METK-141: Add matcher, for select/exclude filtering of mars requests

Author: caraghbiner

src/metkit/CMakeLists.txt

@@ -23,6 +23,8 @@ list( APPEND metkit_srcs
     mars/ClientTask.h
     mars/DHSProtocol.cc
     mars/DHSProtocol.h
+    mars/Matcher.cc
+    mars/Matcher.h
     mars/MarsExpandContext.cc
     mars/MarsExpandContext.h
     mars/MarsExpansion.cc

src/metkit/mars/Matcher.cc

@@ -0,0 +1,97 @@
+/*
+ * (C) Copyright 1996- ECMWF.
+ *
+ * This software is licensed under the terms of the Apache Licence Version 2.0
+ * which can be obtained at http://www.apache.org/licenses/LICENSE-2.0.
+ * In applying this licence, ECMWF does not waive the privileges and immunities
+ * granted to it by virtue of its status as an intergovernmental organisation nor
+ * does it submit to any jurisdiction.
+*/
+
+/// @author Chris Bradley
+
+#include <string>
+#include <map>
+
+#include "eckit/utils/Regex.h"
+#include "eckit/utils/Tokenizer.h"
+#include "eckit/exception/Exceptions.h"
+#include "metkit/mars/MarsRequest.h"
+
+#include "metkit/mars/Matcher.h"
+
+namespace metkit::mars {
+
+namespace {  // helpers
+
+using RegexMap  = std::map<std::string, eckit::Regex>;
+using ValuesMap = std::map<std::string, std::vector<std::string>>;
+
+RegexMap parseKeyRegexList(const std::string& expr) {
+    RegexMap out;
+    if (expr.empty()) {
+        return out;
+    }
+
+    std::vector<std::string> key_vals;
+    eckit::Tokenizer(',')(expr, key_vals);
+
+    eckit::Tokenizer equals('=');
+    for (const std::string& item : key_vals) {
+        std::vector<std::string> kv;
+        equals(item, kv);
+        if (kv.size() != 2) {
+            throw eckit::UserError("Invalid condition " + item + " in expression: " + expr, Here());
+        }
+
+        const std::string& key = kv[0];
+        const std::string& val = kv[1];
+
+        if (out.find(key) != out.end()) {
+            throw eckit::UserError("Duplicate key " + key + " in expression: " + expr, Here());
+        }
+
+        out[key] = eckit::Regex(val);
+    }
+    return out;
+}
+
+} // namespace helpers
+
+Matcher::Matcher(const std::string& expr):
+    regexMap_{parseKeyRegexList(expr)} {
+}
+
+bool Matcher::match(const MarsRequest& request, bool matchOnMissing, ValuePolicy policy) const {
+    ValuesMap vals;
+    for (const auto& kv : regexMap_) {
+        vals[kv.first] = request.values(kv.first, /*emptyOK*/ true);
+    }
+    return match(vals, matchOnMissing, policy);
+}
+
+bool Matcher::match(const ValuesMap& request, bool matchOnMissing, ValuePolicy policy) const {
+    return std::all_of(regexMap_.begin(), regexMap_.end(),
+    [&](const auto& kv) {
+        const auto& keyword = kv.first;
+        const auto& re      = kv.second;
+
+        auto it = request.find(keyword);
+
+        // If the key is missing or present with no values
+        if (it == request.end() || it->second.empty())
+            return matchOnMissing;
+
+        const auto& vals = it->second;
+        auto pred = [&](const std::string& s){ return re.match(s); };
+
+        if (policy == ValuePolicy::Any)
+            return std::any_of(vals.begin(), vals.end(), pred);
+        else if (policy == ValuePolicy::All)
+            return std::all_of(vals.begin(), vals.end(), pred);
+        else
+            throw eckit::SeriousBug("Not implemented ValuePolicy in Matcher::match");
+    });
+}
+
+} // namespace metkit::mars

src/metkit/mars/Matcher.h

@@ -0,0 +1,48 @@
+/*
+ * (C) Copyright 1996- ECMWF.
+ *
+ * This software is licensed under the terms of the Apache Licence Version 2.0
+ * which can be obtained at http://www.apache.org/licenses/LICENSE-2.0.
+ * In applying this licence, ECMWF does not waive the privileges and immunities
+ * granted to it by virtue of its status as an intergovernmental organisation nor
+ * does it submit to any jurisdiction.
+ */
+
+ /// @author Chris Bradley
+
+#include <string>
+#include <map>
+#include "eckit/utils/Regex.h"
+#include "metkit/mars/MarsRequest.h"
+namespace metkit::mars {
+
+// for handling things like:
+//  expr: expver=(0001|o[0-9a-z]{3}),dataset=^climate-dt$
+// the expr is a series of comma separated key=regex pairs
+// where the regex is used to match against the value(s) of the key in a mars request
+
+
+class Matcher {
+public:
+    enum class ValuePolicy { Any, All };
+public:
+    // mars key -> regex
+    using RegexMap  = std::map<std::string, eckit::Regex>;
+
+    using SelectMap = std::map<std::string, eckit::Regex>;
+    using ValuesMap = std::map<std::string, std::vector<std::string>>;  // keyword -> list of values
+
+public:
+    Matcher(const std::string& expr);
+
+    bool match(const ValuesMap& request, bool matchOnMissing, ValuePolicy policy) const;
+    bool match(const MarsRequest& request, bool matchOnMissing, ValuePolicy policy) const;
+
+    const RegexMap& regexMap() const { return regexMap_; }
+
+private:
+    
+    RegexMap regexMap_; // public for now...
+};
+
+}  // namespace metkit::mars