Lua实现的常用string库
--[[
命名空间: xstr
作者: apache(email: [email protected]; website: http://hi.baidu.com/hqwfreefly)
版本号: 0.2 (from 0.1)
创建日期: 2010-10-17
函数列表: trim, capitalize, count, startswith, endswith, expendtabs, isalnum, isalpha, isdigit, islower, isupper,
join, lower, upper, partition, zfill, ljust, rjust, center, dir, help
声明: 该软件为自由软件，遵循GPL协议。如果你需要为xstr增加函数，请在func_list中添加函数名，并在help函数中为其撰写帮助文档
帮助: xstr:dir() 列出命名空间下的函数列表。xstr:help("func")查看func的帮助文档
修改历史: 修改count函数的实现，使用gsub统计个数
--]]
xstr = {
func_list = "trim, capitalize, count, startswith, endswith, expendtabs, isalnum, isalpha, isdigit, islower, isupper, join, lower, upper, partition, zfill, ljust, rjust, center, dir, help",
--[[去除str中的所有空格。成功返回去除空格后的字符串，失败返回nil和失败信息]]
trim = function (self, str)
if str == nil then
return nil, "the string parameter is nil"
end
str = string.gsub(str, " ", "")
return str
end,
--[[将str的第一个字符转化为大写字符。成功返回转换后的字符串，失败返回nil和失败信息]]
capitalize = function(self, str)
if str == nil then
return nil, "the string parameter is nil"
end
local ch = string.sub(str, 1, 1)
local len = string.len(str)
if ch < 'a' or ch > 'z' then
return str
end
ch = string.char(string.byte(ch) - 32)
if len == 1 then
return ch
else
return ch .. string.sub(str, 2, len)
end
end,
--[[统计str中substr出现的次数。from, to用于指定起始位置，缺省状态下from为1，to为字符串长度。成功返回统计个数，失败返回nil和失败信息]]
count = function(self, str, substr, from, to)
if str == nil or substr == nil then
return nil, "the string or the sub-string parameter is nil"
end
from = from or 1
if to == nil or to > string.len(str) then
to = string.len(str)
end
local str_tmp = string.sub(str, from ,to)
local n = 0
_, n = string.gsub(str, substr, '')
return n
end,
--[[判断str是否以substr开头。是返回true，否返回false，失败返回失败信息]]
startswith = function(self, str, substr)
if str == nil or substr == nil then
return nil, "the string or the sub-stirng parameter is nil"
end
if string.find(str, substr) ~= 1 then
return false
else
return true
end
end,
--[[判断str是否以substr结尾。是返回true，否返回false，失败返回失败信息]]
endswith = function(self, str, substr)
if str == nil or substr == nil then
return nil, "the string or the sub-string parameter is nil"
end
str_tmp = string.reverse(str)
substr_tmp = string.reverse(substr)
if string.find(str_tmp, substr_tmp) ~= 1 then
return false
else
return true
end
end,
--[[使用空格替换str中的制表符，默认空格个数为8。返回替换后的字符串]]
expendtabs = function(self, str, n)
if str == nil then
return nil, "the string parameter is nil"
end
n = n or 8
str = string.gsub(str, "\t", string.rep(" ", n))
return str
end,
--[[如果str仅由字母或数字组成，则返回true，否则返回false。失败返回nil和失败信息]]
isalnum = function(self, str)
if str == nil then
return nil, "the string parameter is nil"
end
local len = string.len(str)
for i = 1, len do
local ch = string.sub(str, i, i)
if not ((ch >= 'a' and ch <= 'z') or (ch >= 'A' and ch <= 'Z') or (ch >= '0' and ch <= '9')) then
return false
end
end
return true
end,
--[[如果str全部由字母组成，则返回true，否则返回false。失败返回nil和失败信息]]
isalpha = function(self, str)
if str == nil then
return nil, "the string parameter is nil"
end
local len = string.len(str)
for i = 1, len do
local ch = string.sub(str, i, i)
if not ((ch >= 'a' and ch <= 'z') or (ch >= 'A' and ch <= 'Z')) then
return false
end
end
return true
end,
--[[如果str全部由数字组成，则返回true，否则返回false。失败返回nil和失败信息]]
isdigit = function(self, str)
if str == nil then
return nil, "the string parameter is nil"
end
local len = string.len(str)
for i = 1, len do
local ch = string.sub(str, i, i)
