1 files changed, 106 insertions, 0 deletions
diff --git a/source/luametatex/source/lua/lmtlibrary.c b/source/luametatex/source/lua/lmtlibrary.c
new file mode 100644
index 000000000..ff6822a02
--- /dev/null
+++ b/source/luametatex/source/lua/lmtlibrary.c
@@ -0,0 +1,106 @@
+/*
+    See license.txt in the root of this project.
+*/
+
+
+/*tex
+
+    There is not much here. We only implement a mechanism for storing optional libraries. The
+    engine is self contained and doesn't depend on large and complex libraries. One can (try to)
+    load libraries at runtime. The optional ones that come with the engine end up in the
+    |optional| namespace.
+
+*/
+
+# include "luametatex.h"
+
+void lmt_library_initialize(lua_State *L)
+{
+    lua_getglobal(L,"optional");
+    if (! lua_istable(L, -1)) {
+        lua_pop(L, 1);
+        lua_newtable(L);
+        lua_setglobal(L, "optional");
+    } else {
+        lua_pop(L, 1);
+    }
+}
+
+void lmt_library_register(lua_State *L, const char *name, luaL_Reg functions[])
+{
+    lmt_library_initialize(L);
+    lua_getglobal(L, "optional");
+    lua_pushstring(L, name);
+    lua_newtable(L);
+    luaL_setfuncs(L, functions, 0);
+    lua_rawset(L, -3);
+    lua_pop(L, 1);
+}
+
+lmt_library lmt_library_load(const char *filename)
+{
+    lmt_library lib = { .lib = NULL };
+    if (filename && strlen(filename)) {
+        lib.lib = lmt_library_open_indeed(filename);
+        lib.okay = lib.lib != NULL;
+        if (! lib.okay) {
+            tex_formatted_error("lmt library", "unable to load '%s', quitting\n", filename);
+        }
+    }
+    return lib;
+}
+
+lmt_library_function lmt_library_find(lmt_library lib, const char *source)
+{
+    if (lib.lib && lib.okay) {
+        lmt_library_function target = lmt_library_find_indeed(lib.lib, source);
+        if (target) {
+            return target;
+        } else {
+            lib.okay = 0;
+            tex_formatted_error("lmt library", "unable to locate '%s', quitting\n", source);
+        }
+    }
+    return NULL;
+}
+
+int lmt_library_okay(lmt_library lib)
+{
+    return lib.lib && lib.okay;
+};
+
+/* experiment */
+
+int librarylib_load(lua_State *L)
+{
+    /* So we permit it in mtxrun (for now, when we test). */
+    if (lmt_engine_state.lua_only || lmt_engine_state.permit_loadlib) {
+        const char *filename = lua_tostring(L, 1);
+        const char *openname = lua_tostring(L, 2);
+        if (filename && openname) {
+            lmt_library lib = lmt_library_load(filename);
+            if (lmt_library_okay(lib)) {
+                lua_CFunction target = lmt_library_find_indeed(lib.lib, openname);
+                if (target) {
+                    lua_pushcfunction(L, target);
+                    lua_pushstring(L, filename);
+                    return 2;
+                }
+            }
+        }
+    } else {
+        tex_formatted_error("lmt library", "loading is not permitted, quitting\n");
+    }
+    return 0;
+};
+
+static struct luaL_Reg librarylib_function_list[] = {
+    { "load", librarylib_load },
+    { NULL,   NULL            },
+};
+
+int luaopen_library(lua_State * L)
+{
+    lmt_library_register(L, "library", librarylib_function_list);
+    return 0;
+}