1 files changed, 34 insertions, 14 deletions

diff --git a/examples/listIdCatch.lua b/examples/listIdCatch.lua
index 38ad2e5..3cbc834 100644
--- a/examples/listIdCatch.lua
+++ b/examples/listIdCatch.lua
@@ -1,25 +1,45 @@
 local m = require'lpeglabel'
 
-local errUndef, errId, errComma = 0, 1, 2
+local terror = {}
 
-local terror = {
-  [errUndef] = "Error",
-  [errId] = "Error: expecting an identifier",
-  [errComma] = "Error: expecting ','",
-}
+local function newError(s)
+        table.insert(terror, s)
+        return #terror
+end
+
+local errUndef = newError("undefined")
+local errId = newError("expecting an identifier")
+local errComma = newError("expecting ','")
+
+local function calcline (s, i)
+  if i == 1 then return 1, 1 end
+  local rest, line = s:sub(1,i):gsub("[^\n]*\n", "")
+  local col = #rest
+  return 1 + line, col ~= 0 and col or 1
+end
 
-g = m.P{
+local g = m.P{
   "S",
-        S = m.Lc(m.Lc(m.V"Id" * m.V"List", m.V"ErrId", errId),
+  S = m.Lc(m.Lc(m.V"Id" * m.V"List", m.V"ErrId", errId),
            m.V"ErrComma", errComma),
-        List = -m.P(1)  +  m.V"Comma" * m.V"Id" * m.V"List",
-        Id = m.R'az'^1  +  m.T(errId),
-        Comma = ","  +  m.T(errComma),
+  List = -m.P(1) + (m.V"Comma" + m.T(errComma)) * (m.V"Id" + m.T(errId)) * m.V"List",
+  Id = m.V"Sp" * m.R'az'^1,
+        Comma = m.V"Sp" * ",",
+        Sp = m.S" \n\t"^0,
         ErrId = m.Cc(errId) / terror,
         ErrComma = m.Cc(errComma) / terror
 }
 
-print(g:match("a,b"))
-print(g:match("a b"))
-print(g:match(",b"))
+function mymatch (g, s)
+        local r, e, sfail = g:match(s)
+        if not r then
+                local line, col = calcline(s, #s - #sfail)
+                local msg = "Error at line " .. line .. " (col " .. col .. "): "
+                return r, msg .. terror[e] .. " before '" .. sfail .. "'"
+        end
+        return r
+end
 
+print(mymatch(g, "one,two"))
+print(mymatch(g, "one two"))
+print(mymatch(g, "one,\n two,\nthree,"))