From be06fc096aa28358914bd6a76b4ea380a04b8873 Mon Sep 17 00:00:00 2001
From: Bruce Hill <bitbucket@bruce-hill.com>
Date: Sun, 15 Jul 2018 19:41:22 -0700
Subject: Major changes to how versioning and parsing work. This should be a
 better path going forward to handling upgrades. Old syntax files will stick
 around for compatibility purposes. Old syntax can be parsed into valid syntax
 trees via the old syntax (.peg) files, and then old syntax trees should be
 valid and can be upgraded via the normal code path. This change has lots of
 improvements to Nomsu codegen too.

---
 parser.lua | 50 ++++++++++++++++++++++++++------------------------
 1 file changed, 26 insertions(+), 24 deletions(-)

(limited to 'parser.lua')

diff --git a/parser.lua b/parser.lua
index d928fc8..4689e16 100644
--- a/parser.lua
+++ b/parser.lua
@@ -110,11 +110,12 @@ setmetatable(NOMSU_DEFS, {
     return make_node
   end
 })
-local Parser = { }
-local NOMSU_PATTERN
+local Parser = {
+  version = 2,
+  patterns = { }
+}
 do
-  local peg_tidier = re.compile([[    file <- %nl* version %nl* {~ (def/comment) (%nl+ (def/comment))* %nl* ~}
-    version <- "--" (!"version" [^%nl])* "version" (" ")* (([0-9])+ -> set_version) ([^%nl])*
+  local peg_tidier = re.compile([[    file <- %nl* {~ (def/comment) (%nl+ (def/comment))* %nl* ~}
     def <- anon_def / captured_def
     anon_def <- ({ident} (" "*) ":"
         {~ ((%nl " "+ def_line?)+) / def_line ~}) -> "%1 <- %2"
@@ -124,39 +125,40 @@ do
     err <- ("(!!" { (!("!!)") .)* } "!!)") -> "(({} (%1) %%userdata) => error)"
     ident <- [a-zA-Z_][a-zA-Z0-9_]*
     comment <- "--" [^%nl]*
-    ]], {
-    set_version = function(v)
-      Parser.version = tonumber(v), {
-        nl = NOMSU_DEFS.nl
-      }
-    end
-  })
-  local peg_file = io.open("nomsu.peg")
-  if not peg_file and package.nomsupath then
-    for path in package.nomsupath:gmatch("[^;]+") do
-      peg_file = io.open(path .. "/nomsu.peg")
-      if peg_file then
-        break
+    ]])
+  for version = 1, Parser.version do
+    local peg_file = io.open("nomsu." .. tostring(version) .. ".peg")
+    if not peg_file and package.nomsupath then
+      for path in package.nomsupath:gmatch("[^;]+") do
+        peg_file = io.open(path .. "/nomsu." .. tostring(version) .. ".peg")
+        if peg_file then
+          break
+        end
       end
     end
+    assert(peg_file, "could not find nomsu .peg file")
+    local nomsu_peg = peg_tidier:match(peg_file:read('*a'))
+    peg_file:close()
+    Parser.patterns[version] = re.compile(nomsu_peg, NOMSU_DEFS)
   end
-  assert(peg_file, "could not find nomsu.peg file")
-  local nomsu_peg = peg_tidier:match(peg_file:read('*a'))
-  peg_file:close()
-  NOMSU_PATTERN = re.compile(nomsu_peg, NOMSU_DEFS)
 end
-Parser.parse = function(nomsu_code, source)
+Parser.parse = function(nomsu_code, source, version)
   if source == nil then
     source = nil
   end
+  if version == nil then
+    version = nil
+  end
   source = source or nomsu_code.source
   nomsu_code = tostring(nomsu_code)
+  version = version or nomsu_code:match("^#![^\n]*nomsu[ ]+-V[ ]*([0-9.]+)")
+  version = (version and tonumber(version)) or Parser.version
   local userdata = {
     errors = { },
     source = source,
     comments = { }
   }
-  local tree = NOMSU_PATTERN:match(nomsu_code, nil, userdata)
+  local tree = Parser.patterns[version]:match(nomsu_code, nil, userdata)
   if not (tree) then
     error("In file " .. tostring(colored.blue(tostring(source or "<unknown>"))) .. " failed to parse:\n" .. tostring(colored.onyellow(colored.black(nomsu_code))))
   end
@@ -186,7 +188,7 @@ Parser.parse = function(nomsu_code, source)
       end
       errors = _accum_0
     end
-    error("Errors occurred while parsing:\n\n" .. table.concat(errors, "\n\n"), 0)
+    error("Errors occurred while parsing (v" .. tostring(version) .. "):\n\n" .. table.concat(errors, "\n\n"), 0)
   end
   tree.version = userdata.version
   return tree
-- 
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