/usr/share/lua/5.1/pl/luabalanced.lua is in lua-penlight 1.2.1-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 | --- Extract delimited Lua sequences from strings.
-- Inspired by Damian Conway's Text::Balanced in Perl. <br/>
-- <ul>
-- <li>[1] <a href="http://lua-users.org/wiki/LuaBalanced">Lua Wiki Page</a></li>
-- <li>[2] http://search.cpan.org/dist/Text-Balanced/lib/Text/Balanced.pm</li>
-- </ul> <br/>
-- <pre class=example>
-- local lb = require "pl.luabalanced"
-- --Extract Lua expression starting at position 4.
-- print(lb.match_expression("if x^2 + x > 5 then print(x) end", 4))
-- --> x^2 + x > 5 16
-- --Extract Lua string starting at (default) position 1.
-- print(lb.match_string([["test\"123" .. "more"]]))
-- --> "test\"123" 12
-- </pre>
-- (c) 2008, David Manura, Licensed under the same terms as Lua (MIT license).
-- @class module
-- @name pl.luabalanced
local M = {}
local assert = assert
local table_concat = table.concat
-- map opening brace <-> closing brace.
local ends = { ['('] = ')', ['{'] = '}', ['['] = ']' }
local begins = {}; for k,v in pairs(ends) do begins[v] = k end
-- Match Lua string in string <s> starting at position <pos>.
-- Returns <string>, <posnew>, where <string> is the matched
-- string (or nil on no match) and <posnew> is the character
-- following the match (or <pos> on no match).
-- Supports all Lua string syntax: "...", '...', [[...]], [=[...]=], etc.
local function match_string(s, pos)
pos = pos or 1
local posa = pos
local c = s:sub(pos,pos)
if c == '"' or c == "'" then
pos = pos + 1
while 1 do
pos = assert(s:find("[" .. c .. "\\]", pos), 'syntax error')
if s:sub(pos,pos) == c then
local part = s:sub(posa, pos)
return part, pos + 1
else
pos = pos + 2
end
end
else
local sc = s:match("^%[(=*)%[", pos)
if sc then
local _; _, pos = s:find("%]" .. sc .. "%]", pos)
assert(pos)
local part = s:sub(posa, pos)
return part, pos + 1
else
return nil, pos
end
end
end
M.match_string = match_string
-- Match bracketed Lua expression, e.g. "(...)", "{...}", "[...]", "[[...]]",
-- [=[...]=], etc.
-- Function interface is similar to match_string.
local function match_bracketed(s, pos)
pos = pos or 1
local posa = pos
local ca = s:sub(pos,pos)
if not ends[ca] then
return nil, pos
end
local stack = {}
while 1 do
pos = s:find('[%(%{%[%)%}%]\"\']', pos)
assert(pos, 'syntax error: unbalanced')
local c = s:sub(pos,pos)
if c == '"' or c == "'" then
local part; part, pos = match_string(s, pos)
assert(part)
elseif ends[c] then -- open
local mid, posb
if c == '[' then mid, posb = s:match('^%[(=*)%[()', pos) end
if mid then
pos = s:match('%]' .. mid .. '%]()', posb)
assert(pos, 'syntax error: long string not terminated')
if #stack == 0 then
local part = s:sub(posa, pos-1)
return part, pos
end
else
stack[#stack+1] = c
pos = pos + 1
end
else -- close
assert(stack[#stack] == assert(begins[c]), 'syntax error: unbalanced')
stack[#stack] = nil
if #stack == 0 then
local part = s:sub(posa, pos)
return part, pos+1
end
pos = pos + 1
end
end
end
M.match_bracketed = match_bracketed
-- Match Lua comment, e.g. "--...\n", "--[[...]]", "--[=[...]=]", etc.
-- Function interface is similar to match_string.
local function match_comment(s, pos)
pos = pos or 1
if s:sub(pos, pos+1) ~= '--' then
return nil, pos
end
pos = pos + 2
local partt, post = match_string(s, pos)
if partt then
return '--' .. partt, post
end
local part; part, pos = s:match('^([^\n]*\n?)()', pos)
return '--' .. part, pos
end
-- Match Lua expression, e.g. "a + b * c[e]".
