3 files changed, 433 insertions, 10 deletions

diff --git a/crates/sloth/src/parser/ast.rs b/crates/sloth/src/parser/ast.rs
index 45c4d8f..d472269 100644
--- a/crates/sloth/src/parser/ast.rs
+++ b/crates/sloth/src/parser/ast.rs
@@ -1,3 +1,6 @@
+use crate::lexer::{Token, TokenType};
+#[derive(Debug)]
+#[derive(PartialEq)]
 pub enum BinaryOp {
     Add,
     Con,
@@ -22,28 +25,32 @@ pub enum BinaryOp {
     LogAnd,
     LogOr,
 }
-
+#[derive(Debug)]
+#[derive(PartialEq)]
 pub enum UnaryOp {
     Not,
     Neg,
 
     BWComp,
 }
-
+#[derive(Debug)]
+#[derive(PartialEq)]
 pub enum Literal {
     Integer(i128),
     Float(f64),
     Bool(bool),
     Char(char),
     String(String),
-    Regex(String), 
-    List(Vec<Expr>), // TODO: holy shit we forgor empty listys
+    Regex(String),
+    List(Vec<Expr>), // TODO: holy shit we forgor listys
 }
-
+#[derive(Debug)]
+#[derive(PartialEq)]
 pub enum Expr {
+    Grouping(Box<Expr>),
     BinaryOp {
         op: BinaryOp,
-        lhs: Box<Expr>,
+        lhs: Box<Expr>, 
         rhs: Box<Expr>,
     },
     UnaryOp {
@@ -64,7 +71,7 @@ pub struct FuncArgs {
     pub typ: Option<String>,
 }
 
-pub enum Stmt { 
+pub enum Stmt {
     ExprStmt(Expr),
     DefineFunction {
         ident: String,
@@ -83,13 +90,13 @@ pub enum Stmt {
         typ: Option<String>,
     },
     If {
-        expr: Vec<Expr>,
+        expr: Expr,
         body: Vec<Stmt>,
         else_if: Vec<(Expr, Stmt)>,
         els: Option<Box<Stmt>>,
     },
     For {
-        name: Expr,
+        name: String,
         iter: Expr,
         body: Vec<Stmt>,
     },
@@ -97,4 +104,56 @@ pub enum Stmt {
         condition: Expr,
         body: Vec<Stmt>,
     },
-}
\ No newline at end of file
+}
+
+pub struct AstParser<'a> {
+    tokens: Vec<Token<'a>>,
+    index: usize,
+}
+
+/// Implementation containing utilities used by the parsers internal components
+impl<'a> AstParser<'a> {
+    pub fn new(tokens: Vec<Token<'a>>) -> Self {
+        Self { tokens, index: 0 }
+    }
+    pub fn peek(&self) -> &Token {
+        &self.tokens[self.index]
+    }
+
+    pub fn advance(&mut self) -> Option<&Token> {
+        if self.eof() {
+            return None;
+        }
+
+        self.index += 1;
+        Some(&self.tokens[self.index - 1])
+    }
+
+    pub fn advance_if(&mut self, next: impl FnOnce(&Token) -> bool) -> bool {
+        if self.eof() {
+            return false;
+        }
+
+        if next(self.peek()) {
+            self.advance();
+            return true;
+        }
+
+        false
+    }
+
+    pub fn advance_if_eq(&mut self, next: &TokenType) -> bool {
+        self.advance_if(|it| it.tt == *next)
+    }
+
+    pub fn consume(&mut self, next: TokenType, error: &str) {
+        if std::mem::discriminant(&self.peek().tt) != std::mem::discriminant(&next) {
+            panic!("{error}");
+        }
+        self.advance();
+    }
+
+    pub fn eof(&self) -> bool {
+        self.index >= self.tokens.len()
+    }
+}
diff --git a/crates/sloth/src/parser/expr.rs b/crates/sloth/src/parser/expr.rs
index 8b13789..84aab31 100644
--- a/crates/sloth/src/parser/expr.rs
+++ b/crates/sloth/src/parser/expr.rs
@@ -1 +1,207 @@
+use super::ast::{AstParser, BinaryOp, Expr, Literal, UnaryOp};
+use crate::lexer::TokenType;
 
+/// Implementation containing parsers internal components related to expressions
+impl<'a> AstParser<'a> {
+    // FIXME: Should probably avoid cloning token types
+
+    pub fn expression(&mut self) -> Expr {
+        self.logical_or()
+    }
+
+    fn unary(&mut self) -> Expr {
+        if !self.eof()
+            && matches!(
+                self.peek().tt,
+                TokenType::Bang | TokenType::Plus | TokenType::Minus
+            )
+        {
+            let operator = match self.advance().unwrap().tt.clone() {
+                TokenType::Bang => UnaryOp::Not,
+                TokenType::Tilde => UnaryOp::BWComp,
+                TokenType::Minus => UnaryOp::Neg,
+                _ => UnaryOp::Neg, // TODO: Idk how to not have this shit
+            };
+
+            let rhs = self.unary();
