From 5faa47482bb944285d4827cb6a88bbc8bd9bb8a4 Mon Sep 17 00:00:00 2001
From: Metin Cakircali <metin.cakircali@ecmwf.int>
Date: Tue, 5 May 2026 11:56:38 +0200
Subject: [PATCH 1/3] add print to Matcher

---
 src/metkit/mars/Matcher.cc | 12 +++++++++++-
 src/metkit/mars/Matcher.h  |  9 ++++++++-
 2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/src/metkit/mars/Matcher.cc b/src/metkit/mars/Matcher.cc
index 5397e71f..3a1173a5 100644
--- a/src/metkit/mars/Matcher.cc
+++ b/src/metkit/mars/Matcher.cc
@@ -126,4 +126,14 @@ bool Matcher::match(const RequestLike& request, MatchMissingPolicy matchOnMissin
     });
 }
 
-}  // namespace metkit::mars
\ No newline at end of file
+void Matcher::print(std::ostream& s) const {
+    s << "{";
+    const char* sep = "";
+    for (const auto& [key, regex] : regexMap_) {
+        s << sep << key << "=" << static_cast<const std::string&>(regex);
+        sep = ",";
+    }
+    s << "}";
+}
+
+}  // namespace metkit::mars
diff --git a/src/metkit/mars/Matcher.h b/src/metkit/mars/Matcher.h
index 8d963ac9..3ce49293 100644
--- a/src/metkit/mars/Matcher.h
+++ b/src/metkit/mars/Matcher.h
@@ -62,6 +62,13 @@ class Matcher {
     bool match(const RequestLike& request, MatchMissingPolicy matchOnMissing = MatchOnMissing) const;
     bool match(const MarsRequest& request, MatchMissingPolicy matchOnMissing = MatchOnMissing) const;
 
+    void print(std::ostream& s) const;
+
+    friend std::ostream& operator<<(std::ostream& s, const Matcher& m) {
+        m.print(s);
+        return s;
+    }
+
 private:
 
     std::map<std::string, eckit::Regex> regexMap_;
@@ -85,4 +92,4 @@ class RequestLike {
     virtual std::optional<values_t> get(const std::string& keyword) const = 0;
 };
 
-}  // namespace metkit::mars
\ No newline at end of file
+}  // namespace metkit::mars

From 8a0eae64909bd7f693a1ce7b63f35df4f273261c Mon Sep 17 00:00:00 2001
From: Metin Cakircali <metin.cakircali@ecmwf.int>
Date: Fri, 8 May 2026 13:41:03 +0200
Subject: [PATCH 2/3] test matcher print

---
 tests/test_matcher.cc | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/tests/test_matcher.cc b/tests/test_matcher.cc
index 65ddd26c..b0a65b7e 100644
--- a/tests/test_matcher.cc
+++ b/tests/test_matcher.cc
@@ -12,6 +12,8 @@
 #include "metkit/mars/MarsRequest.h"
 #include "metkit/mars/Matcher.h"
 
+#include <sstream>
+
 using namespace eckit::testing;
 using namespace metkit::mars;
 
@@ -151,6 +153,15 @@ CASE("match empty request") {
     EXPECT_EQUAL(match_all.match(req, Matcher::MatchOnMissing), true);
 }
 
+CASE("streaming matcher is deterministic") {
+    Matcher matcher("stream=^enfo$, expver=(x[0-9a-z]{3}), number=(1|2)", Matcher::Policy::Any);
+
+    std::ostringstream oss;
+    oss << matcher;
+
+    EXPECT_EQUAL(oss.str(), "{expver=(x[0-9a-z]{3}),number=(1|2),stream=^enfo$}");
+}
+
 // ----------------------------------------------------------------------------------------------------------------------
 
 }  // namespace metkit::test

From cb01ae2a88a0379aef5d829cd1f52ba3a48dd15b Mon Sep 17 00:00:00 2001
From: Metin Cakircali <metin.cakircali@ecmwf.int>
Date: Fri, 8 May 2026 13:42:08 +0200
Subject: [PATCH 3/3] add matcher iosfwd

---
 src/metkit/mars/Matcher.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/metkit/mars/Matcher.h b/src/metkit/mars/Matcher.h
index 3ce49293..d173c0f9 100644
--- a/src/metkit/mars/Matcher.h
+++ b/src/metkit/mars/Matcher.h
@@ -14,6 +14,7 @@
 #pragma once
 
 #include <functional>
+#include <iosfwd>
 #include <map>
 #include <string>
 #include <variant>