 Pull requests Packages Projects Releases 9 Wiki Activity

Diagnose and prepare simple and complex or joins. (#396) r=nalexander

Browse source
This commit is contained in:
Richard Newman 2017-03-30 19:14:05 -07:00
parent 8e6f37e709 2b2b5cf696
commit 92cdd72500
14 changed files with 2449 additions and 1640 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

21
core/src/lib.rs
View file

@ -93,6 +93,20 @@ impl TypedValue {
&TypedValue::Keyword(_) => ValueType::Keyword,
}
}
/// Construct a new `TypedValue::Keyword` instance by cloning the provided
/// values. This is expensive, so this might
/// be best limited to tests.
pub fn typed_ns_keyword(ns: &str, name: &str) -> TypedValue {
TypedValue::Keyword(NamespacedKeyword::new(ns, name))
}
/// Construct a new `TypedValue::String` instance by cloning the provided
/// value. This is expensive, so this might
/// be best limited to tests.
pub fn typed_string(s: &str) -> TypedValue {
TypedValue::String(s.to_string())
}
}
// Put this here rather than in `db` simply because it's widely needed.
@ -141,9 +155,9 @@ impl SQLValueType for ValueType {
fn test_typed_value() {
assert!(TypedValue::Boolean(false).is_congruent_with(None));
assert!(TypedValue::Boolean(false).is_congruent_with(ValueType::Boolean));
assert!(!TypedValue::String("foo".to_string()).is_congruent_with(ValueType::Boolean));
assert!(TypedValue::String("foo".to_string()).is_congruent_with(ValueType::String));
assert!(TypedValue::String("foo".to_string()).is_congruent_with(None));
assert!(!TypedValue::typed_string("foo").is_congruent_with(ValueType::Boolean));
assert!(TypedValue::typed_string("foo").is_congruent_with(ValueType::String));
assert!(TypedValue::typed_string("foo").is_congruent_with(None));
}
/// Bit flags used in `flags0` column in temporary tables created during search,
@ -473,3 +487,4 @@ mod test {
}
pub mod intern_set;
pub mod util;

60
core/src/util.rs Normal file
View file

@ -0,0 +1,60 @@
// Copyright 2016 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.
/// Side-effect chaining on `Result`.
pub trait ResultEffect<T> {
/// Invoke `f` if `self` is `Ok`, returning `self`.
fn when_ok<F: FnOnce()>(self, f: F) -> Self;
/// Invoke `f` if `self` is `Err`, returning `self`.
fn when_err<F: FnOnce()>(self, f: F) -> Self;
}
impl<T, E> ResultEffect<T> for Result<T, E> {
fn when_ok<F: FnOnce()>(self, f: F) -> Self {
if self.is_ok() {
f();
}
self
}
fn when_err<F: FnOnce()>(self, f: F) -> Self {
if self.is_err() {
f();
}
self
}
}
/// Side-effect chaining on `Option`.
pub trait OptionEffect<T> {
/// Invoke `f` if `self` is `None`, returning `self`.
fn when_none<F: FnOnce()>(self, f: F) -> Self;
/// Invoke `f` if `self` is `Some`, returning `self`.
fn when_some<F: FnOnce()>(self, f: F) -> Self;
}
impl<T> OptionEffect<T> for Option<T> {
fn when_none<F: FnOnce()>(self, f: F) -> Self {
if self.is_none() {
f();
}
self
}
fn when_some<F: FnOnce()>(self, f: F) -> Self {
if self.is_some() {
f();
}
self
}
}

