benda 0.1.2

Use Bend language functions and capabilities in Python!
Documentation
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#![allow(clippy::cmp_owned)]
use core::panic;
use std::vec;

use bend::fun::{self, Adt, Book, CtrField, Name, Op, Rule, STRINGS};
use bend::imp::{self, Expr, MatchArm, Stmt};
use indexmap::IndexMap;
use num_traits::cast::ToPrimitive;
use pyo3::{Bound, PyAny};
use rustpython_parser::ast::{
    located, CmpOp as rCmpOp, Expr as rExpr, ExprAttribute, ExprBinOp,
    Operator as rOperator, Pattern as rPattern, Stmt as rStmt, StmtAssign,
    StmtClassDef, StmtExpr, StmtFunctionDef, StmtIf, StmtMatch,
};

use crate::benda_ffi::run;
use crate::types::{extract_type, extract_type_expr};

#[derive(Clone, Debug)]
enum FromExpr {
    CtrField(Vec<CtrField>),
    Expr(imp::Expr),
    Statement(imp::Stmt),
}

impl FromExpr {
    pub fn get_var_name(&self) -> Option<Name> {
        if let FromExpr::Expr(Expr::Var { nam }) = self {
            Some(nam.clone())
        } else {
            None
        }
    }
}

#[derive(PartialEq)]
enum CurContext {
    Match,
    Main,
}

struct Context {
    now: CurContext,
    vars: Vec<String>,
    subs: Vec<String>,
}

pub struct Parser<'py> {
    statements: Vec<rStmt>,
    book: Book,
    definitions: Vec<imp::Definition>,
    ctx: Option<Context>,
    fun_args: Vec<(String, Bound<'py, PyAny>)>,
}

impl<'py> Parser<'py> {
    pub fn new(
        statements: Vec<rStmt>,
        fun_args: Vec<(String, Bound<'py, PyAny>)>,
    ) -> Self {
        Self {
            statements,
            book: bend::fun::Book::builtins(),
            definitions: vec![],
            ctx: None,
            fun_args,
        }
    }

    fn parse_switch_expr(&self, att: ExprAttribute) -> Option<FromExpr> {
        if let Some(lib) =
            self.parse_expr_type(*att.value).unwrap().get_var_name()
        {
            let fun = att.attr.to_string();
            if lib.to_string() == "benda" && fun == "switch" {
                return Some(FromExpr::Expr(Expr::Call {
                    fun: Box::new(Expr::Var {
                        nam: Name::new("switch"),
                    }),
                    args: vec![],
                    kwargs: vec![],
                }));
            }
        }
        None
    }

    fn parse_expr_type(&self, expr: rExpr) -> Option<FromExpr> {
        match expr {
            rExpr::Attribute(att) => {
                if let Some(switch) = self.parse_switch_expr(att) {
                    return Some(switch);
                }
                None
            }
            rExpr::Compare(comp) => {
                let left = self.parse_expr_type(*comp.left).unwrap();
                let right = self
                    .parse_expr_type(comp.comparators.first().unwrap().clone())
                    .unwrap();

                let op = match comp.ops.first().unwrap() {
                    rCmpOp::Eq => Op::EQ,
                    rCmpOp::NotEq => Op::NEQ,
                    rCmpOp::Lt => Op::LT,
                    rCmpOp::LtE => todo!(),
                    rCmpOp::Gt => Op::GT,
                    rCmpOp::GtE => todo!(),
                    rCmpOp::Is => todo!(),
                    rCmpOp::IsNot => todo!(),
                    rCmpOp::In => todo!(),
                    rCmpOp::NotIn => todo!(),
                };

                if let (FromExpr::Expr(left), FromExpr::Expr(right)) =
                    (left, right)
                {
                    return Some(FromExpr::Expr(Expr::Opr {
                        op,
                        lhs: Box::new(left),
                        rhs: Box::new(right),
                    }));
                }
                None
            }
            rExpr::BinOp(bin_op) => self.parse_bin_op(bin_op),
            rExpr::Constant(c) => match c.value {
                located::Constant::None => todo!(),
                located::Constant::Bool(_) => todo!(),
                located::Constant::Str(str) => {
                    let nam = Name::new(str.clone());
                    let adt = self.book.adts.get(&nam);

