Updating the documentation and the examples

1 files changed, 28 insertions, 17 deletions

diff --git a/examples/listId1.lua b/examples/listId1.lua
index 0bf26a1..12c0678 100644
--- a/examples/listId1.lua
+++ b/examples/listId1.lua
@@ -1,27 +1,38 @@
 local m = require'lpeglabel'
 
+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
+
 local g = m.P{
   "S",
   S = m.V"Id" * m.V"List",
-  List = -m.P(1) + ("," + m.T(2)) * m.V"Id" * m.V"List",
-  Id = m.R'az'^1 + m.T(1),
+  List = -m.P(1) + (m.V"Comma" + m.T(2)) * (m.V"Id" + m.T(1)) * m.V"List",
+  Id = m.V"Sp" * m.R'az'^1,
+  Comma = m.V"Sp" * ",",
+  Sp = m.S" \n\t"^0,
 }
 
 function mymatch (g, s)
-        local r, e, sfail = g:match(s)
-        if not r then
-                if e == 1 then
-        return r, "Error: expecting an identifier before '" .. sfail .. "'"
-        elseif e == 2 then
-        return r, "Error: expecting ',' before '" .. sfail .. "'"
-        else
-        return r, "Error"
-        end
-        end
-        return r
+  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 .. ")"
+    if e == 1 then
+      return r, msg .. ": expecting an identifier before '" .. sfail .. "'"
+    elseif e == 2 then
+      return r, msg .. ": expecting ',' before '" .. sfail .. "'"
+    else
+      return r, msg
+    end
+  end
+  return r
 end
-        
-print(mymatch(g, "a,b"))
-print(mymatch(g, "a b"))
-print(mymatch(g, ", b"))
+  
+print(mymatch(g, "one,two"))
+print(mymatch(g, "one two"))
+print(mymatch(g, "one,\n two,\nthree,"))