fanqingxuan / lua_utils

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