                    if let Some(_adt) = adt {
                        return Some(FromExpr::Expr(imp::Expr::Var { nam }));
                    }
                    Some(FromExpr::Expr(Expr::Str {
                        val: STRINGS.get(str.as_str()),
                    }))
                }
                located::Constant::Bytes(_) => todo!(),
                located::Constant::Int(val) => {
                    Some(FromExpr::Expr(imp::Expr::Num {
                        val: bend::fun::Num::U24(val.to_u32().unwrap()),
                    }))
                }
                located::Constant::Tuple(_) => todo!(),
                located::Constant::Float(val) => {
                    Some(FromExpr::Expr(imp::Expr::Num {
                        val: bend::fun::Num::F24(val.to_f32().unwrap()),
                    }))
                }
                located::Constant::Complex { real: _, imag: _ } => todo!(),
                located::Constant::Ellipsis => todo!(),
            },

            rExpr::Name(n) => {
                let mut name = n.id.to_string();

                if let Some(ctx) = &self.ctx {
                    if ctx.now == CurContext::Match {
                        for var in &ctx.vars {
                            if *var == n.id.to_string() {
                                name = format!(
                                    "{}.{}",
                                    ctx.subs.first().unwrap(),
                                    var
                                );
                            }
                        }
                    }
                }

                Some(FromExpr::Expr(imp::Expr::Var {
                    nam: Name::new(name),
                }))
            }

            rExpr::Call(c) => {
                let fun = c.clone().func;

                let expr = self.parse_expr_type(*fun);

                if let Some(FromExpr::Expr(Expr::Var { ref nam })) = expr {
                    if let Some(var) = extract_type_expr(c.clone()) {
                        return Some(FromExpr::Expr(var));
                    }

                    let mut args: Vec<Expr> = vec![];

                    for arg in c.args {
                        let arg = self.parse_expr_type(arg);

                        if let Some(FromExpr::Expr(e)) = arg {
                            args.push(e);
                        }
                    }

                    if let Some(val) = self.find_in_ctrs(nam) {
                        return Some(FromExpr::Expr(imp::Expr::Ctr {
                            name: val.clone(),
                            args,
                            kwargs: vec![],
                        }));
                    }
                    return Some(FromExpr::Expr(imp::Expr::Call {
                        fun: Box::new(Expr::Var {
                            nam: Name::new(nam.to_string()),
                        }),
                        args,
                        kwargs: vec![],
                    }));
                }
                expr
            }
            _ => todo!(),
        }
    }

    fn parse_adt_create(
        &self,
        left: &FromExpr,
        right: &FromExpr,
    ) -> Option<FromExpr> {
        if let (Some(nam_l), Some(nam_r)) =
            (left.get_var_name(), right.get_var_name())
        {
            let adt_l = self.book.adts.get(&nam_l);
            let adt_r = self.book.adts.get(&nam_r);

            let mut is_adt = false;

            match (adt_l, adt_r) {
                (None, None) => {}
                (_, _) => {
                    is_adt = true;
                }
            }

            let mut fields: Vec<CtrField> = vec![];

            if is_adt {
                fields.push(CtrField {
                    nam: nam_l.clone(),
                    rec: false,
                });
                fields.push(CtrField {
                    nam: nam_r.clone(),
                    rec: false,
                });
                return Some(FromExpr::CtrField(fields));
            }
        }

        None
    }

    fn parse_bin_op(&self, bin: ExprBinOp) -> Option<FromExpr> {
        // TODO(#5): Treat case where expr type returns None

        let left: FromExpr = self.parse_expr_type(*bin.left).unwrap();
        let right: FromExpr = self.parse_expr_type(*bin.right).unwrap();

        let op: Op = match bin.op {
            rOperator::Add => Op::ADD,
            rOperator::Sub => Op::SUB,
            rOperator::Mult => Op::MUL,
            rOperator::MatMult => todo!(),
            rOperator::Div => Op::DIV,
            rOperator::Mod => todo!(),
            rOperator::Pow => Op::POW,
            rOperator::LShift => Op::SHL,
            rOperator::RShift => Op::SHR,
            rOperator::BitOr => Op::OR,
            rOperator::BitXor => Op::XOR,
            rOperator::BitAnd => Op::AND,
            rOperator::FloorDiv => todo!(),
        };

