fix lite_xl_plugin_api.h

This fixes a longstanding bug with the plugin API.
This commit is not complete, further polish is still needed.

scripts/README.md

@@ -22,6 +22,7 @@ Various scripts and configurations used to configure, build, and package Lite XL
   and run Lite XL, mainly useful for CI and documentation purpose.
   Preferably not to be used in user systems.
 - **fontello-config.json**:    Used by the icons generator.
+- **generate_header.sh**: Generates a header file for native plugin API
 
 [1]: https://github.com/LinusU/node-appdmg
 [2]: https://docs.appimage.org/

scripts/generate_header.sh

@@ -0,0 +1,94 @@
+#!/bin/bash
+
+# https://stackoverflow.com/a/13062682
+uncomment() {
+  [ $# -eq 2 ] && arg="$1" || arg=""
+  eval file="\$$#"
+  sed 's/a/aA/g; s/__/aB/g; s/#/aC/g' "$file" | \
+    gcc -P -E $arg - | \
+    sed 's/aC/#/g; s/aB/__/g; s/aA/a/g'
+}
+
+# this is the magic that turns multiline statements into
+# single line statements
+# LITERALLY DOES NOT WORK WITH PREPROCESSOR
+onelineize() {
+  grep -v '^#' | sed -e ':r;$!{N;br};s/\([^{;]\)\n\s*/\1 /g'
+}
+
+discard_preprocessors() {
+  grep -v '#\(include\|if\|endif\)'
+}
+
+# sed regex for extracting data from function signature
+# if this isn't regex, idk what is
+# LUA_API (return type as \2) (function name as \3) (args as \4)
+sym_regex='^LUA\(LIB\)\?_API\s\+\([^(]\+\)\s*(\([^)]\+\))\s\+(\([^)]\+\))'
+
+# get funcptr declarations
+ptrize() {
+  grep '^LUA' | sed -e "s/$sym_regex/static \2(*\3) (\4)/"
+}
+
+export_sym() {
+  # don't even bother reading this again
+  grep '^LUA' | sed -e "s/$sym_regex/\tIMPORT_SYMBOL(\3, \2, \4)/"
+}
+
+decl() {
+  header="$(uncomment $1 | discard_preprocessors)"
+  header1="$(onelineize <<< "$header")"
+
+  # typedef
+  grep -v '^\(LUA\|#\|extern\)' <<< "$header1"
+  # funcptrs
+  ptrize <<< "$header1"
+  # defines
+  grep '^#' <<< "$header"
+}
+
+decl_export() {
+  uncomment $1 | onelineize | export_sym
+}
+
+LUA_PATH="$1"
+
+cat << EOF
+/**
+The lite_xl plugin API is quite simple. Any shared library can be a plugin file, so long
+as it has an entrypoint that looks like the following, where xxxxx is the plugin name:
+#include "lite_xl_plugin_api.h"
+int lua_open_lite_xl_xxxxx(lua_State* L, void* XL) {
+  lite_xl_plugin_init(XL);
+  ...
+  return 1;
+}
+In linux, to compile this file, you'd do: 'gcc -o xxxxx.so -shared xxxxx.c'. Simple!
+Due to the way the API is structured, you *should not* link or include lua libraries.
+This file was automatically generated by the below code. Do NOT MODIFY DIRECTLY.
+
+
+EOF
+
+cat "$0"
+
+cat << EOF
+**/
+
+
+#ifndef LITE_XL_PLUGIN_API
+#define LITE_XL_PLUGIN_API
+EOF
+
+decl "$LUA_PATH/lua.h"
+decl "$LUA_PATH/lauxlib.h"
+
+echo "#define IMPORT_SYMBOL(name, ret, ...) name = (ret (*) (__VA_ARGS__)) symbol(#name)"
+echo "static void lite_xl_plugin_init(void *XL) {"
+echo -e "\tvoid* (*symbol)(const char *) = (void* (*) (const char *)) XL;"
+
+decl_export "$LUA_PATH/lua.h"
+decl_export "$LUA_PATH/lauxlib.h"
+
+echo "}"
+echo "#endif"