Class NormalizeZeroOrOneSubselectTransform

java.lang.Object

org.eclipse.rdf4j.queryrender.sparql.ir.util.transform.BaseTransform

org.eclipse.rdf4j.queryrender.sparql.ir.util.transform.NormalizeZeroOrOneSubselectTransform

public final class NormalizeZeroOrOneSubselectTransform
extends BaseTransform

Recognize a parsed subselect encoding of a simple zero-or-one property path between two variables and rewrite it to a compact IrPathTriple with a trailing '?' quantifier. Roughly matches a UNION containing a sameTerm(?s, ?o) branch and one or more single-step patterns connecting ?s and ?o (possibly via GRAPH or already-fused path triples). Produces ?s (step1|step2|...) ? ?o. This normalization simplifies common shapes produced by the parser for "?s (p? ) ?o" and enables subsequent path fusions.

Field Summary

Fields inherited from class BaseTransform

ANON_PATH_INVERSE_PREFIX, ANON_PATH_PREFIX

Modifier and Type	Field	Description
static final String	ANON_PATH_INVERSE_PREFIX
static final String	ANON_PATH_PREFIX

Method Summary

Modifier and Type	Method	Description
static IrBGP	apply(IrBGP bgp, TupleExprIRRenderer r)
static boolean	isSameTermFilterBranch(IrBGP b)
static String[]	parseSameTermVars(String text)
static IrPathTriple	tryRewriteZeroOrOne(IrSubSelect ss, TupleExprIRRenderer r)
static IrNode	tryRewriteZeroOrOneNode(IrSubSelect ss, TupleExprIRRenderer r)	Variant of tryRewriteZeroOrOne that returns a generic IrNode.
static Var	varNamed(String name)

Methods inherited from class BaseTransform

bgpWithLines, branchHasAnonPathBridge, copyAllExcept, fuseAdjacentPtThenPt, fuseAdjacentSpThenPt, fuseAltInverseTailBGP, fusePtSpPtSequence, invertNegatedPropertySet, iri, isAnonPathInverseVar, isAnonPathVar, isConstantIriPredicate, joinPathWithLaterSp, mergeNpsMembers, normalizeCompactNps, orientBareNpsForNext, rewriteContainers, sameVar, sameVarOrValue, unionBranchesAllHaveAnonPathBridge, unionBranchesShareAnonPathVarWithAllowedRoleMapping, unionBranchesShareCommonAnonPathVarName, unionIsExplicitAndAllBranchesScoped, varOrValue

Modifier and Type	Method	Description
static IrBGP	bgpWithLines(IrBGP original, List<IrNode> lines)	Build a new IrBGP with the same scope flag and the provided lines.
static boolean	branchHasAnonPathBridge(IrBGP branch)	True if the given branch contains at least one variable with the parser-generated _anon_path_ (or inverse variant) prefix anywhere in its simple triple-like structures.
static void	copyAllExcept(IrBGP from, IrBGP to, IrNode except)
static IrBGP	fuseAdjacentPtThenPt(IrBGP bgp)	Fuse adjacent IrPathTriple nodes when the first's object equals the second's subject.
static IrBGP	fuseAdjacentSpThenPt(IrBGP bgp, TupleExprIRRenderer r)
static IrBGP	fuseAltInverseTailBGP(IrBGP bgp, TupleExprIRRenderer r)	Fuse a path triple whose object is a bridge var with a constant-IRI tail triple that also uses the bridge var, producing a new path with an added '/^p' or '/p' segment.
static IrBGP	fusePtSpPtSequence(IrBGP bgp, TupleExprIRRenderer r)	Fuse a three-line sequence: IrPathTriple (A), IrStatementPattern (B), IrPathTriple (C) into A then ( ^B.p / C ).
static String	invertNegatedPropertySet(String npsText)	If the given path text is a negated property set of the form !
static String	iri(Var pred, TupleExprIRRenderer r)	Convenience: render a constant-IRI predicate Var to text.
static boolean	isAnonPathInverseVar(Var v)	True when the anonymous path var explicitly encodes inverse orientation.
static boolean	isAnonPathVar(Var v)
static boolean	isConstantIriPredicate(IrStatementPattern sp)	Convenience: true iff SP has a constant-IRI predicate.
static IrBGP	joinPathWithLaterSp(IrBGP bgp, TupleExprIRRenderer r)
static String	mergeNpsMembers(String a, String b)	Merge NPS members of two canonical strings '!
static String	normalizeCompactNps(String path)	Normalize compact negated-property-set forms into the canonical parenthesized variant.
static IrBGP	orientBareNpsForNext(IrBGP bgp)	Re-orient a bare negated property set path "!
static IrNode	rewriteContainers(IrNode n, Function<IrBGP,IrBGP> f)	Utility: rewrite container nodes by applying a given function to their inner IrBGP children.
static boolean	sameVar(Var a, Var b)
static boolean	sameVarOrValue(Var a, Var b)	True when both variables denote the same term: compares names if both are variables without value, or compares values if both are constants.
static boolean	unionBranchesAllHaveAnonPathBridge(IrUnion u)	True if all UNION branches contain at least one _anon_path_* variable (or inverse variant).
static boolean	unionBranchesShareAnonPathVarWithAllowedRoleMapping(IrUnion u)	New-scope UNION safety: true iff the two UNION branches share at least one _anon_path_* variable name.
static boolean	unionBranchesShareCommonAnonPathVarName(IrUnion u)	True if all UNION branches share at least one common variable name that starts with the _anon_path_ prefix.
static boolean	unionIsExplicitAndAllBranchesScoped(IrUnion u)	Universal safeguard for explicit user UNIONs: true iff the UNION is marked as new scope and all its branches are also marked as new scope.
static String	varOrValue(Var v, TupleExprIRRenderer r)

Methods inherited from class Object

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

Method Details

apply

public static IrBGP apply(IrBGP bgp,
 TupleExprIRRenderer r)

tryRewriteZeroOrOne

public static IrPathTriple tryRewriteZeroOrOne(IrSubSelect ss,
 TupleExprIRRenderer r)

tryRewriteZeroOrOneNode

public static IrNode tryRewriteZeroOrOneNode(IrSubSelect ss,
 TupleExprIRRenderer r)

Variant of tryRewriteZeroOrOne that returns a generic IrNode. When all step branches are GRAPH-wrapped with the same graph ref, this returns an IrGraph containing the fused IrPathTriple, so that graph context is preserved and downstream coalescing can merge adjacent GRAPH blocks.

parseSameTermVars

public static String[] parseSameTermVars(String text)

isSameTermFilterBranch

public static boolean isSameTermFilterBranch(IrBGP b)

varNamed

public static Var varNamed(String name)