Doing some tests

DialogueManagementScript.sln

@@ -0,0 +1,31 @@
+
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio Version 16
+VisualStudioVersion = 16.0.29911.84
+MinimumVisualStudioVersion = 10.0.40219.1
+Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "DialogueManagementScript", "DialogueManagementScript\DialogueManagementScript.vcxproj", "{709C242E-2FB4-462A-88F5-009D903C463F}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|x64 = Debug|x64
+		Debug|x86 = Debug|x86
+		Release|x64 = Release|x64
+		Release|x86 = Release|x86
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{709C242E-2FB4-462A-88F5-009D903C463F}.Debug|x64.ActiveCfg = Debug|x64
+		{709C242E-2FB4-462A-88F5-009D903C463F}.Debug|x64.Build.0 = Debug|x64
+		{709C242E-2FB4-462A-88F5-009D903C463F}.Debug|x86.ActiveCfg = Debug|Win32
+		{709C242E-2FB4-462A-88F5-009D903C463F}.Debug|x86.Build.0 = Debug|Win32
+		{709C242E-2FB4-462A-88F5-009D903C463F}.Release|x64.ActiveCfg = Release|x64
+		{709C242E-2FB4-462A-88F5-009D903C463F}.Release|x64.Build.0 = Release|x64
+		{709C242E-2FB4-462A-88F5-009D903C463F}.Release|x86.ActiveCfg = Release|Win32
+		{709C242E-2FB4-462A-88F5-009D903C463F}.Release|x86.Build.0 = Release|Win32
+	EndGlobalSection
+	GlobalSection(SolutionProperties) = preSolution
+		HideSolutionNode = FALSE
+	EndGlobalSection
+	GlobalSection(ExtensibilityGlobals) = postSolution
+		SolutionGuid = {3F3B7427-4F15-495C-8609-9A4FB78D9127}
+	EndGlobalSection
+EndGlobal

DialogueManagementScript/DialogueManagementScript.cpp

@@ -0,0 +1,20 @@
+// DialogueManagementScript.cpp : This file contains the 'main' function. Program execution begins and ends there.
+//
+
+#include <iostream>
+
+int main()
+{
+    std::cout << "Hello World!\n";
+}
+
+// Run program: Ctrl + F5 or Debug > Start Without Debugging menu
+// Debug program: F5 or Debug > Start Debugging menu
+
+// Tips for Getting Started: 
+//   1. Use the Solution Explorer window to add/manage files
+//   2. Use the Team Explorer window to connect to source control
+//   3. Use the Output window to see build output and other messages
+//   4. Use the Error List window to view errors
+//   5. Go to Project > Add New Item to create new code files, or Project > Add Existing Item to add existing code files to the project
+//   6. In the future, to open this project again, go to File > Open > Project and select the .sln file