1629
query-algebrizer/src/cc.rs
View file

File diff suppressed because it is too large Load diff

593
query-algebrizer/src/clauses/mod.rs Normal file
View file

@ -0,0 +1,593 @@
// Copyright 2016 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::fmt::{
Debug,
Formatter,
};
use std::collections::{
BTreeMap,
BTreeSet,
HashSet,
};
use std::collections::btree_map::Entry;
use mentat_core::{
Attribute,
Entid,
Schema,
TypedValue,
ValueType,
};
use mentat_query::{
NamespacedKeyword,
NonIntegerConstant,
Pattern,
PatternNonValuePlace,
PatternValuePlace,
Variable,
WhereClause,
};
use errors::{
Result,
};
use types::{
ColumnConstraint,
ColumnIntersection,
DatomsColumn,
DatomsTable,
EmptyBecause,
QualifiedAlias,
QueryValue,
SourceAlias,
TableAlias,
};
mod or;
mod pattern;
mod predicate;
mod resolve;
use validate::validate_or_join;
/// A thing that's capable of aliasing a table name for us.
/// This exists so that we can obtain predictable names in tests.
pub type TableAliaser = Box<FnMut(DatomsTable) -> TableAlias>;
pub fn default_table_aliaser() -> TableAliaser {
let mut i = -1;
Box::new(move |table| {
i += 1;
format!("{}{:02}", table.name(), i)
})
}
fn unit_type_set(t: ValueType) -> HashSet<ValueType> {
let mut s = HashSet::with_capacity(1);
s.insert(t);
s
}
/// A `ConjoiningClauses` (CC) is a collection of clauses that are combined with `JOIN`.
/// The topmost form in a query is a `ConjoiningClauses`.
///
/// - Ordinary pattern clauses turn into `FROM` parts and `WHERE` parts using `=`.
/// - Predicate clauses turn into the same, but with other functions.
/// - `not` turns into `NOT EXISTS` with `WHERE` clauses inside the subquery to
/// bind it to the outer variables, or adds simple `WHERE` clauses to the outer
/// clause.
/// - `not-join` is similar, but with explicit binding.
/// - `or` turns into a collection of `UNION`s inside a subquery, or a simple
/// alternation.
/// `or`'s documentation states that all clauses must include the same vars,
/// but that's an over-simplification: all clauses must refer to the external
/// unification vars.
/// The entire `UNION`-set is `JOIN`ed to any surrounding expressions per the `rule-vars`
/// clause, or the intersection of the vars in the two sides of the `JOIN`.
///
/// Not yet done:
/// - Function clauses with bindings turn into:
/// * Subqueries. Perhaps less efficient? Certainly clearer.
/// * Projection expressions, if only used for output.
/// * Inline expressions?
///---------------------------------------------------------------------------------------
pub struct ConjoiningClauses {
/// `true` if this set of clauses cannot yield results in the context of the current schema.
pub is_known_empty: bool,
pub empty_because: Option<EmptyBecause>,
/// A function used to generate an alias for a table -- e.g., from "datoms" to "datoms123".
aliaser: TableAliaser,
/// A vector of source/alias pairs used to construct a SQL `FROM` list.
pub from: Vec<SourceAlias>,
/// A list of fragments that can be joined by `AND`.
pub wheres: ColumnIntersection,
/// A map from var to qualified columns. Used to project.
pub column_bindings: BTreeMap<Variable, Vec<QualifiedAlias>>,
/// A list of variables mentioned in the enclosing query's :in clause. These must all be bound
/// before the query can be executed. TODO: clarify what this means for nested CCs.
pub input_variables: BTreeSet<Variable>,
/// In some situations -- e.g., when a query is being run only once -- we know in advance the
/// values bound to some or all variables. These can be substituted directly when the query is
/// algebrized.
///
/// Value bindings must agree with `known_types`. If you write a query like
/// ```edn
/// [:find ?x :in $ ?val :where [?x :foo/int ?val]]
/// ```
///
/// and for `?val` provide `TypedValue::String("foo".to_string())`, the query will be known at
/// algebrizing time to be empty.
value_bindings: BTreeMap<Variable, TypedValue>,
/// A map from var to type. Whenever a var maps unambiguously to two different types, it cannot
/// yield results, so we don't represent that case here. If a var isn't present in the map, it
/// means that its type is not known in advance.
pub known_types: BTreeMap<Variable, HashSet<ValueType>>,
/// A mapping, similar to `column_bindings`, but used to pull type tags out of the store at runtime.
/// If a var isn't present in `known_types`, it should be present here.
extracted_types: BTreeMap<Variable, QualifiedAlias>,
}
impl Debug for ConjoiningClauses {
fn fmt(&self, fmt: &mut Formatter) -> ::std::fmt::Result {
fmt.debug_struct("ConjoiningClauses")
.field("is_known_empty", &self.is_known_empty)
.field("from", &self.from)
.field("wheres", &self.wheres)
.field("column_bindings", &self.column_bindings)
.field("input_variables", &self.input_variables)
.field("value_bindings", &self.value_bindings)
.field("known_types", &self.known_types)
.field("extracted_types", &self.extracted_types)
.finish()
}
}
/// Basics.
impl Default for ConjoiningClauses {
fn default() -> ConjoiningClauses {
ConjoiningClauses {
is_known_empty: false,
empty_because: None,
aliaser: default_table_aliaser(),
from: vec![],
wheres: ColumnIntersection::default(),
input_variables: BTreeSet::new(),
column_bindings: BTreeMap::new(),
value_bindings: BTreeMap::new(),
known_types: BTreeMap::new(),
extracted_types: BTreeMap::new(),
}
}
}
impl ConjoiningClauses {
#[allow(dead_code)]
fn with_value_bindings(bindings: BTreeMap<Variable, TypedValue>) -> ConjoiningClauses {
let mut cc = ConjoiningClauses {
value_bindings: bindings,
..Default::default()
};
// Pre-fill our type mappings with the types of the input bindings.
cc.known_types
.extend(cc.value_bindings.iter()
.map(|(k, v)| (k.clone(), unit_type_set(v.value_type()))));
cc
}
}
impl ConjoiningClauses {
fn bound_value(&self, var: &Variable) -> Option<TypedValue> {
self.value_bindings.get(var).cloned()
}
/// Return a single `ValueType` if the given variable is known to have a precise type.
/// Returns `None` if the type of the variable is unknown.
/// Returns `None` if the type of the variable is known but not precise -- "double
/// or integer" isn't good enough.
pub fn known_type(&self, var: &Variable) -> Option<ValueType> {
match self.known_types.get(var) {
Some(types) if types.len() == 1 => types.iter().next().cloned(),
_ => None,
}
}
pub fn bind_column_to_var(&mut self, schema: &Schema, table: TableAlias, column: DatomsColumn, var: Variable) {
// Do we have an external binding for this?
if let Some(bound_val) = self.bound_value(&var) {
// Great! Use that instead.
// We expect callers to do things like bind keywords here; we need to translate these
// before they hit our constraints.
// TODO: recognize when the valueType might be a ref and also translate entids there.
if column == DatomsColumn::Value {
self.constrain_column_to_constant(table, column, bound_val);
} else {
match bound_val {
TypedValue::Keyword(ref kw) => {
if let Some(entid) = self.entid_for_ident(schema, kw) {
self.constrain_column_to_entity(table, column, entid);
} else {
// Impossible.
// For attributes this shouldn't occur, because we check the binding in
// `table_for_places`/`alias_table`, and if it didn't resolve to a valid
// attribute then we should have already marked the pattern as empty.
self.mark_known_empty(EmptyBecause::UnresolvedIdent(kw.clone()));
}
},
TypedValue::Ref(entid) => {
self.constrain_column_to_entity(table, column, entid);
},
_ => {
// One can't bind an e, a, or tx to something other than an entity.
self.mark_known_empty(EmptyBecause::InvalidBinding(column, bound_val));
},
}
}
return;
}
// Will we have an external binding for this?
// If so, we don't need to extract its type. We'll know it later.
let late_binding = self.input_variables.contains(&var);
// If this is a value, and we don't already know its type or where
// to get its type, record that we can get it from this table.
let needs_type_extraction =
!late_binding && // Never need to extract for bound vars.
column == DatomsColumn::Value && // Never need to extract types for refs.
self.known_type(&var).is_none() && // Don't need to extract if we know a single type.
!self.extracted_types.contains_key(&var); // We're already extracting the type.
let alias = QualifiedAlias(table, column);
// If we subsequently find out its type, we'll remove this later -- see
// the removal in `constrain_var_to_type`.
if needs_type_extraction {
self.extracted_types.insert(var.clone(), alias.for_type_tag());
}
self.column_bindings.entry(var).or_insert(vec![]).push(alias);
}
pub fn constrain_column_to_constant(&mut self, table: TableAlias, column: DatomsColumn, constant: TypedValue) {
self.wheres.add_intersection(ColumnConstraint::Equals(QualifiedAlias(table, column), QueryValue::TypedValue(constant)))
}
pub fn constrain_column_to_entity(&mut self, table: TableAlias, column: DatomsColumn, entity: Entid) {
self.wheres.add_intersection(ColumnConstraint::Equals(QualifiedAlias(table, column), QueryValue::Entid(entity)))
}
pub fn constrain_attribute(&mut self, table: TableAlias, attribute: Entid) {
self.constrain_column_to_entity(table, DatomsColumn::Attribute, attribute)
}
pub fn constrain_value_to_numeric(&mut self, table: TableAlias, value: i64) {
self.wheres.add_intersection(ColumnConstraint::Equals(
QualifiedAlias(table, DatomsColumn::Value),
QueryValue::PrimitiveLong(value)))
}
/// Mark the given value as one of the set of numeric types.
fn constrain_var_to_numeric(&mut self, variable: Variable) {
let mut numeric_types = HashSet::with_capacity(2);
numeric_types.insert(ValueType::Double);
numeric_types.insert(ValueType::Long);
let entry = self.known_types.entry(variable);
match entry {
Entry::Vacant(vacant) => {
vacant.insert(numeric_types);
},
Entry::Occupied(mut occupied) => {
let narrowed: HashSet<ValueType> = numeric_types.intersection(occupied.get()).cloned().collect();
match narrowed.len() {