if ch < '0' or ch > '9' then
return false
end
end
return true
end,
--[[如果str全部由小写字母组成，则返回true，否则返回false。失败返回nil和失败信息]]
islower = function(self, str)
if str == nil then
return nil, "the string parameter is nil"
end
local len = string.len(str)
for i = 1, len do
local ch = string.sub(str, i, i)
if ch < 'a' or ch > 'z' then
return false
end
end
return true
end,
--[[如果str全部由大写字母组成，则返回true，否则返回false。失败返回nil和失败信息]]
isupper = function(self, str)
if str == nil then
return nil, "the string parameter is nil"
end
local len = string.len(str)
for i = 1, len do
local ch = string.sub(str, i, i)
if ch < 'A' or ch > 'Z' then
return false
end
end
return true
end,
--[[使用substr连接str中的每个字符，返回连接后的新串。失败返回nil和失败信息]]
join = function(self, str, substr)
if str == nil or substr == nil then
return nil, "the string or the sub-string parameter is nil"
end
local xlen = string.len(str) - 1
if xlen == 0 then
return str
end
local str_tmp = ""
for i = 1, xlen do
str_tmp = str_tmp .. string.sub(str, i, i) .. substr
end
str_tmp = str_tmp .. string.sub(str, xlen + 1, xlen + 1)
return str_tmp
end,
--[[将str中的小写字母替换成大写字母，返回替换后的新串。失败返回nil和失败信息]]
lower = function(self, str)
if str == nil then
return nil, "the string parameter is nil"
end
local len = string.len(str)
local str_tmp = ""
for i = 1, len do
local ch = string.sub(str, i, i)
if ch >= 'A' and ch <= 'Z' then
ch = string.char(string.byte(ch) + 32)
end
str_tmp = str_tmp .. ch
end
return str_tmp
end,
--[[将str中的大写字母替换成小写字母，返回替换后的新串。失败返回nil和失败信息]]
upper = function(self, str)
if str == nil then
return nil, "the string parameter is nil"
end
local len = string.len(str)
local str_tmp = ""
for i = 1, len do
local ch = string.sub(str, i, i)
if ch >= 'a' and ch <= 'z' then
ch = string.char(string.byte(ch) - 32)
end
str_tmp = str_tmp .. ch
end
return str_tmp
end,
--[[将str以substr（从左向右查找）为界限拆分为3部分，返回拆分后的字符串。如果str中无substr则返回str, '', ''。失败返回nil和失败信息]]
partition = function(self, str, substr)
if str == nil or substr == nil then
return nil, "the string or the sub-string parameter is nil"
end
local len = string.len(str)
start_idx, end_idx = string.find(str, substr)
if start_idx == nil or end_idx == len then
return str, '', ''
end
return string.sub(str, 1, start_idx - 1), string.sub(str, start_idx, end_idx), string.sub(str, end_idx + 1, len)
end,
--[[在str前面补0，使其总长度达到n。返回补充后的新串，如果str长度已经超过n，则直接返回str。失败返回nil和失败信息]]
zfill = function(self, str, n)
if str == nil then
return nil, "the string parameter is nil"
end
if n == nil then
return str
end
local format_str = "%0" .. n .. "s"
return string.format(format_str, str)
end,
-----------------------------------------------------------------------------------------------------------------------------------------
--[[设置str的位宽，默认的填充字符为空格。对齐方式为左对齐（rjust为右对齐，center为中间对齐）。返回设置后的字符串。失败返回nil和失败信息]]
ljust = function(self, str, n, ch)
if str == nil then
return nil, "the string parameter is nil"
end
ch = ch or " "
n = tonumber(n) or 0
local len = string.len(str)
return string.rep(ch, n - len) .. str
end,
rjust = function(self, str, n, ch)
if str == nil then
return nil, "the string parameter is nil"
end
ch = ch or " "
n = tonumber(n) or 0
local len = string.len(str)
return str .. string.rep(ch, n - len)
end,
center = function(self, str, n, ch)
if str == nil then
return nil, "the string parameter is nil"
end
ch = ch or " "
n = tonumber(n) or 0
local len = string.len(str)
rn_tmp = math.floor((n - len) / 2)
ln_tmp = n - rn_tmp - len
