From 04d4661dd008284aedc95b2a1f9e120cee17571b Mon Sep 17 00:00:00 2001
From: Carl Hetherington <cth@carlh.net>
Date: Thu, 27 Aug 2020 22:48:00 +0200
Subject: [PATCH] Allow LanguageTag to be constructed from a tag string.

---
 src/language_tag.cc       | 61 +++++++++++++++++++++++++++++++++++++++
 src/language_tag.h        |  3 ++
 test/language_tag_test.cc | 21 +++++++++++++-
 3 files changed, 84 insertions(+), 1 deletion(-)

diff --git a/src/language_tag.cc b/src/language_tag.cc
index 47b46024..b64dab72 100644
--- a/src/language_tag.cc
+++ b/src/language_tag.cc
@@ -36,6 +36,7 @@
 #include "dcp_assert.h"
 #include "exceptions.h"
 #include "language_tag.h"
+#include <boost/algorithm/string.hpp>
 #include <boost/foreach.hpp>
 #include <string>
 
@@ -93,6 +94,66 @@ LanguageTag::Subtag::Subtag (string subtag, SubtagType type)
 }
 
 
+LanguageTag::LanguageTag (string tag)
+{
+	vector<string> parts;
+	boost::split (parts, tag, boost::is_any_of("-"));
+	if (parts.empty()) {
+		throw LanguageTagError (String::compose("Could not parse language tag %1", tag));
+	}
+
+	vector<string>::size_type p = 0;
+	_language = LanguageSubtag (parts[p]);
+	++p;
+
+	if (p == parts.size()) {
+		return;
+	}
+
+	try {
+		_script = ScriptSubtag (parts[p]);
+		++p;
+	} catch (...) {}
+
+	if (p == parts.size()) {
+		return;
+	}
+
+	try {
+		_region = RegionSubtag (parts[p]);
+		++p;
+	} catch (...) {}
+
+	if (p == parts.size()) {
+		return;
+	}
+
+	try {
+		while (true) {
+			_variants.push_back (VariantSubtag(parts[p]));
+			++p;
+			if (p == parts.size()) {
+				return;
+			}
+		}
+	} catch (...) {}
+
+	try {
+		while (true) {
+			_extlangs.push_back (ExtlangSubtag(parts[p]));
+			++p;
+			if (p == parts.size()) {
+				return;
+			}
+		}
+	} catch (...) {}
+
+	if (p < parts.size()) {
+		throw LanguageTagError (String::compose("Unrecognised subtag %1", parts[p]));
+	}
+}
+
+
 string
 LanguageTag::to_string () const
 {
diff --git a/src/language_tag.h b/src/language_tag.h
index 7a6fd159..8aa8a723 100644
--- a/src/language_tag.h
+++ b/src/language_tag.h
@@ -141,6 +141,9 @@ public:
 		bool operator< (ExtlangSubtag const& other) const;
 	};
 
+	LanguageTag () {}
+	LanguageTag (std::string tag);
+
 	void set_language (LanguageSubtag language);
 	void set_script (ScriptSubtag script);
 	void set_region (RegionSubtag region);
diff --git a/test/language_tag_test.cc b/test/language_tag_test.cc
index fd90b629..28c46b63 100644
--- a/test/language_tag_test.cc
+++ b/test/language_tag_test.cc
@@ -41,7 +41,7 @@ using std::vector;
 using std::string;
 
 
-BOOST_AUTO_TEST_CASE (language_tag_test)
+BOOST_AUTO_TEST_CASE (language_tag_create_test)
 {
 	/* Bad subtags raise errors */
 
@@ -177,3 +177,22 @@ BOOST_AUTO_TEST_CASE (language_tag_test)
 	}
 
 }
+
+
+BOOST_AUTO_TEST_CASE (language_tag_parse_test)
+{
+	BOOST_CHECK_THROW (dcp::LanguageTag(""), dcp::LanguageTagError);
+	BOOST_CHECK_THROW (dcp::LanguageTag("...Aw498012351!"), dcp::LanguageTagError);
+	BOOST_CHECK_THROW (dcp::LanguageTag("fish"), dcp::LanguageTagError);
+	BOOST_CHECK_THROW (dcp::LanguageTag("de-Dogr-fish"), dcp::LanguageTagError);
+	BOOST_CHECK_THROW (dcp::LanguageTag("de-Dogr-DE-aranes-fish"), dcp::LanguageTagError);
+
+	BOOST_CHECK_EQUAL (dcp::LanguageTag("de").to_string(), "de");
+	BOOST_CHECK_EQUAL (dcp::LanguageTag("de-Dogr").to_string(), "de-Dogr");
+	BOOST_CHECK_EQUAL (dcp::LanguageTag("de-Dogr-DE").to_string(), "de-Dogr-DE");
+	BOOST_CHECK_EQUAL (dcp::LanguageTag("de-Dogr-DE-aranes").to_string(), "de-Dogr-DE-aranes");
+	BOOST_CHECK_EQUAL (dcp::LanguageTag("de-Dogr-DE-aranes-lemosin").to_string(), "de-Dogr-DE-aranes-lemosin");
+	BOOST_CHECK_EQUAL (dcp::LanguageTag("de-Dogr-DE-aranes-lemosin-abv").to_string(), "de-Dogr-DE-aranes-lemosin-abv");
+	BOOST_CHECK_EQUAL (dcp::LanguageTag("de-Dogr-DE-aranes-lemosin-abv-zsm").to_string(), "de-Dogr-DE-aranes-lemosin-abv-zsm");
+}
+
-- 
2.30.2