IQTree (ontop-model 4.0.0-beta-2-SNAPSHOT API)

All Known Subinterfaces:

BinaryNonCommutativeIQTree, CompositeIQTree<N>, EmptyNode, ExtensionalDataNode, IntensionalDataNode, LeafIQTree, NaryIQTree, NativeNode, TrueNode, UnaryIQTree

All Known Implementing Classes:

AbstractCompositeIQTree, BinaryNonCommutativeIQTreeImpl, DataNodeImpl, EmptyNodeImpl, ExtensionalDataNodeImpl, IntensionalDataNodeImpl, LeafIQTreeImpl, NaryIQTreeImpl, NativeNodeImpl, TrueNodeImpl, UnaryIQTreeImpl
```
public interface IQTree
```

Method Summary

All Methods Instance Methods Abstract Methods Default Methods
Modifier and Type	Method and Description
`IQTree`	`acceptTransformer(IQTreeVisitingTransformer transformer)`
`<T> T`	`acceptVisitor(IQVisitor<T> visitor)`
`IQTree`	`applyDescendingSubstitution(ImmutableSubstitution<? extends VariableOrGroundTerm> descendingSubstitution, Optional<ImmutableExpression> constraint)` Applies the descending substitution and performs SOME optimizations.
`IQTree`	`applyDescendingSubstitutionWithoutOptimizing(ImmutableSubstitution<? extends VariableOrGroundTerm> descendingSubstitution)` Applies the descending substitution WITHOUT applying any additional optimization.
`IQTree`	`applyFreshRenaming(InjectiveVar2VarSubstitution freshRenamingSubstitution)` Particular type of descending substitution: only renaming some variables by external ones.
`com.google.common.collect.ImmutableList<IQTree>`	`getChildren()`
`com.google.common.collect.ImmutableSet<Variable>`	`getKnownVariables()` Variables present in the tree
`com.google.common.collect.ImmutableSet<Variable>`	`getNotInternallyRequiredVariables()` Variables that are the tree proposes for removal if the ancestor trees do not need them.
`com.google.common.collect.ImmutableSet<ImmutableSubstitution<NonVariableTerm>>`	`getPossibleVariableDefinitions()` Returns a set of substitutions that define the projected variables when they are constructed.
`QueryNode`	`getRootNode()`
`VariableNullability`	`getVariableNullability()`
`com.google.common.collect.ImmutableSet<Variable>`	`getVariables()` Variables projected by the tree
`com.google.common.collect.ImmutableSet<com.google.common.collect.ImmutableSet<Variable>>`	`inferUniqueConstraints()` NOT guaranteed to return all the unique constraints (MAY BE INCOMPLETE) Set of sets of determinants.
`boolean`	`isConstructed(Variable variable)` Returns true if the variable is (at least in one branch) constructed by a substitution (in a construction node)
`boolean`	`isDeclaredAsEmpty()` Returns true if corresponds to a EmptyNode
`boolean`	`isDistinct()` Returns true if it guarantees that all its results will be distinct
`boolean`	`isEquivalentTo(IQTree tree)`
`default boolean`	`isLeaf()`
`IQTree`	`liftIncompatibleDefinitions(Variable variable, VariableGenerator variableGenerator)` Tries to lift unions when they have incompatible definitions for a variable.
`IQTree`	`normalizeForOptimization(VariableGenerator variableGenerator)`
`IQTree`	`propagateDownConstraint(ImmutableExpression constraint)` TODO: explain The constraint is used for pruning.
`IQTree`	`removeDistincts()` TODO: find a better name
`IQTree`	`replaceSubTree(IQTree subTreeToReplace, IQTree newSubTree)` If subTreeToReplace is not found, has no effect (besides creating a novel copy).
`void`	`validate()`

