org.deri.iris.evaluation.topdown
Class TopDownHelper

java.lang.Object
  org.deri.iris.evaluation.topdown.TopDownHelper

public class TopDownHelper
extends Object

Collection of helper functions for top-down evaluation strategies

Author:

gigi

Constructor Summary

TopDownHelper()

Method Summary

static ITuple	createTupleFromQueryAndVariableMap(IQuery query, Map<IVariable,ITerm> variableMap) Deprecated.
static Map<IVariable,ITerm>	createVariableMapFromTupleAndQuery(IQuery query, ITuple branchTuple) Given a query and a tuple, create a variable map with the corresponding variable mappings for each variable in the query.
static String	getDebugPrefix(int recursionDepth, boolean inNegationAsFailureFlip) Creates a debug prefix for nice output
static IRelation	getFullSubgoalRelation(IQuery query, IQuery subQuery, Map<IVariable,ITerm> substitution, IRelation relationFromSubtree)
static IRelation	getFullSubgoalRelation(IQuery query, QueryWithSubstitution qws, IRelation relationFromSubtree) Creates a relation by combining the relation from subgoal evaluation and the variable bindings of the current query.
static Map<IVariable,ITerm>	getVariableMapForVariableRenaming(IRule rule, IQuery query) Creates a variable map that will replace variable ?X with ?X1 if the variable occurs in both tuples.
static List<IVariable>	getVariables(IQuery query) Get a list of variables, with no duplicates
static List<IVariable>	getVariables(ITuple tuple) Get a list of variables in the right order, with no duplicates
static boolean	match(ILiteral lit1, ILiteral lit2) Checks if two literals match
static boolean	match(ILiteral queryLiteral, IPredicate factPredicate) Wrapper.
static boolean	match(IPredicate pred1, IPredicate pred2) Checks if two predicates match
static Map<IVariable,ITerm>	mergeSubstitutions(Map<IVariable,ITerm> deeperMap, Map<IVariable,ITerm> higherMap)
static void	printDebug(String msg, int recursionDepth)
static void	printDebug(String msg, int recursionDepth, boolean inNegationAsFailureFlip)
static List<QueryWithSubstitution>	processBuiltin(IQuery query, ILiteral selectedQueryLiteral, IAtom queryLiteralAtom) Process a builtin atom.
static IRule	reMapVariablesInRule(IRule rule, Map<IVariable,ITerm> variableMap) Does variable re-mapping.
static IRule	replaceVariablesInRule(IRule rule, Map<IVariable,ITerm> variableMap) Replaces all variables in a rule with the mapped ones.
static ITuple	resolveTuple(ILiteral literal, Map<IVariable,ITerm> variableMap)
static ITuple	resolveTuple(IQuery query, Map<IVariable,ITerm> variableMap) If variableMap contains variable mappings of variables that are contained in query, those mappings will be resolved and a proper tuple will be created and returned.
static ITuple	resolveTuple(List<IVariable> varList, Map<IVariable,ITerm> variableMap, boolean partialResult)
static IQuery	substituteRuleHeadWithBody(IQuery query, ILiteral selectedLiteral, IRule rule) Replaces a rule head in a Query with the rule body.
static ILiteral	substituteVariablesInToLiteral(ILiteral literal, Map<IVariable,ITerm> variableMap) Replaces Variables in a Literal, and gives back the substituted Literal
static IQuery	substituteVariablesInToQuery(IQuery query, Map<IVariable,ITerm> variableMap) Replaces variables in a query.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

TopDownHelper

public TopDownHelper()

Method Detail

substituteRuleHeadWithBody

public static IQuery substituteRuleHeadWithBody(IQuery query,
                                                ILiteral selectedLiteral,
                                                IRule rule)
                                         throws EvaluationException

Replaces a rule head in a Query with the rule body. Example: Query: ?- a(?X), b(?X), c(?X). Rule: b(?X) :- r(?X), s(?X). Return: ?- a(?X), r(?X), s(?X), c(?X). Note that the rule variables and the query variables MUST NOT intersect. If they do an EvaluationException is thrown. To avoid intersection, do an occur check first.

Parameters:

query - a query element that contains the rule head

selectedLiteral - the selected literal

rule - a rule element

Returns:

A new query element where the rule head is replaced with the rule body, if unifyable with the selected literal.

Throws:

EvaluationException

substituteVariablesInToQuery

public static IQuery substituteVariablesInToQuery(IQuery query,
                                                  Map<IVariable,ITerm> variableMap)

Replaces variables in a query. Example: Query: ?- a( ?X ), b( ?Y ), c( ?Z ). variableMap: { X => 3, Y => 9 } Return: ?- a( 3 ), b( 9 ), c( ?X ).

Parameters:

query - a query element

variableMap - a map of variables and terms

Returns:

A new query element where the matching variables are replaced with the terms from the variableMap

substituteVariablesInToLiteral

public static ILiteral substituteVariablesInToLiteral(ILiteral literal,
                                                      Map<IVariable,ITerm> variableMap)

Replaces Variables in a Literal, and gives back the substituted Literal

Parameters:

literal - a Literal element

variableMap - a map of variables and terms

Returns:

A new Literal element where the matching variables are replaced with the terms from the variableMap

match

public static boolean match(IPredicate pred1,
                            IPredicate pred2)

Checks if two predicates match

Parameters:

pred1 - a predicate element

pred2 - a second predicate element

Returns:

true if the predicates have the same name and arity, false otherwise.

match

public static boolean match(ILiteral lit1,
                            ILiteral lit2)

Checks if two literals match

Parameters:

lit1 - a literal element

lit2 - a second literal element

Returns:

true if the predicates of the literals have the same name and arity, false otherwise.

match

public static boolean match(ILiteral queryLiteral,
                            IPredicate factPredicate)

Wrapper. See match(IPredicate pred1, IPredicate pred2).