0 => {
// TODO: can't borrow as mutable more than once!
//self.mark_known_empty(EmptyBecause::TypeMismatch(occupied.key().clone(), occupied.get().clone(), ValueType::Double)); // I know…
},
1 => {
// Hooray!
self.extracted_types.remove(occupied.key());
},
_ => {
},
};
occupied.insert(narrowed);
},
}
}
/// Constrains the var if there's no existing type.
/// Marks as known-empty if it's impossible for this type to apply because there's a conflicting
/// type already known.
fn constrain_var_to_type(&mut self, variable: Variable, this_type: ValueType) {
// If this variable now has a known attribute, we can unhook extracted types for
// any other instances of that variable.
// For example, given
//
// ```edn
// [:find ?v :where [?x ?a ?v] [?y :foo/int ?v]]
// ```
//
// we will initially choose to extract the type tag for `?v`, but on encountering
// the second pattern we can avoid that.
self.extracted_types.remove(&variable);
// Is there an existing mapping for this variable?
// Any known inputs have already been added to known_types, and so if they conflict we'll
// spot it here.
if let Some(existing) = self.known_types.insert(variable.clone(), unit_type_set(this_type)) {
// There was an existing mapping. Does this type match?
if !existing.contains(&this_type) {
self.mark_known_empty(EmptyBecause::TypeMismatch(variable, existing, this_type));
}
}
}
/// Ensure that the given place has the correct types to be a tx-id.
/// Right now this is mostly unimplemented: we fail hard if anything but a placeholder is
/// present.
fn constrain_to_tx(&mut self, tx: &PatternNonValuePlace) {
match *tx {
PatternNonValuePlace::Placeholder => (),
_ => unimplemented!(), // TODO
}
}
/// Ensure that the given place can be an entity, and is congruent with existing types.
/// This is used for `entity` and `attribute` places in a pattern.
fn constrain_to_ref(&mut self, value: &PatternNonValuePlace) {
// If it's a variable, record that it has the right type.
// Ident or attribute resolution errors (the only other check we need to do) will be done
// by the caller.
if let &PatternNonValuePlace::Variable(ref v) = value {
self.constrain_var_to_type(v.clone(), ValueType::Ref)
}
}
fn mark_known_empty(&mut self, why: EmptyBecause) {
self.is_known_empty = true;
if self.empty_because.is_some() {
return;
}
println!("CC known empty: {:?}.", &why); // TODO: proper logging.
self.empty_because = Some(why);
}
fn entid_for_ident<'s, 'a>(&self, schema: &'s Schema, ident: &'a NamespacedKeyword) -> Option<Entid> {
schema.get_entid(&ident)
}
fn table_for_attribute_and_value<'s, 'a>(&self, attribute: &'s Attribute, value: &'a PatternValuePlace) -> ::std::result::Result<DatomsTable, EmptyBecause> {
if attribute.fulltext {
match value {
&PatternValuePlace::Placeholder =>
Ok(DatomsTable::Datoms), // We don't need the value.
// TODO: an existing non-string binding can cause this pattern to fail.
&PatternValuePlace::Variable(_) =>
Ok(DatomsTable::AllDatoms),
&PatternValuePlace::Constant(NonIntegerConstant::Text(_)) =>
Ok(DatomsTable::AllDatoms),
_ => {
// We can't succeed if there's a non-string constant value for a fulltext
// field.
Err(EmptyBecause::NonStringFulltextValue)
},
}
} else {
Ok(DatomsTable::Datoms)
}
}
fn table_for_unknown_attribute<'s, 'a>(&self, value: &'a PatternValuePlace) -> ::std::result::Result<DatomsTable, EmptyBecause> {
// If the value is known to be non-textual, we can simply use the regular datoms
// table (TODO: and exclude on `index_fulltext`!).
//
// If the value is a placeholder too, then we can walk the non-value-joined view,
// because we don't care about retrieving the fulltext value.
//
// If the value is a variable or string, we must use `all_datoms`, or do the join
// ourselves, because we'll need to either extract or compare on the string.
Ok(
match value {
// TODO: see if the variable is projected, aggregated, or compared elsewhere in
// the query. If it's not, we don't need to use all_datoms here.
&PatternValuePlace::Variable(ref v) => {
// Do we know that this variable can't be a string? If so, we don't need
// AllDatoms. None or String means it could be or definitely is.
match self.known_types.get(v).map(|types| types.contains(&ValueType::String)) {
Some(false) => DatomsTable::Datoms,
_ => DatomsTable::AllDatoms,
}
}
&PatternValuePlace::Constant(NonIntegerConstant::Text(_)) =>
DatomsTable::AllDatoms,
_ =>
DatomsTable::Datoms,
})
}
/// Decide which table to use for the provided attribute and value.
/// If the attribute input or value binding doesn't name an attribute, or doesn't name an
/// attribute that is congruent with the supplied value, we return an `EmptyBecause`.
/// The caller is responsible for marking the CC as known-empty if this is a fatal failure.
fn table_for_places<'s, 'a>(&self, schema: &'s Schema, attribute: &'a PatternNonValuePlace, value: &'a PatternValuePlace) -> ::std::result::Result<DatomsTable, EmptyBecause> {
match attribute {
&PatternNonValuePlace::Ident(ref kw) =>
schema.attribute_for_ident(kw)
.ok_or_else(|| EmptyBecause::InvalidAttributeIdent(kw.clone()))
.and_then(|attribute| self.table_for_attribute_and_value(attribute, value)),
&PatternNonValuePlace::Entid(id) =>
schema.attribute_for_entid(id)
.ok_or_else(|| EmptyBecause::InvalidAttributeEntid(id))
.and_then(|attribute| self.table_for_attribute_and_value(attribute, value)),
// TODO: In a prepared context, defer this decision until a second algebrizing phase.
// #278.
&PatternNonValuePlace::Placeholder =>
self.table_for_unknown_attribute(value),
&PatternNonValuePlace::Variable(ref v) => {
// See if we have a binding for the variable.
match self.bound_value(v) {
// TODO: In a prepared context, defer this decision until a second algebrizing phase.
// #278.
None =>
self.table_for_unknown_attribute(value),
Some(TypedValue::Ref(id)) =>
// Recurse: it's easy.
self.table_for_places(schema, &PatternNonValuePlace::Entid(id), value),
Some(TypedValue::Keyword(ref kw)) =>
// Don't recurse: avoid needing to clone the keyword.
schema.attribute_for_ident(kw)
.ok_or_else(|| EmptyBecause::InvalidAttributeIdent(kw.clone()))
.and_then(|attribute| self.table_for_attribute_and_value(attribute, value)),
Some(v) => {
// This pattern cannot match: the caller has bound a non-entity value to an
// attribute place.
Err(EmptyBecause::InvalidBinding(DatomsColumn::Attribute, v.clone()))
},
}
},
}
}
/// Produce a (table, alias) pair to handle the provided pattern.
/// This is a mutating method because it mutates the aliaser function!
/// Note that if this function decides that a pattern cannot match, it will flip
/// `is_known_empty`.
fn alias_table<'s, 'a>(&mut self, schema: &'s Schema, pattern: &'a Pattern) -> Option<SourceAlias> {
self.table_for_places(schema, &pattern.attribute, &pattern.value)
.map_err(|reason| {
self.mark_known_empty(reason);
})
.map(|table| SourceAlias(table, (self.aliaser)(table)))
.ok()
}
fn get_attribute<'s, 'a>(&self, schema: &'s Schema, pattern: &'a Pattern) -> Option<&'s Attribute> {
match pattern.attribute {
PatternNonValuePlace::Entid(id) =>
schema.attribute_for_entid(id),
PatternNonValuePlace::Ident(ref kw) =>
schema.attribute_for_ident(kw),
_ =>
None,
}
}
fn get_value_type<'s, 'a>(&self, schema: &'s Schema, pattern: &'a Pattern) -> Option<ValueType> {
self.get_attribute(schema, pattern).map(|x| x.value_type)
}
}
/// Expansions.
impl ConjoiningClauses {
/// Take the contents of `column_bindings` and generate inter-constraints for the appropriate
/// columns into `wheres`.
///
/// For example, a bindings map associating a var to three places in the query, like
///
/// ```edn
/// {?foo [datoms12.e datoms13.v datoms14.e]}
/// ```
///
/// produces two additional constraints:
///
/// ```example
/// datoms12.e = datoms13.v
/// datoms12.e = datoms14.e
/// ```
pub fn expand_column_bindings(&mut self) {
for cols in self.column_bindings.values() {
if cols.len() > 1 {
let ref primary = cols[0];
let secondaries = cols.iter().skip(1);
for secondary in secondaries {
// TODO: if both primary and secondary are .v, should we make sure
// the type tag columns also match?
// We don't do so in the ClojureScript version.
self.wheres.add_intersection(ColumnConstraint::Equals(primary.clone(), QueryValue::Column(secondary.clone())));
}
}
}
}
/// When a CC has accumulated all patterns, generate value_type_tag entries in `wheres`
/// to refine value types for which two things are true:
///
/// - There are two or more different types with the same SQLite representation. E.g.,
/// ValueType::Boolean shares a representation with Integer and Ref.
/// - There is no attribute constraint present in the CC.
///
/// It's possible at this point for the space of acceptable type tags to not intersect: e.g.,
/// for the query
///
/// ```edn
/// [:find ?x :where
/// [?x ?y true]
/// [?z ?y ?x]]
/// ```
///
/// where `?y` must simultaneously be a ref-typed attribute and a boolean-typed attribute. This
/// function deduces that and calls `self.mark_known_empty`. #293.
pub fn expand_type_tags(&mut self) {
// TODO.
}
}
impl ConjoiningClauses {
// This is here, rather than in `lib.rs`, because it's recursive: `or` can contain `or`,
// and so on.
pub fn apply_clause(&mut self, schema: &Schema, where_clause: WhereClause) -> Result<()> {
match where_clause {
WhereClause::Pattern(p) => {
self.apply_pattern(schema, p);
Ok(())
},
WhereClause::Pred(p) => {
self.apply_predicate(schema, p)
},
WhereClause::OrJoin(o) => {
validate_or_join(&o)
//?;
//self.apply_or_join(schema, o)
},
_ => unimplemented!(),
}
}
}
// These are helpers that tests use to build Schema instances.
#[cfg(test)]
fn associate_ident(schema: &mut Schema, i: NamespacedKeyword, e: Entid) {
schema.entid_map.insert(e, i.clone());
schema.ident_map.insert(i.clone(), e);
}
#[cfg(test)]
fn add_attribute(schema: &mut Schema, e: Entid, a: Attribute) {
schema.schema_map.insert(e, a);
}

