4.2.18. luerl [1]¶

lua插件扩展实例:

% execute a string
{Return, State} = luerl:do("print(\"Hello, Robert(o)!\")"),
% execute a file
{Return, State} = luerl:dofile("./hello.lua"),
% 其中:
%   Return: lua运行的返回值
%   State: lua内容翻译的中间代码

% separately parse, then execute
State0 = luerl:init(),
{ok, Chunk, State1} = luerl:load("print(\"Hello, Chunk!\")", State0),
{_Ret, _NewState} = luerl:do(Chunk, State1),

%execute a string, get a result:
{ok,A} = luerl:eval("return 1 + 1"),
{ok,A} = luerl:eval(<<"return 1 + 1">>),
% A:2
{A, State} = luerl:do("return 1 + 1"),
{A, State} = luerl:do(<<"return 1 + 1">>),
% A:2

文件:

> cat hello2-2.lua
return 2137 * 42

% execute a file, get a result
{ok,B} = luerl:evalfile("./hello2-2.lua"),
{B, State} = luerl:dofile("./hello2-2.lua"),
% B:89754

标准函数:

luerl:call_function([print], [<<"(8) Hello, standard print function!">>]),
luerl:call_function([print], [<<"(9) Hello, print function!">>], luerl:init())
{Result1,_} = luerl:call_function([table,pack], [<<"a">>,<<"b">>,42]),
{Result1,_} = luerl:call_function([table,pack], [<<"a">>,<<"b">>,42], luerl:init()),
% Result1: [[{1,<<"a">>},{2,<<"b">>},{3,42.0},{<<"n">>,3.0}]]

自定义函数:

% separately parse, then execute (doubles (12) and Chunk2 as assertion)
St2A = luerl:init(),
{ok,Chunk2,St2B} = luerl:load("function chunk2() print(\"(12) Hello\") end", St2A),
{ok,Chunk2,_} = luerl:load(<<"function chunk2() print(\"(12) Hello\") end">>, St2A),
% Result2是lua脚本返回值，不返回则值为[]
{ok,Result2} = luerl:eval(Chunk2, St2B),
{Result2,St2C} = luerl:do(Chunk2, St2B),

% do函数内部会先执行load函数
{Result2,St2D} = luerl:do(<<"function chunk2() print(\"(12) Hello\") end">>, St2A),
% 函数调用
luerl:call_function([chunk2], [], St2C),  % (12) Hello
luerl:call_function([chunk2], [], St2D),  % (12) Hello

文件中的函数:

% cat hello2-3.lua
function no() print("(16) No!") end
print("(15) Maybe ...")
return "(X) Yes!"

% separately parse, then execute a file. The file defines a function no()
St3A = luerl:init(),

% Chunk3是中间代码
% St3B是luerl中间代码
{ok,Chunk3,St3B} = luerl:loadfile("./hello2-3.lua", St3A),
% 执行脚本
{ok,Result3} = luerl:eval(Chunk3, St3B),                    % (15) Maybe ...
{Result3,St3C} = luerl:do(Chunk3, St3B),                    % (15) Maybe ...
{[],_} = luerl:call_function([no], [], St3C),               % (16) No!

复杂的:

% create state
New = luerl:init(),
{_,_New2} = luerl:do("print '(19) hello generix'", New),  % (19) hello generix

% change state
{_,State0} = luerl:do("a = 1000", New),
{_,State01} = luerl:do("a = 1000", New),

% execute a string, using passed in State0
luerl:eval("print('(20) ' .. a)", State0),        % (20) 1000
luerl:eval(<<"print('(21) ' .. a+1)">>, State0),  % (21) 1001
luerl:do("print('(22) ' .. a+2)", State0),        % (22) 1002
luerl:do(<<"print('(23) ' .. a+3)">>, State0),    % (23) 1003

赋值:

% cat hello2-9.lua
function confirm(p)
  return p .. ' (it really is)'
end
return confirm(a)


% separately parse, then execute a file, get a result. The file defines confirm(p)
{ok,Chunk14,St8} = luerl:loadfile("./hello2-9.lua", State07),
{ok,Result14} = luerl:eval(Chunk14, St8),
{Result14,State14} = luerl:do(Chunk14, St8),
io:format("(35) And twice: ~s~n", [Result14]),
{Result14A,_} = luerl:call_function([confirm], [<<"Is it?">>], State14),
io:format("(36) Well: ~s~n", [Result14A]),

实例¶

input1.json:

{
  "name" : "赵卫国",
  "sex" : "male",
  "age" : 18,
  "company" : "qingdao1024"
}

plugin.lua:

function doit(content)
    local json = require("luas.json");
    new = json.decode(content);
    new.name = "simon";
    new.age = 10;
    b = json.encode(new);
    print(b);
end

server.erl:

translate()->
  % 1read input1.json
  FileJsonPath = "luas/input1.json",
  {ok, FileJson} = file:open(FileJsonPath, [read]),
  {ok, Json} = file:read(FileJson, filelib:file_size(FileJsonPath)),
  io:format("1param: ~p~n", [Json]),
  BinJson = list_to_binary(Json),
  translate(BinJson),
  ok.

translate(Json) when is_list(Json)->
  translate(list_to_binary(Json));
translate(BinJson) when is_binary(BinJson)->

  State0 = luerl:init(),
  % 2.1read do1.lua
  FilePath = "./luas/do1.lua",
  {ok, File} = file:open(FilePath, read),
  {ok, Content} = file:read(File, filelib:file_size(FilePath)),

  % 2.2load do1.lua
  {_Result,State2} = luerl:do(Content, State0),

  %4 call function
  {Result, _} = luerl:call_function([doit], [BinJson], State2),
  io:format("Result: ~p~n", [Result]),
  ok.

开源项目luerl:

https://github.com/rvirding/luerl
// add to rebar.conf
{luerl, {git, "https://github.com/rvirding/luerl.git", {tag, "v0.3"}}}

执行:

server:translate().