        if let Some(adt_op) = self.parse_adt_create(&left, &right) {
            return Some(adt_op);
        }

        if let (FromExpr::Expr(left), FromExpr::Expr(right)) = (left, right) {
            let operation = imp::Expr::Opr {
                op,
                lhs: Box::new(left),
                rhs: Box::new(right),
            };

            return Some(FromExpr::Expr(operation));
        }
        todo!()
    }

    fn parse_assign(&mut self, assign: &StmtAssign) -> Option<FromExpr> {
        self.parse_expr_type(*assign.value.clone())
    }

    fn parse_match(
        &mut self,
        m: &StmtMatch,
        stmts: &Vec<rStmt>,
        index: &usize,
    ) -> Option<imp::Stmt> {
        let mut arms: Vec<imp::MatchArm> = vec![];
        let mut patt: Vec<String> = vec![];

        for case in &m.cases {
            let pat = match &case.pattern {
                rPattern::MatchValue(val) => {
                    let expr =
                        self.parse_expr_type(*val.value.clone()).unwrap();
                    match expr {
                        FromExpr::Expr(imp::Expr::Var { nam }) => Some(nam),
                        _ => None,
                    }
                }

                rPattern::MatchClass(class) => {
                    let expr =
                        self.parse_expr_type(*class.cls.clone()).unwrap();

                    for val in class.patterns.clone() {
                        if let rPattern::MatchAs(match_as) = val {
                            if let Some(name) = &match_as.name {
                                patt.push(name.to_string());
                            }
                        }
                    }

                    match expr {
                        FromExpr::Expr(imp::Expr::Var { nam }) => Some(nam),
                        _ => None,
                    }
                }
                rPattern::MatchSingleton(_) => todo!(),
                rPattern::MatchSequence(_) => todo!(),
                rPattern::MatchMapping(_) => todo!(),
                rPattern::MatchStar(_) => todo!(),
                rPattern::MatchAs(_) => todo!(),
                rPattern::MatchOr(_) => todo!(),
            };

            let sub = self.parse_expr_type(*m.subject.clone());

            if let Some(FromExpr::Expr(Expr::Var { nam })) = sub {
                self.ctx = Some(Context {
                    now: CurContext::Match,
                    vars: patt.clone(),
                    subs: vec![nam.to_string()],
                });
            }

            let stmt_arm = self.parse_vec(&case.body.clone(), 0);

            if let Some(pat) = pat {
                let first = self.find_in_ctrs(&pat);
                if let Some(FromExpr::Statement(a)) = stmt_arm {
                    let arm = MatchArm { lft: first, rgt: a };
                    arms.push(arm);
                }
            }
        }

        self.ctx = None;

        if let Some(FromExpr::Expr(subj)) =
            self.parse_expr_type(*m.subject.clone())
        {
            let nxt = self.parse_vec(stmts, index + 1);

            let my_nxt: Option<Box<Stmt>> = match nxt {
                Some(FromExpr::Statement(s)) => Some(Box::new(s)),
                _ => None,
            };

            let name = match subj.clone() {
                Expr::Var { nam } => Some(nam),
                _ => None,
            };

            let ret_match = imp::Stmt::Match {
                arg: Box::new(subj.clone()),
                bnd: name,
                arms,
                nxt: my_nxt,
                with_bnd: vec![],
                with_arg: vec![],
            };

            return Some(ret_match);
        }
        None
    }

    fn parse_switch(
        &mut self,
        name: &String,
        nxt: &Option<FromExpr>,
        stmts: &[rStmt],
        index: &usize,
    ) -> Option<FromExpr> {
        let mut arms: Vec<imp::Stmt> = vec![];
        if let Some(rStmt::Match(m)) = stmts.get(index + 1) {
            for case in &m.cases {
                let stmt_arm = self.parse_vec(&case.body.clone(), 0);

                if let Some(FromExpr::Statement(a)) = stmt_arm {
                    arms.push(a);
                }
            }

            if let Some(FromExpr::Expr(expr)) =
                self.parse_expr_type(*m.subject.clone())
            {
                return Some(FromExpr::Statement(imp::Stmt::Switch {
                    arg: Box::new(expr),
                    bnd: Some(Name::new(name)),
                    arms,
                    nxt: nxt.clone().map(|n| {
                        if let FromExpr::Statement(n) = n {
                            return Box::new(n);
                        }

