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Refactor arg conversion and ground into separate files.

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This commit is contained in:
Richard Newman 2017-06-12 14:22:47 -07:00
parent 54bdd382fb
commit f7a3fd5b17
4 changed files with 597 additions and 531 deletions
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185
query-algebrizer/src/clauses/convert.rs Normal file
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@ -0,0 +1,185 @@
// 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::rc::Rc;
use mentat_core::{
Schema,
SQLValueType,
TypedValue,
ValueType,
};
use mentat_query::{
FnArg,
NonIntegerConstant,
Variable,
};
use clauses::{
ConjoiningClauses,
};
use errors::{
ErrorKind,
Result,
};
use types::{
EmptyBecause,
ValueTypeSet,
};
macro_rules! coerce_to_typed_value {
($var: ident, $val: ident, $types: expr, $type: path, $constructor: path) => { {
Ok(if !$types.contains($type) {
Impossible(EmptyBecause::TypeMismatch {
var: $var.clone(),
existing: $types,
desired: ValueTypeSet::of_one($type),
})
} else {
Val($constructor($val).into())
})
} }
}
pub enum ValueConversion {
Val(TypedValue),
Impossible(EmptyBecause),
}
/// Conversion of FnArgs to TypedValues.
impl ConjoiningClauses {
/// Convert the provided `FnArg` to a `TypedValue`.
/// The conversion depends on, and can fail because of:
/// - Existing known types of a variable to which this arg will be bound.
/// - Existing bindings of a variable `FnArg`.
pub fn typed_value_from_arg<'s>(&self, schema: &'s Schema, var: &Variable, arg: FnArg, known_types: ValueTypeSet) -> Result<ValueConversion> {
use self::ValueConversion::*;
if known_types.is_empty() {
// If this happens, it likely means the pattern has already failed!
return Ok(Impossible(EmptyBecause::TypeMismatch {
var: var.clone(),
existing: known_types,
desired: ValueTypeSet::any(),
}));
}
match arg {
// Longs are potentially ambiguous: they might be longs or entids.
FnArg::EntidOrInteger(x) => {
match (ValueType::Ref.accommodates_integer(x),
known_types.contains(ValueType::Ref),
known_types.contains(ValueType::Long)) {
(true, true, true) => {
// Ambiguous: this arg could be an entid or a long.
// We default to long.
Ok(Val(TypedValue::Long(x)))
},
(true, true, false) => {
// This can only be a ref.
Ok(Val(TypedValue::Ref(x)))
},
(_, false, true) => {
// This can only be a long.
Ok(Val(TypedValue::Long(x)))
},
(false, true, _) => {
// This isn't a valid ref, but that's the type to which this must conform!
Ok(Impossible(EmptyBecause::TypeMismatch {
var: var.clone(),
existing: known_types,
desired: ValueTypeSet::of_longs(),
}))
},
(_, false, false) => {
// Non-overlapping type sets.
Ok(Impossible(EmptyBecause::TypeMismatch {
var: var.clone(),
existing: known_types,
desired: ValueTypeSet::of_longs(),
}))
},
}
},
// If you definitely want to look up an ident, do it before running the query.
FnArg::IdentOrKeyword(x) => {
match (known_types.contains(ValueType::Ref),
known_types.contains(ValueType::Keyword)) {
(true, true) => {
// Ambiguous: this could be a keyword or an ident.
// Default to keyword.
Ok(Val(TypedValue::Keyword(Rc::new(x))))
},
(true, false) => {
// This can only be an ident. Look it up!
match schema.get_entid(&x).map(TypedValue::Ref) {
Some(e) => Ok(Val(e)),
None => Ok(Impossible(EmptyBecause::UnresolvedIdent(x.clone()))),
}
},
(false, true) => {
Ok(Val(TypedValue::Keyword(Rc::new(x))))
},
(false, false) => {
Ok(Impossible(EmptyBecause::TypeMismatch {
var: var.clone(),
existing: known_types,
desired: ValueTypeSet::of_keywords(),
}))
},
}
},
FnArg::Variable(in_var) => {
// TODO: technically you could ground an existing variable inside the query….
if !self.input_variables.contains(&in_var) {
bail!(ErrorKind::UnboundVariable((*in_var.0).clone()));
}
match self.bound_value(&in_var) {
// The type is already known if it's a bound variable….
Some(ref in_value) => Ok(Val(in_value.clone())),
None => {
// The variable is present in `:in`, but it hasn't yet been provided.
// This is a restriction we will eventually relax: we don't yet have a way
// to collect variables as part of a computed table or substitution.
bail!(ErrorKind::UnboundVariable((*in_var.0).clone()))
},
}
},
// This isn't implemented yet.
