vis: refactor Lua integration

Lua support can now be disabled at compile time using:

 $ make CONFIG_LUA=0

This commit also adds an initial Lua API and provides a few
default hooks.

We now also require Lua >= 5.2 due to the uservalue constructs.
In principle the same functionality could be implemented using
function environments from Lua 5.1.

1 files changed, 491 insertions, 0 deletions

diff --git a/vis-lua.c b/vis-lua.c
new file mode 100644
index 0000000..d597772
--- /dev/null
+++ b/vis-lua.c
@@ -0,0 +1,491 @@
+#include <stdarg.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/types.h>
+#include <pwd.h>
+
+#include "vis-lua.h"
+#include "vis-core.h"
+#include "text-motions.h"
+
+#if !CONFIG_LUA
+
+void vis_lua_start(Vis *vis) { }
+void vis_lua_quit(Vis *vis) { }
+void vis_lua_file_open(Vis *vis, File *file) { }
+void vis_lua_file_save(Vis *vis, File *file) { }
+void vis_lua_file_close(Vis *vis, File *file) { }
+void vis_lua_win_open(Vis *vis, Win *win) { }
+void vis_lua_win_close(Vis *vis, Win *win) { }
+bool vis_theme_load(Vis *vis, const char *name) { return true; }
+
+#else
+
+#if 0
+static void stack_dump_entry(lua_State *L, int i) {
+	int t = lua_type(L, i);
+	switch (t) {
+	case LUA_TNIL:
+		printf("nil");
+		break;
+	case LUA_TBOOLEAN:
+		printf(lua_toboolean(L, i) ? "true" : "false");
+		break;
+	case LUA_TLIGHTUSERDATA:
+		printf("lightuserdata(%p)", (void*)lua_touserdata(L, i));
+		break;
+	case LUA_TNUMBER:
+		printf("%g", lua_tonumber(L, i));
+		break;
+	case LUA_TSTRING:
+		printf("`%s'", lua_tostring(L, i));
+		break;
+	case LUA_TTABLE:
+		printf("table[");
+		lua_pushnil(L); /* first key */
+		while (lua_next(L, i > 0 ? i : i - 1)) {
+			stack_dump_entry(L, -2);
+			printf("=");
+			stack_dump_entry(L, -1);
+			printf(",");
+			lua_pop(L, 1); /* remove value, keep key */
+		}
+		printf("]");
+		break;
+	case LUA_TUSERDATA:
+		printf("userdata(%p)", (void*)lua_touserdata(L, i));
+		break;
+	default:  /* other values */
+		printf("%s", lua_typename(L, t));
+		break;
+	}
+}
+
+static void stack_dump(lua_State *L, const char *format, ...) {
+	va_list ap;
+	va_start(ap, format);
+	vprintf(format, ap);
+	va_end(ap);
+	int top = lua_gettop(L);
+	for (int i = 1; i <= top; i++) {
+		printf("%d: ", i);
+		stack_dump_entry(L, i);
+		printf("\n");
+	}
+	printf("\n\n");
+}
+
+#endif
+
+/* returns registry["vis.objects"][addr] if it is of correct type */
+static void *obj_get(lua_State *L, void *addr, const char *type) {
+	lua_getfield(L, LUA_REGISTRYINDEX, "vis.objects");
+	lua_pushlightuserdata(L, addr);
+	lua_gettable(L, -2);
+	lua_remove(L, -2);
+	if (lua_isnil(L, -1)) {
+		lua_pop(L, 1);
+		return NULL;
+	}
+	return luaL_checkudata(L, -1, type);
+}
+
+/* expects a userdatum at the top of the stack and sets
+ *
+ *   registry["vis.objects"][addr] = userdata
+ */
+static void obj_set(lua_State *L, void *addr) {
+	lua_getfield(L, LUA_REGISTRYINDEX, "vis.objects");
+	lua_pushlightuserdata(L, addr);
+	lua_pushvalue(L, -3);
+	lua_settable(L, -3);
