Lua: gmatch multi line string?

Question

I'm trying to make a function that searches through some code to find the line the search term is on, as well as the line's index. The code is a multi line string with new line characters. I was thinking of using gmatch to do this, but I have no clue how.

This is my code at the moment. It's awful, but I can't think of a way to make it any better:

local function search( code, term )
  local matches = {}
  local i = 0
  for line in string.gmatch( code, "[^\r\n]+" ) do
    i = i + 1
    if string.find( line, term, 1, true ) then
      table.insert( matches, { line = i, code = line } )
    end
  end
  return matches
end

Any help would be appreciated!

To correctly count empty lines: for line in string.gmatch( code, "([^\r\n]*)\r?\n?" ) do — Egor Skriptunoff
– Egor Skriptunoff, Commented Jul 17, 2017 at 12:11
@lhf it goes through every single line one by one just to see if one of the lines has the correct string, rather than looking at the lines as a whole, which I feel it could as it's a single string. Also, the part where I add 1 to I feels wrong. I'm used to k and v when looping. — MysteryPancake
– MysteryPancake, Commented Jul 17, 2017 at 13:25

lhf · Accepted Answer · 2017-07-17 23:43:56Z

2

Your solution seem fine to me. The problem with using a single gmactch loop is your requirement to report line numbers. The code below avoids this by embedding line numbers into the code. I've use @ to mark line numbers. You can use any char that does not appear in the source code, even something like \0.

function search(code,term)
    for a,b in code:gmatch("@(%d+):([^\n]-"..term.."[^\n]-)\n") do
        print(a)
        print(b)
    end
end

local n=0
code="\n"..code
code=code:gsub("\n", function () n=n+1 return "\n@"..n..":" end)

search(code,"matc")

edited Jul 17, 2017 at 23:43

answered Jul 17, 2017 at 14:38

lhf

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