Class ConstraintWindows

java.lang.Object
org.ek9lang.compiler.symbolic.ConstraintWindows
public final class ConstraintWindows extends Object
THE shared fold of a constrain as expression into the inclusive numeric window [lo,hi] it narrows to — call this, do not re-derive it.

The long[] {lo, hi} encoding is this package's window currency: CriticalValues tests a window for disjointness, WitnessEnumerator enumerates its edges, SymbolicEngine discharges or refutes against it, and the fuzz generator sprays its edges as test inputs (SymbolHarvester.constraintWindowEdges). This class is the ONE place that knows how a ConstraintExpr becomes that pair, and the one place that renders it for a human. It was extracted from SymbolicEngine's private helpers when the generator needed the same fold — a second copy would have let the verifier and the generator disagree about what a constrained type's admissible values are.

Not the only admissibility route, and not interchangeable with the other one. The window answers "which INTERVAL of values does this constraint admit"; EquivalenceClassModel .admissibleClassCount answers "which of the base type's VALUE-CLASSES does it admit", by probing each class's representative literal through CompileTimeConstraintEvaluator (the evaluator that powers E08260). Those are different questions with different domains — the probe handles String and matches, which have no interval at all, while the window reaches boundary values no representative literal names. Do not fold one into the other, and do not add a third: anything new belongs on one of these two.

Integer only, deliberately. A window is a fold over ORDER, so it is defined only where the constrained base has a total order the compiler can evaluate at compile time as a long. Anything else — a Float or String literal, an or-combination (which is a union, not an interval), <> / matches / contains — yields null, meaning "no decidable window", and every caller must treat null as "know nothing" rather than "empty".

  • Method Details

    • windowOf

      public static long[] windowOf(ConstraintExpr constraint)
      The inclusive numeric window [lo,hi] an Integer constraint narrows to, or null when it is not a decidable numeric window. Handles a single comparison and and-combinations of them; an absent bound stays at the Long extreme, so constrain as > 0 folds to [1, Long.MAX_VALUE].
      Parameters:
      constraint - the constrained type's constraint expression, may be null
      Returns:
      the window, or null when nothing decidable can be said

    • windowText

      public static String windowText(long[] window)
      A window rendered for a human, with an unbounded end shown as an ellipsis rather than the Long extreme that stands in for it.
      Parameters:
      window - the [lo,hi] pair
      Returns:
      the rendered window, e.g. [0, 100] or [1, …]