change applyFn to interface

filter/base.go

@@ -41,11 +41,17 @@ func (c *LineCollector) Lines() []line.Line {
 	return c.lines
 }
 
+// lineApplier is implemented by filter types that embed baseFilter to provide
+// their type-specific matching logic.
+type lineApplier interface {
+	applyInternal(ctx context.Context, lines []line.Line, em LineEmitter) error
+}
+
 // baseFilter provides shared implementations of Apply, ApplyCollect,
 // NewContext, and BufSize for filters that follow the applyInternal pattern.
-// Filters embed this type and set applyFn to their type-specific matching logic.
+// Filters embed this type and set impl to their concrete filter value.
 type baseFilter struct {
-	applyFn func(ctx context.Context, lines []line.Line, em LineEmitter) error
+	impl lineApplier
 }
 
 // NewContext returns a context initialized with the given query for pipeline use.
@@ -59,13 +65,13 @@ func (b *baseFilter) BufSize() int {
 
 // Apply runs the filter's matching logic on lines, sending matches to out.
 func (b *baseFilter) Apply(ctx context.Context, lines []line.Line, out pipeline.ChanOutput) error {
-	return b.applyFn(ctx, lines, &chanEmitter{out: out})
+	return b.impl.applyInternal(ctx, lines, &chanEmitter{out: out})
 }
 
 // ApplyCollect runs the filter and returns matched lines directly as a slice,
 // bypassing channel-based output for better performance in parallel paths.
 func (b *baseFilter) ApplyCollect(ctx context.Context, lines []line.Line) ([]line.Line, error) {
 	c := NewLineCollector(len(lines) / 2)
-	err := b.applyFn(ctx, lines, c)
+	err := b.impl.applyInternal(ctx, lines, c)
 	return c.Lines(), err
 }

filter/fuzzy.go

@@ -34,7 +34,7 @@ func NewFuzzy(sortLongest bool) *Fuzzy {
 	ff := &Fuzzy{
 		sortLongest: sortLongest,
 	}
-	ff.applyFn = ff.applyInternal
+	ff.impl = ff
 	return ff
 }
 

filter/regexp.go

@@ -127,7 +127,7 @@ func newRegexpFilter(name string, flags regexpFlags, quotemeta bool) *Regexp {
 		quotemeta: quotemeta,
 		name:      name,
 	}
-	rf.applyFn = rf.applyInternal
+	rf.impl = rf
 	return rf
 }