rlox/src/frontend/ast.rs

use crate::frontend::{
    source_registry::SourceSlice,
    tokens::{LiteralValue, TokenType},
};
use std::fmt::{Debug, Display};
/*
 * grammar:
 * program -> statement* EOF
 * statement -> expression_statement
 *             | print_statement
 *             | var_statement
 *             | block_statement
 *             | assignment_statement
 *             | if_statement
 *
 * expression_statement -> expression ";"
 * print_statement -> "print" expression ";"
 * var_statement -> "var" IDENTIFIER ("=" expression)? ";"
 * assignment_statement -> IDENTIFIER "=" expression ";"
 * block_statement -> "do" statement* "end"
 * if_statement -> "if" expression "then" statement ("elif" expression "then" statement)* ("else" statement)? "end"
 * while_statement -> "while" expression "do" statement "end"
 *
 * expression -> assignment
 * assignment -> IDENTIFIER "=" assignment | logical_or
 * logical_or -> logical_and (("or" logical_and)*
 * logical_and -> equality (("and" equality)*
 * equality -> comparison (("==" | "!=") comparison)*
 * comparison -> term ((">" | ">=" | "<" | "<=") term)*
 * term -> factor (("+" | "-") factor)*
 * factor -> unary (("*" | "/") unary)*
 * unary -> ("!" | "-") unary | primary
 * primary -> NUMBER | STRING | "true" | "false" | "nil" | "(" expression ")" | IDENTIFIER
 */
#[derive(Clone)]
pub enum Expr {
    Literal {
        value: LiteralValue,
    },
    Binary {
        left: Box<AstNode<Expr>>,
        operator: TokenType,
        right: Box<AstNode<Expr>>,
    },
    Unary {
        operator: TokenType,
        operand: Box<AstNode<Expr>>,
    },
    Grouping {
        expression: Box<AstNode<Expr>>,
    },
    Variable {
        name: String,
    },
}

// Implementazione Display per Expr (per debugging)
impl std::fmt::Display for Expr {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            Expr::Literal { value } => write!(f, "Literal {}", value),
            Expr::Binary {
                left,
                operator,
                right,
            } => write!(f, "Binary ({} {} {})", left.node, operator, right.node),
            Expr::Unary { operator, operand } => write!(f, "Unary ({} {})", operator, operand.node),
            Expr::Grouping { expression } => write!(f, "Grouping (group {})", expression.node),
            Expr::Variable { name } => write!(f, "Variable (variable {})", name),
        }
    }
}

impl Debug for Expr {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            Expr::Literal { value } => write!(f, "{:?}", value),
            Expr::Binary {
                left,
                operator,
                right,
            } => write!(f, "({:?} {:?} {:?})", operator, left.node, right.node),
            Expr::Unary { operator, operand } => write!(f, "({:?} {:?})", operator, operand.node),
            Expr::Grouping { expression } => write!(f, "(group {:?})", expression.node),
            Expr::Variable { name } => write!(f, "(variable {:?})", name),
        }
    }
}

#[derive(Clone)]
pub enum Stmt {
    Expression {
        expression: Box<AstNode<Expr>>,
    },
    Print {
        expression: Box<AstNode<Expr>>,
    },
    Stmt {
        expression: Box<AstNode<Expr>>,
    },
    Var {
        name: String,
        initializer: Option<Box<AstNode<Expr>>>,
    },
    Assign {
        name: String,
        value: Box<AstNode<Expr>>,
    },
    Return {
        expression: Box<AstNode<Expr>>,
    },
    Block {
        statements: Box<Vec<AstNode<Stmt>>>,
    },
    If {
        condition: Box<AstNode<Expr>>,
        then_branch: Box<AstNode<Stmt>>,
        elif_branch: Vec<(Box<AstNode<Expr>>, Box<AstNode<Stmt>>)>,
        else_branch: Option<Box<AstNode<Stmt>>>,
    },
    While {
        condition: Box<AstNode<Expr>>,
        body: Box<AstNode<Stmt>>,
    },
    For {
        variable: Box<AstNode<Expr>>,
        iterable: Box<AstNode<Expr>>,
        body: Box<AstNode<Stmt>>,
    },
}

