Lua print table(类似PHP中的print_r/var_export)

会PHP的人都知道PHP中的print_r/var_export函数，可以方便的用于打印数组或导出变量，Lua中没有提供，实际应用中却是很多时候需要类似的功能。

今天便封装了个简单函数，实现类似功能，用来打印/导出table：

-- dump.lua

--[[
dump对象
@param mixed obj
@return string
]]
function debug.dump(obj)
    local getIndent, quoteStr, wrapKey, wrapVal, dumpObj
    getIndent = function(level)
        return string.rep("\t", level)
    end
    quoteStr = function(str)
        str = string.gsub(str, "[%c\\\"]", {
            ["\t"] = "\\t",
            ["\r"] = "\\r",
            ["\n"] = "\\n",
            ["\""] = "\\\"",
            ["\\"] = "\\\\",
        })
        return ‘"‘ .. str .. ‘"‘
    end
    wrapKey = function(val)
        if type(val) == "number" then
            return "[" .. val .. "]"
        elseif type(val) == "string" then
            return "[" .. quoteStr(val) .. "]"
        else
            return "[" .. tostring(val) .. "]"
        end
    end
    wrapVal = function(val, level)
        if type(val) == "table" then
            return dumpObj(val, level)
        elseif type(val) == "number" then
            return val
        elseif type(val) == "string" then
            return quoteStr(val)
        else
            return tostring(val)
        end
    end
    dumpObj = function(obj, level)
        if type(obj) ~= "table" then
            return wrapVal(obj)
        end
        level = level + 1
        local tokens = {}
        tokens[#tokens + 1] = "{"
        for k, v in pairs(obj) do
            tokens[#tokens + 1] = getIndent(level) .. wrapKey(k) .. " = " .. wrapVal(v, level) .. ","
        end
        tokens[#tokens + 1] = getIndent(level - 1) .. "}"
        return table.concat(tokens, "\n")
    end
    return dumpObj(obj, 0)
end

测试代码：

-- test.lua

local obj = {
    string1 = "Hi! My name is LiXianlin",
    string2 = "aa\tbb\rcc\ndd\\ee\"ff",
    string3 = "a\\tb\\rc\\n\\\\ee\"ff",
    int = 9527,
    float = 3.1415,
    bool = true,
    table = {
        1, 2, 3,
        {
            a = 21,
            b = 22,
            c = 23,
        },
    },
    [88] = 88888,
    [9.7] = 22222,
}
print(debug.dump(obj)

输出结果：

{
        ["string1"] = "Hi! My name is LiXianlin",
        [9.7] = 22222,
        ["table"] = {
                [1] = 1,
                [2] = 2,
                [3] = 3,
                [4] = {
                        ["b"] = 22,
                        ["a"] = 21,
                        ["c"] = 23,
                },
        },
        ["float"] = 3.1415,
        ["int"] = 9527,
        ["string3"] = "a\\tb\\rc\\n\\\\ee\"ff",
        ["bool"] = true,
        ["string2"] = "aa\tbb\rcc\ndd\\ee\"ff",
        [88] = 88888,
}

函数特点：

1、理论上支持无限级table嵌套

2、格式化输出，可读性好

3、输出结果可直接用于lua代码

4、function、userdata、thread类型tostring输出

5、当字符串中含有控制字符时，可能有影响(代码中仅对\t,\r,\n等进行了处理)