FnArg::Constant(NonIntegerConstant::BigInteger(_)) => unimplemented!(),
// These don't make sense here.
FnArg::Vector(_) |
FnArg::SrcVar(_) => bail!(ErrorKind::InvalidGroundConstant),
// These are all straightforward.
FnArg::Constant(NonIntegerConstant::Boolean(x)) => {
coerce_to_typed_value!(var, x, known_types, ValueType::Boolean, TypedValue::Boolean)
},
FnArg::Constant(NonIntegerConstant::Instant(x)) => {
coerce_to_typed_value!(var, x, known_types, ValueType::Instant, TypedValue::Instant)
},
FnArg::Constant(NonIntegerConstant::Uuid(x)) => {
coerce_to_typed_value!(var, x, known_types, ValueType::Uuid, TypedValue::Uuid)
},
FnArg::Constant(NonIntegerConstant::Float(x)) => {
coerce_to_typed_value!(var, x, known_types, ValueType::Double, TypedValue::Double)
},
FnArg::Constant(NonIntegerConstant::Text(x)) => {
coerce_to_typed_value!(var, x, known_types, ValueType::String, TypedValue::String)
},
}
}
}

409
query-algebrizer/src/clauses/ground.rs Normal file
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@ -0,0 +1,409 @@
// 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::{
Binding,
FnArg,
Variable,
VariableOrPlaceholder,
WhereFn,
};
use clauses::{
ConjoiningClauses,
PushComputed,
};
use clauses::convert::ValueConversion;
use errors::{
BindingError,
ErrorKind,
Result,
};
use types::{
ColumnConstraint,
ComputedTable,
EmptyBecause,
QualifiedAlias,
SourceAlias,
ValueTypeSet,
VariableColumn,
};
impl ConjoiningClauses {
/// Take a relation: a matrix of values which will successively bind to named variables of
/// the provided types.
/// Construct a computed table to yield this relation.
/// This function will panic if some invariants are not met.
fn collect_named_bindings<'s>(&mut self, schema: &'s Schema, names: Vec<Variable>, types: Vec<ValueType>, values: Vec<TypedValue>) {
if values.is_empty() {
return;
}
assert!(!names.is_empty());
assert_eq!(names.len(), types.len());
assert!(values.len() >= names.len());
assert_eq!(values.len() % names.len(), 0); // It's an exact multiple.
let named_values = ComputedTable::NamedValues {
names: names.clone(),
values: values,
};
let table = self.computed_tables.push_computed(named_values);
let alias = self.next_alias_for_table(table);
// Stitch the computed table into column_bindings, so we get cross-linking.
for (name, ty) in names.iter().zip(types.into_iter()) {
self.constrain_var_to_type(name.clone(), ty);
self.bind_column_to_var(schema, alias.clone(), VariableColumn::Variable(name.clone()), name.clone());
}
self.from.push(SourceAlias(table, alias));
}
fn apply_ground_place<'s>(&mut self, schema: &'s Schema, var: VariableOrPlaceholder, arg: FnArg) -> Result<()> {
match var {
VariableOrPlaceholder::Placeholder => Ok(()),
VariableOrPlaceholder::Variable(var) => self.apply_ground_var(schema, var, arg),
}
}
/// Constrain the CC to associate the given var with the given ground argument.
/// Marks known-empty on failure.
fn apply_ground_var<'s>(&mut self, schema: &'s Schema, var: Variable, arg: FnArg) -> Result<()> {
let known_types = self.known_type_set(&var);
match self.typed_value_from_arg(schema, &var, arg, known_types)? {
ValueConversion::Val(value) => self.apply_ground_value(var, value),
ValueConversion::Impossible(because) => {
self.mark_known_empty(because);
Ok(())
},
}
}
/// Marks known-empty on failure.
fn apply_ground_value(&mut self, var: Variable, value: TypedValue) -> Result<()> {
if let Some(existing) = self.bound_value(&var) {
if existing != value {
self.mark_known_empty(EmptyBecause::ConflictingBindings {
var: var.clone(),
existing: existing.clone(),
desired: value,
});
return Ok(())
}
} else {
self.bind_value(&var, value.clone());
}
let vt = value.value_type();
// Check to see whether this variable is already associated to a column.
// If so, we want to add an equality filter (or, in the future, redo the existing patterns).
if let Some(QualifiedAlias(table, column)) = self.column_bindings
.get(&var)
.and_then(|vec| vec.get(0).cloned()) {
self.constrain_column_to_constant(table, column, value);
}
// Are we also trying to figure out the type of the value when the query runs?