DialogueManagementScript/DialogueManagementScript.vcxproj

@@ -0,0 +1,159 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <ItemGroup Label="ProjectConfigurations">
+    <ProjectConfiguration Include="Debug|Win32">
+      <Configuration>Debug</Configuration>
+      <Platform>Win32</Platform>
+    </ProjectConfiguration>
+    <ProjectConfiguration Include="Release|Win32">
+      <Configuration>Release</Configuration>
+      <Platform>Win32</Platform>
+    </ProjectConfiguration>
+    <ProjectConfiguration Include="Debug|x64">
+      <Configuration>Debug</Configuration>
+      <Platform>x64</Platform>
+    </ProjectConfiguration>
+    <ProjectConfiguration Include="Release|x64">
+      <Configuration>Release</Configuration>
+      <Platform>x64</Platform>
+    </ProjectConfiguration>
+  </ItemGroup>
+  <PropertyGroup Label="Globals">
+    <VCProjectVersion>16.0</VCProjectVersion>
+    <ProjectGuid>{709C242E-2FB4-462A-88F5-009D903C463F}</ProjectGuid>
+    <Keyword>Win32Proj</Keyword>
+    <RootNamespace>DialogueManagementScript</RootNamespace>
+    <WindowsTargetPlatformVersion>10.0</WindowsTargetPlatformVersion>
+  </PropertyGroup>
+  <Import Project="$(VCTargetsPath)\Microsoft.Cpp.Default.props" />
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'" Label="Configuration">
+    <ConfigurationType>Application</ConfigurationType>
+    <UseDebugLibraries>true</UseDebugLibraries>
+    <PlatformToolset>v142</PlatformToolset>
+    <CharacterSet>Unicode</CharacterSet>
+  </PropertyGroup>
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Release|Win32'" Label="Configuration">
+    <ConfigurationType>Application</ConfigurationType>
+    <UseDebugLibraries>false</UseDebugLibraries>
+    <PlatformToolset>v142</PlatformToolset>
+    <WholeProgramOptimization>true</WholeProgramOptimization>
+    <CharacterSet>Unicode</CharacterSet>
+  </PropertyGroup>
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|x64'" Label="Configuration">
+    <ConfigurationType>Application</ConfigurationType>
+    <UseDebugLibraries>true</UseDebugLibraries>
+    <PlatformToolset>v142</PlatformToolset>
+    <CharacterSet>Unicode</CharacterSet>
+  </PropertyGroup>
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Release|x64'" Label="Configuration">
+    <ConfigurationType>Application</ConfigurationType>
+    <UseDebugLibraries>false</UseDebugLibraries>
+    <PlatformToolset>v142</PlatformToolset>
+    <WholeProgramOptimization>true</WholeProgramOptimization>
+    <CharacterSet>Unicode</CharacterSet>
+  </PropertyGroup>
+  <Import Project="$(VCTargetsPath)\Microsoft.Cpp.props" />
+  <ImportGroup Label="ExtensionSettings">
+  </ImportGroup>
+  <ImportGroup Label="Shared">
+  </ImportGroup>
+  <ImportGroup Label="PropertySheets" Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'">
+    <Import Project="$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props" Condition="exists('$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props')" Label="LocalAppDataPlatform" />
+  </ImportGroup>
+  <ImportGroup Label="PropertySheets" Condition="'$(Configuration)|$(Platform)'=='Release|Win32'">
+    <Import Project="$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props" Condition="exists('$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props')" Label="LocalAppDataPlatform" />
+  </ImportGroup>
+  <ImportGroup Label="PropertySheets" Condition="'$(Configuration)|$(Platform)'=='Debug|x64'">
+    <Import Project="$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props" Condition="exists('$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props')" Label="LocalAppDataPlatform" />
+  </ImportGroup>
+  <ImportGroup Label="PropertySheets" Condition="'$(Configuration)|$(Platform)'=='Release|x64'">
+    <Import Project="$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props" Condition="exists('$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props')" Label="LocalAppDataPlatform" />
+  </ImportGroup>
+  <PropertyGroup Label="UserMacros" />
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'">
+    <LinkIncremental>true</LinkIncremental>
+  </PropertyGroup>
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|x64'">
+    <LinkIncremental>true</LinkIncremental>
+  </PropertyGroup>
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Release|Win32'">
+    <LinkIncremental>false</LinkIncremental>
+  </PropertyGroup>
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Release|x64'">
+    <LinkIncremental>false</LinkIncremental>
+  </PropertyGroup>
+  <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'">
+    <ClCompile>
+      <PrecompiledHeader>
+      </PrecompiledHeader>
+      <WarningLevel>Level3</WarningLevel>
+      <SDLCheck>true</SDLCheck>
+      <PreprocessorDefinitions>WIN32;_DEBUG;_CONSOLE;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <ConformanceMode>true</ConformanceMode>
+    </ClCompile>
+    <Link>
+      <SubSystem>Console</SubSystem>
+      <GenerateDebugInformation>true</GenerateDebugInformation>
+    </Link>
+  </ItemDefinitionGroup>
+  <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Debug|x64'">
+    <ClCompile>
+      <PrecompiledHeader>
+      </PrecompiledHeader>
+      <WarningLevel>Level3</WarningLevel>
+      <SDLCheck>true</SDLCheck>
+      <PreprocessorDefinitions>_DEBUG;_CONSOLE;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <ConformanceMode>true</ConformanceMode>
+    </ClCompile>
+    <Link>
+      <SubSystem>Console</SubSystem>
+      <GenerateDebugInformation>true</GenerateDebugInformation>
+    </Link>
+  </ItemDefinitionGroup>
+  <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Release|Win32'">
+    <ClCompile>
+      <PrecompiledHeader>
+      </PrecompiledHeader>
+      <WarningLevel>Level3</WarningLevel>
+      <FunctionLevelLinking>true</FunctionLevelLinking>
+      <IntrinsicFunctions>true</IntrinsicFunctions>
+      <SDLCheck>true</SDLCheck>
+      <PreprocessorDefinitions>WIN32;NDEBUG;_CONSOLE;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <ConformanceMode>true</ConformanceMode>
+    </ClCompile>
+    <Link>
+      <SubSystem>Console</SubSystem>
+      <EnableCOMDATFolding>true</EnableCOMDATFolding>
+      <OptimizeReferences>true</OptimizeReferences>
+      <GenerateDebugInformation>true</GenerateDebugInformation>
+    </Link>
+  </ItemDefinitionGroup>
+  <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Release|x64'">
+    <ClCompile>
+      <PrecompiledHeader>
+      </PrecompiledHeader>
+      <WarningLevel>Level3</WarningLevel>
+      <FunctionLevelLinking>true</FunctionLevelLinking>
+      <IntrinsicFunctions>true</IntrinsicFunctions>
+      <SDLCheck>true</SDLCheck>
+      <PreprocessorDefinitions>NDEBUG;_CONSOLE;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <ConformanceMode>true</ConformanceMode>
+    </ClCompile>
+    <Link>
+      <SubSystem>Console</SubSystem>
+      <EnableCOMDATFolding>true</EnableCOMDATFolding>
+      <OptimizeReferences>true</OptimizeReferences>
+      <GenerateDebugInformation>true</GenerateDebugInformation>
+    </Link>
+  </ItemDefinitionGroup>
+  <ItemGroup>
+    <ClCompile Include="DialogueManagementScript.cpp" />
+    <ClCompile Include="Token.cpp" />
+  </ItemGroup>
+  <ItemGroup>
+    <ClInclude Include="Token.h" />
+  </ItemGroup>
+  <Import Project="$(VCTargetsPath)\Microsoft.Cpp.targets" />
+  <ImportGroup Label="ExtensionTargets">
+  </ImportGroup>
+</Project>

