rem, common: handle string sanitization

1 files changed, 34 insertions, 5 deletions

diff --git a/common.lua b/common.lua
index c009207..6afde62 100644
--- a/common.lua
+++ b/common.lua
@@ -1,3 +1,5 @@
+local lpeg = require "lpeg"
+
 local string        = require "string"
 local stringformat  = string.format
 
@@ -20,11 +22,38 @@ end
 
 local set_verbosity = function (n) verboselvl = n end
 
+local trim_whitespace
+local unescape_string
+do
+  local P                 = lpeg.P
+  local S                 = lpeg.S
+  local Cs                = lpeg.Cs
+  local p_ws_char         = S" \n\r\t\v"
+  local p_ws              = p_ws_char^1
+  local p_ws_trailing     = p_ws * P (-1)
+  local p_ws_drop         = Cs (  (p_ws^-1 / "")
+                                * (1 - p_ws_trailing)^0
+                                * (p_ws^-1 * P (-1) / ""))
+
+  local p_escape_char     = (P"\\n" / "\n")
+                          + (P"\\r" / "\r")
+                          + (P"\\t" / "\t")
+                          + (P"\\v" / "\v")
+  local p_unescape        = Cs ((p_escape_char + 1)^0)
+
+  local lpegmatch         = lpeg.match
+
+  trim_whitespace = function (s) return lpegmatch (p_ws_drop , s) end
+  unescape_string = function (s) return lpegmatch (p_unescape, s) end
+end
+
 return
-  { println       = mk_out ("stdout", 0, true)
-  , errorln       = mk_out ("stderr", 0, true)
-  , noiseln       = mk_out ("stderr", 1, true)
-  , debugln       = mk_out ("stderr", 2, true)
-  , set_verbosity = set_verbosity
+  { println               = mk_out ("stdout", 0, true)
+  , errorln               = mk_out ("stderr", 0, true)
+  , noiseln               = mk_out ("stderr", 1, true)
+  , debugln               = mk_out ("stderr", 2, true)
+  , set_verbosity         = set_verbosity
+  , trim_whitespace       = trim_whitespace
+  , unescape_string       = unescape_string
   }