// If so, constrain that!
if let Some(table) = self.extracted_types.get(&var)
.map(|qa| qa.0.clone()) {
self.wheres.add_intersection(ColumnConstraint::HasType(table, vt));
}
Ok(())
}
pub fn apply_ground<'s>(&mut self, schema: &'s Schema, where_fn: WhereFn) -> Result<()> {
if where_fn.args.len() != 1 {
bail!(ErrorKind::InvalidNumberOfArguments(where_fn.operator.clone(), where_fn.args.len(), 1));
}
let mut args = where_fn.args.into_iter();
if where_fn.binding.is_empty() {
// The binding must introduce at least one bound variable.
bail!(ErrorKind::InvalidBinding(where_fn.operator.clone(), BindingError::NoBoundVariable));
}
if !where_fn.binding.is_valid() {
// The binding must not duplicate bound variables.
bail!(ErrorKind::InvalidBinding(where_fn.operator.clone(), BindingError::RepeatedBoundVariable));
}
// Scalar and tuple bindings are a little special: because there's only one value,
// we can immediately substitute the value as a known value in the CC, additionally
// generating a WHERE clause if columns have already been bound.
match (where_fn.binding, args.next().unwrap()) {
(Binding::BindScalar(var), constant) =>
self.apply_ground_var(schema, var, constant),
(Binding::BindTuple(places), FnArg::Vector(children)) => {
// Just the same, but we bind more than one column at a time.
if children.len() != places.len() {
// Number of arguments don't match the number of values. TODO: better error message.
bail!(ErrorKind::GroundBindingsMismatch);
}
for (place, arg) in places.into_iter().zip(children.into_iter()) {
self.apply_ground_place(schema, place, arg)? // TODO: short-circuit on impossible.
}
Ok(())
},
// Collection bindings and rel bindings are similar in that they are both
// implemented as a subquery with a projection list and a set of values.
// The difference is that BindColl has only a single variable, and its values
// are all in a single structure. That makes it substantially simpler!
(Binding::BindColl(var), FnArg::Vector(children)) => {
if children.is_empty() {
bail!(ErrorKind::InvalidGroundConstant);
}
// Turn a collection of arguments into a Vec of `TypedValue`s of the same type.
let known_types = self.known_type_set(&var);
// Check that every value has the same type.
let mut accumulated_types = ValueTypeSet::none();
let mut skip: Option<EmptyBecause> = None;
let values = children.into_iter()
.filter_map(|arg| -> Option<Result<TypedValue>> {
// We need to get conversion errors out.
// We also want to mark known-empty on impossibilty, but
// still detect serious errors.
match self.typed_value_from_arg(schema, &var, arg, known_types) {
Ok(ValueConversion::Val(tv)) => {
if accumulated_types.insert(tv.value_type()) &&
!accumulated_types.is_unit() {
// Values not all of the same type.
Some(Err(ErrorKind::InvalidGroundConstant.into()))
} else {
Some(Ok(tv))
}
},
Ok(ValueConversion::Impossible(because)) => {
// Skip this value.
skip = Some(because);
None
},
Err(e) => Some(Err(e.into())),
}
})
.collect::<Result<Vec<TypedValue>>>()?;
if values.is_empty() {
let because = skip.expect("we skipped all rows for a reason");
self.mark_known_empty(because);
return Ok(());
}
// Otherwise, we now have the values and the type.
let types = vec![accumulated_types.exemplar().unwrap()];
let names = vec![var.clone()];
self.collect_named_bindings(schema, names, types, values);
Ok(())
},
(Binding::BindRel(places), FnArg::Vector(rows)) => {
if rows.is_empty() {
bail!(ErrorKind::InvalidGroundConstant);
}
// Grab the known types to which these args must conform, and track
// the places that won't be bound in the output.
let template: Vec<Option<(Variable, ValueTypeSet)>> =
places.iter()
.map(|x| match x {
&VariableOrPlaceholder::Placeholder => None,
&VariableOrPlaceholder::Variable(ref v) => Some((v.clone(), self.known_type_set(v))),
})
.collect();
// The expected 'width' of the matrix is the number of named variables.
let full_width = places.len();
let names: Vec<Variable> = places.into_iter().filter_map(|x| x.into_var()).collect();
let expected_width = names.len();
let expected_rows = rows.len();
if expected_width == 0 {
// They can't all be placeholders.
bail!(ErrorKind::InvalidGroundConstant);
}
// Accumulate values into `matrix` and types into `a_t_f_c`.
