ShapePath.js

A typescript library for executing ShapePaths

This is a monorepo which holds:

• the shape-path-core module and
• a playground (live webapp | source)

language/evaluation changes

2021-07-17 ericP: changed predicate separator for ::thisTripleExpr from . to ~ because . is legal in localNames

2026-08-22: thisTripleExpr:: follows an Inclusion. ShExC's &<#label> compiles to a bare label where a triple expression would be, and it means the expression that label names is part of this body -- which is how the matcher reads it. The axis stopped there, so ~<iri>, which is built on it, reported a shape's body as smaller than the matcher does: a constraint a shape included by reference could not be addressed through that shape at all.

An expression the walk has already reported is not reported again, so an expression that includes itself, and one included twice, are each that expression once. Note that an included expression is one expression however many bodies take it in: @<#A>~<p> and @<#B>~<p> reach the same node when both include it, and something hung there is hung there for both.

2026-08-20: $<label> selects the triple expression declared with that label, joining @<label> (a shape expression) and ~<iri> (the triple constraint on a predicate). ShExJ has no top-level list of triple expressions the way it has shapes, and a label may sit on an EachOf, a OneOf or a TripleConstraint at any depth -- including inside the inline shape of some constraint's value expression -- so the lookup walks the whole schema. $ is the sigil ShExC uses to declare one.

2026-08-19: [N] selects the node at position N, counting from 0.

It is the grammar's shorthand for [index() = N] (filterExpr -> Filter(index, [numericExpr])), and index() has always reported the 0-based position, so the two have to agree. This is not XPath's [1]-is-first: XPath's aggregate is position(), ShapePath's is index(), and the rename is the signal. If ShapePath would rather count from 1, index() moves with it.

Until this was written down, [N] ignored N and passed every node whose position was truthy, so [0], [1] and [2] all selected the same thing -- everything but the first.