impl Display for Stmt {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            Stmt::Expression { expression } => write!(f, "Expression ({})", expression.node),
            Stmt::If {
                condition,
                then_branch,
                elif_branch,
                else_branch,
            } => {
                let mut result = format!("IF ({}) {{\n{}\n}}", condition.node, then_branch.node);
                for (condition, branch) in elif_branch {
                    result.push_str(&format!(
                        " ELIF ({}) {{\n{}\n}}",
                        condition.node, branch.node
                    ));
                }
                if let Some(else_branch) = else_branch {
                    result.push_str(&format!(" ELSE {{\n{}\n}}", else_branch.node));
                }
                write!(f, "IfStmt {}", result)
            }
            Stmt::Print { expression } => write!(f, "Print({});", expression.node),
            Stmt::Stmt { expression } => write!(f, "Stmt({});", expression.node),
            Stmt::Var { name, initializer } => match initializer {
                Some(init) => write!(f, "Var({} = {});", name, init.node),
                None => write!(f, "Var({});", name),
            },
            Stmt::Assign { name, value } => write!(f, "Assign({} = {});", name, value.node),
            Stmt::Return { expression } => write!(f, "Return({});", expression.node),
            Stmt::Block { statements } => write!(
                f,
                "Block([\n{}\n])",
                statements
                    .iter()
                    .map(|stmt| format!("\t \t{}", stmt.node))
                    .collect::<Vec<_>>()
                    .join("\n")
            ),
            Stmt::While { condition, body } => {
                write!(f, "While({}) {{\n{}\n}}", condition.node, body.node)
            }
            Stmt::For {
                variable,
                iterable,
                body,
            } => write!(
                f,
                "For({} in {}) {{\n{}\n}}",
                variable.node, iterable.node, body.node
            ),
        }
    }
}

impl Debug for Stmt {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            Stmt::Expression { expression } => write!(f, " Expression ({:?})", expression.node),
            Stmt::If {
                condition,
                then_branch,
                elif_branch,
                else_branch,
            } => {
                let mut result =
                    format!("IF ({:?}) {{\n{:?}\n}}", condition.node, then_branch.node);
                for (condition, branch) in elif_branch {
                    result.push_str(&format!(
                        " ELIF ({:?}) {{\n{:?}\n}}",
                        condition.node, branch.node
                    ));
                }
                if let Some(else_branch) = else_branch {
                    result.push_str(&format!(" ELSE {{\n{:?}\n}}", else_branch.node));
                }
                write!(f, "IfStmt {:?}", result)
            }
            Stmt::Print { expression } => write!(f, "Print({:?});", expression.node),
            Stmt::Stmt { expression } => write!(f, "Stmt({:?});", expression.node),
            Stmt::Var { name, initializer } => match initializer {
                Some(init) => write!(f, "Var({:?} = {:?});", name, init.node),
                None => write!(f, "Var({:?});", name),
            },
            Stmt::Assign { name, value } => write!(f, "Assign({:?} = {:?});", name, value.node),
            Stmt::Return { expression } => write!(f, "Return({:?});", expression.node),
            Stmt::Block { statements } => write!(
                f,
                "Block([\n{:?}\n])",
                statements
                    .iter()
                    .map(|stmt| format!("{:?}", stmt.node))
                    .collect::<Vec<_>>()
                    .join("\t\t\n")
            ),
            Stmt::While { condition, body } => {
                write!(f, "While({:?}) {{\n{:?}\n}}", condition.node, body.node)
            }
            Stmt::For {
                variable,
                iterable,
                body,
            } => write!(
                f,
                "For({:?} in {:?}) {{\n{:?}\n}}",
                variable.node, iterable.node, body.node
            ),
        }
    }
}

pub trait AstNodeKind {
    fn kind(&self) -> &'static str;
}

impl AstNodeKind for Expr {
    fn kind(&self) -> &'static str {
        match self {
            Expr::Literal { value: _ } => "literal",
            Expr::Binary {
                left: _,
                operator: _,
                right: _,
            } => "binary expression",
            Expr::Unary {
                operator: _,
                operand: _,
            } => "unary expression",
            Expr::Grouping { expression: _ } => "grouping expression",
            Expr::Variable { name: _ } => "variable expression",
        }
    }
}

impl AstNodeKind for Stmt {
    fn kind(&self) -> &'static str {
        match self {
            Stmt::Expression { .. } => "expression",
            Stmt::Var { .. } => "variable declaration",
            Stmt::Assign { .. } => "assignment",
            Stmt::Return { .. } => "return statement",
            Stmt::Block { .. } => "block statement",
            Stmt::If { .. } => "if statement",
            Stmt::Print { .. } => "print statement",
            Stmt::Stmt { .. } => "statement",
            Stmt::While { .. } => "while statement",
            Stmt::For { .. } => "for statement",
        }
    }
}

#[derive(Clone, PartialEq)]
pub struct AstNode<T: AstNodeKind + Debug + Display> {
    pub node: T,
    pub source_slice: SourceSlice,
}

impl<T: AstNodeKind + Debug + Display> Display for AstNode<T> {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        write!(
            f,
            "AstNode \n{{ \n\tnode: {},\n\tsource_slice: {}, \n}}",
            self.node, self.source_slice
        )
    }
}

impl<T: AstNodeKind + Debug + Display> Debug for AstNode<T> {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        write!(
            f,
            "AstNode \n{{ \n\tnode: {:?},\n\tsource_slice: {:?}, \n}}",
            self.node, self.source_slice
        )
    }
}

impl<T: AstNodeKind + Debug + Display> AstNode<T> {
    pub fn new(node: T, source_slice: SourceSlice) -> Self {
        AstNode { node, source_slice }
    }
}