DialogueManagementScript/DialogueManagementScript.vcxproj.filters

@@ -0,0 +1,30 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <ItemGroup>
+    <Filter Include="Source Files">
+      <UniqueIdentifier>{4FC737F1-C7A5-4376-A066-2A32D752A2FF}</UniqueIdentifier>
+      <Extensions>cpp;c;cc;cxx;c++;def;odl;idl;hpj;bat;asm;asmx</Extensions>
+    </Filter>
+    <Filter Include="Header Files">
+      <UniqueIdentifier>{93995380-89BD-4b04-88EB-625FBE52EBFB}</UniqueIdentifier>
+      <Extensions>h;hh;hpp;hxx;h++;hm;inl;inc;ipp;xsd</Extensions>
+    </Filter>
+    <Filter Include="Resource Files">
+      <UniqueIdentifier>{67DA6AB6-F800-4c08-8B7A-83BB121AAD01}</UniqueIdentifier>
+      <Extensions>rc;ico;cur;bmp;dlg;rc2;rct;bin;rgs;gif;jpg;jpeg;jpe;resx;tiff;tif;png;wav;mfcribbon-ms</Extensions>
+    </Filter>
+  </ItemGroup>
+  <ItemGroup>
+    <ClCompile Include="DialogueManagementScript.cpp">
+      <Filter>Source Files</Filter>
+    </ClCompile>
+    <ClCompile Include="Token.cpp">
+      <Filter>Source Files</Filter>
+    </ClCompile>
+  </ItemGroup>
+  <ItemGroup>
+    <ClInclude Include="Token.h">
+      <Filter>Header Files</Filter>
+    </ClInclude>
+  </ItemGroup>
+</Project>

