My patch for lua.c to give lua stand-alone executable better interactive user experience.
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- Subject: My patch for lua.c to give lua stand-alone executable better interactive user experience.
- From: "pan shizhu" <pan.shizhu@...>
- Date: 2008年11月24日 09:09:43 +0800
Hi all,
compared to python, lua executable has several issues:
1. must prefix '=' to expressions, otherwise you cannot end the line.
2. readline history shows 'return ' if you prefix '=' in the previous line.
3. the previous return is not saved into '_' variable, we cannot use it as a calculator.
My patch solve above three issues, now we no longer need the prefix '=' at all, and readline history will show the expressions as is, without prefix a 'return', and the first result of previous return will always saved into _G["_"].
I hope it will be useful for someone.
Usage: cp the patch file into your lua-5.1.4/src and do command: patch -p0 <lua_c.patch
--- lua.c 2007年12月28日 23:32:23.000000000 +0800
+++ lua.c.new 2008年11月24日 08:56:18.000000000 +0800
@@ -184,10 +184,20 @@
l = strlen(b);
if (l > 0 && b[l-1] == '\n') /* line ends with newline? */
b[l-1] = '0円'; /* remove it */
- if (firstline && b[0] == '=') /* first line starts with `=' ? */
- lua_pushfstring(L, "return %s", b+1); /* change it to `return' */
- else
+ if (firstline) { /* for first line, try return it if possible. */
+ char rbuf[LUA_MAXINPUT];
+ snprintf(rbuf, LUA_MAXINPUT-1, "return %s", (b[0]=='=') ? (b+1) : b);
+ rbuf[LUA_MAXINPUT-1] = '0円'; /* ensure zero terminated */
+ int result = luaL_loadstring(L, rbuf);
+ lua_pop(L, 1); /* ignore the output anyway */
+ if (result == LUA_ERRSYNTAX) {
+ lua_pushstring(L, b); /* if syntax error, leave it as is */
+ } else {
+ lua_pushstring(L, rbuf); /* if compile passed, return it */
+ }
+ } else {
lua_pushstring(L, b);
+ }
lua_freeline(L, b);
return 1;
}
@@ -207,6 +217,12 @@
lua_insert(L, -2); /* ...between the two lines */
lua_concat(L, 3); /* join them */
}
+ /* if there is a prefixed 'return', remove it before save to readline() */
+ const char *line = lua_tostring(L, 1);
+ if (strncmp(line, "return ", 7) == 0) {
+ lua_pushstring(L, line+7);
+ lua_replace(L, 1);
+ }
lua_saveline(L, 1);
lua_remove(L, 1); /* remove line */
return status;
@@ -221,6 +237,8 @@
if (status == 0) status = docall(L, 0, 0);
report(L, status);
if (status == 0 && lua_gettop(L) > 0) { /* any result to print? */
+ lua_pushvalue(L, 1);
+ lua_setglobal(L, "_"); /* push the first return value in _G["_"] */
lua_getglobal(L, "print");
lua_insert(L, 1);
if (lua_pcall(L, lua_gettop(L)-1, 0, 0) != 0)