return string.rep(ch, rn_tmp) .. str .. string.rep(ch, ln_tmp)
end,
------------------------------------------------------------------------------------------------------------------------------------------
--[[显示xstr命名空间的所有函数名]]
dir = function(self)
print(self.func_list)
end,
--[[打印指定函数的帮助信息, 打印成功返回true，否则返回false]]
help = function(self, fun_name)
man = {
["trim"] = "xstr:trim(str) --> string | nil, err_msg\n 去除str中的所有空格，返回新串\n print(xstr:trim(\" hello wor ld \") --> helloworld",
["capitalize"] = "xstr:capitalize(str) --> string | nil, err_msg\n 将str的首字母大写，返回新串\n print(xstr:capitalize(\"hello\") --> Hello",
["count"] = "xstr:count(str, substr [, from] [, to]) --> number | nil, err_msg\n 返回str中substr的个数, from和to用于指定统计范围, 缺省状态下为整个字符串\n print(xstr:count(\"hello world!\", \"l\")) --> 3",
["startswith"] = "xstr:startswith(str, substr) --> boolean | nil, err_msg\n 判断str是否以substr开头, 是返回true，否返回false\n print(xstr:startswith(\"hello world\", \"he\") --> true",
["endswith"] = "xstr:endswith(str, substr) --> boolean | nil, err_msg\n 判断str是否以substr结尾, 是返回true, 否返回false\n print(xstr:endswith(\"hello world\", \"d\")) --> true",
["expendtabs"] = "xstr:expendtabs(str, n) --> string | nil, err_msg\n 将str中的Tab制表符替换为n格空格，返回新串。n默认为8\n print(xstr:expendtabs(\"hello world\")) --> hello world",
["isalnum"] = "xstr:isalnum(str) --> boolean | nil, err_msg\n 判断str是否仅由字母和数字组成，是返回true，否返回false\n print(xstr:isalnum(\"hello world:) 123\")) --> false",
["isalpha"] = "xstr:isalpha(str) --> boolean | nil, err_msg\n 判断str是否仅由字母组成，是返回true，否返回false\n print(xstr:isalpha(\"hello WORLD\")) --> true",
["isdigit"] = "xstr:isdigit(str) --> boolean | nil, err_msg\n 判断str是否仅由数字组成，是返回true，否返回false\n print(xstr:isdigit(\"0123456789\")) --> true",
["islower"] = "xstr:islower(str) --> boolean | nil, err_msg\n 判断str是否全部由小写字母组成，是返回true，否返回false\n print(xstr:islower(\"hello world\")) --> true",
["isupper"] = "xstr:isupper(str) --> boolean | nil, err_msg\n 判断str是否全部由大写字母组成，是返回true，否返回false\n print(xstr:isupper(\"HELLO WORLD\")) --> true",
["join"] = "xstr:join(str, substr) --> string | nil, err_msg\n 使用substr连接str中的每个元素，返回新串\n print(xstr:join(\"hello\", \"--\")) --> h--e--l--l--o",
["lower"] = "xstr:lower(str) --> string | nil, err_msg\n 将str中的大写字母小写化，返回新串\n print(xstr:lower(\"HeLLo WORld 2010\")) --> hello wold 2010",
["upper"] = "xstr:upper(str) --> string | nil, err_msg\n 将str中的小写字母大写化，返回新串\n print(xstr:upper(\"hello world 2010\")) --> HELLO WORLD 2010",
["partition"] = "xstr:partition(str, substr) --> string, string, string | nil, err_msg\n 将str按照substr为界限拆分为3部分，返回拆分后的字符串\n print(xstr:partition(\"hello*world\", \"wo\")) --> hello* wo rld",
["zfill"] = "xstr:zfill(str, n) --> string | nil, err_msg\n 在str前补0，使其总长度为n。返回新串\n print(xstr:zfill(\"100\", 5)) --> 00100",
["ljust"] = "xstr:ljust(str, n, ch) --> string | nil, err_msg\n 按左对齐方式，使用ch补充str，使其位宽为n。ch默认为空格，n默认为0\n print(xstr:ljust(\"hello\", 10, \"*\")) --> *****hello",
["rjust"] = "xstr:ljust(str, n, ch) --> string | nil, err_msg\n 按右对齐方式，使用ch补充str，使其位宽为n。ch默认为空格，n默认为0\n print(xstr:ljust(\"hello\", 10, \"*\")) --> hello*****",
["center"] = "xstr:center(str, n, ch) --> string | nil, err_msg\n 按中间对齐方式，使用ch补充str，使其位宽为n。ch默认为空格，n默认为0\n print(xstr:center(\"hello\", 10, \"*\")) --> **hello***",
["dir"] = "xstr:dir()\n 列出xstr命名空间中的函数",
["help"] = "xstr:help(\"func\")\n 打印函数func的帮助文档\n xstr:help(\"dir\") --> \nxstr:dir()\n 列出xstr命名空间中的函数",
}
print(man[fun_name])
end,
}