// This representation of a rectangular matrix is more efficient than one composed
// of N separate vectors.
let mut matrix = Vec::with_capacity(expected_width * expected_rows);
let mut accumulated_types_for_columns = vec![ValueTypeSet::none(); expected_width];
// Loop so we can bail out.
let mut skipped_all: Option<EmptyBecause> = None;
for row in rows.into_iter() {
match row {
FnArg::Vector(cols) => {
// Make sure that every row is the same length.
if cols.len() != full_width {
bail!(ErrorKind::InvalidGroundConstant);
}
// TODO: don't accumulate twice.
let mut vals = Vec::with_capacity(expected_width);
let mut skip: Option<EmptyBecause> = None;
for (col, pair) in cols.into_iter().zip(template.iter()) {
// Now we have (val, Option<(name, known_types)>). Silly,
// but this is how we iter!
// Convert each item in the row.
// If any value in the row is impossible, then skip the row.
// If all rows are impossible, fail the entire CC.
if let &Some(ref pair) = pair {
match self.typed_value_from_arg(schema, &pair.0, col, pair.1)? {
ValueConversion::Val(tv) => vals.push(tv),
ValueConversion::Impossible(because) => {
// Skip this row. It cannot produce bindings.
skip = Some(because);
break;
},
}
}
}
if skip.is_some() {
// Skip this row and record why, in case we skip all.
skipped_all = skip;
continue;
}
// Accumulate the values into the matrix and the types into the type set.
for (val, acc) in vals.into_iter().zip(accumulated_types_for_columns.iter_mut()) {
let inserted = acc.insert(val.value_type());
if inserted && !acc.is_unit() {
// Heterogeneous types.
bail!(ErrorKind::InvalidGroundConstant);
}
matrix.push(val);
}
},
_ => bail!(ErrorKind::InvalidGroundConstant),
}
}
// Do we have rows? If not, the CC cannot succeed.
if matrix.is_empty() {
// We will either have bailed or will have accumulated *something* into the matrix,
// so we can safely unwrap here.
self.mark_known_empty(skipped_all.expect("we skipped for a reason"));
return Ok(());
}
// Take the single type from each set. We know there's only one: we got at least one
// type, 'cos we bailed out for zero rows, and we also bailed out each time we
// inserted a second type.
// By restricting to homogeneous columns, we greatly simplify projection. In the
// future, we could loosen this restriction, at the cost of projecting (some) value
// type tags. If and when we want to algebrize in two phases and allow for
// late-binding input variables, we'll probably be able to loosen this restriction
// with little penalty.
let types = accumulated_types_for_columns.into_iter()
.map(|x| x.exemplar().unwrap())
.collect();
self.collect_named_bindings(schema, names, types, matrix);
Ok(())
},
(_, _) => bail!(ErrorKind::InvalidGroundConstant),
}
}
}
#[cfg(test)]
mod testing {
use super::*;
use mentat_core::{
Attribute,
ValueType,
};
use mentat_query::{
Binding,
FnArg,
NamespacedKeyword,
PlainSymbol,
Variable,
};
use clauses::{
add_attribute,
associate_ident,
};
use types::{
ValueTypeSet,
};
#[test]
fn test_apply_ground() {
let vz = Variable::from_valid_name("?z");
let mut cc = ConjoiningClauses::default();
let mut schema = Schema::default();
associate_ident(&mut schema, NamespacedKeyword::new("foo", "fts"), 100);
add_attribute(&mut schema, 100, Attribute {
value_type: ValueType::String,
index: true,
fulltext: true,
..Default::default()
});
// It's awkward enough to write these expansions that we give the details for the simplest
// case only. See the tests of the translator for more extensive (albeit looser) coverage.
let op = PlainSymbol::new("ground");
cc.apply_ground(&schema, WhereFn {
operator: op,
args: vec![
FnArg::EntidOrInteger(10),
],
binding: Binding::BindScalar(vz.clone()),
}).expect("to be able to apply_ground");
assert!(!cc.is_known_empty());
// Finally, expand column bindings.
cc.expand_column_bindings();
assert!(!cc.is_known_empty());
let clauses = cc.wheres;
assert_eq!(clauses.len(), 0);
let column_bindings = cc.column_bindings;
assert_eq!(column_bindings.len(), 0); // Scalar doesn't need this.
let known_types = cc.known_types;
assert_eq!(known_types.len(), 1);
assert_eq!(known_types.get(&vz).expect("to know the type of ?z"),
&ValueTypeSet::of_one(ValueType::Long));
let value_bindings = cc.value_bindings;
assert_eq!(value_bindings.len(), 1);
assert_eq!(value_bindings.get(&vz).expect("to have a value for ?z"),
&TypedValue::Long(10)); // We default to Long instead of entid.