                        todo!()
                    }),
                    with_bnd: vec![],
                    with_arg: vec![],
                }));
            }
        }
        None
    }

    fn find_in_ctrs(&self, nam: &Name) -> Option<Name> {
        for ctr in self.book.ctrs.clone() {
            for ctr_name in ctr.0.split('/') {
                if nam.to_string() == *ctr_name.to_string() {
                    return Some(ctr.0);
                }
            }
        }
        None
    }

    fn parse_main_call(
        &mut self,
        value: &FromExpr,
        name: &String,
        stmts: &Vec<rStmt>,
        index: usize,
    ) -> Option<FromExpr> {
        if let Some(ctx) = &self.ctx {
            if ctx.now == CurContext::Main {
                if let FromExpr::Expr(Expr::Call {
                    fun,
                    args: _,
                    kwargs: _,
                }) = value.clone()
                {
                    if let Expr::Var { nam } = *fun {
                        if &nam.to_string() == ctx.subs.first().unwrap() {
                            if let FromExpr::Expr(e) = value.clone() {
                                return Some(FromExpr::Statement(
                                    Stmt::Return { term: Box::new(e) },
                                ));
                            }
                        }
                    }
                }
            }

            if ctx.now == CurContext::Main && !ctx.vars.contains(name) {
                return self.parse_vec(stmts, index + 1);
            }
        }
        None
    }

    fn parse_if(
        &mut self,
        stmt_if: &StmtIf,
        stmts: &Vec<rStmt>,
        index: usize,
    ) -> Option<FromExpr> {
        let cond = self.parse_expr_type(*stmt_if.test.clone());
        let then = self.parse_vec(&stmt_if.body, 0);
        let otherwise = self.parse_vec(&stmt_if.orelse, 0);

        let nxt = self.parse_vec(stmts, index + 1);

        let b_nxt = match nxt {
            Some(FromExpr::Statement(nxt)) => Some(Box::new(nxt)),
            _ => None,
        };

        match (cond, then, otherwise, b_nxt) {
            (
                Some(FromExpr::Expr(cond)),
                Some(FromExpr::Statement(then)),
                Some(FromExpr::Statement(otherwise)),
                b_nxt,
            ) => Some(FromExpr::Statement(Stmt::If {
                cond: Box::new(cond),
                then: Box::new(then),
                otherwise: Box::new(otherwise),
                nxt: b_nxt,
            })),
            (_, _, _, _) => {
                panic!("If Statement must have an else.")
            }
        }
    }

    fn parse_stmt_expr(&mut self, expr: &StmtExpr) -> Option<FromExpr> {
        if let Some(ctx) = &self.ctx {
            if ctx.now == CurContext::Main {
                let val = self.parse_expr_type(*expr.value.clone());

                if let Some(FromExpr::Expr(call)) = val {
                    if let Expr::Call {
                        fun,
                        args: _,
                        kwargs: _,
                    } = call.clone()
                    {
                        if let imp::Expr::Var { nam } = *fun {
                            if nam.to_string() == *ctx.subs.first().unwrap() {
                                return Some(FromExpr::Statement(
                                    Stmt::Return {
                                        term: Box::new(call),
                                    },
                                ));
                            }
                        }
                    }
                }
            }
        }

        None
    }

    fn parse_assign_stmt(
        &mut self,
        assign: &StmtAssign,
        stmts: &Vec<rStmt>,
        index: usize,
    ) -> Option<FromExpr> {
        let value = self.parse_assign(assign).unwrap();
        let name = assign
            .targets
            .first()
            .unwrap()
            .clone()
            .name_expr()
            .unwrap()
            .id
            .to_string();

        if let Some(main_call) =
            self.parse_main_call(&value, &name, stmts, index)
        {
            return Some(main_call);
        }

        let nxt = self.parse_vec(stmts, index + 1);

        if let FromExpr::Expr(Expr::Call {
            fun,
            args: _,
            kwargs: _,
        }) = value.clone()
        {
            if let Expr::Var { nam } = *fun {
                if nam.to_string() == "switch" {
                    return self.parse_switch(&name, &nxt, stmts, &index);
                }
            }
        }

