add package pathrouter

1 files changed, 61 insertions, 0 deletions

diff --git a/pathrouter/choice.go b/pathrouter/choice.go
new file mode 100644
index 0000000..09026b8
--- /dev/null
+++ b/pathrouter/choice.go
@@ -0,0 +1,61 @@
+// SPDX-FileCopyrightText: 2026 Stefan Majewsky <majewsky@gmx.net>
+// SPDX-License-Identifier: Apache-2.0
+
+package pathrouter
+
+import (
+	"slices"
+
+	. "go.xyrillian.de/gg/option"
+	"go.xyrillian.de/gg/options"
+)
+
+// Choice is a [Matcher] that accepts all subpaths that are accepted by any of its contained matchers.
+// If multiple matchers accept the requested subpath, the first match wins.
+//
+// Choice is used to specify different matchers for different subpaths,
+// as illustrated in the example in the package docstring.
+func Choice(matchers ...Matcher) Matcher {
+	downcasted := make([]realMatcher, len(matchers))
+	for idx, matcher := range matchers {
+		downcasted[idx] = matcher.downcast()
+	}
+	return choice(downcasted)
+}
+
+func choice(matchers []realMatcher) Matcher {
+	if len(matchers) == 0 {
+		panic("Choice() called without any matchers")
+	}
+
+	var (
+		minLengths     = make([]int, len(matchers))
+		maxLengths     = make([]Option[int], len(matchers))
+		maxLengthIsInf = false
+	)
+	for idx, m := range matchers {
+		minLengths[idx] = m.minLength
+		maxLengths[idx] = m.maxLength
+		if m.maxLength.IsNone() {
+			maxLengthIsInf = true
+		}
+	}
+	maxLength := None[int]()
+	if !maxLengthIsInf {
+		maxLength = options.Max(maxLengths...)
+	}
+
+	return realMatcher{
+		minLength: slices.Min(minLengths),
+		maxLength: maxLength,
+		accept: func(path []string, vars map[string]string) HandlerFunc {
+			for _, m := range matchers {
+				hf := m.accept(path, vars)
+				if hf != nil {
+					return hf
+				}
+			}
+			return nil
+		},
+	}
+}