}
}

3
query-algebrizer/src/clauses/mod.rs
View file

@ -61,12 +61,15 @@ use types::{
ValueTypeSet,
};
mod convert; // Converting args to values.
mod inputs;
mod or;
mod not;
mod pattern;
mod predicate;
mod resolve;
mod ground;
mod where_fn;
use validate::{

531
query-algebrizer/src/clauses/where_fn.rs
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@ -8,193 +8,23 @@
// CONDITIONS OF ANY KIND, either express or implied. See the License for the
// specific language governing permissions and limitations under the License.
use std::rc::Rc;
use mentat_core::{
Schema,
SQLValueType,
TypedValue,
ValueType,
};
use mentat_query::{
Binding,
FnArg,
NonIntegerConstant,
Variable,
VariableOrPlaceholder,
WhereFn,
};
use clauses::{
ConjoiningClauses,
PushComputed,
};
use errors::{
BindingError,
ErrorKind,
Result,
};
use super::QualifiedAlias;
use types::{
ColumnConstraint,
ComputedTable,
EmptyBecause,
SourceAlias,
ValueTypeSet,
VariableColumn,
};
macro_rules! coerce_to_typed_value {
($var: ident, $val: ident, $types: expr, $type: path, $constructor: path) => { {
Ok(if !$types.contains($type) {
Impossible(EmptyBecause::TypeMismatch {
var: $var.clone(),
existing: $types,
desired: ValueTypeSet::of_one($type),
})
} else {
Val($constructor($val).into())
})
} }
}
enum ValueConversion {
Val(TypedValue),
Impossible(EmptyBecause),
}
/// Conversion of FnArgs to TypedValues.
impl ConjoiningClauses {
/// Convert the provided `FnArg` to a `TypedValue`.
/// The conversion depends on, and can fail because of:
/// - Existing known types of a variable to which this arg will be bound.
/// - Existing bindings of a variable `FnArg`.
fn typed_value_from_arg<'s>(&self, schema: &'s Schema, var: &Variable, arg: FnArg, known_types: ValueTypeSet) -> Result<ValueConversion> {
use self::ValueConversion::*;
if known_types.is_empty() {
// If this happens, it likely means the pattern has already failed!
return Ok(Impossible(EmptyBecause::TypeMismatch {
var: var.clone(),
existing: known_types,
desired: ValueTypeSet::any(),
}));
}
match arg {
// Longs are potentially ambiguous: they might be longs or entids.
FnArg::EntidOrInteger(x) => {
match (ValueType::Ref.accommodates_integer(x),
known_types.contains(ValueType::Ref),
known_types.contains(ValueType::Long)) {
(true, true, true) => {
// Ambiguous: this arg could be an entid or a long.
// We default to long.
Ok(Val(TypedValue::Long(x)))
},
(true, true, false) => {
// This can only be a ref.
Ok(Val(TypedValue::Ref(x)))
},
(_, false, true) => {
// This can only be a long.
Ok(Val(TypedValue::Long(x)))
},
(false, true, _) => {
// This isn't a valid ref, but that's the type to which this must conform!
Ok(Impossible(EmptyBecause::TypeMismatch {
var: var.clone(),
existing: known_types,
desired: ValueTypeSet::of_longs(),
}))
},
(_, false, false) => {
// Non-overlapping type sets.
Ok(Impossible(EmptyBecause::TypeMismatch {
var: var.clone(),
existing: known_types,
desired: ValueTypeSet::of_longs(),
}))
},
}
},
// If you definitely want to look up an ident, do it before running the query.
FnArg::IdentOrKeyword(x) => {
match (known_types.contains(ValueType::Ref),
known_types.contains(ValueType::Keyword)) {
(true, true) => {
// Ambiguous: this could be a keyword or an ident.
// Default to keyword.
Ok(Val(TypedValue::Keyword(Rc::new(x))))
},
(true, false) => {
// This can only be an ident. Look it up!
match schema.get_entid(&x).map(TypedValue::Ref) {
Some(e) => Ok(Val(e)),
None => Ok(Impossible(EmptyBecause::UnresolvedIdent(x.clone()))),
}
},
(false, true) => {
Ok(Val(TypedValue::Keyword(Rc::new(x))))
},
(false, false) => {
Ok(Impossible(EmptyBecause::TypeMismatch {
var: var.clone(),
existing: known_types,
desired: ValueTypeSet::of_keywords(),
}))
},
}
},
FnArg::Variable(in_var) => {
// TODO: technically you could ground an existing variable inside the query….
if !self.input_variables.contains(&in_var) {
bail!(ErrorKind::UnboundVariable((*in_var.0).clone()));
}
match self.bound_value(&in_var) {
// The type is already known if it's a bound variable….