+	lua_pop(L, 1);
+}
+
+static void obj_del(lua_State *L, void *addr) {
+	lua_pushnil(L);
+	obj_set(L, addr);
+}
+
+static void *obj_new(lua_State *L, void *addr, const char *type) {
+	if (!addr)
+		return NULL;
+	void **handle = (void**)obj_get(L, addr, type);
+	if (!handle) {
+		handle = lua_newuserdata(L, sizeof(addr));
+		obj_set(L, addr);
+		*handle = addr;
+		luaL_getmetatable(L, type);
+		lua_setmetatable(L, -2);
+		lua_newtable(L);
+		lua_setuservalue(L, -2);
+	}
+	return *handle;
+}
+
+static void *obj_arg_get(lua_State *L, int idx, const char *type) {
+	void **addr = luaL_checkudata(L, idx, type);
+	return obj_get(L, *addr, type);
+}
+
+static void *obj_check(lua_State *L, int idx, const char *type) {
+	void **addr = luaL_checkudata(L, idx, type);
+	if (!obj_get(L, *addr, type))
+		return NULL;
+	lua_pop(L, 1);
+	return *addr;
+}
+
+static int index_common(lua_State *L) {
+	lua_getmetatable(L, 1);
+	lua_pushvalue(L, 2);
+	lua_gettable(L, -2);
+	if (lua_isnil(L, -1)) {
+		lua_getuservalue(L, 1);
+		lua_pushvalue(L, 2);
+		lua_gettable(L, -2);
+	}
+	return 1;
+}
+
+static int newindex_common(lua_State *L) {
+	lua_getuservalue(L, 1);
+	lua_pushvalue(L, 2);
+	lua_pushvalue(L, 3);
+	lua_settable(L, -3);
+	return 0;
+}
+
+static int windows_iter(lua_State *L);
+
+static int windows(lua_State *L) {
+	Vis *vis = (Vis*)lua_touserdata(L, lua_upvalueindex(1));
+	Win **handle = lua_newuserdata(L, sizeof *handle);
+	*handle = vis->windows;
+	lua_pushcclosure(L, windows_iter, 1);
+	return 1;
+}
+
+static int windows_iter(lua_State *L) {
+	Win **handle = (Win**)lua_touserdata(L, lua_upvalueindex(1));
+	if (!*handle)
+		return 0;
+	Win *win = obj_new(L, *handle, "vis.window");
+	if (!win)
+		return 0;
+	*handle = win->next;
+	return 1;
+}
+
+static int files_iter(lua_State *L);
+
+static int files(lua_State *L) {
+	Vis *vis = (Vis*)lua_touserdata(L, lua_upvalueindex(1));
+	File **handle = lua_newuserdata(L, sizeof *handle);
+	*handle = vis->files;
+	lua_pushcclosure(L, files_iter, 1);
+	return 1;
+}
+
+static int files_iter(lua_State *L) {
+	File **handle = (File**)lua_touserdata(L, lua_upvalueindex(1));
+	if (!*handle)
+		return 0;
+	File *file = obj_new(L, *handle, "vis.file");
+	if (!file)
+		return 0;
+	*handle = file->next;
+	return 1;
+}
+
+static int command(lua_State *L) {
+	Vis *vis = (Vis*)lua_touserdata(L, lua_upvalueindex(1));
+	const char *cmd = luaL_checkstring(L, 1);
+	bool ret = vis_cmd(vis, cmd);
+	lua_pushboolean(L, ret);
+	return 1;
+}
+
+static int info(lua_State *L) {
+	Vis *vis = (Vis*)lua_touserdata(L, lua_upvalueindex(1));
+	const char *msg = luaL_checkstring(L, 1);
+	vis_info_show(vis, "%s", msg);
+	return 0;
+}
+
+static const struct luaL_Reg vis_lua[] = {
+	{ "files", files },
+	{ "windows", windows },
+	{ "command", command },
+	{ "info", info },
+	{ NULL, NULL },
+};
+
+static int window_index(lua_State *L) {
+	Win *win = obj_check(L, 1, "vis.window");
+	if (!win) {
+		lua_pushnil(L);
+		return 1;
+	}
+
+	if (lua_isstring(L, 2)) {