Parameters:

queryLiteral -

factPredicate -

Returns:

true if the predicates of the literals have the same name and arity, false otherwise.

getVariables

public static List<IVariable> getVariables(IQuery query)

Get a list of variables, with no duplicates

Parameters:

query - the query

Returns:

A unique list of variables

getVariables

public static List<IVariable> getVariables(ITuple tuple)

Get a list of variables in the right order, with no duplicates

Parameters:

tuple - the ITuple tuple

Returns:

A unique list of variables. The list is empty if the tuple contains no variables.

getVariableMapForVariableRenaming

public static Map<IVariable,ITerm> getVariableMapForVariableRenaming(IRule rule,
                                                                     IQuery query)
                                                              throws RuleUnsafeException

Creates a variable map that will replace variable ?X with ?X1 if the variable occurs in both tuples.

Parameters:

rule - a rule

query - a query

Returns:

a variable map that maps the old variable names to the new ones

Throws:

RuleUnsafeException - thrown if the rule contains unbound variables

createVariableMapFromTupleAndQuery

public static Map<IVariable,ITerm> createVariableMapFromTupleAndQuery(IQuery query,
                                                                      ITuple branchTuple)

Given a query and a tuple, create a variable map with the corresponding variable mappings for each variable in the query.

Parameters:

query - the query

branchTuple - the tuple

Returns:

a new variable map containing mappings for all unique variables in query

createTupleFromQueryAndVariableMap

@Deprecated
public static ITuple createTupleFromQueryAndVariableMap(IQuery query,
                                                                   Map<IVariable,ITerm> variableMap)

Deprecated.

Given a query and a variable map, create a tuple with the corresponding terms for each variable in the query.

Parameters:

query - the query

variableMap - a map containing the variable mappings

Returns:

a new tuple

resolveTuple

public static ITuple resolveTuple(IQuery query,
                                  Map<IVariable,ITerm> variableMap)

If variableMap contains variable mappings of variables that are contained in query, those mappings will be resolved and a proper tuple will be created and returned. e.g. query = ?- q(?X) variableMap = ?X = 1 return = (1)

Parameters:

query - a IQuery which can contain variables

variableMap - map that stores variable mappings

Returns:

a tuple containing the resolved variables of the query

resolveTuple

public static ITuple resolveTuple(ILiteral literal,
                                  Map<IVariable,ITerm> variableMap)

resolveTuple

public static ITuple resolveTuple(List<IVariable> varList,
                                  Map<IVariable,ITerm> variableMap,
                                  boolean partialResult)

mergeSubstitutions

public static Map<IVariable,ITerm> mergeSubstitutions(Map<IVariable,ITerm> deeperMap,
                                                      Map<IVariable,ITerm> higherMap)

replaceVariablesInRule

public static IRule replaceVariablesInRule(IRule rule,
                                           Map<IVariable,ITerm> variableMap)

Replaces all variables in a rule with the mapped ones. Always modifies the head too.

Parameters:

rule - a rule

variableMap - a variable map

Returns:

rule with replaced variables

reMapVariablesInRule

public static IRule reMapVariablesInRule(IRule rule,
                                         Map<IVariable,ITerm> variableMap)

Does variable re-mapping. Inverse function to replaceVariablesInRule(IRule, Map)

Parameters:

rule - a rule

variableMap - a variable map

Returns:

rule with replaced variables.

getDebugPrefix

public static String getDebugPrefix(int recursionDepth,
                                    boolean inNegationAsFailureFlip)

Creates a debug prefix for nice output

Parameters:

recursionDepth - depth of recursion (0 = root)

inNegationAsFailureFlip - true is this a NAF tree, false otherwise

Returns:

debug prefix string

printDebug

public static void printDebug(String msg,
                              int recursionDepth)

printDebug

public static void printDebug(String msg,
                              int recursionDepth,
                              boolean inNegationAsFailureFlip)

getFullSubgoalRelation

public static IRelation getFullSubgoalRelation(IQuery query,
                                               QueryWithSubstitution qws,
                                               IRelation relationFromSubtree)

Creates a relation by combining the relation from subgoal evaluation and the variable bindings of the current query. e.g. ?- p( ?X, ?Y, ?Z ) | ?- q( ?Y, ?Z ) // subgoal When a mapping ?X = 1 is already known, and the subgoal evaluation returned ( 2, 3 ) - which means that ?Y = 2 and ?Z = 3 - a relation ( 1, 2, 3 ) for the variables ( ?X, ?Y, ?Z ) will be created.

Parameters:

query - a query

qws - a query with proper substitution, which is a subgoal of query

relationFromSubtree - relation returned by evaluation the subgoal qws

Returns:

a relation which covers all variables in query

getFullSubgoalRelation

public static IRelation getFullSubgoalRelation(IQuery query,
                                               IQuery subQuery,
                                               Map<IVariable,ITerm> substitution,
                                               IRelation relationFromSubtree)

processBuiltin

public static List<QueryWithSubstitution> processBuiltin(IQuery query,
                                                         ILiteral selectedQueryLiteral,
                                                         IAtom queryLiteralAtom)
                                                  throws EvaluationException

Process a builtin atom.

Parameters:

query - the whole query

selectedQueryLiteral - the selected literal

queryLiteralAtom -

Returns:

List of new queries and the associated substitutions

Throws:

EvaluationException - on failure