        if let FromExpr::Expr(val) = value {
            return Some(FromExpr::Statement(imp::Stmt::Assign {
                pat: imp::AssignPattern::Var(Name::new(name)),
                val: Box::new(val),
                nxt: nxt.map(|n| {
                    if let FromExpr::Statement(n) = n {
                        return Box::new(n);
                    }

                    todo!()
                }),
            }));
        }

        Some(value)
    }

    fn parse_vec(
        &mut self,
        stmts: &Vec<rStmt>,
        index: usize,
    ) -> Option<FromExpr> {
        let stmt = match stmts.get(index) {
            Some(s) => s,
            None => {
                return None;
            }
        };

        match stmt {
            rStmt::Assign(assign) => {
                self.parse_assign_stmt(assign, stmts, index)
            }
            rStmt::If(stmt_if) => self.parse_if(stmt_if, stmts, index),
            rStmt::Return(r) => match &r.value {
                Some(val) => {
                    let term = self.parse_expr_type(*val.clone()).unwrap();
                    if let FromExpr::Expr(term) = term {
                        return Some(FromExpr::Statement(imp::Stmt::Return {
                            term: Box::new(term),
                        }));
                    }

                    todo!()
                }
                None => None,
            },
            rStmt::Expr(expr) => self.parse_stmt_expr(expr),
            rStmt::Match(m) => {
                if let Some(val) = self.parse_match(m, stmts, &index) {
                    return Some(FromExpr::Statement(val));
                }
                None
            }
            _ => None,
        }
    }

    fn add_adt(&mut self, nam: Name, adt: Adt) {
        if let Some(adt) = self.book.adts.get(&nam) {
            if adt.builtin {
                panic!(
                    "{} is a built-in datatype and should not be overridden.",
                    nam
                );
            } else {
                panic!("Repeated datatype '{}'", nam);
            }
        } else {
            for ctr in adt.ctrs.keys() {
                match self.book.ctrs.entry(ctr.clone()) {
                    indexmap::map::Entry::Vacant(e) => {
                        _ = e.insert(nam.clone());
                    }
                    indexmap::map::Entry::Occupied(e) => {
                        if self
                            .book
                            .adts
                            .get(e.get())
                            .is_some_and(|adt| adt.builtin)
                        {
                            panic!(
                                "{} is a built-in constructor and should not be overridden.",
                                e.key()
                            );
                        } else {
                            panic!("Repeated constructor '{}'", e.key());
                        }
                    }
                }
            }
        }
        self.book.adts.insert(nam.clone(), adt);
    }

    // Creates a Bend Definition for each argument for the annotaded function.
    fn parse_fun_args(&mut self, parsed_types: &Vec<(String, imp::Expr)>) {
        for (name, expr) in parsed_types {
            let u_type = expr.clone().to_fun();

            let nam = Name::new(name.to_string());

            let def = fun::Definition {
                name: nam.clone(),
                rules: vec![Rule {
                    pats: vec![],
                    body: u_type,
                }],
                builtin: false,
            };

            self.book.defs.insert(nam, def);
        }
    }

    // This function searchs for the Call of the annotaded function.
    // It uses the Call to create a Bend main.
    pub fn parse_main(
        &mut self,
        fun_name: &str,
        py_args: &[String],
    ) -> Option<imp::Definition> {
        self.ctx = Some(Context {
            now: CurContext::Main,
            vars: py_args.to_vec(),
            subs: vec![fun_name.to_string()],
        });

        let mut parsed_types: Vec<(String, imp::Expr)> = vec![];

        for arg in self.fun_args.iter() {
            parsed_types.push((
                arg.0.clone(),
                extract_type(arg.1.clone(), &self.book).unwrap(),
            ));
        }

        self.parse_fun_args(&parsed_types);

        let mut new_args: Vec<Expr> = vec![];

        for arg in parsed_types.clone() {
            match arg.1 {
                imp::Expr::Var { nam: _ } => {}
                _ => new_args.push(Expr::Var {
                    nam: Name::new(arg.0),
                }),
            }
        }

        let first = Stmt::Return {
            term: Box::new(Expr::Call {
                fun: Box::new(imp::Expr::Var {
                    nam: Name::new(fun_name.to_string()),
                }),
                args: new_args,
                kwargs: vec![],
            }),
        };

