Removing the "A_" prefix on action names, and improving the quality of

as_lua_id() (guaranteed injectivity).

4 files changed, 43 insertions, 37 deletions

diff --git a/core/metaprogramming.nom b/core/metaprogramming.nom
index 0f894b8..0f64bac 100644
--- a/core/metaprogramming.nom
+++ b/core/metaprogramming.nom
@@ -94,13 +94,13 @@ test:
     assume ((foo 1) == "outer")
 compile [local action %actions %body] to:
     lua> ".."
-        local fn_name = "A_"..string.as_lua_id(\%actions[1].stub)
+        local fn_name = string.as_lua_id(\%actions[1].stub)
         local \%args = table.map(\%actions[1]:get_args(), function(a) return tostring(nomsu:compile(a)) end)
         local lua = LuaCode(tree.source, fn_name, " = ", \(compile as (%args -> %body)))
         lua:add_free_vars({fn_name})
         for i=2,#\%actions do
             local alias = \%actions[i]
-            local alias_name = "A_"..string.as_lua_id(alias.stub)
+            local alias_name = string.as_lua_id(alias.stub)
             lua:add_free_vars({alias_name})
             local \%alias_args = table.map(alias:get_args(), function(a) return tostring(nomsu:compile(a)) end)
             lua:append("\\n", alias_name, " = ")
@@ -125,11 +125,11 @@ test:
 compile [action %actions %body] to (..)
     lua> ".."
         local lua = \(compile as (local action %actions %body))
-        lua:remove_free_vars(table.map(\%actions, function(a) return "A_"..string.as_lua_id(a.stub) end))
+        lua:remove_free_vars(table.map(\%actions, function(a) return string.as_lua_id(a.stub) end))
         return lua
 
 test:
-    assume ((action (say %)) == (=lua "A_say_1"))
+    assume ((action (say %)) == (=lua "say_1"))
 compile [action %action] to (Lua value (%action as lua id))
 
 test:
@@ -209,7 +209,7 @@ compile [%tree as lua return] to (..)
     Lua value "nomsu:compile(\(%tree as lua expr)):as_statements('return ')"
 
 compile [remove action %action] to (..)
-    Lua "A_\(=lua "string.as_lua_id(\(%action.stub))") = nil"
+    Lua "\(=lua "string.as_lua_id(\(%action.stub))") = nil"
 
 test:
     assume ("\(\(foo \%x) as nomsu)" == "foo %x") or barf ".."
@@ -224,7 +224,7 @@ action [%var as lua identifier, %var as lua id] (..)
     lua> ".."
         if type(\%var) == 'string' then return string.as_lua_id(\%var)
         elseif \%var.type == 'Var' then return "_"..string.as_lua_id(\%var[1])
-        elseif \%var.type == 'Action' then return "A_"..string.as_lua_id(\%var.stub)
+        elseif \%var.type == 'Action' then return string.as_lua_id(\%var.stub)
         end
 
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
diff --git a/lib/object.nom b/lib/object.nom
index 6aa0630..8d59190 100644
--- a/lib/object.nom
+++ b/lib/object.nom
@@ -84,9 +84,9 @@ compile [object %classname extends %parent %class_body] to:
                         return inst
                     end,
                 })
-                nomsu["A_"..string.as_lua_id("new "..class.name)] = class
-                nomsu["A_"..string.as_lua_id("new "..class.name.." 1")] = class
-                nomsu["A_"..string.as_lua_id(class.name)] = function() return class end
+                nomsu[string.as_lua_id("new "..class.name)] = class
+                nomsu[string.as_lua_id("new "..class.name.." 1")] = class
+                nomsu[string.as_lua_id(class.name)] = function() return class end
                 class.__index = class
                 class.class = class
                 class.__tostring = function(inst)
diff --git a/nomsu_compiler.lua b/nomsu_compiler.lua
index 11bdc9d..f37960f 100644
--- a/nomsu_compiler.lua
+++ b/nomsu_compiler.lua
@@ -37,7 +37,8 @@ local AST = require("syntax_tree")
 local Parser = require("parser")
 SOURCE_MAP = { }
 string.as_lua_id = function(str)
-  str = gsub(str, "x([0-9A-F][0-9A-F])", "x\0%1")
+  str = gsub(str, "^\0*$", "%1\0")
+  str = gsub(str, "x([0-9A-F][0-9A-F])", "x78%1")
   str = gsub(str, "%W", function(c)
     if c == ' ' then
       return '_'
@@ -45,16 +46,19 @@ string.as_lua_id = function(str)
       return format("x%02X", byte(c))
     end
   end)
+  str = str:gsub("^_*%d", "_%1")
   return str
 end
-table.map = function(self, fn)
-  local _accum_0 = { }
-  local _len_0 = 1
-  for _, v in ipairs(self) do
-    _accum_0[_len_0] = fn(v)
-    _len_0 = _len_0 + 1
-  end
-  return _accum_0
+table.map = function(t, fn)
+  return setmetatable((function()
+    local _accum_0 = { }
+    local _len_0 = 1
+    for _, v in ipairs(t) do
+      _accum_0[_len_0] = fn(v)
+      _len_0 = _len_0 + 1
+    end
+    return _accum_0
+  end)(), getmetatable(t))
 end
 table.fork = function(t, values)
   return setmetatable(values or { }, {
@@ -106,7 +110,7 @@ local NomsuCompiler = setmetatable({
   end
 })
 do
-  NomsuCompiler.NOMSU_COMPILER_VERSION = 5
+  NomsuCompiler.NOMSU_COMPILER_VERSION = 6
   NomsuCompiler.NOMSU_SYNTAX_VERSION = Parser.version
   NomsuCompiler.nomsu = NomsuCompiler
   NomsuCompiler.parse = function(self, ...)
@@ -489,10 +493,10 @@ do
   NomsuCompiler.compile = function(self, tree)
     if tree.version then
       do
-        local get_version = self['A_' .. string.as_lua_id("Nomsu version")]
+        local get_version = self[string.as_lua_id("Nomsu version")]
         if get_version then
           do
-            local upgrade = self['A_' .. string.as_lua_id("1 upgraded from 2 to 3")]
+            local upgrade = self[string.as_lua_id("1 upgraded from 2 to 3")]
             if upgrade then
               tree = upgrade(tree, tree.version, get_version())
             end
@@ -529,11 +533,6 @@ do
       local lua = LuaCode.Value(tree.source)
       if tree.target then
         lua:append(self:compile(tree.target), ":")
-        if string.as_lua_id(stub):match("^[0-9]") then
-          lua:append("_")
-        end
-      else
-        lua:append("A_")
       end
       lua:append(string.as_lua_id(stub), "(")
       local args = { }
diff --git a/nomsu_compiler.moon b/nomsu_compiler.moon
index 70e3f40..439285e 100644
--- a/nomsu_compiler.moon
+++ b/nomsu_compiler.moon
@@ -29,16 +29,27 @@ Parser = require("parser")
 export SOURCE_MAP
 SOURCE_MAP = {}
 
