solar_parse/parser/

stmt.rs

use super::item::VarFlags;
use crate::{PResult, Parser, parser::SeqSep};
use smallvec::SmallVec;
use solar_ast::{token::*, *};
use solar_data_structures::CollectAndApply;
use solar_interface::{Ident, Span, SpannedOption, Symbol, kw, sym};

impl<'sess, 'ast, 'cb> Parser<'sess, 'ast, 'cb> {
    /// Parses a statement.
    #[instrument(level = "trace", skip_all)]
    pub fn parse_stmt(&mut self) -> PResult<'sess, Stmt<'ast>> {
        self.with_recursion_limit("statement", |this| {
            let docs = this.parse_doc_comments();
            this.parse_spanned(Self::parse_stmt_kind).map(|(span, kind)| Stmt { docs, kind, span })
        })
    }

    /// Parses a statement into a new allocation.
    pub fn parse_stmt_boxed(&mut self) -> PResult<'sess, Box<'ast, Stmt<'ast>>> {
        self.parse_stmt().map(|stmt| self.alloc(stmt))
    }

    /// Parses a statement kind.
    fn parse_stmt_kind(&mut self) -> PResult<'sess, StmtKind<'ast>> {
        let mut semi = true;
        let kind = if self.eat_keyword(kw::If) {
            semi = false;
            self.parse_stmt_if()
        } else if self.eat_keyword(kw::While) {
            semi = false;
            self.parse_stmt_while()
        } else if self.eat_keyword(kw::Do) {
            self.parse_stmt_do_while()
        } else if self.eat_keyword(kw::For) {
            semi = false;
            self.parse_stmt_for()
        } else if self.eat_keyword(kw::Unchecked) {
            semi = false;
            self.parse_block().map(StmtKind::UncheckedBlock)
        } else if self.check(TokenKind::OpenDelim(Delimiter::Brace)) {
            semi = false;
            self.parse_block().map(StmtKind::Block)
        } else if self.eat_keyword(kw::Continue) {
            Ok(StmtKind::Continue)
        } else if self.eat_keyword(kw::Break) {
            Ok(StmtKind::Break)
        } else if self.eat_keyword(kw::Return) {
            let expr = if self.check(TokenKind::Semi) { None } else { Some(self.parse_expr()?) };
            Ok(StmtKind::Return(expr))
        } else if self.eat_keyword(kw::Throw) {
            let msg = "`throw` statements have been removed; use `revert`, `require`, or `assert` instead";
            Err(self.dcx().err(msg).span(self.prev_token.span))
        } else if self.eat_keyword(kw::Try) {
            semi = false;
            self.parse_stmt_try().map(|stmt| StmtKind::Try(self.alloc(stmt)))
        } else if self.eat_keyword(kw::Assembly) {
            semi = false;
            self.parse_stmt_assembly().map(StmtKind::Assembly)
        } else if self.eat_keyword(kw::Emit) {
            self.parse_path_call().map(|(path, params)| StmtKind::Emit(path, params))
        } else if self.check_keyword(kw::Revert) && self.look_ahead(1).is_ident() {
            self.bump(); // `revert`
            self.parse_path_call().map(|(path, params)| StmtKind::Revert(path, params))
        } else if self.check_keyword(sym::underscore) && self.look_ahead(1).kind == TokenKind::Semi
        {
            self.bump(); // `_`
            Ok(StmtKind::Placeholder)
        } else {
            self.parse_simple_stmt_kind()
        };
        if semi && kind.is_ok() {
            self.expect_semi()?;
        }
        kind
    }

    /// Parses a block of statements.
    pub(super) fn parse_block(&mut self) -> PResult<'sess, Block<'ast>> {
        let lo = self.token.span;
        self.parse_delim_seq(Delimiter::Brace, SeqSep::none(), true, Self::parse_stmt)
            .map(|stmts| Block { span: lo.to(self.prev_token.span), stmts })
    }

