Add string decode/encode api

src/ifcparse/character_decoder.h

@@ -67,10 +67,6 @@ class IFC_PARSE_API character_decoder {
     std::string get(size_t& offset);
 };
 
-} // namespace ifcopenshell
-
-namespace ifcopenshell {
-
 class IFC_PARSE_API character_encoder {
   private:
     std::u32string str_;
@@ -80,6 +76,6 @@ class IFC_PARSE_API character_encoder {
     operator std::string();
 };
 
-} // namespace IfcWrite
+} // namespace ifcopenshell
 
 #endif

src/ifcparse/parse.cpp

@@ -550,6 +550,26 @@ std::string token::to_string() {
     return result;
 }
 
+std::string ifcopenshell::encode_spf_string(const std::string& value) {
+    return character_encoder(value);
+}
+
+std::string ifcopenshell::decode_spf_string(const std::string& value) {
+    std::string wrapped;
+    auto value_p = &value;
+    if (!value.empty() && value.front() != '\'') {
+        wrapped = "'" + value + "'";
+        value_p = &wrapped;
+    }
+    file_reader<full_buffer_impl> reader(*value_p, caller_fed_tag{});
+    spf_lexer<file_reader<full_buffer_impl>> lexer(&reader);
+    token decoded = lexer.next();
+    if (!decoded.is_string()) {
+        throw exception("Expected an SPF string");
+    }
+    return decoded.as_string();
+}
+
 namespace {
 
 template<typename Variant, typename T>

src/ifcparse/parse.h

@@ -47,6 +47,10 @@ extern IFC_PARSE_API const char *IFCOPENSHELL_VERSION;
 
 namespace ifcopenshell {
 
+IFC_PARSE_API std::string encode_spf_string(const std::string& value);
+
+IFC_PARSE_API std::string decode_spf_string(const std::string& value);
+
 /// A stream of tokens to be read from a file_reader.
 template <typename Reader>
 class IFC_PARSE_API spf_lexer {

src/ifcparse/tests/test_ifcopenshell_parse.cpp

@@ -2,9 +2,19 @@
 
 #include <catch2/catch_test_macros.hpp>
 #include <ifcparse/file.h>
+#include <ifcparse/parse.h>
 #include <string>
 #include <vector>
 
+TEST_CASE("SPF strings can be encoded and decoded", "[ifcparse]") {
+    const std::string decoded = "Caf\xC3\xA9" "'s \\";
+    const std::string encoded = R"('Caf\X2\00E9\X0\''s \\')";
+
+    CHECK(ifcopenshell::encode_spf_string(decoded) == encoded);
+    CHECK(ifcopenshell::decode_spf_string(encoded) == decoded);
+    CHECK(ifcopenshell::decode_spf_string(encoded.substr(1, encoded.size() - 2)) == decoded);
+}
+
 TEST_CASE("IfcPropertySetDefinitionSet references are resolved without replacing their owner", "[ifcparse]") {
     const std::string fixture = std::string(IFCOPENSHELL_TEST_FIXTURES) + "/ColumnPSetsOfSets.ifc";
     ifcopenshell::file file(fixture);