+-- Convert an arbitrary string into a valid Lua identifier. This function is injective,
+-- but not idempotent, i.e. if (x != y) then (as_lua_id(x) != as_lua_id(y)),
+-- but as_lua_id(x) is not necessarily equal to as_lua_id(as_lua_id(x))
 string.as_lua_id = (str)->
-    -- Cut up escape-sequence-like chunks
-    str = gsub str, "x([0-9A-F][0-9A-F])", "x\0%1"
-    -- Alphanumeric unchanged, spaces to underscores, and everything else to hex escape sequences
+    -- Empty strings are not valid lua identifiers, so treat them like "\0",
+    -- and treat "\0" as "\0\0", etc. to preserve injectivity.
+    str = gsub str, "^\0*$", "%1\0"
+    -- Escape 'x' when it precedes something that looks like an uppercase hex sequence.
+    -- This way, all Lua IDs can be unambiguously reverse-engineered, but normal usage
+    -- of 'x' won't produce ugly Lua IDs.
+    -- i.e. "x" -> "x", "oxen" -> "oxen", but "Hex2Dec" -> "Hex782Dec" and "He-ec" -> "Hex2Dec"
+    str = gsub str, "x([0-9A-F][0-9A-F])", "x78%1"
+    -- Map spaces to underscores, and everything else non-alphanumeric to hex escape sequences
     str = gsub str, "%W", (c)->
         if c == ' ' then '_'
         else format("x%02X", byte(c))
+    -- Lua IDs can't start with numbers, so map "1" -> "_1", "_1" -> "__1", etc.
+    str = str\gsub "^_*%d", "_%1"
     return str
 
-table.map = (fn)=> [fn(v) for _,v in ipairs(@)]
+table.map = (t, fn)-> setmetatable([fn(v) for _,v in ipairs(t)], getmetatable(t))
 table.fork = (t, values)-> setmetatable(values or {}, {__index:t})
 table.copy = (t)-> setmetatable({k,v for k,v in pairs(t)}, getmetatable(t))
 
@@ -63,7 +74,7 @@ NomsuCompiler = setmetatable {name:"Nomsu"},
     __index: (k)=> if _self = rawget(@, "self") then _self[k] else nil
     __tostring: => @name
 with NomsuCompiler
-    .NOMSU_COMPILER_VERSION = 5
+    .NOMSU_COMPILER_VERSION = 6
     .NOMSU_SYNTAX_VERSION = Parser.version
     .nomsu = NomsuCompiler
     .parse = (...)=> Parser.parse(...)
@@ -312,8 +323,8 @@ with NomsuCompiler
 
     .compile = (tree)=>
         if tree.version
-            if get_version = @['A_'..string.as_lua_id("Nomsu version")]
-                if upgrade = @['A_'..string.as_lua_id("1 upgraded from 2 to 3")]
+            if get_version = @[string.as_lua_id("Nomsu version")]
+                if upgrade = @[string.as_lua_id("1 upgraded from 2 to 3")]
                     tree = upgrade(tree, tree.version, get_version!)
         switch tree.type
             when "Action"
@@ -331,10 +342,6 @@ with NomsuCompiler
                 lua = LuaCode.Value(tree.source)
                 if tree.target
                     lua\append @compile(tree.target), ":"
-                    if string.as_lua_id(stub)\match("^[0-9]")
-                        lua\append "_"
-                else
-                    lua\append "A_"
                 lua\append(string.as_lua_id(stub),"(")
                 args = {}
                 for i, tok in ipairs tree