    /// Parses an if statement.
    fn parse_stmt_if(&mut self) -> PResult<'sess, StmtKind<'ast>> {
        self.expect(TokenKind::OpenDelim(Delimiter::Parenthesis))?;
        let expr = self.parse_expr()?;
        self.expect(TokenKind::CloseDelim(Delimiter::Parenthesis))?;
        let true_stmt = self.parse_stmt()?;
        let else_stmt =
            if self.eat_keyword(kw::Else) { Some(self.parse_stmt_boxed()?) } else { None };
        Ok(StmtKind::If(expr, self.alloc(true_stmt), else_stmt))
    }

    /// Parses a while statement.
    fn parse_stmt_while(&mut self) -> PResult<'sess, StmtKind<'ast>> {
        self.expect(TokenKind::OpenDelim(Delimiter::Parenthesis))?;
        let expr = self.parse_expr()?;
        self.expect(TokenKind::CloseDelim(Delimiter::Parenthesis))?;
        let stmt = self.parse_stmt()?;
        Ok(StmtKind::While(expr, self.alloc(stmt)))
    }

    /// Parses a do-while statement.
    fn parse_stmt_do_while(&mut self) -> PResult<'sess, StmtKind<'ast>> {
        let stmt = self.parse_stmt()?;
        let stmt = self.alloc(stmt);
        self.expect_keyword(kw::While)?;
        self.expect(TokenKind::OpenDelim(Delimiter::Parenthesis))?;
        let expr = self.parse_expr()?;
        self.expect(TokenKind::CloseDelim(Delimiter::Parenthesis))?;
        Ok(StmtKind::DoWhile(stmt, expr))
    }

    /// Parses a for statement.
    fn parse_stmt_for(&mut self) -> PResult<'sess, StmtKind<'ast>> {
        self.expect(TokenKind::OpenDelim(Delimiter::Parenthesis))?;

        let init = if self.check(TokenKind::Semi) { None } else { Some(self.parse_simple_stmt()?) };
        self.expect(TokenKind::Semi)?;

        let cond = if self.check(TokenKind::Semi) { None } else { Some(self.parse_expr()?) };
        self.expect_semi()?;

        let next = if self.check_noexpect(TokenKind::CloseDelim(Delimiter::Parenthesis)) {
            None
        } else {
            Some(self.parse_expr()?)
        };
        self.expect(TokenKind::CloseDelim(Delimiter::Parenthesis))?;
        let body = self.parse_stmt_boxed()?;
        Ok(StmtKind::For { init: init.map(|init| self.alloc(init)), cond, next, body })
    }

    /// Parses a try statement.
    fn parse_stmt_try(&mut self) -> PResult<'sess, StmtTry<'ast>> {
        let expr = self.parse_expr()?;
        let mut clauses = SmallVec::<[_; 4]>::new();

        let mut lo = self.token.span;
        let returns = if self.eat_keyword(kw::Returns) {
            self.parse_parameter_list(false, VarFlags::FUNCTION)?
        } else {
            Default::default()
        };
        let block = self.parse_block()?;
        let span = lo.to(self.prev_token.span);
        clauses.push(TryCatchClause { name: None, args: returns, block, span });

        lo = self.token.span;
        self.expect_keyword(kw::Catch)?;
        loop {
            let name = self.parse_ident_opt()?;
            let args = if self.check(TokenKind::OpenDelim(Delimiter::Parenthesis)) {
                self.parse_parameter_list(false, VarFlags::FUNCTION)?
            } else {
                Default::default()
            };
            let block = self.parse_block()?;
            let span = lo.to(self.prev_token.span);
            clauses.push(TryCatchClause { name, args, block, span });
            lo = self.token.span;
            if !self.eat_keyword(kw::Catch) {
                break;
            }
        }

        let clauses = self.alloc_smallvec(clauses);
        Ok(StmtTry { expr, clauses })
    }

    /// Parses an assembly block.
    fn parse_stmt_assembly(&mut self) -> PResult<'sess, StmtAssembly<'ast>> {
        let dialect = self.parse_str_lit_opt();
        let flags = if self.check(TokenKind::OpenDelim(Delimiter::Parenthesis)) {
            self.parse_paren_comma_seq(false, Self::parse_str_lit)?
        } else {
            Default::default()
        };
        let block = self.parse_yul_block()?;
        Ok(StmtAssembly { dialect, flags, block })
    }