DialogueManagementScript/DialogueManagementScript.vcxproj.user

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project ToolsVersion="Current" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <PropertyGroup />
+</Project>

DialogueManagementScript/Token.cpp

@@ -0,0 +1 @@
+#include "Token.h"

DialogueManagementScript/Token.h

@@ -0,0 +1,5 @@
+#pragma once
+class Token
+{
+};
+

compiler.lua

@@ -1,21 +1,30 @@
---~ t = debug.getmetatable ("")
---~ t.__index = function(self,k)
---~ 	if type(k)=="number" then
---~ 		return string.sub(self,k,k)
---~ 	end
---~ end
+function tprint (tbl, indent)
+  if not indent then indent = 0 end
+  for k, v in pairs(tbl) do
+    formatting = string.rep("  ", indent) .. k .. ": "
+    if type(v) == "table" then
+      print(formatting)
+      tprint(v, indent+1)
+    else
+      print(formatting .. tostring(v))
+    end
+  end
+end
+
+
 Token = {}
 Token.__index = Token
-local INTEGER, PLUS, EOF, MINUS, MUL, DIV, LPAREN, RPAREN = "INT","+","EOF", "-", "*", "/", "(", ")"
+local INTEGER, PLUS, EOF, MINUS, MUL, DIV, LPAREN, RPAREN, BEGIN, END, DOT, ID, ASSIGN, SEMI = "INT","+","EOF", "-", "*", "/", "(", ")", "BEGIN", "END", "DOT", "ID", "ASSIGN", "SEMI"
 function Token.__tostring(self)
 	return string.format("Token(%s, %s)",self.type,self.value)
 end
 function Token:new(tp,val)
 	local c = {}
 	setmetatable(c,self)
+	c.Type = 'Token'
 	c.type = tp
 	c.value = val
-	print("Token:"..tp)
+	--print("Token:"..tp)
 	return c
 end
 
@@ -24,22 +33,45 @@ Lexer.__index = Lexer
 function Lexer:new(text)
 	local c = {}
 	setmetatable(c,self)
-	self.text = text
-	self.pos = 1
-	self.current_char = self.text:sub(1,1)
-	self.stop = false
+	c.Type = 'Lexer'
+	c.text = text
+	c.pos = 1
+	c.current_char = c.text:sub(1,1)
+	c.stop = false
 	return c
 end
 function Lexer:advance()
 	self.pos = self.pos + 1
 	if self.pos > #self.text then
 		self.current_char = false
+		return
 	else
 		self.current_char = self.text:sub(self.pos,self.pos)
 	end
 end
-function Lexer:error()
-	error("Invalid character")
+local RESERVED_KEYWORDS = {
+	BEGIN = Token:new('BEGIN',BEGIN),
+	END = Token:new('END',END)
+}
+function Lexer:_id()
+	local result = ''
+	while self.current_char and self.current_char:match("%w") do
+		result = result .. self.current_char
+		self:advance()
+	end
+	local token = RESERVED_KEYWORDS[result] or Token:new(ID,result)
+	return token
+end
+function Lexer:peek()
+	local peek_pos = self.pos + 1
+	if peek_pos > #self.text then
+		return
+	else
+		return self.text:sub(peek_pos,peek_pos)
+	end
+end
+function Lexer:error(err)
+	error(err)
 end
 function Lexer:skip_whitespace()
 	while self.current_char and self.current_char:match("%s") do
@@ -57,110 +89,392 @@ end
 function Lexer:get_next_token()
 	while self.current_char do
 		::continue::
-		if self.current_char:match("%s") then
+		if self.current_char and self.current_char:match("%s") then
 			self:skip_whitespace()
 			goto continue
 		end
-		if self.current_char:match("%d") then
+		if self.current_char and self.current_char:match("%d") then
 			return Token:new(INTEGER,self:integer())
 		end
-		if self.current_char == "+" then
+		if self.current_char and self.current_char == "+" then
 			self:advance()
 			return Token:new(PLUS,"+")
 		end
-		if self.current_char == "-" then--55+77
+		if self.current_char and self.current_char == "-" then--55+77
 			self:advance()
 			return Token:new(MINUS,"-")
 		end
-		if self.current_char == "*" then
+		if self.current_char and self.current_char == "*" then
 			self:advance()
 			return Token:new(MUL,"*")
 		end
-		if self.current_char == "/" then
+		if self.current_char and self.current_char == "/" then
 			self:advance()
 			return Token:new(DIV,"/")
 		end
-		if self.current_char == "(" then
+		if self.current_char and self.current_char == "(" then
 			self:advance()
 			return Token:new(LPAREN,"(")
 		end
-		if self.current_char == ")" then
+		if self.current_char and self.current_char == ")" then
 			self:advance()
 			return Token:new(RPAREN,")")
 		end
-		self:error("Invalid Symbol!")
+		if self.current_char and self.current_char:match("%w") then
+			return self:_id()
 		end
-	return Token:new(EOF, nil)
+		if self.current_char and self.current_char == ":" and self:peek() == "=" then
+			self:advance()
+			self:advance()
+			return Token:new(ASSIGN, ":=")
+		end
+		if self.current_char and self.current_char == ";" then
+			self:advance()
+			return Token:new(SEMI, ';')
+		end
+		if self.current_char and self.current_char == "." then
+			self:advance()
+			return Token:new(DOT,".")
+		end
+		if self.current_char == false then
+			return Token:new(EOF, "EOF")
+		end
+		self:error("Invalid Symbol! "..tostring(self.current_char))
+	end
+	return Token:new(EOF, "EOF")
 end
 