+		const char *key = lua_tostring(L, 2);
+		if (strcmp(key, "file") == 0) {
+			obj_new(L, win->file, "vis.file");
+			return 1;
+		}
+	}
+
+	return index_common(L);
+}
+
+static int window_newindex(lua_State *L) {
+	Win *win = obj_check(L, 1, "vis.window");
+	if (!win)
+		return 0;
+	return newindex_common(L);
+}
+
+static const struct luaL_Reg window_funcs[] = {
+	{ "__index", window_index },
+	{ "__newindex", window_newindex },
+	{ NULL, NULL },
+};
+
+static int file_index(lua_State *L) {
+	File *file = obj_check(L, 1, "vis.file");
+	if (!file) {
+		lua_pushnil(L);
+		return 1;
+	}
+
+	if (lua_isstring(L, 2)) {
+		const char *key = lua_tostring(L, 2);
+		if (strcmp(key, "name") == 0) {
+			lua_pushstring(L, file->name);
+			return 1;
+		}
+	}
+
+	return index_common(L);
+}
+
+static int file_newindex(lua_State *L) {
+	File *file = obj_check(L, 1, "vis.file");
+	if (!file)
+		return 0;
+	return newindex_common(L);
+}
+
+static int file_insert(lua_State *L) {
+	File *file = obj_check(L, 1, "vis.file");
+	if (file) {
+		size_t pos = luaL_checkunsigned(L, 2);
+		size_t len;
+		luaL_checkstring(L, 3);
+		const char *data = lua_tolstring(L, 3, &len);
+ 		bool ret = text_insert(file->text, pos, data, len);
+		lua_pushboolean(L, ret);
+	} else {
+		lua_pushboolean(L, false);
+	}
+	return 1;
+}
+
+static int file_delete(lua_State *L) {
+	File *file = obj_check(L, 1, "vis.file");
+	if (file) {
+		size_t pos = luaL_checkunsigned(L, 2);
+		size_t len = luaL_checkunsigned(L, 3);
+		bool ret = text_delete(file->text, pos, len);
+		lua_pushboolean(L, ret);
+	} else {
+		lua_pushboolean(L, false);
+	}
+	return 1;
+}
+
+static int file_lines_iter(lua_State *L);
+
+static int file_lines(lua_State *L) {
+	obj_arg_get(L, 1, "vis.file");
+	size_t *pos = lua_newuserdata(L, sizeof *pos);
+	*pos = 0;
+	lua_pushcclosure(L, file_lines_iter, 2);
+	return 1;
+}
+
+static int file_lines_iter(lua_State *L) {
+	File *file = *(File**)lua_touserdata(L, lua_upvalueindex(1));
+	size_t *pos = lua_touserdata(L, lua_upvalueindex(2));
+	size_t new_pos = text_line_next(file->text, *pos);
+	size_t len = new_pos - *pos;
+	if (len == 0)
+		return 0;
+	char *buf = malloc(len);
+	if (!buf)
+		return 0;
+	len = text_bytes_get(file->text, *pos, len, buf);
+	lua_pushlstring(L, buf, len);
+	free(buf);
+	*pos = new_pos;
+	return 1;
+}
+
+static const struct luaL_Reg file_funcs[] = {
+	{ "__index", file_index },
+	{ "__newindex", file_newindex },
+	{ "insert", file_insert },
+	{ "delete", file_delete },
+	{ "lines", file_lines },
+	{ NULL, NULL },
+};
+
+
+static void vis_lua_event(Vis *vis, const char *name) {
+	lua_State *L = vis->lua;
+	lua_getglobal(L, "vis");
+	lua_getfield(L, -1, "events");
+	if (lua_istable(L, -1)) {
+		lua_getfield(L, -1, name);
+	}
+	lua_remove(L, -2);
+}
+
+void vis_lua_start(Vis *vis) {
+	lua_State *L = luaL_newstate();
+	if (!L)
+		return;
+	vis->lua = L;
+	luaL_openlibs(L);
+
+	/* try to get users home directory */
+	const char *home = getenv("HOME");
+	if (!home || !*home) {