    /// Parses a simple statement. These are just variable declarations and expressions.
    fn parse_simple_stmt(&mut self) -> PResult<'sess, Stmt<'ast>> {
        let docs = self.parse_doc_comments();
        self.parse_spanned(Self::parse_simple_stmt_kind).map(|(span, kind)| Stmt {
            docs,
            kind,
            span,
        })
    }

    /// Parses a simple statement kind. These are just variable declarations and expressions.
    ///
    /// Also used in the for loop initializer. Does not parse the trailing semicolon.
    fn parse_simple_stmt_kind(&mut self) -> PResult<'sess, StmtKind<'ast>> {
        let lo = self.token.span;
        if self.eat(TokenKind::OpenDelim(Delimiter::Parenthesis)) {
            let mut none_elements = SmallVec::<[_; 8]>::new();
            while self.eat(TokenKind::Comma) {
                none_elements.push(self.prev_token.span.shrink_to_hi());
            }

            let (statement_type, iap) = self.try_parse_iap()?;
            match statement_type {
                LookAheadInfo::VariableDeclaration => {
                    let mut variables = none_elements
                        .into_iter()
                        .map(SpannedOption::None)
                        .collect::<SmallVec<[_; 8]>>();
                    let ty = iap.into_ty(self);
                    variables.push(SpannedOption::Some(
                        self.parse_variable_definition_with(VarFlags::FUNCTION, ty)?,
                    ));
                    self.parse_optional_items_seq_required(
                        Delimiter::Parenthesis,
                        &mut variables,
                        |this| this.parse_variable_definition(VarFlags::FUNCTION),
                    )?;
                    self.expect(TokenKind::Eq)?;
                    let expr = self.parse_expr()?;
                    Ok(StmtKind::DeclMulti(self.alloc_smallvec(variables), expr))
                }
                LookAheadInfo::Expression => {
                    let mut components = none_elements
                        .into_iter()
                        .map(SpannedOption::None)
                        .collect::<SmallVec<[_; 8]>>();
                    let expr = iap.into_expr(self);
                    components.push(SpannedOption::Some(self.parse_expr_with(expr)?));
                    self.parse_optional_items_seq_required(
                        Delimiter::Parenthesis,
                        &mut components,
                        Self::parse_expr,
                    )?;
                    let partially_parsed = Expr {
                        span: lo.to(self.prev_token.span),
                        kind: ExprKind::Tuple(self.alloc_smallvec(components)),
                    };
                    self.parse_expr_with(Some(self.alloc(partially_parsed))).map(StmtKind::Expr)
                }
                LookAheadInfo::IndexAccessStructure => unreachable!(),
            }
        } else {
            let (statement_type, iap) = self.try_parse_iap()?;
            match statement_type {
                LookAheadInfo::VariableDeclaration => {
                    let ty = iap.into_ty(self);
                    self.parse_variable_definition_with(VarFlags::VAR, ty)
                        .map(|var| StmtKind::DeclSingle(self.alloc(var)))
                }
                LookAheadInfo::Expression => {
                    let expr = iap.into_expr(self);
                    self.parse_expr_with(expr).map(StmtKind::Expr)
                }
                LookAheadInfo::IndexAccessStructure => unreachable!(),
            }
        }
    }

    /// Parses a `delim`-delimited, comma-separated list of maybe-optional items.
    /// E.g. `(a, b) => [Some, Some]`, `(, a,, b,) => [None, Some, None, Some, None]`.
    ///
    /// All elements are wrapped in a `SpannedOption<T>`, so that even for uninformed elements,
    /// AST consumers can be aware of the location of the separators.
    pub(super) fn parse_optional_items_seq<T>(
        &mut self,
        delim: Delimiter,
        mut f: impl FnMut(&mut Self) -> PResult<'sess, T>,
    ) -> PResult<'sess, SmallVec<[SpannedOption<T>; 8]>> {
        self.expect(TokenKind::OpenDelim(delim))?;

        let mut out = SmallVec::<[_; 8]>::new();

