skullbrain-parser 0.1.0

#![allow(missing_docs)]
use cstree::interning::{Resolver, TokenKey};
use skullbrain_lexer::ModifierKind;

use crate::cst::utils::children;

use super::*;

define_cst_node! {
    /// A `break` statement.
    pub struct Break {
        kind: SyntaxKind::LoopBreak,
        child: [optional_expr => Expr],
        tokens : [
            /// A `break` token
            break_token BreakToken => SyntaxKind::Keyword
        ],
    }
}

define_cst_node! {
    /// A `continue` statement.
    pub struct Continue {
        kind: SyntaxKind::LoopContinue,
        tokens: [
            /// A `continue` token
            continue_token ContinueToken => SyntaxKind::Keyword
        ],
    }
}

define_cst_node! {
    /// A `return` statement.
    pub struct Return {
        kind: SyntaxKind::Return,
        child: [optional_expr => Expr],
        tokens: [
            /// A `return` token
            return_token ReturnToken => SyntaxKind::Keyword
        ],
    }
}

define_cst_node! {
    /// A `throw` statement.
    pub struct Throw {
        kind: SyntaxKind::ThrowError,
        child: [expr => Expr],
        tokens: [
            /// A `throw` token
            throw_token ThrowToken => SyntaxKind::Keyword
        ],
    }
}

define_cst_node! {
    /// A block expr
    pub struct BlockExpr {
        kind : SyntaxKind::DelimitedRange,
        nogen tokens: [
            open_token OpenBraceToken => SyntaxKind::OpenBrace,
            close_token CloseBraceToken => SyntaxKind::CloseBrace
        ],
    }
}

impl BlockExpr {
    /// All the child statements (top-level `Expr` nodes) in this block.
    pub fn exprs(&self) -> impl Iterator<Item = Expr> + use<'_> {
        // skip the delimiters and cast each inner element
        self.syntax.children_with_tokens().map(Expr::cast_element)
    }
}
define_cst_node! {
    ///
    pub struct ParenExpr {
        kind : SyntaxKind::DelimitedRange,
        nogen tokens: [
            open_token OpenParenToken => SyntaxKind::OpenParen,
            close_token CloseParenToken => SyntaxKind::CloseParen
        ],
    }
}

impl ParenExpr {
    /// All the expressions inside the parentheses.
    pub fn exprs(&self) -> impl Iterator<Item = Expr> + use<'_> {
        self.syntax.children_with_tokens().map(Expr::cast_element)
    }
}

define_cst_node! {
    /// A type .
    pub struct Type {
        kind: SyntaxKind::Type,
        nogen tokens: [
            ident IdentToken => SyntaxKind::Ident
        ],
        forward: [
            signature SyntaxKind::FunctionSignature => FunctionSignature
        ],
    }
}

define_cst_node! {
    /// A function signature .
    pub struct FunctionSignature {
        kind : SyntaxKind::FunctionSignature,
        child : [return_ty => Type],
        tokens: [
            /// A `->` token
            return_ty_token ReturnTypeToken => SyntaxKind::Arrow
        ],
    }
}

define_cst_node! {
    /// Wrapper around the `ParenRange` to iterate `Parameter`.
    pub struct Parameters {}
}

impl FunctionSignature {
    ///
    pub fn parameters(&self) -> Option<Parameters> {
        utils::child::<ParenRange>(&self.syntax).map(|paren| Parameters {
            syntax: paren.syntax,
        })
    }

    ///
    pub fn open_brace_token(&self) -> Option<OpenParenToken> {
        utils::child::<ParenRange>(&self.syntax)?.open_token()
    }

    ///
    pub fn close_brace_token(&self) -> Option<CloseParenToken> {
        utils::child::<ParenRange>(&self.syntax)?.close_token()
    }
}

///
pub enum CommaSeperated<T> {
    Comma(CommaToken),
    Item(T),
}

impl Parameters {
    /// Iterate each `Parameter` inside `( ... )`.
    pub fn iter(&self) -> impl Iterator<Item = CommaSeperated<Parameter>> + '_ {
        self.syntax
            .children_with_tokens()
            .filter_map(|it| match it {
                cstree::util::NodeOrToken::Node(node) if Parameter::can_cast(node.kind()) => {
                    let Some(item) = Parameter::cast(node.clone()) else {
                        unreachable!()
                    };

                    Some(CommaSeperated::Item(item))
                }
                cstree::util::NodeOrToken::Token(tok) if CommaToken::can_cast(tok.kind()) => {
                    let Some(comma) = CommaToken::cast(tok.clone()) else {
                        unreachable!()
                    };