+		struct passwd *pw = getpwuid(getuid());
+		if (pw)
+			home = pw->pw_dir;
+	}
+
+	/* extends lua's package.path with:
+	 * - $VIS_PATH/lexers
+	 * - $HOME/.vis/lexers
+	 * - /usr/local/share/vis/lexers
+	 * - /usr/share/vis/lexers
+	 * - package.path (standard lua search path)
+	 */
+	int paths = 3;
+	lua_getglobal(L, "package");
+
+	const char *vis_path = getenv("VIS_PATH");
+	if (vis_path) {
+		lua_pushstring(L, vis_path);
+		lua_pushstring(L, "/lexers/?.lua;");
+		lua_concat(L, 2);
+		paths++;
+	}
+
+	if (home && *home) {
+		lua_pushstring(L, home);
+		lua_pushstring(L, "/.vis/lexers/?.lua;");
+		lua_concat(L, 2);
+		paths++;
+	}
+
+	lua_pushstring(L, "/usr/local/share/vis/lexers/?.lua;");
+	lua_pushstring(L, "/usr/share/vis/lexers/?.lua;");
+	lua_getfield(L, -paths, "path");
+	lua_concat(L, paths);
+	lua_setfield(L, -2, "path");
+	lua_pop(L, 1); /* package */
+
+	/* table in registry to track lifetimes of C objects */
+	lua_newtable(L);
+	lua_setfield(L, LUA_REGISTRYINDEX, "vis.objects");
+	/* metatable used to type check user data */
+	luaL_newmetatable(L, "vis.file");
+	luaL_setfuncs(L, file_funcs, 0);
+	luaL_newmetatable(L, "vis.window");
+	luaL_setfuncs(L, window_funcs, 0);
+	/* vis module table with up value as the C pointer */
+	luaL_newlibtable(L, vis_lua);
+	lua_pushlightuserdata(L, vis);
+	luaL_setfuncs(L, vis_lua, 1);
+	lua_setglobal(L, "vis");
+
+	lua_getglobal(L, "require");
+	lua_pushstring(L, "visrc");
+	lua_pcall(L, 1, 0, 0);
+}
+
+void vis_lua_quit(Vis *vis) {
+	lua_State *L = vis->lua;
+	if (L)
+		lua_close(L);
+}
+
+void vis_lua_file_open(Vis *vis, File *file) {
+
+}
+
+void vis_lua_file_save(Vis *vis, File *file) {
+
+}
+
+void vis_lua_file_close(Vis *vis, File *file) {
+	lua_State *L = vis->lua;
+	vis_lua_event(vis, "file_close");
+	if (lua_isfunction(L, -1)) {
+		obj_new(L, file, "vis.file");
+		lua_pcall(L, 1, 0, 0);
+	}
+	obj_del(L, file);
+	lua_pop(L, 1);
+}
+
+void vis_lua_win_open(Vis *vis, Win *win) {
+	lua_State *L = vis->lua;
+	vis_lua_event(vis, "win_open");
+	if (lua_isfunction(L, -1)) {
+		obj_new(L, win, "vis.window");
+		lua_pcall(L, 1, 0, 0);
+	}
+	lua_pop(L, 1);
+}
+
+void vis_lua_win_close(Vis *vis, Win *win) {
+	lua_State *L = vis->lua;
+	vis_lua_event(vis, "win_close");
+	if (lua_isfunction(L, -1)) {
+		obj_new(L, win, "vis.window");
+		lua_pcall(L, 1, 0, 0);
+	}
+	obj_del(L, win);
+	lua_pop(L, 1);
+}
+
+bool vis_theme_load(Vis *vis, const char *name) {
+	lua_State *L = vis->lua;
+	if (!L)
+		return false;
+	/* package.loaded['themes/'..name] = nil
+	 * require 'themes/'..name */
+	lua_pushstring(L, "themes/");
+	lua_pushstring(L, name);
+	lua_concat(L, 2);
+	lua_getglobal(L, "package");
+	lua_getfield(L, -1, "loaded");
+	lua_pushvalue(L, -3);
+	lua_pushnil(L);
+	lua_settable(L, -3);
+	lua_pop(L, 2);
+	lua_getglobal(L, "require");
+	lua_pushvalue(L, -2);
+	if (lua_pcall(L, 1, 0, 0))
+		return false;
+	for (Win *win = vis->windows; win; win = win->next)
+		view_syntax_set(win->view, view_syntax_get(win->view));
+	return true;
+}
+
+#endif