        // Handle leading commas, e.g., `(, a, b)`.
        while self.eat(TokenKind::Comma) {
            out.push(SpannedOption::None(self.prev_token.span.shrink_to_lo()));
        }

        // Handle the first potential item. If the list is not closing,
        // we assume there's at least one item.
        if !self.check(TokenKind::CloseDelim(delim)) {
            out.push(SpannedOption::Some(f(self)?));
        }

        // Call the helper to parse the rest of the sequence.
        self.parse_optional_items_seq_required(delim, &mut out, f)?;
        Ok(out)
    }

    fn parse_optional_items_seq_required<T>(
        &mut self,
        delim: Delimiter,
        out: &mut SmallVec<[SpannedOption<T>; 8]>,
        mut f: impl FnMut(&mut Self) -> PResult<'sess, T>,
    ) -> PResult<'sess, ()> {
        let (comma, close) = (TokenKind::Comma, TokenKind::CloseDelim(delim));

        // Handle early close delimiter.
        if self.eat(close) {
            return Ok(());
        }

        // Expect comma separator.
        self.expect(comma)?;

        // Handle subsequent elements until finding the close token.
        loop {
            let item = if self.check(comma) || self.check(close) { None } else { Some(f(self)?) };
            if self.eat(comma) {
                let element = match item {
                    Some(val) => SpannedOption::Some(val),
                    None => SpannedOption::None(self.prev_token.span.shrink_to_lo()),
                };
                out.push(element);
            } else if self.eat(close) {
                let element = match item {
                    Some(val) => SpannedOption::Some(val),
                    None => SpannedOption::None(self.prev_token.span.shrink_to_lo()),
                };
                out.push(element);
                return Ok(());
            } else {
                return self.unexpected();
            }
        }
    }

    /// Parses a path and a list of call arguments.
    fn parse_path_call(&mut self) -> PResult<'sess, (AstPath<'ast>, CallArgs<'ast>)> {
        let path = self.parse_path()?;
        let params = self.parse_call_args()?;
        Ok((path, params))
    }

    /// Never returns `LookAheadInfo::IndexAccessStructure`.
    fn try_parse_iap(&mut self) -> PResult<'sess, (LookAheadInfo, IndexAccessedPath<'ast>)> {
        // https://github.com/argotorg/solidity/blob/194b114664c7daebc2ff68af3c573272f5d28913/libsolidity/parsing/Parser.cpp#L1961
        if let ty @ (LookAheadInfo::VariableDeclaration | LookAheadInfo::Expression) =
            self.peek_statement_type()
        {
            return Ok((ty, IndexAccessedPath::default()));
        }

        let iap = self.parse_iap()?;
        let ty = if self.token.is_non_reserved_ident(self.in_yul)
            || self.token.is_location_specifier()
        {
            // `a.b memory`, `a[b] c`
            LookAheadInfo::VariableDeclaration
        } else {
            LookAheadInfo::Expression
        };
        Ok((ty, iap))
    }

    fn peek_statement_type(&mut self) -> LookAheadInfo {
        // https://github.com/argotorg/solidity/blob/194b114664c7daebc2ff68af3c573272f5d28913/libsolidity/parsing/Parser.cpp#L2528
        if self.token.is_keyword_any(&[kw::Mapping, kw::Function]) {
            return LookAheadInfo::VariableDeclaration;
        }

        if self.check_nr_ident() || self.check_elementary_type() {
            let next = self.look_ahead(1);
            if self.token.is_elementary_type() && next.is_ident_where(|id| id.name == kw::Payable) {
                return LookAheadInfo::VariableDeclaration;
            }
            if next.is_non_reserved_ident(self.in_yul)
                || next.is_location_specifier()
                // These aren't valid but we include them for a better error message.
                || next.is_mutability_specifier()
                || next.is_visibility_specifier()
            {
                return LookAheadInfo::VariableDeclaration;
            }
            if matches!(next.kind, TokenKind::OpenDelim(Delimiter::Bracket) | TokenKind::Dot) {
                return LookAheadInfo::IndexAccessStructure;
            }
        }
        LookAheadInfo::Expression
    }