Some(ref in_value) => Ok(Val(in_value.clone())),
None => {
// The variable is present in `:in`, but it hasn't yet been provided.
// This is a restriction we will eventually relax: we don't yet have a way
// to collect variables as part of a computed table or substitution.
bail!(ErrorKind::UnboundVariable((*in_var.0).clone()))
},
}
},
// This isn't implemented yet.
FnArg::Constant(NonIntegerConstant::BigInteger(_)) => unimplemented!(),
// These don't make sense here.
FnArg::Vector(_) |
FnArg::SrcVar(_) => bail!(ErrorKind::InvalidGroundConstant),
// These are all straightforward.
FnArg::Constant(NonIntegerConstant::Boolean(x)) => {
coerce_to_typed_value!(var, x, known_types, ValueType::Boolean, TypedValue::Boolean)
},
FnArg::Constant(NonIntegerConstant::Instant(x)) => {
coerce_to_typed_value!(var, x, known_types, ValueType::Instant, TypedValue::Instant)
},
FnArg::Constant(NonIntegerConstant::Uuid(x)) => {
coerce_to_typed_value!(var, x, known_types, ValueType::Uuid, TypedValue::Uuid)
},
FnArg::Constant(NonIntegerConstant::Float(x)) => {
coerce_to_typed_value!(var, x, known_types, ValueType::Double, TypedValue::Double)
},
FnArg::Constant(NonIntegerConstant::Text(x)) => {
coerce_to_typed_value!(var, x, known_types, ValueType::String, TypedValue::String)
},
}
}
}
/// Application of `where` functions.
impl ConjoiningClauses {
/// There are several kinds of functions binding variables in our Datalog:
@ -211,365 +41,4 @@ impl ConjoiningClauses {
_ => bail!(ErrorKind::UnknownFunction(where_fn.operator.clone())),
}
}
fn apply_ground_place<'s>(&mut self, schema: &'s Schema, var: VariableOrPlaceholder, arg: FnArg) -> Result<()> {
match var {
VariableOrPlaceholder::Placeholder => Ok(()),
VariableOrPlaceholder::Variable(var) => self.apply_ground_var(schema, var, arg),
}
}
/// Constrain the CC to associate the given var with the given ground argument.
/// Marks known-empty on failure.
fn apply_ground_var<'s>(&mut self, schema: &'s Schema, var: Variable, arg: FnArg) -> Result<()> {
let known_types = self.known_type_set(&var);
match self.typed_value_from_arg(schema, &var, arg, known_types)? {
ValueConversion::Val(value) => self.apply_ground_value(var, value),
ValueConversion::Impossible(because) => {
self.mark_known_empty(because);
Ok(())
},
}
}
/// Marks known-empty on failure.
fn apply_ground_value(&mut self, var: Variable, value: TypedValue) -> Result<()> {
if let Some(existing) = self.bound_value(&var) {
if existing != value {
self.mark_known_empty(EmptyBecause::ConflictingBindings {
var: var.clone(),
existing: existing.clone(),
desired: value,
});
return Ok(())
}
} else {
self.bind_value(&var, value.clone());
}
let vt = value.value_type();
// Check to see whether this variable is already associated to a column.
// If so, we want to add an equality filter (or, in the future, redo the existing patterns).
if let Some(QualifiedAlias(table, column)) = self.column_bindings
.get(&var)
.and_then(|vec| vec.get(0).cloned()) {
self.constrain_column_to_constant(table, column, value);
}
// Are we also trying to figure out the type of the value when the query runs?
// If so, constrain that!
if let Some(table) = self.extracted_types.get(&var)
.map(|qa| qa.0.clone()) {
self.wheres.add_intersection(ColumnConstraint::HasType(table, vt));
}
Ok(())
}
/// Take a relation: a matrix of values which will successively bind to named variables of
/// the provided types.
/// Construct a computed table to yield this relation.
/// This function will panic if some invariants are not met.
fn collect_named_bindings<'s>(&mut self, schema: &'s Schema, names: Vec<Variable>, types: Vec<ValueType>, values: Vec<TypedValue>) {
if values.is_empty() {
return;
}
assert!(!names.is_empty());
assert_eq!(names.len(), types.len());
assert!(values.len() >= names.len());
assert_eq!(values.len() % names.len(), 0); // It's an exact multiple.
let named_values = ComputedTable::NamedValues {
names: names.clone(),
values: values,
};
let table = self.computed_tables.push_computed(named_values);
let alias = self.next_alias_for_table(table);
// Stitch the computed table into column_bindings, so we get cross-linking.
