From 3b36a48b7ce5a53a9366f3b31f94311f178e2553 Mon Sep 17 00:00:00 2001
From: Lukasz Kasprzak <lukas@labunix.xyz>
Date: Sat, 12 Sep 2026 01:22:12 +0200
Subject: krino: matching — scan, ignore, conditions, extraction, duplicates,
 explain, dry run
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---
 cmd/krino/explain.go | 70 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 70 insertions(+)
 create mode 100644 cmd/krino/explain.go

(limited to 'cmd/krino/explain.go')

diff --git a/cmd/krino/explain.go b/cmd/krino/explain.go
new file mode 100644
index 0000000..a4d0253
--- /dev/null
+++ b/cmd/krino/explain.go
@@ -0,0 +1,70 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+package main
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"io"
+	"strings"
+
+	"krino/internal/cond"
+	"krino/internal/engine"
+	"krino/internal/xdg"
+)
+
+func init() { commands["explain"] = cmdExplain }
+
+// cmdExplain evaluates every rule of FILE's directory against it and shows
+// each test's result.
+func cmdExplain(g *globals, args []string, stdout, stderr io.Writer) int {
+	fs := flagSet("explain", g)
+	if code, ok := parse(fs, args, stdout, stderr); !ok {
+		return code
+	}
+	if fs.NArg() != 1 {
+		return usageError(stderr, "usage: krino explain FILE")
+	}
+
+	e, errs := engine.Load(mainFile(g))
+	if len(errs) > 0 {
+		printDiags(stderr, errs)
+		return 2
+	}
+
+	x, err := e.Explain(context.Background(), xdg.Expand(fs.Arg(0)))
+	if err != nil {
+		fmt.Fprintf(stderr, "krino: %v\n", err)
+		return 2
+	}
+
+	fmt.Fprintf(stdout, "%s  (directory %s)\n", xdg.Abbrev(x.File.Path), x.Dir.Name)
+	if x.Skip != "" {
+		fmt.Fprintf(stdout, "krino would not look at this file: %s\n", x.Skip)
+	}
+	fmt.Fprintln(stdout)
+	for _, rt := range x.Rules {
+		if rt.Stopped != "" {
+			fmt.Fprintf(stdout, "rule %s: not evaluated, %s\n", rt.Rule.Name, rt.Stopped)
+			continue
+		}
+		status := "no"
+		if rt.Match {
+			status = "MATCH"
+		}
+		fmt.Fprintf(stdout, "rule %s: %s\n", rt.Rule.Name, status)
+		printTrace(stdout, rt.Trace)
+	}
+	return 0
+}
+
+// printTrace writes t's Format output with every line prefixed by two
+// spaces.
+func printTrace(w io.Writer, t *cond.Trace) {
+	var buf bytes.Buffer
+	t.Format(&buf)
+	for _, line := range strings.Split(strings.TrimRight(buf.String(), "\n"), "\n") {
+		fmt.Fprintf(w, "  %s\n", line)
+	}
+}
-- 
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