+            return Expr::UnaryOp {
+                op: (operator),
+                value: (Box::new(rhs)),
+            };
+        }
+
+        self.call()
+    }
+
+    fn call(&mut self) -> Expr {
+        let mut expr = self.primary();
+
+        if self.advance_if_eq(&TokenType::OpeningParen) {
+            let mut arguments = Vec::<Expr>::new();
+
+            if self.peek().tt != TokenType::ClosingParen {
+                loop {
+                    arguments.push(self.expression());
+                    if !self.advance_if_eq(&TokenType::Comma) {
+                        break;
+                    }
+                }
+            }
+
+            self.consume(
+                TokenType::ClosingParen,
+                "Expected ')' to close off function call",
+            );
+
+            // let Expr::Variable(_ident) = expr else { panic!("uh oh spaghettio"); };
+
+            expr = Expr::Call {
+                ident: (Box::new(expr)),
+                args: (arguments),
+            }
+        }
+
+        expr
+    }
+
+    fn primary(&mut self) -> Expr {
+        match self.advance().unwrap().tt.clone() {
+            TokenType::Integer(literal) => Expr::Literal(Literal::Integer(literal)),
+            TokenType::Float(literal) => Expr::Literal(Literal::Float(literal)),
+            TokenType::Boolean(literal) => Expr::Literal(Literal::Bool(literal)),
+            TokenType::Character(literal) => Expr::Literal(Literal::Char(literal)),
+            TokenType::String(literal) => Expr::Literal(Literal::String(literal)),
+            TokenType::Regex(literal) => Expr::Literal(Literal::Regex(literal)),
+            TokenType::Identifier(ident) => Expr::Variable(ident),
+            TokenType::OpeningParen => {
+                let expr = self.expression();
+                self.consume(TokenType::ClosingParen, "Must end expression with ')'");
+                Expr::Grouping(Box::new(expr))
+            }
+            _ => unimplemented!("{:?}", self.peek()),
+        }
+    }
+}
+
+// Macro to generate repetitive binary expressions. Things like addition,
+// multiplication, exc.
+macro_rules! binary_expr {
+    ($name:ident, $parent:ident, $pattern:pat) => {
+        fn $name(&mut self) -> Expr {
+            let mut expr = self.$parent();
+
+            while !self.eof() && matches!(self.peek().tt, $pattern) {
+                let operator = match self.advance().unwrap().tt.clone() {
+                    TokenType::Plus => BinaryOp::Add,
+                    TokenType::PlusPlus => BinaryOp::Con,
+                    TokenType::Minus => BinaryOp::Sub,
+                    TokenType::Star => BinaryOp::Mul,
+                    TokenType::StarStar => BinaryOp::Pow,
+                    TokenType::Slash => BinaryOp::Div,
+                    TokenType::Perc => BinaryOp::Mod,
+
+                    TokenType::LtLt => BinaryOp::BWSftRight,
+                    TokenType::GtGt => BinaryOp::BWSftLeft,
+                    TokenType::Amp => BinaryOp::BWAnd,
+                    TokenType::Pipe => BinaryOp::BWOr,
+                    TokenType::Caret => BinaryOp::BWXor,
+
+                    TokenType::Lt => BinaryOp::Lt,
+                    TokenType::Gt => BinaryOp::Gt,
+                    TokenType::LtEq => BinaryOp::LtEq,
+                    TokenType::GtEq => BinaryOp::GtEq,
+                    TokenType::EqEq => BinaryOp::EqEq,
+                    TokenType::BangEq => BinaryOp::NotEq,
+                    TokenType::AmpAmp => BinaryOp::LogAnd,
+                    TokenType::PipePipe => BinaryOp::LogOr,
+                    _ => BinaryOp::Add, // TODO: Idk how to not have this shit
+                };
+
+                let rhs = self.$parent();
+                expr = Expr::BinaryOp {
+                    op: (operator),
+                    lhs: (Box::new(expr)),
+                    rhs: (Box::new(rhs)),
+                }
+            }
+
+            expr
+        }
+    };
+}
+
+#[rustfmt::skip]
+#[allow(unused_parens)]
+impl<'a> AstParser<'a> {
+    // Binary expressions in order of precedence from lowest to highest.