for (name, ty) in names.iter().zip(types.into_iter()) {
self.constrain_var_to_type(name.clone(), ty);
self.bind_column_to_var(schema, alias.clone(), VariableColumn::Variable(name.clone()), name.clone());
}
self.from.push(SourceAlias(table, alias));
}
pub fn apply_ground<'s>(&mut self, schema: &'s Schema, where_fn: WhereFn) -> Result<()> {
if where_fn.args.len() != 1 {
bail!(ErrorKind::InvalidNumberOfArguments(where_fn.operator.clone(), where_fn.args.len(), 1));
}
let mut args = where_fn.args.into_iter();
if where_fn.binding.is_empty() {
// The binding must introduce at least one bound variable.
bail!(ErrorKind::InvalidBinding(where_fn.operator.clone(), BindingError::NoBoundVariable));
}
if !where_fn.binding.is_valid() {
// The binding must not duplicate bound variables.
bail!(ErrorKind::InvalidBinding(where_fn.operator.clone(), BindingError::RepeatedBoundVariable));
}
// Scalar and tuple bindings are a little special: because there's only one value,
// we can immediately substitute the value as a known value in the CC, additionally
// generating a WHERE clause if columns have already been bound.
match (where_fn.binding, args.next().unwrap()) {
(Binding::BindScalar(var), constant) =>
self.apply_ground_var(schema, var, constant),
(Binding::BindTuple(places), FnArg::Vector(children)) => {
// Just the same, but we bind more than one column at a time.
if children.len() != places.len() {
// Number of arguments don't match the number of values. TODO: better error message.
bail!(ErrorKind::GroundBindingsMismatch);
}
for (place, arg) in places.into_iter().zip(children.into_iter()) {
self.apply_ground_place(schema, place, arg)? // TODO: short-circuit on impossible.
}
Ok(())
},
// Collection bindings and rel bindings are similar in that they are both
// implemented as a subquery with a projection list and a set of values.
// The difference is that BindColl has only a single variable, and its values
// are all in a single structure. That makes it substantially simpler!
(Binding::BindColl(var), FnArg::Vector(children)) => {
if children.is_empty() {
bail!(ErrorKind::InvalidGroundConstant);
}
// Turn a collection of arguments into a Vec of `TypedValue`s of the same type.
let known_types = self.known_type_set(&var);
// Check that every value has the same type.
let mut accumulated_types = ValueTypeSet::none();
let mut skip: Option<EmptyBecause> = None;
let values = children.into_iter()
.filter_map(|arg| -> Option<Result<TypedValue>> {
// We need to get conversion errors out.
// We also want to mark known-empty on impossibilty, but
// still detect serious errors.
match self.typed_value_from_arg(schema, &var, arg, known_types) {
Ok(ValueConversion::Val(tv)) => {
if accumulated_types.insert(tv.value_type()) &&
!accumulated_types.is_unit() {
// Values not all of the same type.
Some(Err(ErrorKind::InvalidGroundConstant.into()))
} else {
Some(Ok(tv))
}
},
Ok(ValueConversion::Impossible(because)) => {
// Skip this value.
skip = Some(because);
None
},
Err(e) => Some(Err(e.into())),
}
})
.collect::<Result<Vec<TypedValue>>>()?;
if values.is_empty() {
let because = skip.expect("we skipped all rows for a reason");
self.mark_known_empty(because);
return Ok(());
}
// Otherwise, we now have the values and the type.
let types = vec![accumulated_types.exemplar().unwrap()];
let names = vec![var.clone()];
self.collect_named_bindings(schema, names, types, values);
Ok(())
},
(Binding::BindRel(places), FnArg::Vector(rows)) => {
if rows.is_empty() {
bail!(ErrorKind::InvalidGroundConstant);
}
// Grab the known types to which these args must conform, and track
// the places that won't be bound in the output.
let template: Vec<Option<(Variable, ValueTypeSet)>> =
places.iter()
.map(|x| match x {
&VariableOrPlaceholder::Placeholder => None,
&VariableOrPlaceholder::Variable(ref v) => Some((v.clone(), self.known_type_set(v))),
})
.collect();
// The expected 'width' of the matrix is the number of named variables.
let full_width = places.len();
let names: Vec<Variable> = places.into_iter().filter_map(|x| x.into_var()).collect();
let expected_width = names.len();
let expected_rows = rows.len();
if expected_width == 0 {
// They can't all be placeholders.
bail!(ErrorKind::InvalidGroundConstant);
}
// Accumulate values into `matrix` and types into `a_t_f_c`.