    fn parse_iap(&mut self) -> PResult<'sess, IndexAccessedPath<'ast>> {
        // https://github.com/argotorg/solidity/blob/194b114664c7daebc2ff68af3c573272f5d28913/libsolidity/parsing/Parser.cpp#L2559
        let mut path = SmallVec::<[_; 4]>::new();
        if self.check_nr_ident() {
            path.push(IapKind::Member(self.parse_ident()?));
            while self.eat(TokenKind::Dot) {
                let id = match self.ident_or_err(true) {
                    Ok(id) => id,
                    Err(err) => {
                        err.emit();
                        path.push(IapKind::Member(Ident::new(
                            Symbol::DUMMY,
                            self.prev_token.span.shrink_to_hi(),
                        )));
                        break;
                    }
                };
                if id.name != kw::Address && id.is_reserved(self.in_yul) {
                    self.expected_ident_found_err().emit();
                }
                self.bump(); // `id`
                path.push(IapKind::Member(id));
            }
        } else if self.check_elementary_type() {
            let (span, kind) = self.parse_spanned(Self::parse_elementary_type)?;
            path.push(IapKind::MemberTy(span, kind));
        } else {
            return self.unexpected();
        }
        let n_idents = path
            .iter()
            .take_while(|kind| matches!(kind, IapKind::Member(_) | IapKind::MemberTy(..)))
            .count();

        while self.check(TokenKind::OpenDelim(Delimiter::Bracket)) {
            let (span, kind) = self.parse_spanned(Self::parse_expr_index_kind)?;
            path.push(IapKind::Index(span, kind));
        }

        Ok(IndexAccessedPath { path, n_idents })
    }
}

#[derive(Debug)]
enum LookAheadInfo {
    /// `a.b`, `a[b]`
    IndexAccessStructure,
    VariableDeclaration,
    Expression,
}

#[derive(Debug)]
enum IapKind<'ast> {
    /// `[...]`
    Index(Span, IndexKind<'ast>),
    /// `<ident>` or `.<ident>`
    Member(Ident),
    /// `<ty>`
    MemberTy(Span, ElementaryType),
}

#[derive(Debug, Default)]
struct IndexAccessedPath<'ast> {
    path: SmallVec<[IapKind<'ast>; 4]>,
    /// The number of elements in `path` that are `IapKind::Member[Ty]` at the start.
    n_idents: usize,
}

impl<'ast> IndexAccessedPath<'ast> {
    fn into_ty(self, parser: &mut Parser<'_, 'ast, '_>) -> Option<Type<'ast>> {
        // https://github.com/argotorg/solidity/blob/194b114664c7daebc2ff68af3c573272f5d28913/libsolidity/parsing/Parser.cpp#L2617
        let mut path = self.path.into_iter();
        let first = path.next()?;

        let mut ty = if let IapKind::MemberTy(span, kind) = first {
            debug_assert_eq!(self.n_idents, 1);
            Type { span, kind: TypeKind::Elementary(kind) }
        } else {
            debug_assert!(self.n_idents >= 1);
            let first = std::iter::once(&first);
            let path = first
                .chain(path.as_slice())
                .map(|x| match x {
                    IapKind::Member(id) => *id,
                    kind => unreachable!("{kind:?}"),
                })
                .take(self.n_idents);
            let path = CollectAndApply::collect_and_apply(path, |path| parser.alloc_path(path));
            Type { span: path.span(), kind: TypeKind::Custom(path) }
        };

        for index in path.skip(self.n_idents - 1) {
            let (span, kind) = match index {
                IapKind::Index(span, kind) => (span, kind),
                IapKind::Member(_) | IapKind::MemberTy(..) => panic!("parsed too much"),
            };
            let size = match kind {
                IndexKind::Index(expr) => expr,
                IndexKind::Range(l, r) => {
                    let msg = "expected array length, got range expression";
                    parser.dcx().emit_err(span, msg);
                    l.or(r)
                }
            };
            let span = ty.span.to(span);
            ty =
                Type { span, kind: TypeKind::Array(parser.alloc(TypeArray { element: ty, size })) };
        }

