Comparing main...scijava-ops-image/image-equation · scijava/scijava

ctrueden

Commits on May 26, 2026

This implementation brings back the image.equation Op from ImageJ Ops,
but using Parsington instead of JavaScript for deterministic evaluation.

- Equation.java — the image.equation Op with a Computer signature
  (String, RandomAccessibleInterval<T>)). Parses the expression once
  into a SyntaxTree, then iterates pixels with a localizing cursor,
  updating position before each evaluation. Any per-pixel runtime error
  yields NaN.

- EquationEvaluator.java — extends Parsington's DefaultTreeEvaluator.
  Exposes p[0..n], x/y/z/t, pi/e, and reflects every public-static
  numeric java.lang.Math method.

- EquationTest.java — 10 tests covering constants, p[i], axis
  shorthands, single- and multi-arg math, pi/e, a 3D image,
  reproducibility, random() distribution, and the NaN-on-bad-expression
  contract.

Adds parsington as a dependency to scijava-ops-image.

Notable design notes:
- parens(...) returns the single arg unwrapped, or an Object[] for
  multi-arg, so function() can pick Math overloads.
- brackets(...) returns a marker BracketIndex so function(fn, args)
  can distinguish p[i] from cos(x).
- Multi-arg function args came through as unresolved Variable tokens;
  resolved via Parsington's value(arg) before reflection.
- Single-threaded for now — Parsington's evaluator is stateful, and the
  op is documented as a demo helper, so top performance is not critical.

Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>

and claude committed

May 26, 2026

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