Add linter plugin to easily make linters

runtime/plugins/linter/linter.lua

@@ -0,0 +1,32 @@
+function linter_lint(linter, cmd, errorformat)
+    view:ClearGutterMessages(linter)
+
+    local handle = io.popen(cmd)
+    local lines = linter_split(handle:read("*a"), "\n")
+    handle:close()
+
+    messenger:Message(view.Buf.Path)
+    local regex = errorformat:gsub("%%f", "(.+)"):gsub("%%l", "(%d+)"):gsub("%%m", "(.+)")
+    for _,line in ipairs(lines) do
+        if string.find(line, regex) then
+            local file, line, msg = string.match(line, regex)
+            if linter_basename(view.Buf.Path) == linter_basename(file) then
+                view:GutterMessage(linter, tonumber(line), msg, 2)
+            end
+        end
+    end
+end
+
+function linter_split(str, sep)
+    local result = {}
+    local regex = ("([^%s]+)"):format(sep)
+    for each in str:gmatch(regex) do
+        table.insert(result, each)
+    end
+    return result
+end
+
+function linter_basename(file)
+    local name = string.gsub(file, "(.*/)(.*)", "%2")
+    return name
+end