From e8bcb186e31156cc2fbf27d51b3760d27a6d2669 Mon Sep 17 00:00:00 2001
From: Starfflame <starfflame@derpymail.org>
Date: Mon, 17 May 2021 20:59:46 -0500
Subject: [PATCH] Add instruction pointers

---
 CoreHelpers.tl      |  4 ++++
 DataStructures.tl   | 25 ++++++++++++++++++++---
 ForthInterpreter.tl | 49 ++++++++++++++++++++++++++++++---------------
 3 files changed, 59 insertions(+), 19 deletions(-)

diff --git a/CoreHelpers.tl b/CoreHelpers.tl
index 34c4ba3..89c1767 100644
--- a/CoreHelpers.tl
+++ b/CoreHelpers.tl
@@ -59,5 +59,9 @@ function CoreHelpers.parseToken(state: Environment): string
 	return token
 end
 
+function CoreHelpers.reset(env: Environment)
+	env.instructionPointer.index = 0 -- will get incremented after this instruction
+end
+
 return CoreHelpers
 
diff --git a/DataStructures.tl b/DataStructures.tl
index 1584310..c08c581 100644
--- a/DataStructures.tl
+++ b/DataStructures.tl
@@ -22,11 +22,18 @@ local type DataStructures = record
     new: function(WordInfo, function(Environment), boolean): WordInfo
   end
 
-
+  record Pointer
+    index: number
+    referant: {number: any}
+    deref: function(self: Pointer): any
+    inc: function(self: Pointer)
+    new: function(self: Pointer): Pointer
+  end
 
   record Environment
     dataStacks: {Stack}
     compilerStack: Stack
+    returnStack: Stack
     activeDataStack: Stack
     interrupts: {function(Environment)}
     activeInputStream: InputStream
@@ -36,13 +43,14 @@ local type DataStructures = record
     addDataStack: function(Environment, Stack)
     changeCompilerStack: function(Environment, Stack)
     changeActiveDataStack: function(Environment, number)
-
+    
+    instructionPointer: Pointer
   end
   
 end
 
 local Stack, Environment, Dictionary, WordInfo = DataStructures.Stack, DataStructures.Environment, DataStructures.Dictionary, DataStructures.WordInfo
-
+local Pointer = DataStructures.Pointer
 local wordi_mt = {__index = WordInfo}
 function WordInfo:new(funct: function(Environment, ...: any), imm: boolean): WordInfo
   return setmetatable({func = funct, immediate = imm} as WordInfo, wordi_mt)
@@ -109,6 +117,17 @@ function Dictionary:new(): Dictionary
   return setmetatable({contents = {}} as Dictionary, dict_mt)
 end
 
+function Pointer:deref(): any
+  return self.referant[self.index]
+end
+function Pointer:inc()
+  self.index = self.index + 1
+end
+local pointer_mt = {__index = Pointer}
+function Pointer:new(): Pointer
+  return setmetatable({referant = {}, index = 1} as Pointer, pointer_mt)
+end
+
 return DataStructures
 
 
diff --git a/ForthInterpreter.tl b/ForthInterpreter.tl
index 56228a2..a6c20d0 100644
--- a/ForthInterpreter.tl
+++ b/ForthInterpreter.tl
@@ -4,8 +4,9 @@ local istream = require("InputStream")
 local Stack, Dictionary, WordInfo, Environment = ds.Stack, ds.Dictionary, ds.WordInfo, ds.Environment
 local helpers = require("CoreHelpers")
 local isNumber, skipWhitespace, parseToken = helpers.isNumber, helpers.skipWhitespace, helpers.parseToken
+local reset = helpers.reset
 local machineEnvironment = Environment:new()
-
+local Pointer = ds.Pointer
 function standardInputRefill(): string
 	local input = io.read().."\n"
 	return input
@@ -17,23 +18,39 @@ machineEnvironment.activeInputStream = standardInputStream
 machineEnvironment.activeDataStack = Stack:new()
 table.insert(machineEnvironment.dictionaries, CoreWords)
 
-
-while(true) do
-	skipWhitespace(machineEnvironment)
-	local token: string = parseToken(machineEnvironment)
-	if isNumber(token) then
-		machineEnvironment.activeDataStack:push(tonumber(token))
-	else
-		for i, dictionary in ipairs(machineEnvironment.dictionaries) do
-			local wordinfo = dictionary:lookup(token)
-			if wordinfo then
-				(wordinfo as WordInfo).func(machineEnvironment)
-				goto continue
+function outerInterpreter(env: Environment)
+	while(true) do
+		skipWhitespace(env)
+		local token: string = parseToken(env)
+		if isNumber(token) then
+			env.activeDataStack:push(tonumber(token))
+		else
+			for i, dictionary in ipairs(env.dictionaries) do
+				local wordinfo = dictionary:lookup(token)
+				if wordinfo then
+					(wordinfo as WordInfo).func(env)
+					goto continue
+				end
 			end
+			print(string.format('%q ?', token))
+			::continue::
 		end
-		print(string.format('%q ?', token))
-	  ::continue::
-  end
+	end
 end
 
+function innerInterpreter(env: Environment)
+	while(true) do
+		(env.instructionPointer:deref() as function(Environment))(env)
+		env.instructionPointer:inc()
+	end
+end
 
+local interpreterInstructions = {outerInterpreter, reset}
+local startPointer = Pointer:new()
+startPointer.referant = interpreterInstructions
+startPointer.index = 0
+
+machineEnvironment.instructionPointer = startPointer
+
+
+outerInterpreter(machineEnvironment)