From 3d1865de59bebfa70041ddf538721a934c1a39ba Mon Sep 17 00:00:00 2001
From: Pasha Bibko <156938226+PashaBibko@users.noreply.github.com>
Date: Mon, 11 Aug 2025 17:46:58 +0100
Subject: [PATCH] Finished parser functions

Time for fixing bugs YAYYYYYYYYYYY
---
 LXC/LXC.cpp           |   2 +-
 examples/Basic.lx     |   6 +++
 parser/src/Parser.cpp | 102 ++++++++++++++++++++++++++++++++++++++----
 3 files changed, 100 insertions(+), 10 deletions(-)
 create mode 100644 examples/Basic.lx

diff --git a/LXC/LXC.cpp b/LXC/LXC.cpp
index 8164298..61ac09f 100644
--- a/LXC/LXC.cpp
+++ b/LXC/LXC.cpp
@@ -9,7 +9,7 @@ int main(int argc, char** argv)
     using namespace PashaBibko::LXC;
     using namespace PashaBibko;
 
-    std::filesystem::path src = "examples/Fib.lx";
+    std::filesystem::path src = "examples/Basic.lx";
 
     // Reads the given file to a string //
     Util::ReturnVal fileContents = Util::ReadFile(src);
diff --git a/examples/Basic.lx b/examples/Basic.lx
new file mode 100644
index 0000000..334383e
--- /dev/null
+++ b/examples/Basic.lx
@@ -0,0 +1,6 @@
+func<int> main()
+{
+	int: res = 5 + 34
+
+	return res
+}
diff --git a/parser/src/Parser.cpp b/parser/src/Parser.cpp
index 23aae2a..1c77059 100644
--- a/parser/src/Parser.cpp
+++ b/parser/src/Parser.cpp
@@ -109,7 +109,7 @@ namespace PashaBibko::LXC::Parser
     static Util::ReturnVal<AST::NodeValuePtr, ParserError> ParseFunctionCall(ParserContext& ctx)
     {
         // Checks if the upcoming pattern matches a function signature: [Identifier(function name), OpenBracket(Start of params)] //
-        if (!ctx.Expect(std::array{ Lexer::Token::Identifier, Lexer::Token::OpenParen }))
+        if (ctx.Expect(std::array{ Lexer::Token::Identifier, Lexer::Token::OpenParen }))
         {
             // Captures the function name and advances over it and the start paren //
             const Lexer::Token* functionNameToken = ctx.At();
@@ -130,7 +130,10 @@ namespace PashaBibko::LXC::Parser
                 ctx.Advance();
 
                 // Adds the current argument to the ValueList //
-                arguments.push_back(std::move(ParsePrimary(ctx).Result()));
+                Util::ReturnVal arg = ParsePrimary(ctx);
+                if (arg.Failed())
+                    return Util::FunctionFail<ParserError>(arg.Error<Util::Result::Force>());
+                arguments.push_back(std::move(arg.Result<Util::Result::Force>()));
             }
         }
 
@@ -138,18 +141,99 @@ namespace PashaBibko::LXC::Parser
         return ParsePrimary(ctx);
     }
 
-    static Util::ReturnVal<AST::NodePtr, ParserError> ParseOperation(ParserContext& ctx)
-    {}
+    static Util::ReturnVal<AST::NodeValuePtr, ParserError> ParseOperation(ParserContext& ctx)
+    {
+        // Parses the left hand side of the operation //
+        Util::ReturnVal lhs = ParseFunctionCall(ctx);
+        if (lhs.Failed())
+            return Util::FunctionFail<ParserError>(lhs.Error<Util::Result::Force>());
+
+        // Checks if the left hand side was part of an operation //
+        const Lexer::Token* operand = ctx.At();
+        if (operand != nullptr && Lexer::Token::IsTypeClass<Lexer::TokenClass::Operator>(operand->type))
+        {
+            // Iterates over the operand and parses the right hand side of the operation //
+            ctx.Advance();
+            Util::ReturnVal rhs = ParseOperation(ctx);
+            if (rhs.Failed())
+                return Util::FunctionFail<ParserError>(rhs.Error<Util::Result::Force>());
+
+            // Else the sides can be returned as an operation //
+            return Internal::CreateNodeV<AST::Operation>(lhs.Result<Util::Result::Force>(), operand->type, rhs.Result<Util::Result::Force>());
+        }
+
+        // If not returns the left node on its own //
+        return std::move(lhs.Result<Util::Result::Force>());
+    }
 