- Method Detail
  - getRootNode
```
QueryNode getRootNode()
```
  - getChildren
```
com.google.common.collect.ImmutableList<IQTree> getChildren()
```
  - getVariables
```
com.google.common.collect.ImmutableSet<Variable> getVariables()
```
    Variables projected by the tree
  - acceptTransformer
```
IQTree acceptTransformer(IQTreeVisitingTransformer transformer)
```
  - acceptVisitor
```
<T> T acceptVisitor(IQVisitor<T> visitor)
```
  - normalizeForOptimization
```
IQTree normalizeForOptimization(VariableGenerator variableGenerator)
```
  - liftIncompatibleDefinitions
```
IQTree liftIncompatibleDefinitions(Variable variable,
                                   VariableGenerator variableGenerator)
```
    Tries to lift unions when they have incompatible definitions for a variable. Union branches with compatible definitions are kept together
  - isLeaf
```
default boolean isLeaf()
```
  - applyDescendingSubstitution
```
IQTree applyDescendingSubstitution(ImmutableSubstitution<? extends VariableOrGroundTerm> descendingSubstitution,
                                   Optional<ImmutableExpression> constraint)
```
    Applies the descending substitution and performs SOME optimizations. Designed to be called DURING the "structural/semantic optimization" phase.
  - applyFreshRenaming
```
IQTree applyFreshRenaming(InjectiveVar2VarSubstitution freshRenamingSubstitution)
```
    Particular type of descending substitution: only renaming some variables by external ones. Isolated from regular descending substitutions as it preserves the properties of the tree (e.g. it remains normalized if it was already)
  - applyDescendingSubstitutionWithoutOptimizing
```
IQTree applyDescendingSubstitutionWithoutOptimizing(ImmutableSubstitution<? extends VariableOrGroundTerm> descendingSubstitution)
```
    Applies the descending substitution WITHOUT applying any additional optimization. Designed to be called AFTER the "structural/semantic optimization" phase.
  - getKnownVariables
```
com.google.common.collect.ImmutableSet<Variable> getKnownVariables()
```
    Variables present in the tree
  - isConstructed
```
boolean isConstructed(Variable variable)
```
    Returns true if the variable is (at least in one branch) constructed by a substitution (in a construction node)
  - isDistinct
```
boolean isDistinct()
```
    Returns true if it guarantees that all its results will be distinct
  - isDeclaredAsEmpty
```
boolean isDeclaredAsEmpty()
```
    Returns true if corresponds to a EmptyNode
  - getVariableNullability
```
VariableNullability getVariableNullability()
```
  - isEquivalentTo
```
boolean isEquivalentTo(IQTree tree)
```
  - propagateDownConstraint
```
IQTree propagateDownConstraint(ImmutableExpression constraint)
```
    TODO: explain The constraint is used for pruning. It remains enforced by a parent tree.
  - removeDistincts
```
IQTree removeDistincts()
```
    TODO: find a better name
  - validate
```
void validate()
       throws InvalidIntermediateQueryException
```
    Throws:
    
    InvalidIntermediateQueryException
  - replaceSubTree
```
IQTree replaceSubTree(IQTree subTreeToReplace,
                      IQTree newSubTree)
```
    If subTreeToReplace is not found, has no effect (besides creating a novel copy).
  - getPossibleVariableDefinitions
```
com.google.common.collect.ImmutableSet<ImmutableSubstitution<NonVariableTerm>> getPossibleVariableDefinitions()
```
    Returns a set of substitutions that define the projected variables when they are constructed. Guarantee: each tuple in the result set having constructed values matches at least one of these substitutions. It is advised to call this method on a normalized IQ so as to reduce the number of possible substitutions (normalization drops unsatisfiable substitutions). The intended usage of this method it to determine the definition of a variable from the returned substitution. Therefore this method is robust to simple variable renaming and to multiple complex substitutions. E.g. if [x/x2], [x2/x3] and [x3/URI("http://myURI{}", x4] are three substitutions found in that order in a same branch, then x/URI("http://myURI{}", x4) will be the only output substitution for that branch.
  - inferUniqueConstraints
```
com.google.common.collect.ImmutableSet<com.google.common.collect.ImmutableSet<Variable>> inferUniqueConstraints()
```
    NOT guaranteed to return all the unique constraints (MAY BE INCOMPLETE) Set of sets of determinants. Warning: some determinants may be nullable!
  - getNotInternallyRequiredVariables
```
com.google.common.collect.ImmutableSet<Variable> getNotInternallyRequiredVariables()
```
    Variables that are the tree proposes for removal if the ancestor trees do not need them.

Interface IQTree

Method Summary

Method Detail

getRootNode

getChildren

getVariables

acceptTransformer

acceptVisitor

normalizeForOptimization

liftIncompatibleDefinitions

isLeaf

applyDescendingSubstitution

applyFreshRenaming

applyDescendingSubstitutionWithoutOptimizing

getKnownVariables

isConstructed

isDistinct

isDeclaredAsEmpty

getVariableNullability

isEquivalentTo

propagateDownConstraint

removeDistincts

validate

replaceSubTree

getPossibleVariableDefinitions

inferUniqueConstraints

getNotInternallyRequiredVariables