-- Function interface is similar to match_string.
local wordop = {['and']=true, ['or']=true, ['not']=true}
local is_compare = {['>']=true, ['<']=true, ['~']=true}
local function match_expression(s, pos)
pos = pos or 1
local posa = pos
local lastident
local poscs, posce
while pos do
local c = s:sub(pos,pos)
if c == '"' or c == "'" or c == '[' and s:find('^[=%[]', pos+1) then
local part; part, pos = match_string(s, pos)
assert(part, 'syntax error')
elseif c == '-' and s:sub(pos+1,pos+1) == '-' then
-- note: handle adjacent comments in loop to properly support
-- backtracing (poscs/posce).
poscs = pos
while s:sub(pos,pos+1) == '--' do
local part; part, pos = match_comment(s, pos)
assert(part)
pos = s:match('^%s*()', pos)
posce = pos
end
elseif c == '(' or c == '{' or c == '[' then
local part; part, pos = match_bracketed(s, pos)
elseif c == '=' and s:sub(pos+1,pos+1) == '=' then
pos = pos + 2 -- skip over two-char op containing '='
elseif c == '=' and is_compare[s:sub(pos-1,pos-1)] then
pos = pos + 1 -- skip over two-char op containing '='
elseif c:match'^[%)%}%];,=]' then
local part = s:sub(posa, pos-1)
return part, pos
elseif c:match'^[%w_]' then
local newident,newpos = s:match('^([%w_]+)()', pos)
if pos ~= posa and not wordop[newident] then -- non-first ident
local pose = ((posce == pos) and poscs or pos) - 1
while s:match('^%s', pose) do pose = pose - 1 end
local ce = s:sub(pose,pose)
if ce:match'[%)%}\'\"%]]' or
ce:match'[%w_]' and not wordop[lastident]
then
local part = s:sub(posa, pos-1)
return part, pos
end
end
lastident, pos = newident, newpos
else
pos = pos + 1
end
pos = s:find('[%(%{%[%)%}%]\"\';,=%w_%-]', pos)
end
local part = s:sub(posa, #s)
return part, #s+1
end
M.match_expression = match_expression
-- Match name list (zero or more names). E.g. "a,b,c"
-- Function interface is similar to match_string,
-- but returns array as match.
local function match_namelist(s, pos)
pos = pos or 1
local list = {}
while 1 do
local c = #list == 0 and '^' or '^%s*,%s*'
local item, post = s:match(c .. '([%a_][%w_]*)%s*()', pos)
if item then pos = post else break end
list[#list+1] = item
end
return list, pos
end
M.match_namelist = match_namelist
-- Match expression list (zero or more expressions). E.g. "a+b,b*c".
-- Function interface is similar to match_string,
-- but returns array as match.
local function match_explist(s, pos)
pos = pos or 1
local list = {}
while 1 do
if #list ~= 0 then
local post = s:match('^%s*,%s*()', pos)
if post then pos = post else break end
end
local item; item, pos = match_expression(s, pos)
assert(item, 'syntax error')
list[#list+1] = item
end
return list, pos
end
M.match_explist = match_explist
-- Replace snippets of code in Lua code string <s>
-- using replacement function f(u,sin) --> sout.
-- <u> is the type of snippet ('c' = comment, 's' = string,
-- 'e' = any other code).
-- Snippet is replaced with <sout> (unless <sout> is nil or false, in
-- which case the original snippet is kept)
-- This is somewhat analogous to string.gsub .
local function gsub(s, f)
local pos = 1
local posa = 1
local sret = ''
while 1 do
pos = s:find('[%-\'\"%[]', pos)
if not pos then break end
if s:match('^%-%-', pos) then
local exp = s:sub(posa, pos-1)
if #exp > 0 then sret = sret .. (f('e', exp) or exp) end
local comment; comment, pos = match_comment(s, pos)
sret = sret .. (f('c', assert(comment)) or comment)
posa = pos
else
local posb = s:find('^[\'\"%[]', pos)
local str
if posb then str, pos = match_string(s, posb) end
if str then
local exp = s:sub(posa, posb-1)
if #exp > 0 then sret = sret .. (f('e', exp) or exp) end
sret = sret .. (f('s', str) or str)
posa = pos
else
pos = pos + 1
end
end
end
local exp = s:sub(posa)
if #exp > 0 then sret = sret .. (f('e', exp) or exp) end
return sret
end
M.gsub = gsub
return M
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