Support searching in the NFA using the metacharacters.

* src/paca.mjs
  (searchNFAStep): Now instead of just checking if the node has a
    transition via a character literal directly, we also check (via the
    `performTransition()` function) if a metacharacter interpretation
    allows a transition to happen.
  (intepretMetacharacter): Add function that "executes" the action
    representation in the "meta" attribute of the object, when present.
    It is somewhat ad-hoc now, doing checks that implicitly only exist
    for "." or "class" metacharacters, but OK for now, given the
    possibilities.
  (performTransition): Do the fallback to `interpretMetacharacter()`,
    giving it an empty object when the node doesn't have the "meta"
    attribute.
* tests/paca.mjs (test_{interpretMetacharacter,performTransition): Add
  routine test implementation.

1 files changed, 25 insertions, 1 deletions

diff --git a/src/paca.mjs b/src/paca.mjs
index 77a7a4b..216dc2e 100644
--- a/src/paca.mjs
+++ b/src/paca.mjs
@@ -761,10 +761,34 @@ const allDirects = (stateID, nodes) =>
 			).flat(),
 		)].toSorted();
 
+const interpretMetacharacter = ({ op, to, matches, ranges }, char) => {
+	if (!op) {
+		return null;
+	}
+
+	if (op === true) {
+		return to;
+	}
+
+	if (matches.has(char)) {
+		return op === "includes" && to;
+	}
+
+	if (inRange(ranges, char)) {
+		return op === "includes" && to;
+	}
+
+	return op === "excludes" && to;
+};
+
+const performTransition = (nodes, char) => id =>
+	nodes[id].transitions[char] ||
+	interpretMetacharacter(nodes[id].meta || {}, char);
+
 const searchNFAStep = nodes => (directStates, char) =>
 	[...new Set(
 		directStates
-			.map(id => nodes[id].transitions[char])
+			.map(performTransition(nodes, char))
 			.filter(x => !!x)
 			.map(id => allDirects(id, nodes))
 			.flat()