        Some(ty)
    }

    fn into_expr(self, parser: &mut Parser<'_, 'ast, '_>) -> Option<Box<'ast, Expr<'ast>>> {
        // https://github.com/argotorg/solidity/blob/194b114664c7daebc2ff68af3c573272f5d28913/libsolidity/parsing/Parser.cpp#L2658
        let mut path = self.path.into_iter();

        let mut expr = parser.alloc(match path.next()? {
            IapKind::Member(ident) => Expr::from_ident(ident),
            IapKind::MemberTy(span, kind) => {
                Expr { span, kind: ExprKind::Type(Type { span, kind: TypeKind::Elementary(kind) }) }
            }
            IapKind::Index(..) => panic!("should not happen"),
        });
        for index in path {
            expr = parser.alloc(match index {
                IapKind::Member(ident) => {
                    Expr { span: expr.span.to(ident.span), kind: ExprKind::Member(expr, ident) }
                }
                IapKind::MemberTy(..) => panic!("should not happen"),
                IapKind::Index(span, kind) => {
                    Expr { span: expr.span.to(span), kind: ExprKind::Index(expr, kind) }
                }
            });
        }
        Some(expr)
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use solar_interface::{Result, Session, source_map::FileName};

    #[test]
    fn optional_items_seq() {
        #[allow(clippy::type_complexity)]
        fn check(tests: &[(&str, &[Option<&str>])]) {
            let sess = Session::builder().with_test_emitter().single_threaded().build();
            sess.enter_sequential(|| -> Result {
                for &(s, results) in tests.iter() {
                    let name = s.to_string();
                    let arena = Arena::new();
                    let mut parser =
                        Parser::from_source_code(&sess, &arena, FileName::Custom(name), s)?;

                    let list = parser
                        .parse_optional_items_seq(Delimiter::Parenthesis, Parser::parse_ident)
                        .map_err(|e| e.emit())
                        .unwrap_or_else(|_| panic!("src: {s:?}"));
                    sess.dcx.has_errors().unwrap();

                    let formatted: Vec<_> = list
                        .iter()
                        .map(|item| match item {
                            SpannedOption::Some(ident) => {
                                let data = Some(ident.as_str());
                                let snip = sess.source_map().span_to_snippet(ident.span).unwrap();
                                (data, snip)
                            }
                            SpannedOption::None(span) => {
                                let data = None;
                                let snip = sess.source_map().span_to_snippet(*span).unwrap();
                                (data, snip)
                            }
                        })
                        .collect();

                    // Format the expected results for comparison
                    let expected: Vec<_> = results
                        .iter()
                        .map(|&data| (data, data.unwrap_or("").to_string()))
                        .collect();

                    assert_eq!(formatted, expected, "{s:?}");
                }
                Ok(())
            })
            .unwrap();
        }

        check(&[
            ("()", &[]),
            ("(a)", &[Some("a")]),
            // invalid syntax
            // ("(,)", &[None, None]),
            ("(a,)", &[Some("a"), None]),
            ("(,b)", &[None, Some("b")]),
            ("(a,b)", &[Some("a"), Some("b")]),
            ("(a,b,)", &[Some("a"), Some("b"), None]),
            // invalid syntax
            // ("(,,)", &[None, None, None]),
            ("(a,,)", &[Some("a"), None, None]),
            ("(a,b,)", &[Some("a"), Some("b"), None]),
            ("(a,b,c)", &[Some("a"), Some("b"), Some("c")]),
            ("(,b,c)", &[None, Some("b"), Some("c")]),
            ("(,,c)", &[None, None, Some("c")]),
            ("(a,,c)", &[Some("a"), None, Some("c")]),
        ]);
    }
}