This is a pure Lua library that provides a set of utility functions for dealing with strings,tables,files and some others.

debug

first you must require the module if you need use it in your code.

local debug = require 'utils.debug'

print() print a scalar value or table

Notice:

a) can not print nil value .

b) will print json format if the params is table.

local a = 56
debug.print('hello',a) --output: hello  56
debug.print(false,true,3.4)  --output:false true 3.4
debug.print({1,2,3,4}) --output json:[1,2,3,4]

die() Output a message and terminate the current script

debug.print("hello") --output:hello
debug.die("this is die") --output: this is die
debug.print("can not print this line")

string

first you must require the module if you need use it in your code.

local util_string = require 'utils.string'

trim() Strip whitespace from the beginning and end of a string

print(util_string.trim(" hello ")) -- output:"hello"
print(util_string.trim("helloaa",'a')) -- output:"hello"

ltrim() Strip whitespace from the beginning of a string

print(util_string.ltrim(" hello ")) --output:"hello "
print(util_string.ltrim("ahelloa",'a')) -- output:"helloa"

rtrim() Strip whitespace from the end of a string

print(util_string.rtrim(" hello ")) --output:" hello"
print(util_string.rtrim("ahelloa",'a')) -- output:"ahello"

startswith() check whether a string is start with some charactors

print(util_string.startswith("hello",'he')) --output:true
print(util_string.startswith("hello",'H')) --output:false

endswith() check whether a string is end with some charactors

print(util_string.endswith("hello",'o')) -- output:true
print(util_string.endswith("hello",'O')) -- output:false

split() split a string into table

util_string.split("a#b#c#d",'#') --output:{'a','b','c','d'}

contains() Checks if a value exists in a string

print(util_string.contains("hello world",'H')) --output:false
print(util_string.contains("hello world",'e')) --output:true

replace() Replace all occurrences of the search string with the replacement string

print(util_string.replace("hello world world",'world','lua')) -- output:hello lua lua

len() get string length

print(util_string.len("hello")) -- output:5

upper() Make a string uppercase

print(util_string.upper("hello world")) -- output:HELLO WORLD

lower() Make a string lowercase

print(util_string.lower("Hello world")) -- output:hello world

ucwords() Uppercase the first character of each word in a string

print(util_string.ucwords("hello world")) --output:Hello World
print(util_string.ucwords("hello#world",'#')) -- output:Hello#World

ucfirst() Make a string's first character uppercase

print(util_string.ucfirst("hello world")) --output:Hello world

reverse() Reverse a string

print(util_string.reverse("hello")) -- output:olleh

substr() Return part of a string

print(util_string.substr("hello",2,3)) -- output:el

print(util_string.substr("hello",-3)) --output:llo

table

first you must require the module if you need use it in your code.

local util_table = require 'utils.table'

is_empty() Determine whether a variable is empty,return true or false

util_table.is_empty({})  -- output:true
util_table.is_empty({name="json"})  -- output:false

reverse() Return an array with elements in reverse order

debug.print(util_table.reverse({'a','b','c'})) -- output:{'c','b','a'}

unique() Removes duplicate values from an array

debug.print(util_table.unique({'a','b','a','c'})) -- output:{'a','b','c'}

implode() Join array elements with a string

debug.print(util_table.implode({'a','b','a','c'},'#')) -- output:a#b#a#c

copy() Deep copies a table into a new table.

local a = {'a','b','c'}
local b = util_table.copy(a)
debug.print(a==b) -- output:false

is_array() Finds whether a variable is an array

local a = {'a','b','c'}
debug.print(util_table.is_array(a)) -- output:true
debug.print(util_table.is_array('hello')) -- output:false
debug.print(util_table.is_array({name='json',age=32})) -- output:false

merge() Merge arrays into a new array. if the key is same, and the after element will override the before.

local a = {'a','b','c','d'}
local b = {1,2}
debug.print(util_table.merge(a,b))  -- output:{1,2,'c','d'}

local a = {name='json',age=32}
local b = {1,2}
debug.print(util_table.merge(a,b))  --output:{1,2,name='json',age=32}

contains() Checks if a value exists in a table,return true or false

local a = {'a','b','c'}
debug.print(util_table.contains(a,'a')) -- output:true

debug.print(util_table.contains(a,'11')) --output:false

keys() return a table containing the keys of the provided table

local a = {name='json',age=32}
debug.print(util_table.keys(a))  -- output:{'name','json'}

values() return a table containing the values of the provided table

local a = {name='json',age=32}
debug.print(util_table.values(a)) -- output:{'json',32}

append() append the contents of (array-like) table b into table a

local a = {'a','b','c'}
local b = {1,2,3}
util_table.append(a,b)
debug.print(a)  -- output:{'a','b','c',1,2,3}

push() Push one or more elements onto the end of table

local a = {'a','b','c'}
util_table.push(a,1,2,3)
debug.print(a)  -- output:{'a','b','c',1,2,3}

pop() Pop the element off the end of table

local a = {'a','b','c'}
util_table.pop(a)
debug.print(a)  -- output:{'a','b'}

unshift() Prepend one or more elements to the beginning of an table

local a = {'a','b','c'}
util_table.unshift(a,1,2,3)
debug.print(a)  -- output:{3,2,1,'a','b','c'}

shift() Shift an element off the beginning of table

local a = {'a','b','c'}
util_table.shift(a)
debug.print(a) -- output:{'b','c'}

key_exists() Checks if the given key or index exists in the table, return true or false

local tab = {name='json',age=32}
debug.print(util_table.key_exists('info',tab)) -- output:false
debug.print(util_table.key_exists('name',tab)) -- output:true

search() Searches the table for a given value and returns the first corresponding key if successful

local tab = {name='json',age=32}
debug.print(util_table.search('json',tab)) -- output:name
debug.print(util_table.search('info',tab)) -- output:nil

slice(tab,index,length) Extract a slice of the table. the first argument is the table, the second is the index, and the third is the slice length, default is the last if you not give.

