More quirky char class syntax scenarios.

Author: SimY4

core/src/main/java/com/github/simy4/coregex/core/CoregexParser.java

@@ -251,7 +251,7 @@ private Coregex literal(Context ctx) {
 
   /*
    * <pre>{@code
-   * set ::= '[', [ '^' ], { set-item }, ']'
+   * set ::= '[', [ '^' ], set-item, { [ '&&' ], set-item }, ']'
    * }</pre>
    */
   private Set set(Context ctx) {
@@ -261,9 +261,28 @@ private Set set(Context ctx) {
       ctx.match('^');
       negated = true;
     }
-    Set.Builder set = Set.builder(ctx.flags);
+    Set.Builder set = Set.builder(ctx.flags), intersect = null;
+    setItem(set, ctx);
     while (']' != ctx.peek()) {
+      boolean mustIntersect = false;
+      if ('&' == ctx.peek() && '&' == ctx.peek(2)) {
+        ctx.match('&');
+        ctx.match('&');
+        if (null != intersect) {
+          set = intersect.intersect(set.build());
+        }
+        intersect = set;
+        set = Set.builder(ctx.flags);
+        mustIntersect = '[' == ctx.peek();
+      }
       setItem(set, ctx);
+      if (mustIntersect) {
+        set = intersect.intersect(set.build());
+        intersect = null;
+      }
+    }
+    if (null != intersect) {
+      set = intersect.intersect(set.build());
     }
     ctx.match(']');
     return (negated ? set.negate() : set).build();
@@ -283,16 +302,6 @@ private void setItem(Set.Builder set, Context ctx) {
       case '[':
         set.union(set(ctx));
         break;
-      case '&':
-        ctx.match('&');
-        ch = ctx.peek();
-        if ('&' == ch) {
-          ctx.match('&');
-          set.intersect(set(ctx));
-        } else {
-          set.single('&');
-        }
-        break;
       case '-':
         ctx.match('-');
         set.single('-');

core/src/test/scala/com/github/simy4/coregex/core/CoregexParserSuite.scala

@@ -1027,14 +1027,21 @@ class CoregexParserSuite extends ScalaCheckSuite with CoregexArbitraries {
           3,
           6
         ) -> Pattern.compile("((?i)[a-z]+(?-i)-[A-Z]){3,6}"),
-        new Quantified(
-          set() {
+        new Concat(
+          new Quantified(
+            set() {
+              _.range('a', 'z')
+                .intersect(set()(_.union(set()(_.set('a', 'e', 'i', 'o', 'u').negate()).set())).set())
+            },
+            1
+          ),
+          set()(_.single(']')),
+          set()(
             _.range('a', 'z')
-              .range('A', 'Z')
-              .intersect(set()(_.set('a', 'e', 'i', 'o', 'u', 'A', 'E', 'I', 'O', 'U').negate()).set())
-          },
-          1
-        )       -> Pattern.compile("[a-zA-Z&&[^aeiouAEIOU]]+"),
+              .intersect(set()(_.set('a', 'e', 'i', 'o', 'u')).set())
+              .intersect(set()(_.set('e', 'i')).set())
+          )
+        )       -> Pattern.compile("[a-z&&[^aeiou]]+[]][a-z&&aeiou&&ei]"),
         empty() -> Pattern.compile("^(?:||)$")
       )
     rng <- List(new RandomRNG())

core/src/test/scala/com/github/simy4/coregex/core/SetSuite.scala

@@ -52,9 +52,11 @@ class SetSuite extends ScalaCheckSuite with CoregexArbitraries {
   }
 
   property("sampled should not be in intersection") {
-    forAll { (set: Set, ch: Char) =>
-      val intersection = Set.builder().union(set).intersect(Set.builder().single(ch).build()).build()
-      !intersection.test(ch.toInt) :| s"$ch in [$intersection]"
+    forAll { (left: Set, right: Set, seed1: Long, seed2: Long) =>
+      val leftWithCommon = Set.builder().union(left).single(right.sample(seed1)).build()
+      val intersection   = Set.builder().union(leftWithCommon).intersect(right).build()
+      val generated      = intersection.sample(seed2)
+      (leftWithCommon.test(generated.toInt) && right.test(generated.toInt)) :| s"$generated in [$intersection]"
     }
   }