+    binary_expr!(logical_or      , logical_and     , (TokenType::PipePipe));
+    binary_expr!(logical_and     , equality        , (TokenType::AmpAmp));
+    binary_expr!(equality        , comparison      , (TokenType::BangEq | TokenType::EqEq));
+    binary_expr!(comparison      , bitwise_shifting, (TokenType::Lt     | TokenType::Gt    | TokenType::LtEq | TokenType::GtEq));
+    binary_expr!(bitwise_shifting, additive        , (TokenType::LtLt   | TokenType::GtGt));
+    binary_expr!(additive        , multiplicative  , (TokenType::Plus   | TokenType::Minus));
+    binary_expr!(multiplicative  , unary           , (TokenType::Star   | TokenType::Slash | TokenType::Perc));
+}
+
+#[cfg(test)]
+mod tests {
+    use itertools::Itertools;
+    use super::{AstParser, BinaryOp, Expr, Literal};
+
+    use crate::{lexer::{Lexer}, parser::ast::UnaryOp};
+
+    #[test]
+    fn basic_expression_a() {
+        let lexer = Lexer::new("3 + 5 * 4");
+        let tokens = lexer.collect_vec();
+
+        let expected_ast = Expr::BinaryOp {
+            op: BinaryOp::Add,
+            lhs: Box::new(Expr::Literal(Literal::Integer(3))),
+            rhs: Box::new(Expr::BinaryOp {
+                op: BinaryOp::Mul,
+                lhs: Box::new(Expr::Literal(Literal::Integer(5))),
+                rhs: Box::new(Expr::Literal(Literal::Integer(4))),
+            }),
+        };
+
+        let mut parser = AstParser::new(tokens);
+        let generated_ast = parser.expression();
+
+        println!("Expected AST:\n{expected_ast:#?}\n\n");
+        println!("Generated AST:\n{generated_ast:#?}\n\n");
+
+        assert_eq!(expected_ast, generated_ast);
+    }
+
+    #[test]
+    fn basic_expression_b() {
+        let lexer = Lexer::new("17 - (-5 + 5) / 6");
+        let tokens = lexer.collect_vec();
+
+        let expected_ast = Expr::BinaryOp {
+            op: BinaryOp::Sub,
+            lhs: Box::new(Expr::Literal(Literal::Integer(17))),
+            rhs: Box::new(Expr::BinaryOp {
+                op: BinaryOp::Div,
+                lhs: Box::new(Expr::Grouping(Box::new(Expr::BinaryOp {
+                    op: BinaryOp::Add,
+                    lhs: Box::new(Expr::UnaryOp {
+                        op: UnaryOp::Neg,
+                        value: Box::new(Expr::Literal(Literal::Integer(5))),
+                    }),
+                    rhs: Box::new(Expr::Literal(Literal::Integer(5))),
+                }))),
+                rhs: Box::new(Expr::Literal(Literal::Integer(6))),
+            }),
+        };
+
+        let mut parser = AstParser::new(tokens);
+        let generated_ast = parser.expression();
+
+        println!("Expected AST:\n{expected_ast:#?}\n\n");
+        println!("Generated AST:\n{generated_ast:#?}\n\n");
+
+        assert_eq!(expected_ast, generated_ast);
+    }
+}
\ No newline at end of file
diff --git a/crates/sloth/src/parser/stmt.rs b/crates/sloth/src/parser/stmt.rs
index 8b13789..c5c0c6a 100644
--- a/crates/sloth/src/parser/stmt.rs
+++ b/crates/sloth/src/parser/stmt.rs
@@ -1 +1,159 @@
+use super::ast::{AstParser, Expr, Stmt};
+use crate::lexer::TokenType;
 
+impl<'a> AstParser<'a> {
+    pub fn parse(&mut self) -> Vec<Stmt> {
+        let mut statements = Vec::new();
+
+        while !self.eof() {
+            statements.push(self.statement());
+        }
+
+        statements
+    }
+
+    fn statement(&mut self) -> Stmt {
+        if self.advance_if_eq(&TokenType::Var) {
+            return self.var_statement();
+        }
+
+        if self.advance_if_eq(&TokenType::Val) {
+            return self.val_statement();
+        }
+
+        if self.advance_if_eq(&TokenType::If) {
+            return self.if_statement();
+        }
+
+        // if self.advance_if_eq(&TokenType::For) {
+        //     return self.for_statement();
+        // }
+
+        if self.advance_if_eq(&TokenType::While) {
+            return self.while_statement();