if the index is negative, and the slice with count from back.
```
local tab = {'a','b','c','d'}
debug.print(util_table.slice(tab,2))  -- output:{'b','c','d'}
debug.print(util_table.slice(tab,2,2)) --output:{'b','c'}  
debug.print(util_table.slice(tab,-3)) --output:{'b','c','d'}
```

to_array() convert table to list

local tab = {name='json',age=32,}
debug.print(util_table.to_array(tab))  -- output:{'json',32}

sort() sort with a function

local tab = {4,2,-6,3}
util_table.sort(tab)
debug.print(tab)  --output:{-6,2,3,4}

util_table.sort(tab,function(a,b) 
    return math.abs( a ) < math.abs( b ) 
end)
debug.print(tab)  --output:{2,3,4,-6}

filter(tab,callback) Filters elements of an array using a callback function. filter the false value if you not give the function, and If the callback function returns true, the current value from table is returned into the result array.
```
local tab = {4,2,false,3}

debug.print(util_table.filter(tab))  --output:{4,2,3}

local a = util_table.filter(tab,function(a)
    return a and a%2==1
end)
debug.print(a)  --output:{3}
```

pluck(tab,column,index_key) Return the values from a single column in the input array

returns the values from a single column of the array, identified by the column_key. Optionally, an index_key may be provided to index the values in the returned array by the values from the index_key column of the input array.

local list = {
    {id='1',name='json',age=32},
    {id='2',name='fanqingxuan',age=29},
    {id='3',name='lua',age=45}
}

debug.print(util_table.pluck(list,'name')) --output:{'json','fanqingxuan','lua'}
debug.print(util_table.pluck(list,'name','id')) --putput:{['1']='json',['2']='fanqingxuan',['3']='lua'}

debug.print(util_table.pluck(list,nil,'id'))
--oputput:{['1']={id='1',name='json',age=32},['2']={id='2',name='fanqingxuan',age=29},['3']={id='3',name='lua',age=45}}

io

first you must require the module if you need use it in your code.

local io = require 'utils.io'

file_get_contents get contents from file, return the content str and err

local data,err = io.file_get_contents('./utils/cjson.lua')
debug.print(data) -- output the content in file cjson.lua

file_put_contents(file,data,mode) Write file contents.

return true upon success, or false + error message on failure

io.file_put_contents('a.txt',"hello world") -- will clear a.txt content, then write 'hello world' to a.txt

io.file_put_contents('a.txt',"hello world","a+") -- will append 'hello world' to a.txt

file_exists() Checks whether a file exists

debug.print(io.file_exists("index.lua") )-- output:true

local exists,err = io.file_exists("index1.lua")

if not exists then
	print("file not exists with err:"..err)
end

execute_cmd()Execute an external program

local data,err = io.execute_cmd('ls -ll')

console

first you must require the module if you need use it in your code.

local console = require 'utils.console'

This library is for command, and can print some text with colors.

console.red(" this is red color");
console.yellow(" this is yellow color");
console.white(" this is white color");
console.blue(" this is blue color");
console.green(" this is green color");
console.magenta(" this is magenta color");
console.cyan(" this is cyan color");

And you can also write log with diffent color:

console.log("this is log")
console.trace("this is trace log")
console.info("this is info log")
console.warn("this is warn log")
console.error("this is error log")
console.debug("this is debug log")
console.fatal("this is fatal log")

The module also provide two function for sucess or fail output:

console.success("the code run success")
console.error("there something error")

json

first you must require the module if you need use it in your code.

local json = require 'utils.cjson'

Notice: you must confirm you have installed cjson library in your system, if not please install it with luarocks.

encode() Returns the JSON representation of a value

local arr = {
    name = 'json',
    age = 32
}
debug.print(json.encode(arr)) -- output string:{"age":32,"name":"json"}

decode() Decodes a JSON string

local str = '{"age":32,"name":"json"}'
debug.print(json.decode(str).name) --output:json

other library

The project also collect some useful third library, You can click the link and read the detail document.

ansicolors a useful library for output color text
argparse a library for parse arguments from command line
classic a library that you can make your lua code more like oop
date a library that for date and time calculations
dkjson a module for encoding and decoding JSON data
md5 a module for generating md5 string
redis-lua you can use redis with this module
memcached you can play with memcached
net-url a library that can parse URL with querystring and build new URL easily

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README.md

README.md

This is a pure Lua library that provides a set of utility functions for dealing with strings,tables,files and some others.

debug

string

table

io

console

json

other library

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README.md

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README.md

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This is a pure Lua library that provides a set of utility functions for dealing with strings,tables,files and some others.

debug

string

table

io

console

json

other library