说明： 为JSE编写的轻量级、快速、以Java为中心的Lua解释器，具有字符串、表、包、数学、io、os、调试、co...
(Lightweight, fast, Java-centric Lua interpreter written for JSE, with string, table, package, math, io, os, debug, coroutine & luajava libraries, JSR-223 bindings, all metatags and unique direct lua-to-java-bytecode compiling.)
# Getting Started with LuaJ
Maven:
```
io.github.taoguan
luaj
1.0.2
```
# 1 - Introduction
## Features of Luaj
Luaj is a lua interpreter based on the **5.3.x** version of lua with the following features in mind:
- **Not support `goto` and `label` statement**
- **Support `continue` statement**
- Java-centric implementation of lua vm built to leverage standard Java features.
- Lightweight, high performance execution of lua, can direct be compiled to java bytecode.
# 2 - Syntax BNF
```
chunk ::= block
block ::= {stat} [retstat]
stat ::= ';' |
varlist '=' explist |
functioncall |
break |
continue |
do block end |
while exp do block end |
repeat block until exp |
if exp then block {elseif exp then block} [else block] end |
for Name '=' exp ',' exp [',' exp] do block end |
for namelist in explist do block end |
function funcname funcbody |
local function Name funcbody |
local namelist ['=' explist]
retstat ::= return [explist] [';']
funcname ::= Name {'.' Name} [':' Name]
varlist ::= var {',' var}
var ::= Name | prefixexp '[' exp ']' | prefixexp '.' Name
namelist ::= Name {',' Name}
explist ::= exp {',' exp}
exp ::= nil | false | true | Numeral | LiteralString | '...' | functiondef |
prefixexp | tableconstructor | exp binop exp | unop exp
prefixexp ::= var | functioncall | '(' exp ')'
functioncall ::= prefixexp args | prefixexp ':' Name args
args ::= '(' [explist] ')' | tableconstructor | LiteralString
functiondef ::= function funcbody
funcbody ::= '(' [parlist] ')' block end
parlist ::= namelist [',' '...'] | '...'
tableconstructor ::= '{' [fieldlist] '}'
fieldlist ::= field {fieldsep field} [fieldsep]
field ::= '[' exp ']' '=' exp | Name '=' exp | exp
fieldsep ::= ',' | ';'
binop ::= '+' | '-' | '*' | '/' | '//' | '^' | '%' |
'&' | '~' | '|' | '>>' | '<<' | '..' |
'<' | '<=' | '>' | '>=' | '==' | '~=' |
and | or
unop ::= '-' | not | '#' | '~'
```
# 3 - Examples
## 3.1 Lua script
grammar-test.lua :
```
#!/bin/luaj
-- varlist '=' explist
--[[long comment]]
gvar11, gvar21, gvar22, gvar41, gvar42, gvar43 = nil, false, true, 'test1', "test2", [[long string\n, hello]]
gvar31, gvar32, gvar33, gvar34, gvar35, gvar36 = 10, -12, 123456789457, -0XFE, 123456789456.12, 1.2345678945613E11
gvar51, gvar52, gvar53 = {3,'test1', false}, {test1=34, ['test2']=55}, {test1=34, ['test2']=55, 4, 7, 9, [2]=8, [100]=53}
print(gvar11,gvar21,gvar22,gvar41,gvar42,gvar43)
print(gvar31,gvar32,gvar33,gvar34,gvar35,gvar36)
print(gvar51,gvar52,gvar53);
local var11, var21, var22, var41, var42, var43 = nil, false, true, 'test1', "test2", [[long string\n, hello]]
local var31, var32, var33, var34, var35, var36 = 10, -12, 123456789457, -0XFE, 123456789456.12, 1.2345678945613E11
local var51, var52, var53 = {3,'test1', false}, {test1=34, ['test2']=55}, {test1=34, ['test2']=55, 4, 7, 9, [2]=8, [100]=53}
print(var11, var21, var22, var41, var42, var43)
print(var31, var32, var33, var34, var35, var36)
print(var51, var52, var53);
-- function funcname funcbody
function var52.addVar(self,...)