383
query-algebrizer/src/clauses/or.rs Normal file
View file

@ -0,0 +1,383 @@
// Copyright 2016 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.
// WIP
#![allow(dead_code, unused_imports, unused_variables)]
use mentat_core::{
Entid,
Schema,
TypedValue,
ValueType,
};
use mentat_query::{
NonIntegerConstant,
OrJoin,
OrWhereClause,
Pattern,
PatternValuePlace,
PatternNonValuePlace,
PlainSymbol,
Predicate,
SrcVar,
UnifyVars,
WhereClause,
};
use clauses::ConjoiningClauses;
use errors::{
Result,
Error,
ErrorKind,
};
use types::{
ColumnConstraint,
ColumnIntersection,
DatomsColumn,
DatomsTable,
EmptyBecause,
NumericComparison,
QualifiedAlias,
QueryValue,
SourceAlias,
TableAlias,
};
/// Return true if both left and right are the same variable or both are non-variable.
fn _simply_matches_place(left: &PatternNonValuePlace, right: &PatternNonValuePlace) -> bool {
match (left, right) {
(&PatternNonValuePlace::Variable(ref a), &PatternNonValuePlace::Variable(ref b)) => a == b,
(&PatternNonValuePlace::Placeholder, &PatternNonValuePlace::Placeholder) => true,
(&PatternNonValuePlace::Entid(_), &PatternNonValuePlace::Entid(_)) => true,
(&PatternNonValuePlace::Entid(_), &PatternNonValuePlace::Ident(_)) => true,
(&PatternNonValuePlace::Ident(_), &PatternNonValuePlace::Ident(_)) => true,
(&PatternNonValuePlace::Ident(_), &PatternNonValuePlace::Entid(_)) => true,
_ => false,
}
}
/// Return true if both left and right are the same variable or both are non-variable.
fn _simply_matches_value_place(left: &PatternValuePlace, right: &PatternValuePlace) -> bool {
match (left, right) {
(&PatternValuePlace::Variable(ref a), &PatternValuePlace::Variable(ref b)) => a == b,
(&PatternValuePlace::Placeholder, &PatternValuePlace::Placeholder) => true,
(&PatternValuePlace::Variable(_), _) => false,
(_, &PatternValuePlace::Variable(_)) => false,
(&PatternValuePlace::Placeholder, _) => false,
(_, &PatternValuePlace::Placeholder) => false,
_ => true,
}
}
pub enum DeconstructedOrJoin {
KnownSuccess,
KnownEmpty(EmptyBecause),
Unit(OrWhereClause),
UnitPattern(Pattern),
Simple(Vec<Pattern>),
Complex(OrJoin),
}
/// Application of `or`. Note that this is recursive!
impl ConjoiningClauses {
fn apply_or_where_clause(&mut self, schema: &Schema, clause: OrWhereClause) -> Result<()> {
match clause {
OrWhereClause::Clause(clause) => self.apply_clause(schema, clause),
// A query might be:
// [:find ?x :where (or (and [?x _ 5] [?x :foo/bar 7]))]
// which is equivalent to dropping the `or` _and_ the `and`!
OrWhereClause::And(clauses) => {
for clause in clauses {
self.apply_clause(schema, clause)?;
}
Ok(())
},
}
}
fn apply_or_join(&mut self, schema: &Schema, mut or_join: OrJoin) -> Result<()> {
// Simple optimization. Empty `or` clauses disappear. Unit `or` clauses
// are equivalent to just the inner clause.
match or_join.clauses.len() {
0 => Ok(()),
1 => self.apply_or_where_clause(schema, or_join.clauses.pop().unwrap()),
_ => self.apply_non_trivial_or_join(schema, or_join),
}
}
/// Find out if the `OrJoin` is simple. A simple `or` is one in
/// which:
/// - Every arm is a pattern, so that we can use a single table alias for all.
/// - Each pattern should run against the same table, for the same reason.
/// - Each pattern uses the same variables. (That's checked by validation.)
/// - Each pattern has the same shape, so we can extract bindings from the same columns
/// regardless of which clause matched.
///
/// Like this:
///
/// ```edn
/// [:find ?x
/// :where (or [?x :foo/knows "John"]
/// [?x :foo/parent "Ámbar"]
/// [?x :foo/knows "Daphne"])]
/// ```
///
/// While we're doing this diagnosis, we'll also find out if:
/// - No patterns can match: the enclosing CC is known-empty.
/// - Some patterns can't match: they are discarded.
/// - Only one pattern can match: the `or` can be simplified away.
fn deconstruct_or_join(&self, schema: &Schema, or_join: OrJoin) -> DeconstructedOrJoin {
// If we have explicit non-maximal unify-vars, we *can't* simply run this as a
// single pattern --
// ```
// [:find ?x :where [?x :foo/bar ?y] (or-join [?x] [?x :foo/baz ?y])]
// ```
// is *not* equivalent to
// ```
// [:find ?x :where [?x :foo/bar ?y] [?x :foo/baz ?y]]
// ```
if !or_join.is_fully_unified() {
// It's complex because we need to make sure that non-unified vars
// mentioned in the body of the `or-join` do not unify with variables
// outside the `or-join`. We can't naïvely collect clauses into the
// same CC. TODO: pay attention to the unify list when generating
// constraints. Temporarily shadow variables within each `or` branch.
return DeconstructedOrJoin::Complex(or_join);
}
match or_join.clauses.len() {
0 => DeconstructedOrJoin::KnownSuccess,
// It's safe to simply 'leak' the entire clause, because we know every var in it is
// supposed to unify with the enclosing form.
1 => DeconstructedOrJoin::Unit(or_join.clauses.into_iter().next().unwrap()),
_ => self._deconstruct_or_join(schema, or_join),
}
}
/// This helper does the work of taking a known-non-trivial `or` or `or-join`,
/// walking the contained patterns to decide whether it can be translated simply
/// -- as a collection of constraints on a single table alias -- or if it needs to
/// be implemented as a `UNION`.
///
/// See the description of `deconstruct_or_join` for more details. This method expects
/// to be called _only_ by `deconstruct_or_join`.
fn _deconstruct_or_join(&self, schema: &Schema, or_join: OrJoin) -> DeconstructedOrJoin {
// Preconditions enforced by `deconstruct_or_join`.
assert_eq!(or_join.unify_vars, UnifyVars::Implicit);
assert!(or_join.clauses.len() >= 2);
// We're going to collect into this.
// If at any point we hit something that's not a suitable pattern, we'll
// reconstruct and return a complex `OrJoin`.
let mut patterns: Vec<Pattern> = Vec::with_capacity(or_join.clauses.len());
// Keep track of the table we need every pattern to use.
let mut expected_table: Option<DatomsTable> = None;
// Technically we might have several reasons, but we take the last -- that is, that's the
// reason we don't have at least one pattern!
// We'll return this as our reason if no pattern can return results.
let mut empty_because: Option<EmptyBecause> = None;
// Walk each clause in turn, bailing as soon as we know this can't be simple.
let mut clauses = or_join.clauses.into_iter();
while let Some(clause) = clauses.next() {
// If we fail half-way through processing, we want to reconstitute the input.
// Keep a handle to the clause itself here to smooth over the moved `if let` below.
let last: OrWhereClause;
if let OrWhereClause::Clause(WhereClause::Pattern(p)) = clause {
// Compute the table for the pattern. If we can't figure one out, it means
// the pattern cannot succeed; we drop it.
// Inside an `or` it's not a failure for a pattern to be unable to match, which
// manifests as a table being unable to be found.
let table = self.table_for_places(schema, &p.attribute, &p.value);
match table {
Err(e) => {
empty_because = Some(e);
// Do not accumulate this pattern at all. Add lightness!
continue;
},
Ok(table) => {
// Check the shape of the pattern against a previous pattern.
let same_shape =
if let Some(template) = patterns.get(0) {
template.source == p.source && // or-arms all use the same source anyway.
_simply_matches_place(&template.entity, &p.entity) &&
_simply_matches_place(&template.attribute, &p.attribute) &&
_simply_matches_value_place(&template.value, &p.value) &&
_simply_matches_place(&template.tx, &p.tx)
} else {
// No previous pattern.
true
};
// All of our clauses that _do_ yield a table -- that are possible --
// must use the same table in order for this to be a simple `or`!
if same_shape {
if expected_table == Some(table) {
patterns.push(p);
continue;
}
if expected_table.is_none() {
expected_table = Some(table);
patterns.push(p);
continue;
}
}
// Otherwise, we need to keep this pattern so we can reconstitute.
// We'll fall through to reconstruction.
}
}
last = OrWhereClause::Clause(WhereClause::Pattern(p));
} else {
last = clause;
}
// If we get here, it means one of our checks above failed. Reconstruct and bail.
let reconstructed: Vec<OrWhereClause> =
// Non-empty patterns already collected…
patterns.into_iter()
.map(|p| OrWhereClause::Clause(WhereClause::Pattern(p)))
// … then the clause we just considered…
.chain(::std::iter::once(last))
// … then the rest of the iterator.
.chain(clauses)
.collect();
return DeconstructedOrJoin::Complex(OrJoin {
unify_vars: UnifyVars::Implicit,
clauses: reconstructed,
});
}
// If we got here without returning, then `patterns` is what we're working with.
// If `patterns` is empty, it means _none_ of the clauses in the `or` could succeed.
match patterns.len() {
0 => {
assert!(empty_because.is_some());
DeconstructedOrJoin::KnownEmpty(empty_because.unwrap())
},
1 => DeconstructedOrJoin::UnitPattern(patterns.pop().unwrap()),
_ => DeconstructedOrJoin::Simple(patterns),
}
}
/// Only call this with an `or_join` with 2 or more patterns.
fn apply_non_trivial_or_join(&mut self, schema: &Schema, or_join: OrJoin) -> Result<()> {
assert!(or_join.clauses.len() >= 2);
match self.deconstruct_or_join(schema, or_join) {
DeconstructedOrJoin::KnownSuccess => {
// The pattern came to us empty -- `(or)`. Do nothing.
Ok(())
},
DeconstructedOrJoin::KnownEmpty(reason) => {
// There were no arms of the join that could be mapped to a table.
// The entire `or`, and thus the CC, cannot yield results.
self.mark_known_empty(reason);
Ok(())
},
DeconstructedOrJoin::Unit(clause) => {
// There was only one clause. We're unifying all variables, so we can just apply here.
self.apply_or_where_clause(schema, clause)
},
DeconstructedOrJoin::UnitPattern(pattern) => {
// Same, but simpler.
self.apply_pattern(schema, pattern);
Ok(())
},
DeconstructedOrJoin::Simple(patterns) => {
// Hooray! Fully unified and plain ol' patterns that all use the same table.
// Go right ahead and produce a set of constraint alternations that we can collect,
// using a single table alias.
// TODO
self.apply_simple_or_join(schema, patterns)
},
DeconstructedOrJoin::Complex(_) => {
// Do this the hard way. TODO
unimplemented!();
},
}
}
/// A simple `or` join is effectively a single pattern in which an individual column's bindings
/// are not a single value. Rather than a pattern like
///
/// ```edn
/// [?x :foo/knows "John"]
/// ```
///
/// we have
///
/// ```edn
/// (or [?x :foo/knows "John"]
/// [?x :foo/hates "Peter"])
/// ```
///
/// but the generated SQL is very similar: the former is
///
/// ```sql
/// WHERE datoms00.a = 99 AND datoms00.v = 'John'
/// ```
///
/// with the latter growing to
///
/// ```sql
/// WHERE (datoms00.a = 99 AND datoms00.v = 'John')
/// OR (datoms00.a = 98 AND datoms00.v = 'Peter')
/// ```
///
fn apply_simple_or_join(&mut self, schema: &Schema, patterns: Vec<Pattern>) -> Result<()> {
assert!(patterns.len() >= 2);
// Each constant attribute might _expand_ the set of possible types of the value-place
// variable. We thus generate a set of possible types, and we intersect it with the
// types already possible in the CC. If the resultant set is empty, the pattern cannot match.
// If the final set isn't unit, we must project a type tag column.
// If one of the alternations requires a type that is impossible in the CC, then we can
// discard that alternate:
//
// ```edn
// [:find ?x
// :where [?a :some/int ?x]
// (or [_ :some/otherint ?x]
// [_ :some/string ?x])]
// ```
//
// can simplify to
//
// ```edn
// [:find ?x
// :where [?a :some/int ?x]
// [_ :some/otherint ?x]]
// ```
//
// Similarly, if the value place is constant, it must be of a type that doesn't determine
// a different table for any of the patterns.
// TODO
// Begin by building a base CC that we'll use to produce constraints from each pattern.
// Populate this base CC with whatever variables are already known from the CC to which
// we're applying this `or`.
// This will give us any applicable type constraints or column mappings.
// Then generate a single table alias, based on the first pattern, and use that to make any
// new variable mappings we will need to extract values.
Ok(())
}
}

