Lua:除非被引用，否则将字符串拆分为单词

Question

因此，我有以下代码在空白之间分割字符串：

text = "I am 'the text'"
for string in text:gmatch("%S+") do
    print(string)
end

结果：

I
am
'the
text'

但我需要这样做：

I
am
the text --[[yep, without the quotes]]

我该怎么做？

编辑：为了补充这个问题，我们的想法是将参数从一个程序传递到另一个程序。以下是我正在处理的拉取请求，目前正在审查中：https://github.com/mpv-player/mpv/pull/1619

Answer 1

可以通过巧妙的解析来实现这一点，但另一种方法可能是跟踪一个简单的状态，并根据引用片段的检测来合并片段。像这样的东西可能会起作用：

local text = [[I "am" 'the text' and "some more text with '" and "escaped " text"]]
local spat, epat, buf, quoted = [=[^(['"])]=], [=[(['"])$]=]
for str in text:gmatch("%S+") do
  local squoted = str:match(spat)
  local equoted = str:match(epat)
  local escaped = str:match([=[(*)['"]$]=])
  if squoted and not quoted and not equoted then
    buf, quoted = str, squoted
  elseif buf and equoted == quoted and #escaped % 2 == 0 then
    str, buf, quoted = buf .. ' ' .. str, nil, nil
  elseif buf then
    buf = buf .. ' ' .. str
  end
  if not buf then print((str:gsub(spat,""):gsub(epat,""))) end
end
if buf then print("Missing matching quote for "..buf) end

这将打印：

I
am
the text
and
some more text with '
and
escaped " text

已更新以处理混合引号和转义引号。已更新以删除引号。已更新以处理引用的单词。

Answer 2

试试这个：

text = [[I am 'the text' and '' here is "another text in quotes" and this is the end]]
local e = 0
while true do
    local b = e+1
    b = text:find("%S",b)
    if b==nil then break end
    if text:sub(b,b)=="'" then
        e = text:find("'",b+1)
        b = b+1
    elseif text:sub(b,b)=='"' then
        e = text:find('"',b+1)
        b = b+1
    else
        e = text:find("%s",b+1)
    end
    if e==nil then e=#text+1 end
    print("["..text:sub(b,e-1).."]")
end

Answer 3

Lua模式的功能不足以正确处理此任务。这里是一个LPeg解决方案改编自Lua Lexer。它同时处理单引号和双引号。

local lpeg = require 'lpeg'
local P, S, C, Cc, Ct = lpeg.P, lpeg.S, lpeg.C, lpeg.Cc, lpeg.Ct
local function token(id, patt) return Ct(Cc(id) * C(patt)) end
local singleq = P "'" * ((1 - S "'rnf\") + (P '\' * 1)) ^ 0 * "'"
local doubleq = P '"' * ((1 - S '"rnf\') + (P '\' * 1)) ^ 0 * '"'
local white = token('whitespace', S('rnft ')^1)
local word = token('word', (1 - S("' rnft""))^1)
local string = token('string', singleq + doubleq)
local tokens = Ct((string + white + word) ^ 0)

input = [["This is a string" 'another string' these are words]]
for _, tok in ipairs(lpeg.match(tokens, input)) do
  if tok[1] ~= "whitespace" then
     if tok[1] == "string" then
        print(tok[2]:sub(2,-2)) -- cut off quotes
     else
       print(tok[2])
     end
  end
end

输出：

This is a string
another string
these
are
words