local arg = {...}
local len = #arg
print('arg len = '..len)
local result = 0;
for i,v in ipairs(arg) do
print('i='..i..';v='..v)
if i == 1 then continue end
if i == 3 then break end
result = result + v
end
return result
end
function var52:minusVar(...)
local arg = {...}
local len = #arg
print('arg len = '..len)
local result;
for i,v in ipairs(arg) do
if i == 1 then continue end
if result == nil then result = v end
result = result - v
end
return result
end
-- functioncall
local testAddVar1 = var52.addVar(var52, 1,2,3,4,5)
local testAddVar2 = var52:addVar(1,2,3,4,6)
print(testAddVar1, testAddVar2)
local testMinusVar1 = var52.minusVar(var52, 1,2,3,4,5)
local testMinusVar2 = var52:minusVar(1,2,3,4,6)
print(testMinusVar1, testMinusVar2)
-- call java method
local javesystem = luajava.bindClass("java.lang.System")
local curTime = javesystem:currentTimeMillis();
print(curTime)
local date = luajava.newInstance("java.util.Date")
print(date.getTime(date))
print(date:getTime())
-- ArithOp test
local var31, var32= 2, -3
print(var31 + var32, var31 - var32, var31 * var32, var32 / var31, var32 // var31, var31 ^ var32, var32 % var31)
print(var31 & var32, var31 | var32, var31 ~ var32, ~var31)
print(var31 << var32, var31 >> var32)
print(var31 > var32, var31 >= var32, var31 < var32, var31 <= var32, var31 == var32, var31 ~= var32)
local var21, var22 = false, true
print(var21 and var22, var21 or var22, not var21)
print(var21, var22)
local fun1 = function()
local var21, var22 = 7, 8
local var33 = var31 * var32
print(var21, var22)
print(string.format('var33=%s', var33))
end
fun1()
print(var21, var22)
local testContinue1 = 1
while testContinue1 < 10
do
if testContinue1 == 5 then
testContinue1 = testContinue1 + 1;
continue end
if testContinue1 == 7 then break end
print('testContinue1='..testContinue1)
testContinue1 = testContinue1 + 1
end
print('testContinue1-done')
local testContinue2 = 1
repeat
if testContinue2 == 5 then
testContinue2 = testContinue2 + 1;
continue end
if testContinue2 == 7 then break end
print('testContinue2='..testContinue2)
testContinue2 = testContinue2 + 1
until testContinue2 >= 10
print('testContinue2-done')
for testContinue3 = 1,10,1
do
if testContinue3 == 5 then
testContinue3 = testContinue3 + 1;
continue end
if testContinue3 == 7 then break end
print('testContinue3='..testContinue3)
testContinue3 = testContinue3 + 1
end
print('testContinue3-done')
local testContinue4Table = {4, 5, 6, 7, 8, 9, 10, 11, 12, 13}
for i, v in ipairs(testContinue4Table)
do
if i == 5 then
continue end
if i == 7 then break end
print('testContinue4='..i..'-v:'..v)
end
print('testContinue4-done')
return var52
```
## 3.2 Java execute lua script
```
String luaFileName = AppTest.class.getClassLoader().getResource("grammar-test.lua").toURI().getPath();
Globals globals = JsePlatform.standardGlobals();
//LuaJC.install(globals); // You can use LuaJC to improve performance. It will compile lua script to java bytecode using BCEL.
LuaValue result = globals.loadfile(luaFileName).call();
System.out.println(result);
// java call lua method
LuaValue func = result.get(LuaValue.valueOf("addVar"));
int funcResult = func.invoke(LuaValue.varargsOf(new LuaValue[]{result, LuaValue.valueOf(1),
LuaValue.valueOf(2), LuaValue.valueOf(3)})).arg1().checkint();
System.out.println(String.format("funcResult=%s", funcResult));
Prototype p = globals.compilePrototype(new FileInputStream(luaFileName), "grammar-test");
Print.print(p);
```