Allow parser.lua to be used as an argument parser

parser.lua

@@ -95,7 +95,11 @@ end
 
 local function get_next_table(state, in_pos)
     if state[DATA] == nil or #state[DATA] == 0 then
-        return get_next_common(state, in_pos, EOZ)
+        if state[STATE] == nil then
+            return in_pos, state
+        else
+            return get_next_common(state, in_pos, EOZ)
+        end
     end
     in_pos = in_pos + 1
     local token = state[DATA][in_pos - state[OFFDATA]]
@@ -129,15 +133,14 @@ local function stream(defs, data)
     local state = {}
     local fn
     state[STATE] = defs
-    if type(data) == "string" then
-        state[DATA] = data
-        state[GEN] = function() end
-        fn = get_next_string
-    else
+    if type(data) == "function" then
         state[DATA] = data()
         state[GEN] = data
-        fn = type(state[DATA]) == "string" and get_next_string or get_next_table
+    else
+        state[DATA] = data
+        state[GEN] = function() end
     end
+    fn = type(state[DATA]) == "table" and get_next_table or get_next_string
     state[OFFDATA] = 0
     return fn, state, state[OFFDATA]
 end

printtokens.lua

@@ -18,18 +18,47 @@
 
 local parser = require "parser"
 
-do
-    local filename = arg[1]
-    local luatokens = require "luatokens"
-    local file = io.open(filename, "r")
-    local tokens = luatokens.defs
-    local state, err, etoken, estate = parser.parse(tokens, function() return file:read(8192) end)
-    if state then
-        for i,v in ipairs(state) do
-            v = luatokens.reverse_keywords[v] or luatokens.reverse_tokens[v] or v
-            print(i, v) -- TODO formatting
-        end
-    else
-        print("Parse error")
+-- CLI argument rules
+local defs = parser.selfify({})
+defs['-'] = function(state, token)
+    if state.filename then
+        error("Must specify only one filename")
+    end
+    state.filename = true
+    state.file = io.stdin
+    return "self"
+end
+defs[""] = function(state, token)
+    if state.filename then
+        error("Must specify only one filename")
+    end
+    state.filename = token
+    state.file, state.err = io.open(state.filename, "r")
+    return "self"
+end
+defs[parser.EOZ] = function(state, token)
+    if not state.file then
+        error((state.filename and (state.err or "") or "No file specified") )
+    end
+    return {}
+end
+defs[-1] = function(state, token, rule)
+    if token ~= parser.EOZ and token:sub(1,1) == "-" and not rule then
+        error("Unknown option: " .. token)
     end
 end
+defs['--'] = parser.selfify({[""] = defs[""]})
+
+local state = parser.parse(defs, arg)
+local luatokens = require "luatokens"
+local file = state.file
+local tokens = luatokens.defs
+local state, err, etoken, estate = parser.parse(tokens, function() return file:read(8192) end)
+if state then
+    for i,v in ipairs(state) do
+        v = luatokens.reverse_keywords[v] or luatokens.reverse_tokens[v] or v
+        print(i, v) -- TODO formatting
+    end
+else
+    print("Parse error")
+end