        Some(imp::Definition {
            name: Name::new("main"),
            params: vec![],
            body: first,
        })
    }

    fn parse_class_def(&mut self, class: &StmtClassDef) {
        let is_dataclass = class.decorator_list.iter().any(|exp| {
            if let rExpr::Name(nam) = exp {
                if nam.id.to_string() == "dataclass" {
                    return true;
                }
            }
            false
        });

        let iden = class.name.to_string();
        let mut adt = Adt {
            ctrs: IndexMap::new(),
            builtin: false,
        };

        if is_dataclass {
            for stmt in &class.body {
                match stmt {
                    rStmt::AnnAssign(assign) => {
                        let mut target = String::default();
                        if let rExpr::Name(nam) = *assign.target.clone() {
                            target = nam.id.to_string();
                        }

                        let ctr_field = CtrField {
                            nam: Name::new(target),
                            rec: true,
                        };

                        let new_name = Name::new(iden.to_string());

                        match adt.ctrs.get_mut(&new_name) {
                            Some(vec) => {
                                vec.push(ctr_field);
                            }
                            None => {
                                adt.ctrs
                                    .insert(new_name.clone(), vec![ctr_field]);
                            }
                        }
                    }
                    _ => todo!(),
                }
            }
            self.add_adt(Name::new(iden.clone()), adt);
        }
    }

    fn parse_type_alias(&mut self, assign: &StmtAssign) {
        let iden = assign.targets.first().unwrap();

        let name: String;

        if let rExpr::Name(iden) = iden {
            name = iden.id.to_string();
            let mut adt = Adt {
                ctrs: IndexMap::new(),
                builtin: false,
            };

            let body = self.parse_expr_type(*assign.value.clone());

            if let Some(FromExpr::CtrField(ctr)) = body {
                for ct in ctr.clone() {
                    let new_ctr = self.book.ctrs.swap_remove(&ct.nam);

                    let new_adt = self.book.adts.swap_remove(&new_ctr.unwrap());

                    let mut ctrs: Vec<CtrField> = vec![];
                    for ca in new_adt.unwrap().ctrs.values() {
                        for i in ca {
                            ctrs.push(i.clone());
                        }
                    }

                    adt.ctrs.insert(
                        Name::new(format!("{}/{}", name, ct.nam)),
                        ctrs.clone(),
                    );
                }
            }

            self.add_adt(Name::new(name), adt);
        }
    }

    fn parse_function_def(&mut self, fun_def: &StmtFunctionDef) {
        let args = *fun_def.args.clone();
        let mut names: Vec<Name> = vec![];

        for arg in args.args {
            names.push(Name::new(arg.def.arg.to_string()));
        }

        let expr = self.parse_vec(&fun_def.body, 0);

        if let Some(FromExpr::Statement(e)) = expr {
            let def = imp::Definition {
                name: Name::new(fun_def.name.to_string()),
                params: names,
                body: e,
            };
            self.definitions.push(def);
        }
    }

    // Main function of the library, it parses the Python Module
    pub fn parse(
        &mut self,
        fun: &str,
        py_args: &[String],
    ) -> Result<String, String> {
        for stmt in self.statements.clone() {
            match stmt {
                rStmt::FunctionDef(fun_def) => {
                    self.parse_function_def(&fun_def)
                }
                // Treats an type alias, example: Type = A | B
                rStmt::Assign(assign) => self.parse_type_alias(&assign),
                // Treats an dataclass case
                rStmt::ClassDef(class) => self.parse_class_def(&class),
                _ => {}
            }
        }

        // Turns all the parsed functions into Bend functional representation
        for def in &self.definitions {
            let fun_def = def.clone().to_fun(false).unwrap();
            self.book.defs.insert(fun_def.name.clone(), fun_def.clone());
        }

        let main_def = self.parse_main(fun, py_args).unwrap();

        self.book
            .defs
            .insert(Name::new("main"), main_def.to_fun(true).unwrap());

        self.book.entrypoint = None;

        //println!("BEND:\n {}", self.book.display_pretty());

        let return_val = run(&self.book, "run");

        match return_val {
            Ok(val) => match val {
                Some(val) => Ok(val.0.to_string()),
                None => Err(String::from("Could not parse HVM output")),
            },

            Err(e) => Err(e.to_string()),
        }
    }
}