-Interpreter = {}
-Interpreter.__index = Interpreter
-function Interpreter:new(lexer)
+AST = {}
+AST.__index = AST
+function AST:new()
 	local c = {}
 	setmetatable(c,self)
-	c.lexer = lexer
-	c.current_token = c.lexer:get_next_token()
+	c.Type = 'AST'
 	return c
 end
-function Interpreter:error()
+
+Compound = {}
+Compound.__index = AST
+function Compound:new()
+	local c = {}
+	setmetatable(c,self)
+	c.Type = 'Compound'
+	c.children = {}
+	return c
+end
+
+Assign = {}
+Assign.__index = AST
+function Assign:new(left,op,right)
+	local c = {}
+	setmetatable(c,self)
+	c.Type = 'Assign'
+	c.left = left
+	c.op = op
+	c.token = op
+	c.right = right
+	return c
+end
+
+Var = {}
+Var.__index = AST
+function Var:new(token)
+	local c = {}
+	setmetatable(c,self)
+	c.Type = "Var"
+	c.token = token
+	c.value = token.value
+	return c
+end
+
+NoOp = {}
+NoOp.__index = AST
+function NoOp:new()
+	local c = {}
+	setmetatable(c,self)
+	c.Type = "NoOp"
+	return c
+end
+
+UnaryOp = {}
+UnaryOp.__index = AST
+function UnaryOp:new(op,expr)
+	local c = {}
+	setmetatable(c,self)
+	c.Type = 'UnaryOp'
+	c.token = op
+	c.op = op
+	c.expr = expr
+	return c
+end
+
+BinOp = {}
+BinOp.__index = AST
+function BinOp:new(left, op, right)
+	local c = {}
+	setmetatable(c,self)
+	c.Type = 'BinOp'
+	c.left = left
+	c.token = op
+	c.op = op
+	c.right = right
+	return c
+end
+
+Num = {}
+Num.__index = AST
+function Num:new(token)
+	local c = {}
+	setmetatable(c,self)
+	c.Type = 'Num'
+	c.token = token
+	c.value = token.value
+	return c
+end
+
+Parser = {}
+Parser.__index = Parser
+function Parser:new(lexer)
+	local c = {}
+	setmetatable(c,self)
+	c.Type = 'Parser'
+	c.lexer = lexer
+	c.current_token = lexer:get_next_token()
+	return c
+end
+function Parser:error()
 	error('Error Invalid Syntax')
 end
-function Interpreter:eat(token_type)
+function Parser:eat(token_type)
 	if self.current_token.type == token_type then
 		self.current_token = self.lexer:get_next_token()
 	else
 		self:error()
 	end
 end
-function Interpreter:factor()
+function Parser:program()
+	local node = self:compound_statement()
+	self:eat(DOT)
+	return node
+end
+function Parser:compound_statement()
+	self:eat(BEGIN)
+	local nodes = self:statement_list()
+	self:eat(END)
+
+	local root = Compound:new()
+	for _,node in pairs(nodes) do
+		table.insert(root.children,node)
+	end
+
+	return root
+end
+function Parser:statement_list()
+	local node = self:statement()
+
+	local results = {node}
+
+	while self.current_token.type == SEMI do
+		self:eat(SEMI)
+		table.insert(results,self:statement())
+	end
+	
+	if self.current_token.type == ID then
+		self:error()
+	end
+
+	return results
+end
+function Parser:statement()
+	local node
+	if self.current_token.type == BEGIN then
+		node = self:compound_statement()
+	elseif self.current_token.type == ID then
+		node = self:assignment_statement()
+	else
+		node = self:empty()
+	end
+	return node
+end
+function Parser:assignment_statement()
+	local left = self:variable()
 	local token = self.current_token
-	if token.type == INTEGER then
+	self:eat(ASSIGN)
+	local right = self:expr()
+	local node = Assign:new(left, token, right)
+	return node
+end
+function Parser:variable()
+	local node = Var:new(self.current_token)
+	self:eat(ID)
+	return node
+end
+function Parser:empty()
+	return NoOp:new()
+end
+function Parser:factor()
+	local token = self.current_token
+	local node
+	if token.type == PLUS then
+		self:eat(PLUS)
+		node = UnaryOp:new(token,self:factor())
+		return node
+	elseif token.type == MINUS then
+		self:eat(MINUS)
+		node = UnaryOp:new(token,self:factor())
+		return node
+	elseif token.type == INTEGER then
 		self:eat(INTEGER)
-		return token.value
+		return Num:new(token)
 	elseif token.type == LPAREN then
 		self:eat(LPAREN)
-		local result = self:expr()
+		local node = self:expr()
 		self:eat(RPAREN)
-		return result