814
query-algebrizer/src/clauses/pattern.rs Normal file
View file

@ -0,0 +1,814 @@
// Copyright 2016 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::{
Schema,
TypedValue,
ValueType,
};
use mentat_query::{
Pattern,
PatternValuePlace,
PatternNonValuePlace,
SrcVar,
};
use clauses::ConjoiningClauses;
use types::{
ColumnConstraint,
DatomsColumn,
EmptyBecause,
SourceAlias,
};
/// Application of patterns.
impl ConjoiningClauses {
/// Apply the constraints in the provided pattern to this CC.
///
/// This is a single-pass process, which means it is naturally incomplete, failing to take into
/// account all information spread across two patterns.
///
/// If the constraints cannot be satisfied -- for example, if this pattern includes a numeric
/// attribute and a string value -- then the `is_known_empty` field on the CC is flipped and
/// the function returns.
///
/// A pattern being impossible to satisfy isn't necessarily a bad thing -- this query might
/// have branched clauses that apply to different knowledge bases, and might refer to
/// vocabulary that isn't (yet) used in this one.
///
/// Most of the work done by this function depends on the schema and ident maps in the DB. If
/// these change, then any work done is invalid.
///
/// There's a lot more we can do here and later by examining the
/// attribute:
///
/// - If it's unique, and we have patterns like
///
/// [?x :foo/unique 5] [?x :foo/unique ?y]
///
/// then we can either prove impossibility (the two objects must
/// be equal) or deduce identity and simplify the query.
///
/// - The same, if it's cardinality-one and the entity is known.
///
/// - If there's a value index on this attribute, we might want to
/// run this pattern early in the query.
///
/// - A unique-valued attribute can sometimes be rewritten into an
/// existence subquery instead of a join.
fn apply_pattern_clause_for_alias<'s>(&mut self, schema: &'s Schema, pattern: &Pattern, alias: &SourceAlias) {
if self.is_known_empty {
return;
}
// Process each place in turn, applying constraints.
// Both `e` and `a` must be entities, which is equivalent here
// to being typed as Ref.
// Sorry for the duplication; Rust makes it a pain to abstract this.
// The transaction part of a pattern must be an entid, variable, or placeholder.
self.constrain_to_tx(&pattern.tx);
self.constrain_to_ref(&pattern.entity);
self.constrain_to_ref(&pattern.attribute);
let ref col = alias.1;
match pattern.entity {
PatternNonValuePlace::Placeholder =>
// Placeholders don't contribute any column bindings, nor do
// they constrain the query -- there's no need to produce
// IS NOT NULL, because we don't store nulls in our schema.
(),
PatternNonValuePlace::Variable(ref v) =>
self.bind_column_to_var(schema, col.clone(), DatomsColumn::Entity, v.clone()),
PatternNonValuePlace::Entid(entid) =>
self.constrain_column_to_entity(col.clone(), DatomsColumn::Entity, entid),
PatternNonValuePlace::Ident(ref ident) => {
if let Some(entid) = self.entid_for_ident(schema, ident) {
self.constrain_column_to_entity(col.clone(), DatomsColumn::Entity, entid)
} else {
// A resolution failure means we're done here.
self.mark_known_empty(EmptyBecause::UnresolvedIdent(ident.clone()));
return;
}
}
}
match pattern.attribute {
PatternNonValuePlace::Placeholder =>
(),
PatternNonValuePlace::Variable(ref v) =>
self.bind_column_to_var(schema, col.clone(), DatomsColumn::Attribute, v.clone()),
PatternNonValuePlace::Entid(entid) => {
if !schema.is_attribute(entid) {
// Furthermore, that entid must resolve to an attribute. If it doesn't, this
// query is meaningless.
self.mark_known_empty(EmptyBecause::InvalidAttributeEntid(entid));
return;
}
self.constrain_attribute(col.clone(), entid)
},
PatternNonValuePlace::Ident(ref ident) => {
if let Some(entid) = self.entid_for_ident(schema, ident) {
self.constrain_attribute(col.clone(), entid);
if !schema.is_attribute(entid) {
self.mark_known_empty(EmptyBecause::InvalidAttributeIdent(ident.clone()));
return;
}
} else {
// A resolution failure means we're done here.
self.mark_known_empty(EmptyBecause::UnresolvedIdent(ident.clone()));
return;
}
}
}
// Determine if the pattern's value type is known.
// We do so by examining the value place and the attribute.
// At this point it's possible that the type of the value is
// inconsistent with the attribute; in that case this pattern
// cannot return results, and we short-circuit.
let value_type = self.get_value_type(schema, pattern);
match pattern.value {
PatternValuePlace::Placeholder =>
(),
PatternValuePlace::Variable(ref v) => {
if let Some(this_type) = value_type {
// Wouldn't it be nice if we didn't need to clone in the found case?
// It doesn't matter too much: collisons won't be too frequent.
self.constrain_var_to_type(v.clone(), this_type);
if self.is_known_empty {
return;
}
}
self.bind_column_to_var(schema, col.clone(), DatomsColumn::Value, v.clone());
},
PatternValuePlace::EntidOrInteger(i) =>
// If we know the valueType, then we can determine whether this is an entid or an
// integer. If we don't, then we must generate a more general query with a
// value_type_tag.
if let Some(ValueType::Ref) = value_type {
self.constrain_column_to_entity(col.clone(), DatomsColumn::Value, i);
} else {
// If we have a pattern like:
//
// `[123 ?a 1]`
//
// then `1` could be an entid (ref), a long, a boolean, or an instant.
//
// We represent these constraints during execution:
//
// - Constraining the value column to the plain numeric value '1'.
// - Constraining its type column to one of a set of types.
//
self.constrain_value_to_numeric(col.clone(), i);
},
PatternValuePlace::IdentOrKeyword(ref kw) => {
// If we know the valueType, then we can determine whether this is an ident or a
// keyword. If we don't, then we must generate a more general query with a
// value_type_tag.
// We can also speculatively try to resolve it as an ident; if we fail, then we
// know it can only return results if treated as a keyword, and we can treat it as
// such.
if let Some(ValueType::Ref) = value_type {
if let Some(entid) = self.entid_for_ident(schema, kw) {
self.constrain_column_to_entity(col.clone(), DatomsColumn::Value, entid)
} else {
// A resolution failure means we're done here: this attribute must have an
// entity value.
self.mark_known_empty(EmptyBecause::UnresolvedIdent(kw.clone()));
return;
}
} else {
// It must be a keyword.
self.constrain_column_to_constant(col.clone(), DatomsColumn::Value, TypedValue::Keyword(kw.clone()));
self.wheres.add_intersection(ColumnConstraint::HasType(col.clone(), ValueType::Keyword));
};
},
PatternValuePlace::Constant(ref c) => {
// TODO: don't allocate.
let typed_value = c.clone().into_typed_value();
if !typed_value.is_congruent_with(value_type) {
// If the attribute and its value don't match, the pattern must fail.
// We can never have a congruence failure if `value_type` is `None`, so we
// forcibly unwrap here.
let value_type = value_type.expect("Congruence failure but couldn't unwrap");
let why = EmptyBecause::ValueTypeMismatch(value_type, typed_value);
self.mark_known_empty(why);
return;
}
// TODO: if we don't know the type of the attribute because we don't know the
// attribute, we can actually work backwards to the set of appropriate attributes
// from the type of the value itself! #292.
let typed_value_type = typed_value.value_type();
self.constrain_column_to_constant(col.clone(), DatomsColumn::Value, typed_value);
// If we can't already determine the range of values in the DB from the attribute,
// then we must also constrain the type tag.
//
// Input values might be:
//
// - A long. This is handled by EntidOrInteger.
// - A boolean. This is unambiguous.
// - A double. This is currently unambiguous, though note that SQLite will equate 5.0 with 5.
// - A string. This is unambiguous.
// - A keyword. This is unambiguous.
//
// Because everything we handle here is unambiguous, we generate a single type
// restriction from the value type of the typed value.
if value_type.is_none() {
self.wheres.add_intersection(ColumnConstraint::HasType(col.clone(), typed_value_type));
}
},
}
}
pub fn apply_pattern<'s, 'p>(&mut self, schema: &'s Schema, pattern: Pattern) {
// For now we only support the default source.
match pattern.source {
Some(SrcVar::DefaultSrc) | None => (),
_ => unimplemented!(),
};
if let Some(alias) = self.alias_table(schema, &pattern) {
self.apply_pattern_clause_for_alias(schema, &pattern, &alias);
self.from.push(alias);
} else {
// We didn't determine a table, likely because there was a mismatch
// between an attribute and a value.
// We know we cannot return a result, so we short-circuit here.
self.mark_known_empty(EmptyBecause::AttributeLookupFailed);
return;
}
}
}
#[cfg(test)]
mod testing {
use super::*;
use std::collections::BTreeMap;
use mentat_core::attribute::Unique;
use mentat_core::{
Attribute,
};
use mentat_query::{
NamespacedKeyword,
NonIntegerConstant,
PlainSymbol,
Variable,
};
use clauses::{
add_attribute,
associate_ident,
unit_type_set,
};
use types::{
ColumnConstraint,
DatomsTable,
QualifiedAlias,
QueryValue,
SourceAlias,
};
#[test]
fn test_unknown_ident() {
let mut cc = ConjoiningClauses::default();
let schema = Schema::default();
cc.apply_pattern(&schema, Pattern {
source: None,
entity: PatternNonValuePlace::Variable(Variable(PlainSymbol::new("?x"))),
attribute: PatternNonValuePlace::Ident(NamespacedKeyword::new("foo", "bar")),
value: PatternValuePlace::Constant(NonIntegerConstant::Boolean(true)),
tx: PatternNonValuePlace::Placeholder,
});
assert!(cc.is_known_empty);
}
#[test]
fn test_unknown_attribute() {
let mut cc = ConjoiningClauses::default();
let mut schema = Schema::default();
associate_ident(&mut schema, NamespacedKeyword::new("foo", "bar"), 99);
cc.apply_pattern(&schema, Pattern {
source: None,
entity: PatternNonValuePlace::Variable(Variable(PlainSymbol::new("?x"))),
attribute: PatternNonValuePlace::Ident(NamespacedKeyword::new("foo", "bar")),
value: PatternValuePlace::Constant(NonIntegerConstant::Boolean(true)),
tx: PatternNonValuePlace::Placeholder,
});
assert!(cc.is_known_empty);
}
#[test]
fn test_apply_simple_pattern() {
let mut cc = ConjoiningClauses::default();
let mut schema = Schema::default();
associate_ident(&mut schema, NamespacedKeyword::new("foo", "bar"), 99);
add_attribute(&mut schema, 99, Attribute {
value_type: ValueType::Boolean,
..Default::default()
});
let x = Variable(PlainSymbol::new("?x"));
cc.apply_pattern(&schema, Pattern {
source: None,
entity: PatternNonValuePlace::Variable(x.clone()),
attribute: PatternNonValuePlace::Ident(NamespacedKeyword::new("foo", "bar")),
value: PatternValuePlace::Constant(NonIntegerConstant::Boolean(true)),
tx: PatternNonValuePlace::Placeholder,
});
// println!("{:#?}", cc);
let d0_e = QualifiedAlias("datoms00".to_string(), DatomsColumn::Entity);
let d0_a = QualifiedAlias("datoms00".to_string(), DatomsColumn::Attribute);
let d0_v = QualifiedAlias("datoms00".to_string(), DatomsColumn::Value);
// After this, we know a lot of things:
assert!(!cc.is_known_empty);
assert_eq!(cc.from, vec![SourceAlias(DatomsTable::Datoms, "datoms00".to_string())]);
// ?x must be a ref.
assert_eq!(cc.known_type(&x).unwrap(), ValueType::Ref);
// ?x is bound to datoms0.e.
assert_eq!(cc.column_bindings.get(&x).unwrap(), &vec![d0_e.clone()]);
// Our 'where' clauses are two:
// - datoms0.a = 99
// - datoms0.v = true
// No need for a type tag constraint, because the attribute is known.
assert_eq!(cc.wheres, vec![
ColumnConstraint::Equals(d0_a, QueryValue::Entid(99)),
ColumnConstraint::Equals(d0_v, QueryValue::TypedValue(TypedValue::Boolean(true))),
].into());
}
#[test]
fn test_apply_unattributed_pattern() {
let mut cc = ConjoiningClauses::default();
let schema = Schema::default();
let x = Variable(PlainSymbol::new("?x"));
cc.apply_pattern(&schema, Pattern {
source: None,
entity: PatternNonValuePlace::Variable(x.clone()),
attribute: PatternNonValuePlace::Placeholder,
value: PatternValuePlace::Constant(NonIntegerConstant::Boolean(true)),
tx: PatternNonValuePlace::Placeholder,
});
// println!("{:#?}", cc);
let d0_e = QualifiedAlias("datoms00".to_string(), DatomsColumn::Entity);
let d0_v = QualifiedAlias("datoms00".to_string(), DatomsColumn::Value);
assert!(!cc.is_known_empty);
assert_eq!(cc.from, vec![SourceAlias(DatomsTable::Datoms, "datoms00".to_string())]);
// ?x must be a ref.
assert_eq!(cc.known_type(&x).unwrap(), ValueType::Ref);
// ?x is bound to datoms0.e.
assert_eq!(cc.column_bindings.get(&x).unwrap(), &vec![d0_e.clone()]);
// Our 'where' clauses are two:
// - datoms0.v = true
// - datoms0.value_type_tag = boolean
// TODO: implement expand_type_tags.
assert_eq!(cc.wheres, vec![
ColumnConstraint::Equals(d0_v, QueryValue::TypedValue(TypedValue::Boolean(true))),
ColumnConstraint::HasType("datoms00".to_string(), ValueType::Boolean),
].into());
}
/// This test ensures that we do less work if we know the attribute thanks to a var lookup.
#[test]
fn test_apply_unattributed_but_bound_pattern_with_returned() {
let mut cc = ConjoiningClauses::default();
let mut schema = Schema::default();
associate_ident(&mut schema, NamespacedKeyword::new("foo", "bar"), 99);
add_attribute(&mut schema, 99, Attribute {
