Updating examples to the new semantics

1 files changed, 20 insertions, 38 deletions

diff --git a/examples/expRec.lua b/examples/expRec.lua
index 52bd40a..d111ab0 100644
--- a/examples/expRec.lua
+++ b/examples/expRec.lua
@@ -2,28 +2,17 @@ local m = require"lpeglabel"
 local re = require"relabel"
 
 local labels = {
-  {"ExpTermFirst",  "expected an expression"},
-  {"ExpTermOp",   "expected a term after the operator"},
-  {"MisClose",  "missing a closing ')' after the expression"},
+  ExpTermFirst  =  "expected an expression",
+  ExpTermOp     =  "expected a term after the operator",
+  MisClose      =  "missing a closing ')' after the expression",
 }
 
-local function labelindex(labname)
-  for i, elem in ipairs(labels) do
-    if elem[1] == labname then
-      return i
-    end
-  end
-  error("could not find label: " .. labname)
-end
-
 local errors, subject
 
-local function expect(patt, labname)
-  local i = labelindex(labname)
-  return patt + m.T(i)
+local function expect(patt, lab)
+  return patt + m.T(lab)
 end
 
-
 local num = m.R("09")^1 / tonumber
 local op = m.S("+-")
 
@@ -41,22 +30,13 @@ local function compute(tokens)
   return result
 end
 
-local g = m.P {
-        "Exp",
-        Exp = m.Ct(m.V"OperandFirst" * (m.C(op) * m.V"Operand")^0) / compute,
-        OperandFirst = expect(m.V"Term", "ExpTermFirst"),
-        Operand = expect(m.V"Term", "ExpTermOp"),
-        Term = num + m.V"Group",
-        Group = "(" * m.V"Exp" * expect(")", "MisClose"),
-}
-
 function recorderror(pos, lab)
         local line, col = re.calcline(subject, pos)
-        table.insert(errors, { line = line, col = col, msg = labels[lab][2] })
+        table.insert(errors, { line = line, col = col, msg = labels[lab] })
 end
 
-function record (labname)
-        return (m.Cp() * m.Cc(labelindex(labname))) / recorderror
+function record (lab)
+        return (m.Cp() * m.Cc(lab)) / recorderror
 end
 
 function sync (p)
@@ -67,21 +47,23 @@ function defaultValue (p)
         return p or m.Cc(1000) 
 end
 
-local grec = m.P {
-        "S",
-        S = m.Rec(m.V"A", m.V"ErrExpTermFirst", labelindex("ExpTermFirst")), -- default value is 0
-        A = m.Rec(m.V"Sg", m.V"ErrExpTermOp", labelindex("ExpTermOp")),
-        Sg = m.Rec(g, m.V"ErrMisClose", labelindex("MisClose")),
-        ErrExpTermFirst = record("ExpTermFirst") * sync(op + ")") * defaultValue(),
-        ErrExpTermOp = record("ExpTermOp") * sync(op + ")") * defaultValue(),
-        ErrMisClose = record("MisClose") * sync(m.P")") * defaultValue(m.P""),
+local g = m.P {
+        "Exp",
+        Exp           = m.Ct(m.V"OperandFirst" * (m.C(op) * m.V"Operand")^0) / compute,
+        OperandFirst  = expect(m.V"Term", "ExpTermFirst"),
+        Operand       = expect(m.V"Term", "ExpTermOp"),
+        Term          = num + m.V"Group",
+        Group         = "(" * m.V"Exp" * expect(")", "MisClose"),
+        ExpTermFirst  = record("ExpTermFirst") * sync(op + ")") * defaultValue(),
+        ExpTermOp     = record("ExpTermOp") * sync(op + ")") * defaultValue(),
+        MisClose      = record("MisClose") * sync(m.P")") * defaultValue(m.P""),
 }
-               
+
 local function eval(input)
         errors = {}
         io.write("Input: ", input, "\n")
         subject = input
-  local result, label, suffix = grec:match(input)
+  local result, label, suffix = g:match(input)
   io.write("Syntactic errors found: " .. #errors, "\n")
         if #errors > 0 then
     local out = {}