+		return node
+	else
+		node = self:variable()
+		return node
 	end
 end
-function Interpreter:term()
-	local result = self:factor()
+function Parser:term()
+	local node = self:factor()
 	local token
 	while self.current_token.type == MUL or self.current_token.type == DIV do
 		token = self.current_token
 		if token.type == MUL then
 			self:eat(MUL)
-			result = result * self:factor()
 		elseif token.type == DIV then
 			self:eat(DIV)
-			result = result / self:factor()
 		end
+		node = BinOp:new(node,token,self:factor())
 	end
-	return result
+
+	return node
 end
-function Interpreter:expr()
-	local result = self:term()
+function Parser:expr()
+	local node = self:term()
 	local token
 	while self.current_token.type == PLUS or self.current_token.type == MINUS do
 		token = self.current_token
 		if token.type == PLUS then
 			self:eat(PLUS)
-			result = result + self:term()
 		elseif token.type == MINUS then
 			self:eat(MINUS)
-			result = result - self:term()
+		end
+		node = BinOp:new(node,token,self:term())
+	end
+
+	return node
+end
+function Parser:parse()
+	local node = self:program()
+	if self.current_token.type ~= EOF then
+		self:error()
+	end
+	return node
+end
+
+NodeVisitor = {}
+NodeVisitor.__index = NodeVisitor
+function NodeVisitor:new(node)
+	local c = {}
+	setmetatable(c,self)
+	c.Type = 'NodeVisitor'
+	return c
+end
+function NodeVisitor:visit(node)
+	local visitor = self["visit_".. node.Type] or self.generic_visit
+	return visitor(self,node)
+end
+function NodeVisitor:generic_visit(node)
+	error("No visit_"..node.Type.." method")
+end
+
+Interpreter = {}
+Interpreter.__index = NodeVisitor
+function Interpreter:new(parser)
+	local c = {}
+	setmetatable(c,self)
+	c.Type = 'Interpreter'
+	c.parser = parser
+	c.GLOBAL_SCOPE = {}
+	function c:visit_Compound(node)
+		for _,child in pairs(node.children) do
+			self:visit(child)
 		end
 	end
-	return result
+	function c:visit_Assign(node)
+		local var_name = node.left.value
+		self.GLOBAL_SCOPE[var_name] = self:visit(node.right)
 	end
-while true do
-	io.write("calc> ")
-	local text = io.read()
-	if text then
-		l = Lexer:new(text)
-		i = Interpreter:new(l)
-		result = i:expr()
-		print(result)
+	function c:visit_Var(node)
+		local var_name = node.value
+		local val = self.GLOBAL_SCOPE[var_name]
+		if val then
+			return val
+		else
+			error("NameError:"..var_name)
 		end
 	end
+	function c:visit_NoOp(node)
+		return
+	end
+	function c:visit_BinOp(node)
+		if node.op.type == PLUS then
+			return self:visit(node.left) + self:visit(node.right)
+		elseif node.op.type == MINUS then
+			return self:visit(node.left) - self:visit(node.right)
+		elseif node.op.type == MUL then
+			return self:visit(node.left) * self:visit(node.right)
+		elseif node.op.type == DIV then
+			return self:visit(node.left) / self:visit(node.right)
+		end
+	end
+	function c:visit_UnaryOp(node)
+		local op = node.op.type
+		if op == PLUS then
+			return self:visit(node.expr)
+		elseif op == MINUS then
+			return -self:visit(node.expr)
+		end
+	end
+	function c:visit_Num(node)
+		return node.value
+	end
+	function c:interpret()
+		local tree = self.parser:parse()
+		return self:visit(tree)
+	end
+	return c
+end
+
+text = [[
+BEGIN
+    BEGIN
+        number := 2;
+        a := number;
+        b := 10 * a + 10 * number / 4;
+        c := a - - b
+    END;
+    x := 11;
+END.
+]]
+lexer = Lexer:new(text)
+parser = Parser:new(lexer)
+interpreter = Interpreter:new(parser)
+tprint(parser)
+-- interpreter:interpret()
+-- for i,v in pairs(interpreter.GLOBAL_SCOPE) do
+-- 	print(i,v)
+-- end
+-- while true do
+-- 	io.write("calc> ")
+-- 	local text = io.read()
+-- 	if text then
+-- 		lexer = Lexer:new(text)
+-- 		parser = Parser:new(lexer)
+-- 		interpreter = Interpreter:new(parser)
+-- 		result = interpreter:interpret()
+-- 		print(result)
+-- 	end
+-- end