     static Util::ReturnVal<AST::NodePtr, ParserError> ParseReturn(ParserContext& ctx)
-    {}
+    {
+        // Checks if it is at a return statement //
+        const Lexer::Token* at = ctx.At();
+        if (at == nullptr)
+            return Util::FunctionFail<ParserError>(); // <- TODO: Make an actual error
+
+        if (at->type == Lexer::Token::Return)
+        {
+            // Iterates over the return token and parses the value to be returned //
+            ctx.Advance();
+            Util::ReturnVal returnVal = ParseOperation(ctx);
+            if (returnVal.Failed())
+                return Util::FunctionFail<ParserError>(returnVal.Error<Util::Result::Force>());
+
+            return Internal::CreateNode<AST::ReturnStatement>(returnVal.Result<Util::Result::Force>());
+        }
+
+        // Else traverses down the call stack (has to be upcasted) //
+        Util::ReturnVal value = ParseOperation(ctx);
+        if (value.Failed())
+            return Util::FunctionFail<ParserError>(value.Error());
+
+        AST::NodePtr upcast = std::move(value.Result<Util::Result::Force>());
+        return upcast;
+    }
 
     static Util::ReturnVal<AST::NodePtr, ParserError> ParseVarDeclaration(ParserContext& ctx)
-    {}
-
-    static Util::ReturnVal<AST::NodePtr, ParserError> Parse(ParserContext& ctx)
     {
-        return (AST::NodePtr)nullptr;
+        // Checks for the pattern of a variable declaration //
+        if (ctx.Expect(std::array{ Lexer::Token::Identifier, Lexer::Token::Colon }))
+        {
+            // Can safely advance over the pattern (types are not checked/stored yet) //
+            ctx.Advance(2);
+
+            const Lexer::Token* varName = ctx.At();
+            std::string varNameStr = varName->Str();
+            if (varName == nullptr)
+                return Util::FunctionFail<ParserError>(); // <- TODO: Make an actual error
+
+            if (varName->type != Lexer::Token::Identifier)
+                return Util::FunctionFail<ParserError>(); // <- TODO: Make an actual error
+
+            // Checks for a default value for the variable //
+            const Lexer::Token* varAssign = ctx.Peek();
+            if (varAssign == nullptr)
+                return Internal::CreateNode<AST::VarDeclaration>(varNameStr);
+
+            if (varAssign->type != Lexer::Token::Assign)
+                return Internal::CreateNode<AST::VarDeclaration>(varNameStr);
+
+            // Creates a node with the default value of the variable //
+            ctx.Advance();
+            Util::ReturnVal defaultVal = ParseOperation(ctx);
+            if (defaultVal.Failed())
+                return Util::FunctionFail<ParserError>(defaultVal.Error<Util::Result::Force>());
+
+            return Internal::CreateNode<AST::VarDeclaration>(varNameStr, defaultVal.Result<Util::Result::Force>());
+        }
+
+        // Else traverses up the call stack //
+        return ParseReturn(ctx);
+    }
+
+    static inline Util::ReturnVal<AST::NodePtr, ParserError> Parse(ParserContext& ctx)
+    {
+        // Alias for the top of the call stack //
+        return ParseVarDeclaration(ctx);
     }
 
     static Util::ReturnVal<FunctionAST, ParserError> ParseFunction(ParserContext& ctx)