+        }
+
+        // If we couldn't parse a statement return an expression statement
+        self.expression_statement()
+    }
+
+    fn var_statement(&mut self) -> Stmt {
+        let TokenType::Identifier(ident) = self.peek().tt.clone() else {
+            panic!("Identifier expected after 'var'");
+        };
+
+        self.advance(); // Advancing from the identifier TODO: Check for type
+        self.consume(TokenType::Eq, "Expected '=' after identifier");
+
+        let value = self.expression();
+
+        self.consume(TokenType::SemiColon, "Expected ';' at end of statement");
+
+        Stmt::DefineVariable {
+            name: (ident),
+            value: (value),
+            typ: (None),
+        }
+    }
+
+    fn val_statement(&mut self) -> Stmt {
+        let TokenType::Identifier(ident) = self.peek().tt.clone() else {
+            panic!("Identifier expected after 'val'");
+        };
+
+        self.advance(); // Advancing from the identifier
+        self.consume(TokenType::Eq, "Expected '=' after identifier");
+
+        let value = self.expression();
+
+        self.consume(TokenType::SemiColon, "Expected ';' at end of statement");
+
+        Stmt::DefineValue {
+            name: (ident),
+            value: (value),
+            typ: (None),
+        }
+    }
+
+    fn if_statement(&mut self) -> Stmt {
+        let condition = self.expression();
+
+        self.consume(
+            TokenType::OpeningBrace,
+            "Expected '{' at beggining of block",
+        );
+        let mut body = Vec::new();
+        while !self.eof() && self.peek().tt != TokenType::ClosingBrace {
+            body.push(self.statement());
+        }
+
+        Stmt::If {
+            expr: (condition),
+            body: (body),
+            else_if: (Vec::new()),
+            els: (None),
+        } // TODO: implement else if and else
+    }
+
+    // fn for_statement(&mut self) -> Stmt {
+    //     let binding = self.expression();
+    //     let Expr::Variable(binding) = binding else {
+    //         panic!("Left side of for statement must be identifier");
+    //     };
+
+    //     self.consume(
+    //         TokenType::In,
+    //         "Expected 'in' in between identifier and range",
+    //     );
+
+    //     let range_start = self.expression();
+    //     self.consume(
+    //         TokenType::DotDot,
+    //         "Expected '..' denoting min and max of range",
+    //     );
+    //     let range_end = self.expression();
+
+    //     let mut body = Vec::new();
+    //     while !self.eof() && self.peek().tt != TokenType::ClosingBrace {
+    //         body.push(self.statement());
+    //     }
+
+    //     Stmt::For { name: (binding), iter: (), body: (body) }
+    // } TODO: Fix this garbage
+
+    fn while_statement(&mut self) -> Stmt {
+        let condition = self.expression();
+
+        self.consume(
+            TokenType::OpeningBrace,
+            "Expected '{' at beggining of block",
+        );
+        let mut body = Vec::new();
+        while !self.eof() && self.peek().tt != TokenType::ClosingBrace {
+            body.push(self.statement());
+        }
+
+        Stmt::While { condition, body }
+    }
+
+    fn expression_statement(&mut self) -> Stmt {
+        let expr = self.expression();
+
+        // FIXME: Move assignment handling
+        if self.advance_if_eq(&TokenType::Eq) {
+            if let Expr::Variable(ident) = &expr {
+                let value = self.expression();
+
+                self.consume(TokenType::SemiColon, "Expected ';' at end of statement");
+                return Stmt::DefineVariable {
+                    name: (ident.clone()),
+                    value: (value),
+                    typ: (None),
+                };
+            }
+        }
+
+        self.consume(TokenType::SemiColon, "Expected ';' at end of statement");
+        Stmt::ExprStmt(expr)
+    }
+}