value_type: ValueType::Boolean,
..Default::default()
});
let x = Variable(PlainSymbol::new("?x"));
let a = Variable(PlainSymbol::new("?a"));
let v = Variable(PlainSymbol::new("?v"));
cc.input_variables.insert(a.clone());
cc.value_bindings.insert(a.clone(), TypedValue::Keyword(NamespacedKeyword::new("foo", "bar")));
cc.apply_pattern(&schema, Pattern {
source: None,
entity: PatternNonValuePlace::Variable(x.clone()),
attribute: PatternNonValuePlace::Variable(a.clone()),
value: PatternValuePlace::Variable(v.clone()),
tx: PatternNonValuePlace::Placeholder,
});
// println!("{:#?}", cc);
let d0_e = QualifiedAlias("datoms00".to_string(), DatomsColumn::Entity);
let d0_a = QualifiedAlias("datoms00".to_string(), DatomsColumn::Attribute);
assert!(!cc.is_known_empty);
assert_eq!(cc.from, vec![SourceAlias(DatomsTable::Datoms, "datoms00".to_string())]);
// ?x must be a ref.
assert_eq!(cc.known_type(&x).unwrap(), ValueType::Ref);
// ?x is bound to datoms0.e.
assert_eq!(cc.column_bindings.get(&x).unwrap(), &vec![d0_e.clone()]);
assert_eq!(cc.wheres, vec![
ColumnConstraint::Equals(d0_a, QueryValue::Entid(99)),
].into());
}
/// Queries that bind non-entity values to entity places can't return results.
#[test]
fn test_bind_the_wrong_thing() {
let mut cc = ConjoiningClauses::default();
let schema = Schema::default();
let x = Variable(PlainSymbol::new("?x"));
let a = Variable(PlainSymbol::new("?a"));
let v = Variable(PlainSymbol::new("?v"));
let hello = TypedValue::String("hello".to_string());
cc.input_variables.insert(a.clone());
cc.value_bindings.insert(a.clone(), hello.clone());
cc.apply_pattern(&schema, Pattern {
source: None,
entity: PatternNonValuePlace::Variable(x.clone()),
attribute: PatternNonValuePlace::Variable(a.clone()),
value: PatternValuePlace::Variable(v.clone()),
tx: PatternNonValuePlace::Placeholder,
});
assert!(cc.is_known_empty);
assert_eq!(cc.empty_because.unwrap(), EmptyBecause::InvalidBinding(DatomsColumn::Attribute, hello));
}
/// This test ensures that we query all_datoms if we're possibly retrieving a string.
#[test]
fn test_apply_unattributed_pattern_with_returned() {
let mut cc = ConjoiningClauses::default();
let schema = Schema::default();
let x = Variable(PlainSymbol::new("?x"));
let a = Variable(PlainSymbol::new("?a"));
let v = Variable(PlainSymbol::new("?v"));
cc.apply_pattern(&schema, Pattern {
source: None,
entity: PatternNonValuePlace::Variable(x.clone()),
attribute: PatternNonValuePlace::Variable(a.clone()),
value: PatternValuePlace::Variable(v.clone()),
tx: PatternNonValuePlace::Placeholder,
});
// println!("{:#?}", cc);
let d0_e = QualifiedAlias("all_datoms00".to_string(), DatomsColumn::Entity);
assert!(!cc.is_known_empty);
assert_eq!(cc.from, vec![SourceAlias(DatomsTable::AllDatoms, "all_datoms00".to_string())]);
// ?x must be a ref.
assert_eq!(cc.known_type(&x).unwrap(), ValueType::Ref);
// ?x is bound to datoms0.e.
assert_eq!(cc.column_bindings.get(&x).unwrap(), &vec![d0_e.clone()]);
assert_eq!(cc.wheres, vec![].into());
}
/// This test ensures that we query all_datoms if we're looking for a string.
#[test]
fn test_apply_unattributed_pattern_with_string_value() {
let mut cc = ConjoiningClauses::default();
let schema = Schema::default();
let x = Variable(PlainSymbol::new("?x"));
cc.apply_pattern(&schema, Pattern {
source: None,
entity: PatternNonValuePlace::Variable(x.clone()),
attribute: PatternNonValuePlace::Placeholder,
value: PatternValuePlace::Constant(NonIntegerConstant::Text("hello".to_string())),
tx: PatternNonValuePlace::Placeholder,
});
// println!("{:#?}", cc);
let d0_e = QualifiedAlias("all_datoms00".to_string(), DatomsColumn::Entity);
let d0_v = QualifiedAlias("all_datoms00".to_string(), DatomsColumn::Value);
assert!(!cc.is_known_empty);
assert_eq!(cc.from, vec![SourceAlias(DatomsTable::AllDatoms, "all_datoms00".to_string())]);
// ?x must be a ref.
assert_eq!(cc.known_type(&x).unwrap(), ValueType::Ref);
// ?x is bound to datoms0.e.
assert_eq!(cc.column_bindings.get(&x).unwrap(), &vec![d0_e.clone()]);
// Our 'where' clauses are two:
// - datoms0.v = 'hello'
// - datoms0.value_type_tag = string
// TODO: implement expand_type_tags.
assert_eq!(cc.wheres, vec![
ColumnConstraint::Equals(d0_v, QueryValue::TypedValue(TypedValue::String("hello".to_string()))),
ColumnConstraint::HasType("all_datoms00".to_string(), ValueType::String),
].into());
}
#[test]
fn test_apply_two_patterns() {
let mut cc = ConjoiningClauses::default();
let mut schema = Schema::default();
associate_ident(&mut schema, NamespacedKeyword::new("foo", "bar"), 99);
associate_ident(&mut schema, NamespacedKeyword::new("foo", "roz"), 98);
add_attribute(&mut schema, 99, Attribute {
value_type: ValueType::Boolean,
..Default::default()
});
add_attribute(&mut schema, 98, Attribute {
value_type: ValueType::String,
..Default::default()
});
let x = Variable(PlainSymbol::new("?x"));
let y = Variable(PlainSymbol::new("?y"));
cc.apply_pattern(&schema, Pattern {
source: None,
entity: PatternNonValuePlace::Variable(x.clone()),
attribute: PatternNonValuePlace::Ident(NamespacedKeyword::new("foo", "roz")),
value: PatternValuePlace::Constant(NonIntegerConstant::Text("idgoeshere".to_string())),
tx: PatternNonValuePlace::Placeholder,
});
cc.apply_pattern(&schema, Pattern {
source: None,
entity: PatternNonValuePlace::Variable(x.clone()),
attribute: PatternNonValuePlace::Ident(NamespacedKeyword::new("foo", "bar")),
value: PatternValuePlace::Variable(y.clone()),
tx: PatternNonValuePlace::Placeholder,
});
// Finally, expand column bindings to get the overlaps for ?x.
cc.expand_column_bindings();
println!("{:#?}", cc);
let d0_e = QualifiedAlias("datoms00".to_string(), DatomsColumn::Entity);
let d0_a = QualifiedAlias("datoms00".to_string(), DatomsColumn::Attribute);
let d0_v = QualifiedAlias("datoms00".to_string(), DatomsColumn::Value);
let d1_e = QualifiedAlias("datoms01".to_string(), DatomsColumn::Entity);
let d1_a = QualifiedAlias("datoms01".to_string(), DatomsColumn::Attribute);
assert!(!cc.is_known_empty);
assert_eq!(cc.from, vec![
SourceAlias(DatomsTable::Datoms, "datoms00".to_string()),
SourceAlias(DatomsTable::Datoms, "datoms01".to_string()),
]);
// ?x must be a ref.
assert_eq!(cc.known_type(&x).unwrap(), ValueType::Ref);
// ?x is bound to datoms0.e and datoms1.e.
assert_eq!(cc.column_bindings.get(&x).unwrap(),
&vec![
d0_e.clone(),
d1_e.clone(),
]);
// Our 'where' clauses are four:
// - datoms0.a = 98 (:foo/roz)
// - datoms0.v = "idgoeshere"
// - datoms1.a = 99 (:foo/bar)
// - datoms1.e = datoms0.e
assert_eq!(cc.wheres, vec![
ColumnConstraint::Equals(d0_a, QueryValue::Entid(98)),
ColumnConstraint::Equals(d0_v, QueryValue::TypedValue(TypedValue::String("idgoeshere".to_string()))),
ColumnConstraint::Equals(d1_a, QueryValue::Entid(99)),
ColumnConstraint::Equals(d0_e, QueryValue::Column(d1_e)),
].into());
}
#[test]
fn test_value_bindings() {
let mut schema = Schema::default();
associate_ident(&mut schema, NamespacedKeyword::new("foo", "bar"), 99);
add_attribute(&mut schema, 99, Attribute {
value_type: ValueType::Boolean,
..Default::default()
});
let x = Variable(PlainSymbol::new("?x"));
let y = Variable(PlainSymbol::new("?y"));
let b: BTreeMap<Variable, TypedValue> =
vec![(y.clone(), TypedValue::Boolean(true))].into_iter().collect();
let mut cc = ConjoiningClauses::with_value_bindings(b);
cc.apply_pattern(&schema, Pattern {
source: None,
entity: PatternNonValuePlace::Variable(x.clone()),
attribute: PatternNonValuePlace::Ident(NamespacedKeyword::new("foo", "bar")),
value: PatternValuePlace::Variable(y.clone()),
tx: PatternNonValuePlace::Placeholder,
});
let d0_e = QualifiedAlias("datoms00".to_string(), DatomsColumn::Entity);
let d0_a = QualifiedAlias("datoms00".to_string(), DatomsColumn::Attribute);
let d0_v = QualifiedAlias("datoms00".to_string(), DatomsColumn::Value);
// ?y has been expanded into `true`.
assert_eq!(cc.wheres, vec![
ColumnConstraint::Equals(d0_a, QueryValue::Entid(99)),
ColumnConstraint::Equals(d0_v, QueryValue::TypedValue(TypedValue::Boolean(true))),
].into());
// There is no binding for ?y.
assert!(!cc.column_bindings.contains_key(&y));
// ?x is bound to the entity.
assert_eq!(cc.column_bindings.get(&x).unwrap(),
&vec![d0_e.clone()]);
}
#[test]
/// Bind a value to a variable in a query where the type of the value disagrees with the type of
/// the variable inferred from known attributes.
fn test_value_bindings_type_disagreement() {
let mut schema = Schema::default();
associate_ident(&mut schema, NamespacedKeyword::new("foo", "bar"), 99);
add_attribute(&mut schema, 99, Attribute {
value_type: ValueType::Boolean,
..Default::default()
});
let x = Variable(PlainSymbol::new("?x"));
let y = Variable(PlainSymbol::new("?y"));
let b: BTreeMap<Variable, TypedValue> =
vec![(y.clone(), TypedValue::Long(42))].into_iter().collect();
let mut cc = ConjoiningClauses::with_value_bindings(b);
cc.apply_pattern(&schema, Pattern {
source: None,
entity: PatternNonValuePlace::Variable(x.clone()),
attribute: PatternNonValuePlace::Ident(NamespacedKeyword::new("foo", "bar")),
value: PatternValuePlace::Variable(y.clone()),
tx: PatternNonValuePlace::Placeholder,
});
// The type of the provided binding doesn't match the type of the attribute.
assert!(cc.is_known_empty);
}
#[test]
/// Bind a non-textual value to a variable in a query where the variable is used as the value
/// of a fulltext-valued attribute.
fn test_fulltext_type_disagreement() {
let mut schema = Schema::default();
associate_ident(&mut schema, NamespacedKeyword::new("foo", "bar"), 99);
add_attribute(&mut schema, 99, Attribute {
value_type: ValueType::String,
fulltext: true,
..Default::default()
});
let x = Variable(PlainSymbol::new("?x"));
let y = Variable(PlainSymbol::new("?y"));
let b: BTreeMap<Variable, TypedValue> =
vec![(y.clone(), TypedValue::Long(42))].into_iter().collect();
let mut cc = ConjoiningClauses::with_value_bindings(b);
cc.apply_pattern(&schema, Pattern {
source: None,
entity: PatternNonValuePlace::Variable(x.clone()),
attribute: PatternNonValuePlace::Ident(NamespacedKeyword::new("foo", "bar")),
value: PatternValuePlace::Variable(y.clone()),
tx: PatternNonValuePlace::Placeholder,
});
// The type of the provided binding doesn't match the type of the attribute.
assert!(cc.is_known_empty);
}
#[test]
/// Apply two patterns with differently typed attributes, but sharing a variable in the value
/// place. No value can bind to a variable and match both types, so the CC is known to return
/// no results.
fn test_apply_two_conflicting_known_patterns() {
let mut cc = ConjoiningClauses::default();
let mut schema = Schema::default();
associate_ident(&mut schema, NamespacedKeyword::new("foo", "bar"), 99);
associate_ident(&mut schema, NamespacedKeyword::new("foo", "roz"), 98);
add_attribute(&mut schema, 99, Attribute {
value_type: ValueType::Boolean,
..Default::default()
});
add_attribute(&mut schema, 98, Attribute {
value_type: ValueType::String,
unique: Some(Unique::Identity),
..Default::default()
});
let x = Variable(PlainSymbol::new("?x"));
let y = Variable(PlainSymbol::new("?y"));
cc.apply_pattern(&schema, Pattern {
source: None,
entity: PatternNonValuePlace::Variable(x.clone()),
attribute: PatternNonValuePlace::Ident(NamespacedKeyword::new("foo", "roz")),
value: PatternValuePlace::Variable(y.clone()),
tx: PatternNonValuePlace::Placeholder,
});
cc.apply_pattern(&schema, Pattern {
source: None,
entity: PatternNonValuePlace::Variable(x.clone()),
attribute: PatternNonValuePlace::Ident(NamespacedKeyword::new("foo", "bar")),
value: PatternValuePlace::Variable(y.clone()),
tx: PatternNonValuePlace::Placeholder,
});
// Finally, expand column bindings to get the overlaps for ?x.
cc.expand_column_bindings();
assert!(cc.is_known_empty);
assert_eq!(cc.empty_because.unwrap(),
EmptyBecause::TypeMismatch(y.clone(), unit_type_set(ValueType::String), ValueType::Boolean));
}
#[test]
#[should_panic(expected = "assertion failed: cc.is_known_empty")]
/// This test needs range inference in order to succeed: we must deduce that ?y must
/// simultaneously be a boolean-valued attribute and a ref-valued attribute, and thus
/// the CC can never return results.
fn test_apply_two_implicitly_conflicting_patterns() {
let mut cc = ConjoiningClauses::default();
let schema = Schema::default();
// [:find ?x :where
// [?x ?y true]
// [?z ?y ?x]]
let x = Variable(PlainSymbol::new("?x"));
let y = Variable(PlainSymbol::new("?y"));
let z = Variable(PlainSymbol::new("?z"));
cc.apply_pattern(&schema, Pattern {
source: None,
entity: PatternNonValuePlace::Variable(x.clone()),
attribute: PatternNonValuePlace::Variable(y.clone()),
value: PatternValuePlace::Constant(NonIntegerConstant::Boolean(true)),
tx: PatternNonValuePlace::Placeholder,
});
cc.apply_pattern(&schema, Pattern {
source: None,
entity: PatternNonValuePlace::Variable(z.clone()),
attribute: PatternNonValuePlace::Variable(y.clone()),
value: PatternValuePlace::Variable(x.clone()),
tx: PatternNonValuePlace::Placeholder,
});
// Finally, expand column bindings to get the overlaps for ?x.
cc.expand_column_bindings();
assert!(cc.is_known_empty);
assert_eq!(cc.empty_because.unwrap(),
EmptyBecause::TypeMismatch(x.clone(), unit_type_set(ValueType::Ref), ValueType::Boolean));
}
}

