Initial commit: Klammertext source distribution

Curated source subset assembled by klammertext-dev's doc/make_dist.sh: the Klammermachine (mac), the Standard Klammer Set (sks), the commands (com), editor plugins and install guides (doc), a test subset (tst), and lib/bin placeholders. Builds with 'make -C com'.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

mac/eval_cpp.cpp

@@ -0,0 +1,43 @@
+#include <memory>
+#include <dlfcn.h>
+
+#include "eval_cpp.h"
+#include "util.h"
+#include "log.h"
+#include "file.h"
+#include "show.h"
+
+Eval_cpp::Eval_cpp(Machine& machine, Locator loc)
+    : m_machine(machine)
+    , m_loc(loc)
+{
+    (void)K::log(3);
+}
+
+std::string Eval_cpp::eval(fs::path library_path, std::string function_name)
+{
+    (void)K::log(3, library_path, function_name);
+    // msg() << "library path: " << library_path.string().c_str() << "\n";
+    void* handle = dlopen(library_path.string().c_str(), RTLD_LAZY);
+    if (!handle) {
+        const char* error = dlerror();
+        std::string error_desc = error ? error : "unknown error";
+        throw File_error("Cannot open library: " + library_path.string() + "\n  " + error_desc, m_loc);
+    }
+    dlerror();
+    typedef std::string (*func_t)(Machine);
+    func_t func = (func_t) dlsym(handle, function_name.c_str());
+    const char* dlsym_error = dlerror();
+    if (dlsym_error) {
+        std::string error_desc(dlsym_error);
+        dlclose(handle);
+        std::stringstream ss {};
+        ss << "Cannot load symbol " << function_name
+           << " from library " << library_path << ":\n  " << error_desc;
+        throw File_error(ss.str(), m_loc, false);
+    }
+    std::string result = func(m_machine);
+    dlclose(handle);
+    return result;
+}
+