// This representation of a rectangular matrix is more efficient than one composed
// of N separate vectors.
let mut matrix = Vec::with_capacity(expected_width * expected_rows);
let mut accumulated_types_for_columns = vec![ValueTypeSet::none(); expected_width];
// Loop so we can bail out.
let mut skipped_all: Option<EmptyBecause> = None;
for row in rows.into_iter() {
match row {
FnArg::Vector(cols) => {
// Make sure that every row is the same length.
if cols.len() != full_width {
bail!(ErrorKind::InvalidGroundConstant);
}
// TODO: don't accumulate twice.
let mut vals = Vec::with_capacity(expected_width);
let mut skip: Option<EmptyBecause> = None;
for (col, pair) in cols.into_iter().zip(template.iter()) {
// Now we have (val, Option<(name, known_types)>). Silly,
// but this is how we iter!
// Convert each item in the row.
// If any value in the row is impossible, then skip the row.
// If all rows are impossible, fail the entire CC.
if let &Some(ref pair) = pair {
match self.typed_value_from_arg(schema, &pair.0, col, pair.1)? {
ValueConversion::Val(tv) => vals.push(tv),
ValueConversion::Impossible(because) => {
// Skip this row. It cannot produce bindings.
skip = Some(because);
break;
},
}
}
}
if skip.is_some() {
// Skip this row and record why, in case we skip all.
skipped_all = skip;
continue;
}
// Accumulate the values into the matrix and the types into the type set.
for (val, acc) in vals.into_iter().zip(accumulated_types_for_columns.iter_mut()) {
let inserted = acc.insert(val.value_type());
if inserted && !acc.is_unit() {
// Heterogeneous types.
bail!(ErrorKind::InvalidGroundConstant);
}
matrix.push(val);
}
},
_ => bail!(ErrorKind::InvalidGroundConstant),
}
}
// Do we have rows? If not, the CC cannot succeed.
if matrix.is_empty() {
// We will either have bailed or will have accumulated *something* into the matrix,
// so we can safely unwrap here.
self.mark_known_empty(skipped_all.expect("we skipped for a reason"));
return Ok(());
}
// Take the single type from each set. We know there's only one: we got at least one
// type, 'cos we bailed out for zero rows, and we also bailed out each time we
// inserted a second type.
// By restricting to homogeneous columns, we greatly simplify projection. In the
// future, we could loosen this restriction, at the cost of projecting (some) value
// type tags. If and when we want to algebrize in two phases and allow for
// late-binding input variables, we'll probably be able to loosen this restriction
// with little penalty.
let types = accumulated_types_for_columns.into_iter()
.map(|x| x.exemplar().unwrap())
.collect();
self.collect_named_bindings(schema, names, types, matrix);
Ok(())
},
(_, _) => bail!(ErrorKind::InvalidGroundConstant),
}
}
}
#[cfg(test)]
mod testing {
use super::*;
use mentat_core::{
Attribute,
ValueType,
};
use mentat_query::{
Binding,
FnArg,
NamespacedKeyword,
PlainSymbol,
Variable,
};
use clauses::{
add_attribute,
associate_ident,
};
use types::{
ValueTypeSet,
};
#[test]
fn test_apply_ground() {
let vz = Variable::from_valid_name("?z");
let mut cc = ConjoiningClauses::default();
let mut schema = Schema::default();
associate_ident(&mut schema, NamespacedKeyword::new("foo", "fts"), 100);
add_attribute(&mut schema, 100, Attribute {
value_type: ValueType::String,
index: true,
fulltext: true,
..Default::default()
});
// It's awkward enough to write these expansions that we give the details for the simplest
// case only. See the tests of the translator for more extensive (albeit looser) coverage.
let op = PlainSymbol::new("ground");
cc.apply_ground(&schema, WhereFn {
operator: op,
args: vec![
FnArg::EntidOrInteger(10),
],
binding: Binding::BindScalar(vz.clone()),
}).expect("to be able to apply_ground");
assert!(!cc.is_known_empty());
// Finally, expand column bindings.
cc.expand_column_bindings();
assert!(!cc.is_known_empty());
let clauses = cc.wheres;
assert_eq!(clauses.len(), 0);
let column_bindings = cc.column_bindings;
assert_eq!(column_bindings.len(), 0); // Scalar doesn't need this.
let known_types = cc.known_types;
assert_eq!(known_types.len(), 1);
assert_eq!(known_types.get(&vz).expect("to know the type of ?z"),
&ValueTypeSet::of_one(ValueType::Long));
let value_bindings = cc.value_bindings;
assert_eq!(value_bindings.len(), 1);
assert_eq!(value_bindings.get(&vz).expect("to have a value for ?z"),
&TypedValue::Long(10)); // We default to Long instead of entid.
}
}