233
query-algebrizer/src/clauses/predicate.rs Normal file
View file

@ -0,0 +1,233 @@
// Copyright 2016 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::{
Schema,
};
use mentat_query::{
Predicate,
};
use clauses::ConjoiningClauses;
use errors::{
Result,
ErrorKind,
};
use types::{
ColumnConstraint,
NumericComparison,
};
/// Application of predicates.
impl ConjoiningClauses {
/// There are several kinds of predicates/functions in our Datalog:
/// - A limited set of binary comparison operators: < > <= >= !=.
/// These are converted into SQLite binary comparisons and some type constraints.
/// - A set of predicates like `fulltext` and `get-else` that are translated into
/// SQL `MATCH`es or joins, yielding bindings.
/// - In the future, some predicates that are implemented via function calls in SQLite.
///
/// At present we have implemented only the five built-in comparison binary operators.
pub fn apply_predicate<'s, 'p>(&mut self, schema: &'s Schema, predicate: Predicate) -> Result<()> {
// Because we'll be growing the set of built-in predicates, handling each differently,
// and ultimately allowing user-specified predicates, we match on the predicate name first.
if let Some(op) = NumericComparison::from_datalog_operator(predicate.operator.0.as_str()) {
self.apply_numeric_predicate(schema, op, predicate)
} else {
bail!(ErrorKind::UnknownFunction(predicate.operator.clone()))
}
}
/// This function:
/// - Resolves variables and converts types to those more amenable to SQL.
/// - Ensures that the predicate functions name a known operator.
/// - Accumulates a `NumericInequality` constraint into the `wheres` list.
#[allow(unused_variables)]
pub fn apply_numeric_predicate<'s, 'p>(&mut self, schema: &'s Schema, comparison: NumericComparison, predicate: Predicate) -> Result<()> {
if predicate.args.len() != 2 {
bail!(ErrorKind::InvalidNumberOfArguments(predicate.operator.clone(), predicate.args.len(), 2));
}
// Go from arguments -- parser output -- to columns or values.
// Any variables that aren't bound by this point in the linear processing of clauses will
// cause the application of the predicate to fail.
let mut args = predicate.args.into_iter();
let left = self.resolve_numeric_argument(&predicate.operator, 0, args.next().unwrap())?;
let right = self.resolve_numeric_argument(&predicate.operator, 1, args.next().unwrap())?;
// These arguments must be variables or numeric constants.
// TODO: generalize argument resolution and validation for different kinds of predicates:
// as we process `(< ?x 5)` we are able to check or deduce that `?x` is numeric, and either
// simplify the pattern or optimize the rest of the query.
// To do so needs a slightly more sophisticated representation of type constraints — a set,
// not a single `Option`.
// TODO: static evaluation. #383.
let constraint = ColumnConstraint::NumericInequality {
operator: comparison,
left: left,
right: right,
};
self.wheres.add_intersection(constraint);
Ok(())
}
}
#[cfg(test)]
mod testing {
use super::*;
use std::collections::HashSet;
use mentat_core::attribute::Unique;
use mentat_core::{
Attribute,
TypedValue,
ValueType,
};
use mentat_query::{
FnArg,
NamespacedKeyword,
Pattern,
PatternNonValuePlace,
PatternValuePlace,
PlainSymbol,
Variable,
};
use clauses::{
add_attribute,
associate_ident,
};
use types::{
ColumnConstraint,
EmptyBecause,
QueryValue,
};
#[test]
/// Apply two patterns: a pattern and a numeric predicate.
/// Verify that after application of the predicate we know that the value
/// must be numeric.
fn test_apply_numeric_predicate() {
let mut cc = ConjoiningClauses::default();
let mut schema = Schema::default();
associate_ident(&mut schema, NamespacedKeyword::new("foo", "bar"), 99);
add_attribute(&mut schema, 99, Attribute {
value_type: ValueType::Long,
..Default::default()
});
let x = Variable(PlainSymbol::new("?x"));
let y = Variable(PlainSymbol::new("?y"));
cc.apply_pattern(&schema, Pattern {
source: None,
entity: PatternNonValuePlace::Variable(x.clone()),
attribute: PatternNonValuePlace::Placeholder,
value: PatternValuePlace::Variable(y.clone()),
tx: PatternNonValuePlace::Placeholder,
});
assert!(!cc.is_known_empty);
let op = PlainSymbol::new("<");
let comp = NumericComparison::from_datalog_operator(op.plain_name()).unwrap();
assert!(cc.apply_numeric_predicate(&schema, comp, Predicate {
operator: op,
args: vec![
FnArg::Variable(Variable(PlainSymbol::new("?y"))), FnArg::EntidOrInteger(10),
]}).is_ok());
assert!(!cc.is_known_empty);
// Finally, expand column bindings to get the overlaps for ?x.
cc.expand_column_bindings();
assert!(!cc.is_known_empty);
// After processing those two clauses, we know that ?y must be numeric, but not exactly
// which type it must be.
assert_eq!(None, cc.known_type(&y)); // Not just one.
let expected: HashSet<ValueType> = vec![ValueType::Double, ValueType::Long].into_iter().collect();
assert_eq!(Some(&expected), cc.known_types.get(&y));
let clauses = cc.wheres;
assert_eq!(clauses.len(), 1);
assert_eq!(clauses.0[0], ColumnConstraint::NumericInequality {
operator: NumericComparison::LessThan,
left: QueryValue::Column(cc.column_bindings.get(&y).unwrap()[0].clone()),
right: QueryValue::TypedValue(TypedValue::Long(10)),
}.into());
}
#[test]
/// Apply three patterns: an unbound pattern to establish a value var,
/// a predicate to constrain the val to numeric types, and a third pattern to conflict with the
/// numeric types and cause the pattern to fail.
fn test_apply_conflict_with_numeric_range() {
let mut cc = ConjoiningClauses::default();
let mut schema = Schema::default();
associate_ident(&mut schema, NamespacedKeyword::new("foo", "bar"), 99);
associate_ident(&mut schema, NamespacedKeyword::new("foo", "roz"), 98);
add_attribute(&mut schema, 99, Attribute {
value_type: ValueType::Long,
..Default::default()
});
add_attribute(&mut schema, 98, Attribute {
value_type: ValueType::String,
unique: Some(Unique::Identity),
..Default::default()
});
let x = Variable(PlainSymbol::new("?x"));
let y = Variable(PlainSymbol::new("?y"));
cc.apply_pattern(&schema, Pattern {
source: None,
entity: PatternNonValuePlace::Variable(x.clone()),
attribute: PatternNonValuePlace::Placeholder,
value: PatternValuePlace::Variable(y.clone()),
tx: PatternNonValuePlace::Placeholder,
});
assert!(!cc.is_known_empty);
let op = PlainSymbol::new(">=");
let comp = NumericComparison::from_datalog_operator(op.plain_name()).unwrap();
assert!(cc.apply_numeric_predicate(&schema, comp, Predicate {
operator: op,
args: vec![
FnArg::Variable(Variable(PlainSymbol::new("?y"))), FnArg::EntidOrInteger(10),
]}).is_ok());
assert!(!cc.is_known_empty);
cc.apply_pattern(&schema, Pattern {
source: None,
entity: PatternNonValuePlace::Variable(x.clone()),
attribute: PatternNonValuePlace::Ident(NamespacedKeyword::new("foo", "roz")),
value: PatternValuePlace::Variable(y.clone()),
tx: PatternNonValuePlace::Placeholder,
});
// Finally, expand column bindings to get the overlaps for ?x.
cc.expand_column_bindings();
assert!(cc.is_known_empty);
assert_eq!(cc.empty_because.unwrap(),
EmptyBecause::TypeMismatch(y.clone(),
vec![ValueType::Double, ValueType::Long].into_iter()
.collect(),
ValueType::String));
}
}

87
query-algebrizer/src/clauses/resolve.rs Normal file
View file

@ -0,0 +1,87 @@
// Copyright 2016 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::{
TypedValue,
};
use mentat_query::{
FnArg,
NonIntegerConstant,
PlainSymbol,
};
use clauses::ConjoiningClauses;
use errors::{
Result,
Error,
ErrorKind,
};
use types::{
EmptyBecause,
QueryValue,
};
/// Argument resolution.
impl ConjoiningClauses {
/// Take a function argument and turn it into a `QueryValue` suitable for use in a concrete
/// constraint.
/// Additionally, do two things:
/// - Mark the pattern as known-empty if any argument is known non-numeric.
/// - Mark any variables encountered as numeric.
pub fn resolve_numeric_argument(&mut self, function: &PlainSymbol, position: usize, arg: FnArg) -> Result<QueryValue> {
use self::FnArg::*;
match arg {
FnArg::Variable(var) => {
self.constrain_var_to_numeric(var.clone());
self.column_bindings
.get(&var)
.and_then(|cols| cols.first().map(|col| QueryValue::Column(col.clone())))
.ok_or_else(|| Error::from_kind(ErrorKind::UnboundVariable(var)))
},
// Can't be an entid.
EntidOrInteger(i) => Ok(QueryValue::TypedValue(TypedValue::Long(i))),
Ident(_) |
SrcVar(_) |
Constant(NonIntegerConstant::Boolean(_)) |
Constant(NonIntegerConstant::Text(_)) |
Constant(NonIntegerConstant::BigInteger(_)) => {
self.mark_known_empty(EmptyBecause::NonNumericArgument);
bail!(ErrorKind::NonNumericArgument(function.clone(), position));
},
Constant(NonIntegerConstant::Float(f)) => Ok(QueryValue::TypedValue(TypedValue::Double(f))),
}
}
/// Take a function argument and turn it into a `QueryValue` suitable for use in a concrete
/// constraint.
#[allow(dead_code)]
fn resolve_argument(&self, arg: FnArg) -> Result<QueryValue> {
use self::FnArg::*;
match arg {
FnArg::Variable(var) => {
self.column_bindings
.get(&var)
.and_then(|cols| cols.first().map(|col| QueryValue::Column(col.clone())))
.ok_or_else(|| Error::from_kind(ErrorKind::UnboundVariable(var)))
},
EntidOrInteger(i) => Ok(QueryValue::PrimitiveLong(i)),
Ident(_) => unimplemented!(), // TODO
Constant(NonIntegerConstant::Boolean(val)) => Ok(QueryValue::TypedValue(TypedValue::Boolean(val))),
Constant(NonIntegerConstant::Float(f)) => Ok(QueryValue::TypedValue(TypedValue::Double(f))),
Constant(NonIntegerConstant::Text(s)) => Ok(QueryValue::TypedValue(TypedValue::String(s.clone()))),
Constant(NonIntegerConstant::BigInteger(_)) => unimplemented!(),
SrcVar(_) => unimplemented!(),
}
}
}

13
query-algebrizer/src/lib.rs
View file

@ -17,7 +17,8 @@ extern crate mentat_query;
mod errors;
mod types;
mod validate;
mod cc;
mod clauses;
use mentat_core::{
Schema,
@ -27,7 +28,6 @@ use mentat_query::{
FindQuery,
FindSpec,
SrcVar,
WhereClause,
};
pub use errors::{
@ -42,7 +42,7 @@ pub struct AlgebraicQuery {
pub find_spec: FindSpec,
has_aggregates: bool,
pub limit: Option<u64>,
pub cc: cc::ConjoiningClauses,
pub cc: clauses::ConjoiningClauses,
}
impl AlgebraicQuery {
@ -72,7 +72,7 @@ impl AlgebraicQuery {
pub fn algebrize(schema: &Schema, parsed: FindQuery) -> Result<AlgebraicQuery> {
// TODO: integrate default source into pattern processing.
// TODO: flesh out the rest of find-into-context.
let mut cc = cc::ConjoiningClauses::default();
let mut cc = clauses::ConjoiningClauses::default();
let where_clauses = parsed.where_clauses;
for where_clause in where_clauses {
cc.apply_clause(schema, where_clause)?;
@ -88,12 +88,15 @@ pub fn algebrize(schema: &Schema, parsed: FindQuery) -> Result<AlgebraicQuery> {
})
}
pub use cc::{
pub use clauses::{
ConjoiningClauses,
};
pub use types::{
ColumnAlternation,
ColumnConstraint,
ColumnConstraintOrAlternation,
ColumnIntersection,
DatomsColumn,
DatomsTable,
QualifiedAlias,

