From 90a958a30ba1b9d4bc46412c71a1d069cfa512e1 Mon Sep 17 00:00:00 2001
From: Pasha Bibko <156938226+PashaBibko@users.noreply.github.com>
Date: Thu, 24 Jul 2025 17:49:23 +0100
Subject: [PATCH] Started implementation of parser

---
 Common/modules/Result.h |  9 ++++-
 parser/inc/Parser.h     |  8 ++++
 parser/src/Parser.cpp   | 85 ++++++++++++++++++++++++++++++++++++++---
 3 files changed, 94 insertions(+), 8 deletions(-)

diff --git a/Common/modules/Result.h b/Common/modules/Result.h
index 7b88780..69643ed 100644
--- a/Common/modules/Result.h
+++ b/Common/modules/Result.h
@@ -7,7 +7,7 @@
 
 namespace LXC::Util
 {
-    // Util function to stop/ the program //
+    // Util function to stop the program //
     inline void Stop()
     {
         // Only checks for a debugger when compiled in Debug mode //
@@ -64,10 +64,15 @@ namespace LXC::Util
     {
         public:
             // Constructor for function sucess //
-            ReturnVal(ResultType result)
+            ReturnVal(const ResultType& result)
                 : m_Result(result), m_FunctionFailed(false)
             {}
 
+            // Move constructor (for large objects) //
+            ReturnVal(ResultType&& result)
+                : m_Result(std::move(result)), m_FunctionFailed(false)
+            {}
+
             // Constructor for function fail //
             ReturnVal(FunctionFail<ErrorType> error)
                 : m_Error(error.error), m_FunctionFailed(true)
diff --git a/parser/inc/Parser.h b/parser/inc/Parser.h
index 7569001..5598fd7 100644
--- a/parser/inc/Parser.h
+++ b/parser/inc/Parser.h
@@ -11,6 +11,14 @@ namespace LXC::Parser
 
     struct FunctionAST
     {
+        FunctionAST() :
+            name{}, contents{}
+        {}
+
+        FunctionAST(FunctionAST&& other) :
+            name{}, contents{}
+        {}
+
         std::string name;
         AST::SyntaxBranch contents;
     };
diff --git a/parser/src/Parser.cpp b/parser/src/Parser.cpp
index 0913e7b..cb19374 100644
--- a/parser/src/Parser.cpp
+++ b/parser/src/Parser.cpp
@@ -4,13 +4,86 @@
 
 namespace LXC::Parser
 {
-    Util::ReturnVal<std::vector<FunctionAST>, ParserError> TurnTokensIntoAST(const Lexer::LexerOutput& input)
+    class ParserContext final
+    {
+        public:
+            // Sets the information of the context //
+            ParserContext(const Lexer::LexerOutput& inputTokens) :
+                input(inputTokens), length(inputTokens.size()), index(0)
+            {}
+
+            // Returns a pointer to the token x-distance away (default 1) //
+            inline const Lexer::Token* Peek(size_t peekDistance = 1) const
+            {
+                // Checks if at the end of the tokens before fetching to stop errors //
+                size_t peekIndex = index + peekDistance;
+                if (peekIndex >= length)
+                    return nullptr;
+
+                return &input[peekIndex];
+            }
+
+            // Advances x-distance in the tokens (default 1) //
+            inline const Lexer::Token* Next(size_t distance = 1)
+            {
+                // Adds the distance and checks if in bounds to stop read errors //
+                index += distance;
+                if (index >= length)
+                    return nullptr;
+
+                return &input[index];
+            }
+
+            // Is the current index in bounds //
+            inline bool InBounds() const { return index < length; }
+
+            // Output //
+            std::vector<FunctionAST> output;
+
+        private:
+            size_t index;
+
+            const Lexer::LexerOutput& input;
+            const size_t length;
+    };
+
+    static Util::ReturnVal<void*, ParserError> ParseFunction(const ParserContext& ctx)
     {
-        for (const auto& token : input)
-        {
-            Util::PrintLn(token);
-        }
-        
         return Util::FunctionFail<ParserError>();
     }
+
+    Util::ReturnVal<std::vector<FunctionAST>, ParserError> TurnTokensIntoAST(const Lexer::LexerOutput& input)
+    {   
+        // Creates the context of the Parser from the tokens and the output of the function //
+        ParserContext ctx(input);
+
+        // Continues whilst in the bounds of the tokens //
+        while (ctx.InBounds())
+        {
+            // Peeks the next token (guaranteed to not be at the end) //
+            const Lexer::Token* current = ctx.Peek();
+
+            // Switches over the type of the current token to run the correct logic //
+            switch (current->type)
+            {
+                // Only functions are currently supported //
+                case Lexer::Token::FunctionDef:
+                {
+                    // Parses the function and add it to the vector if there are no errors //
+                    Util::ReturnVal func = ParseFunction(ctx);
+                    if (func.Failed())
+                        return Util::FunctionFail<ParserError>(func.Error());
+
+                    break;
+                }
+
+                // The rest return a function-fail //
+                default:
+                    return Util::FunctionFail<ParserError>(); // <- TODO: Make an actual error
+            }
+        }
+
+        // Returns the output as it has gone through all the tokens //
+        return std::move(ctx.output); // Moves instead of copying, (required due to std::unique_ptr<>)
+    }
 }