Various improvements to our Lua parser

- Encode the DFA as a virtual machine (identical to lrgrep) rather than
   compiling it to a series of Lua functions. While this is a little
   slower and uglier, it's much more space efficient, shaving off 16Kb.

 - Minimise the DFA properly. This only shaves off a few states, but
   every little helps.

 - Run the error handling code from a non-reduced parser stack. This was
   incredibly nasty to get right (and positions are still not correctly
   handled), but it fixes several broken error messages.

projects/core/src/test/resources/test-rom/spec/modules/cc/internal/syntax/parser_exhaustive_spec.md

@@ -8,7 +8,7 @@
 ```
 
 ```txt
-Unexpected until.
+Unexpected until. Expected a statement.
    |
  1 | break until
    |       ^^^^^
@@ -76,7 +76,7 @@
 ```
 
 ```txt
-Unexpected while.
+Unexpected while. Expected a statement.
    |
  1 | for xyz , xyz while
    |               ^^^^^
@@ -96,6 +96,22 @@
 ```
 
 
+```lua
+for xyz = xyz , xyz , xyz do until
+-- Line 1: 'end' expected near 'until' (program)
+```
+
+```txt
+Unexpected until. Expected end or another statement.
+   |
+ 1 | for xyz = xyz , xyz , xyz do until
+   | ^^^ Block started here.
+   |
+ 1 | for xyz = xyz , xyz , xyz do until
+   |                              ^^^^^ Expected end of block here.
+```
+
+
 ```lua
 for xyz = xyz , xyz , xyz while
 -- Line 1: 'do' expected near 'while' (program)
@@ -290,10 +306,13 @@
 ```
 
 ```txt
-Unexpected until. Expected a statement.
+Unexpected until. Expected end or another statement.
    |
  1 | function xyz ( ) until
-   |                  ^^^^^
+   | ^^^^^^^^ Block started here.
+   |
+ 1 | function xyz ( ) until
+   |                  ^^^^^ Expected end of block here.
 ```
 
 
@@ -303,7 +322,7 @@
 ```
 
 ```txt
-Unexpected while.
+Unexpected while. Expected ( to start function arguments.
    |
  1 | function xyz while
    |              ^^^^^
@@ -316,10 +335,13 @@
 ```
 
 ```txt
-Unexpected until. Expected a statement.
+Unexpected until. Expected end or another statement.
    |
  1 | function ( ) until
-   |              ^^^^^
+   | ^^^^^^^^ Block started here.
+   |
+ 1 | function ( ) until
+   |              ^^^^^ Expected end of block here.
 ```
 
 
@@ -843,7 +865,7 @@
 Unexpected until. Expected end or another statement.
    |
  1 | if xyz then else until
-   | ^^ Block started here.
+   |             ^^^^ Block started here.
    |
  1 | if xyz then else until
    |                  ^^^^^ Expected end of block here.
@@ -943,10 +965,13 @@ # while
 ```
 
 ```txt
-Unexpected until. Expected a statement.
+Unexpected until. Expected end or another statement.
    |
  1 | local function xyz ( ) until
-   |                        ^^^^^
+   | ^^^^^^^^^^^^^^ Block started here.
+   |
+ 1 | local function xyz ( ) until
+   |                        ^^^^^ Expected end of block here.
 ```
 
 

projects/core/src/test/resources/test-rom/spec/modules/cc/internal/syntax/parser_spec.md

@@ -209,6 +209,38 @@ ## Expecting `end`
    |                 ^ Expected end of block here.
 ```
 
+```lua
+if true then
+else
+  print("Hello")
+```
+
+```txt
+Unexpected end of file. Expected end or another statement.
+   |
+ 2 | else
+   | ^^^^ Block started here.
+   |
+ 3 |   print("Hello")
+   |                 ^ Expected end of block here.
+```
+
+```lua
+if true then
+elseif true then
+  print("Hello")
+```
+
+```txt
+Unexpected end of file. Expected end or another statement.
+   |
+ 2 | elseif true then
+   | ^^^^^^ Block started here.
+   |
+ 3 |   print("Hello")
+   |                 ^ Expected end of block here.
+```
+
 ```lua
 while true do
   print("Hello")
@@ -224,6 +256,48 @@ ## Expecting `end`
    |                 ^ Expected end of block here.
 ```
 
+```lua
+local function f()
+```
+
+```txt
+Unexpected end of file. Expected end or another statement.
+   |
+ 1 | local function f()
+   | ^^^^^^^^^^^^^^ Block started here.
+   |
+ 1 | local function f()
+   |                   ^ Expected end of block here.
+```
+
+```lua
+function f()
+```
+
+```txt
+Unexpected end of file. Expected end or another statement.
+   |
+ 1 | function f()
+   | ^^^^^^^^ Block started here.
+   |
+ 1 | function f()
+   |             ^ Expected end of block here.
+```
+
+```lua
+return function()
+```
+
+```txt
+Unexpected end of file. Expected end or another statement.
+   |
+ 1 | return function()
+   |        ^^^^^^^^ Block started here.
+   |
+ 1 | return function()
+   |                  ^ Expected end of block here.
+```
+
 While we typically see these errors at the end of the file, there are some cases
 where it may occur before then:
 
@@ -276,6 +350,7 @@ ## Unexpected `end`
    |
  3 | end
    | ^^^
+Your program contains more ends than needed. Check each block (if, for, function, ...) only has one end.
 ```
 
 ```lua
@@ -291,4 +366,5 @@ ## Unexpected `end`
    |
  4 |   end
    |   ^^^
+Your program contains more ends than needed. Check each block (if, for, function, ...) only has one end.
 ```