compiler2.lua

@@ -0,0 +1,28 @@
+file = io.open("test.dms","rb")
+content = file:read("*a")
+line_num = 0
+function string:trim()
+    return (self:gsub("^%s*(.-)%s*$", "%1"))
+end
+local choice
+for line in content:gmatch("(.-)\n") do
+    line_num = line_num + 1
+    line = line:trim()
+    ::back::
+    if line:match("^%[[_:,%w%(%)]+%]") then
+        print(line_num,"BLOCK_START",line)
+    elseif line:match("choice%s+\".+\"%s*:") then
+        print(line_num,"CHOICE_BLOCK",line)
+        choice = true
+    elseif choice then
+        choice = false
+        if line:match("\".*\"%s*[_:,%w%(%)]+%(.*%)") then
+            print(line_num,"CHOICE_OPTION",line)
+            choice = true
+        else
+            goto back
+        end
+    else
+        print(line_num,line)
+    end
+end

test.dms

@@ -10,8 +10,11 @@ LOADFILE
 	Ryan: "Hello how are you doing?"
 	Bob: "I'm good you?"
 	
-	
 	list = {1,2,3,true,false, {1,2,3}}
+	a = list[1]
+	list[1] = "Hello"
+	
+	::label::
 	
 	choice "Pick one:":
 		"first" func()