143
query-algebrizer/src/types.rs
View file

@ -8,6 +8,8 @@
// 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::HashSet;
use std::fmt::{
Debug,
Formatter,
@ -19,6 +21,12 @@ use mentat_core::{
TypedValue,
ValueType,
};
use mentat_query::{
NamespacedKeyword,
Variable,
};
/// This enum models the fixed set of default tables we have -- two
/// tables and two views.
#[derive(PartialEq, Eq, Clone, Copy, Debug)]
@ -186,6 +194,90 @@ pub enum ColumnConstraint {
HasType(TableAlias, ValueType),
}
#[derive(PartialEq, Eq, Debug)]
pub enum ColumnConstraintOrAlternation {
Constraint(ColumnConstraint),
Alternation(ColumnAlternation),
}
impl From<ColumnConstraint> for ColumnConstraintOrAlternation {
fn from(thing: ColumnConstraint) -> Self {
ColumnConstraintOrAlternation::Constraint(thing)
}
}
/// A `ColumnIntersection` constraint is satisfied if all of its inner constraints are satisfied.
/// An empty intersection is always satisfied.
#[derive(PartialEq, Eq)]
pub struct ColumnIntersection(pub Vec<ColumnConstraintOrAlternation>);
impl From<Vec<ColumnConstraint>> for ColumnIntersection {
fn from(thing: Vec<ColumnConstraint>) -> Self {
ColumnIntersection(thing.into_iter().map(|x| x.into()).collect())
}
}
impl Default for ColumnIntersection {
fn default() -> Self {
ColumnIntersection(vec![])
}
}
impl IntoIterator for ColumnIntersection {
type Item = ColumnConstraintOrAlternation;
type IntoIter = ::std::vec::IntoIter<ColumnConstraintOrAlternation>;
fn into_iter(self) -> Self::IntoIter {
self.0.into_iter()
}
}
impl ColumnIntersection {
pub fn len(&self) -> usize {
self.0.len()
}
pub fn is_empty(&self) -> bool {
self.0.is_empty()
}
pub fn add_intersection(&mut self, constraint: ColumnConstraint) {
self.0.push(ColumnConstraintOrAlternation::Constraint(constraint));
}
}
/// A `ColumnAlternation` constraint is satisfied if at least one of its inner constraints is
/// satisfied. An empty `ColumnAlternation` is never satisfied.
#[derive(PartialEq, Eq, Debug)]
pub struct ColumnAlternation(pub Vec<ColumnIntersection>);
impl Default for ColumnAlternation {
fn default() -> Self {
ColumnAlternation(vec![])
}
}
impl IntoIterator for ColumnAlternation {
type Item = ColumnIntersection;
type IntoIter = ::std::vec::IntoIter<ColumnIntersection>;
fn into_iter(self) -> Self::IntoIter {
self.0.into_iter()
}
}
impl ColumnAlternation {
pub fn add_alternate(&mut self, intersection: ColumnIntersection) {
self.0.push(intersection);
}
}
impl Debug for ColumnIntersection {
fn fmt(&self, f: &mut Formatter) -> ::std::fmt::Result {
write!(f, "{:?}", self.0)
}
}
impl Debug for ColumnConstraint {
fn fmt(&self, f: &mut Formatter) -> ::std::fmt::Result {
use self::ColumnConstraint::*;
@ -204,3 +296,54 @@ impl Debug for ColumnConstraint {
}
}
}
#[derive(PartialEq, Clone)]
pub enum EmptyBecause {
// Var, existing, desired.
TypeMismatch(Variable, HashSet<ValueType>, ValueType),
NonNumericArgument,
NonStringFulltextValue,
UnresolvedIdent(NamespacedKeyword),
InvalidAttributeIdent(NamespacedKeyword),
InvalidAttributeEntid(Entid),
InvalidBinding(DatomsColumn, TypedValue),
ValueTypeMismatch(ValueType, TypedValue),
AttributeLookupFailed, // Catch-all, because the table lookup code is lazy. TODO
}
impl Debug for EmptyBecause {
fn fmt(&self, f: &mut Formatter) -> ::std::fmt::Result {
use self::EmptyBecause::*;
match self {
&TypeMismatch(ref var, ref existing, ref desired) => {
write!(f, "Type mismatch: {:?} can't be {:?}, because it's already {:?}",
var, desired, existing)
},
&NonNumericArgument => {
write!(f, "Non-numeric argument in numeric place")
},
&NonStringFulltextValue => {
write!(f, "Non-string argument for fulltext attribute")
},
&UnresolvedIdent(ref kw) => {
write!(f, "Couldn't resolve keyword {}", kw)
},
&InvalidAttributeIdent(ref kw) => {
write!(f, "{} does not name an attribute", kw)
},
&InvalidAttributeEntid(entid) => {
write!(f, "{} is not an attribute", entid)
},
&InvalidBinding(ref column, ref tv) => {
write!(f, "{:?} cannot name column {:?}", tv, column)
},
&ValueTypeMismatch(value_type, ref typed_value) => {
write!(f, "Type mismatch: {:?} doesn't match attribute type {:?}",
typed_value, value_type)
},
&AttributeLookupFailed => {
write!(f, "Attribute lookup failed")
},
}
}
}

2
query-algebrizer/src/validate.rs
View file

@ -14,7 +14,6 @@ use mentat_query::{
ContainsVariables,
OrJoin,
Variable,
WhereClause,
UnifyVars,
};
@ -89,7 +88,6 @@ mod tests {
PatternNonValuePlace,
PatternValuePlace,
PlainSymbol,
SrcVar,
UnifyVars,
Variable,
WhereClause,

22
query-sql/src/lib.rs
View file

@ -81,6 +81,9 @@ pub enum Constraint {
left: ColumnOrExpression,
right: ColumnOrExpression,
},
Or {
constraints: Vec<Constraint>,
},
And {
constraints: Vec<Constraint>,
},
@ -260,6 +263,11 @@ impl QueryFragment for Constraint {
},
&And { ref constraints } => {
// An empty intersection is true.
if constraints.is_empty() {
out.push_sql("1");
return Ok(())
}
out.push_sql("(");
interpose!(constraint, constraints,
{ constraint.push_sql(out)? },
@ -268,6 +276,20 @@ impl QueryFragment for Constraint {
Ok(())
},
&Or { ref constraints } => {
// An empty alternation is false.
if constraints.is_empty() {
out.push_sql("0");
return Ok(())
}
out.push_sql("(");
interpose!(constraint, constraints,
{ constraint.push_sql(out)? },
{ out.push_sql(" OR ") });
out.push_sql(")");
Ok(())
}
&In { ref left, ref list } => {
left.push_sql(out)?;
out.push_sql(" IN (");

29
query-translator/src/translate.rs
View file

@ -25,7 +25,10 @@ use mentat_query::{
use mentat_query_algebrizer::{
AlgebraicQuery,
ColumnAlternation,
ColumnConstraint,
ColumnConstraintOrAlternation,
ColumnIntersection,
ConjoiningClauses,
DatomsColumn,
DatomsTable,
@ -66,6 +69,32 @@ impl ToColumn for QualifiedAlias {
}
}
impl ToConstraint for ColumnIntersection {
fn to_constraint(self) -> Constraint {
Constraint::And {
constraints: self.into_iter().map(|x| x.to_constraint()).collect()
}
}
}
impl ToConstraint for ColumnAlternation {
fn to_constraint(self) -> Constraint {
Constraint::Or {
constraints: self.into_iter().map(|x| x.to_constraint()).collect()
}
}
}
impl ToConstraint for ColumnConstraintOrAlternation {
fn to_constraint(self) -> Constraint {
use self::ColumnConstraintOrAlternation::*;
match self {
Alternation(alt) => alt.to_constraint(),
Constraint(c) => c.to_constraint(),
}
}
}
impl ToConstraint for ColumnConstraint {
fn to_constraint(self) -> Constraint {
use self::ColumnConstraint::*;

60
query/src/lib.rs
View file

@ -44,6 +44,27 @@ pub type SrcVarName = String; // Do not include the required syntactic
#[derive(Clone, PartialEq, Eq, PartialOrd, Ord)]
pub struct Variable(pub PlainSymbol);
impl Variable {
pub fn as_str(&self) -> &str {
(self.0).0.as_str()
}
pub fn to_string(&self) -> String {
(self.0).0.clone()
}
pub fn name(&self) -> PlainSymbol {
self.0.clone()
}
/// Return a new `Variable`, assuming that the provided string is a valid name.
pub fn from_valid_name(name: &str) -> Variable {
let s = PlainSymbol::new(name);
assert!(s.is_var_symbol());
Variable(s)
}
}
pub trait FromValue<T> {
fn from_value(v: &edn::Value) -> Option<T>;
}
@ -504,12 +525,31 @@ pub enum UnifyVars {
Explicit(Vec<Variable>),
}
impl WhereClause {
pub fn is_pattern(&self) -> bool {
match self {
&WhereClause::Pattern(_) => true,
_ => false,
}
}
}
#[derive(Clone, Debug, Eq, PartialEq)]
pub enum OrWhereClause {
Clause(WhereClause),
And(Vec<WhereClause>),
}
impl OrWhereClause {
pub fn is_pattern_or_patterns(&self) -> bool {
match self {
&OrWhereClause::Clause(WhereClause::Pattern(_)) => true,
&OrWhereClause::And(ref clauses) => clauses.iter().all(|clause| clause.is_pattern()),
_ => false,
}
}
}
#[derive(Clone, Debug, Eq, PartialEq)]
pub struct OrJoin {
pub unify_vars: UnifyVars,
@ -540,6 +580,24 @@ pub struct FindQuery {
// TODO: in_rules;
}
impl OrJoin {
/// Return true if either the `OrJoin` is `UnifyVars::Implicit`, or if
/// every variable mentioned inside the join is also mentioned in the `UnifyVars` list.
pub fn is_fully_unified(&self) -> bool {
match &self.unify_vars {
&UnifyVars::Implicit => true,
&UnifyVars::Explicit(ref vars) => {
// We know that the join list must be a subset of the vars in the pattern, or
// it would have failed validation. That allows us to simply compare counts here.
// TODO: in debug mode, do a full intersection, and verify that our count check
// returns the same results.
let mentioned = self.collect_mentioned_variables();
vars.len() == mentioned.len()
}
}
}
}
pub trait ContainsVariables {
fn accumulate_mentioned_variables(&self, acc: &mut BTreeSet<Variable>);
fn collect_mentioned_variables(&self) -> BTreeSet<Variable> {
@ -614,4 +672,4 @@ impl ContainsVariables for Pattern {
acc_ref(acc, v)
}
}
}
}