1 files changed, 37 insertions, 1 deletions
diff --git a/internal/config/dir.go b/internal/config/dir.go
index 74c538a..461d912 100644
--- a/internal/config/dir.go
+++ b/internal/config/dir.go
@@ -19,9 +19,41 @@ type Dir struct {
 	PathText string // as written in the file
 	Settings Settings
 	Ignore   []string // gitignore patterns, in order
+	Excludes []*Exclude
 	Rules    []*Rule
 }
 
+// Exclude is one (exclude COND...) form: a file for which every condition
+// holds is set aside before any rule runs. Forms may repeat, so a file is
+// excluded when any one form matches it.
+type Exclude struct {
+	Pos  sexp.Pos
+	Text string       // the form as written, whitespace collapsed, for check and explain
+	When []*sexp.Node // the conditions, all of which must hold
+}
+
+// parseExclude reads an (exclude COND...) form from src; nil when it has no
+// usable condition.
+func parseExclude(n *sexp.Node, src []byte, d *diags) *Exclude {
+	conds := n.Args()
+	if len(conds) == 0 {
+		d.at(n, "(exclude) needs a condition, like (exclude (type iso))")
+		return nil
+	}
+	bad := false
+	for _, c := range conds {
+		if c.Kind != sexp.List {
+			d.at(c, "exclude: a condition is a form like (type pdf), not %s", c)
+			bad = true
+		}
+	}
+	if bad {
+		return nil
+	}
+	text := strings.Join(strings.Fields(string(src[n.Pos.Offset:n.End.Offset])), " ")
+	return &Exclude{Pos: n.Pos, Text: text, When: conds}
+}
+
 // Rule is a named condition with the actions it performs.
 type Rule struct {
 	Name     string
@@ -97,6 +129,10 @@ func ParseDir(name, file string, src []byte) (*Dir, []*Diag) {
 				}
 				dir.Ignore = append(dir.Ignore, a.Text)
 			}
+		case head == "exclude":
+			if x := parseExclude(n, src, d); x != nil {
+				dir.Excludes = append(dir.Excludes, x)
+			}
 		case head == "rule":
 			r := parseRule(n, d)
 			if r == nil {
@@ -111,7 +147,7 @@ func ParseDir(name, file string, src []byte) (*Dir, []*Diag) {
 		case isSetting(head):
 			dir.Settings.parse(n, d, seen)
 		default:
-			d.at(n, "unknown form (%s ...); a directory file has path, ignore, rule and settings like (recursive yes)", head)
+			d.at(n, "unknown form (%s ...); a directory file has path, ignore, exclude, rule and settings like (recursive yes)", head)
 		}
 	}
 	if pathNode == nil {