                    Some(CommaSeperated::Comma(comma))
                }
                _ => None,
            })
    }
}

define_cst_node! {
    /// A `while` loop.
    pub struct While {
        kind: SyntaxKind::WhileLoop,
        tokens: [
            /// A `while` token
            while_token WhileToken => SyntaxKind::Keyword
        ],
        forward: [
            body SyntaxKind::Body => BlockExpr,
            condition SyntaxKind::Condition => ParenExpr
        ],
    }
}

define_cst_node! {
    /// A `for (...) { … }` loop.
    pub struct ForLoop {
        kind: SyntaxKind::ForLoop,
    }
}

define_cst_token! {
    ///
    pub struct ForIterOpenToken { kind : SyntaxKind::ForIterOpen}
}

define_cst_token! {
    ///
    pub struct ForIterCloseToken { kind : SyntaxKind::ForIterClose}
}

impl ForLoop {
    ///
    pub fn open_token(&self) -> Option<ForIterOpenToken> {
        let value = children::<ParenRange>(&self.syntax).next()?.syntax;
        utils::token::<ForIterOpenToken>(&value, SyntaxKind::ForIterOpen)
    }
    ///
    pub fn close_token(&self) -> Option<ForIterCloseToken> {
        let value = children::<ParenRange>(&self.syntax).next()?.syntax;
        utils::token::<ForIterCloseToken>(&value, SyntaxKind::ForIterClose)
    }

    ///
    pub fn body(&self) -> Option<BlockExpr> {
        children(&self.syntax).last()
    }

    ///
    pub fn iter(&self) -> Option<ParenExpr> {
        children(&self.syntax).next()
    }
}

define_cst_node! {
    /// A `try { … } catch { … }` block.
    pub struct TryCatch {
        kind: SyntaxKind::TryCatch,
        child: [try_arm => TryArm],
    }
}

define_cst_node! {
    /// A `try { ... }  arm.
    pub struct TryArm {
        kind : SyntaxKind::Try,
        child:[block => BlockExpr],
        tokens:[
            /// A `try` token
            try_token TryToken => SyntaxKind::Keyword
        ],
    }
}

define_cst_node! {
    /// A `catch <TYPE> { … }` arm.
    pub struct CatchArm {
        kind : SyntaxKind::Catch,
        child:[catch_ty => CatchType,block => BlockExpr],
        tokens:[
            /// A `catch` token
            catch_token CatchToken => SyntaxKind::Keyword
        ],
    }
}

define_cst_node! {
    /// The <TYPE> part in a  `catch <TYPE> { … }` arm.
    pub struct CatchType {
        kind : SyntaxKind::Parameter,
        child : [ty => Type,try_arm => TryArm],
        nogen tokens : [
            name IdentToken => SyntaxKind::Ident,
            colon_token ColonToken => SyntaxKind::Colon
        ],
    }
}

impl TryCatch {
    ///
    pub fn catch_arms(&self) -> impl Iterator<Item = CatchArm> + use<'_> {
        utils::children::<CatchArm>(&self.syntax)
    }
}

define_cst_node! {
    /// A type alias declaration.
    pub struct TypeAlias {
        kind: SyntaxKind::TypeAlias,
        child : [modifiers => Modifiers,aliased => Type],
        tokens: [
            /// A `alias` token
            alias_token AliasToken => SyntaxKind::Keyword
        ],
        nogen tokens: [
            assignment_token AssignmentToken => SyntaxKind::Assignment,
            name IdentToken => SyntaxKind::Ident
        ],
    }
}

define_cst_node! {
    /// A variable declaration.
    pub struct VariableStmt {
        kind: SyntaxKind::VariableDeclaration,
        child:[modifiers => Modifiers,initialiser => BlockExpr],
    }
}
impl VariableStmt {
    ///
    pub fn name(&self) -> Option<IdentToken> {
        Parameter::forward_name_from(&self.syntax)
    }

    ///
    pub fn ty(&self) -> Option<Type> {
        Parameter::forward_type_from(&self.syntax)
    }

    ///
    pub fn var_token(&self) -> VariableToken {
        let Some(tok) = utils::token_with(&self.syntax, |k| {
            matches!(
                k,
                SyntaxKind::MutableVariableKeyword | SyntaxKind::ImmutableVariableKeyword
            )
        }) else {
            unreachable!()
        };

        VariableToken { token: tok.clone() }
    }
}

define_cst_token! {
    /// A `var` token
    pub struct VariableToken {}
}

impl VariableToken {
    ///
    pub fn is_mutable(&self) -> bool {
        matches!(self.token.kind(), SyntaxKind::MutableVariableKeyword)
    }
}

impl CstToken for VariableToken {
    fn can_cast(kind: SyntaxKind) -> bool {
        matches!(
            kind,
            SyntaxKind::MutableVariableKeyword | SyntaxKind::ImmutableVariableKeyword
        )
    }

    fn cast(token: SyntaxToken) -> Option<Self> {
        Self::can_cast(token.kind()).then(|| Self { token })
    }

    fn token(&self) -> &SyntaxToken {
        &self.token
    }
}

define_cst_node! {
    /// A function parameter
    pub struct Parameter {
        kind: SyntaxKind::Parameter,
        child :[ty => Type],

        nogen tokens: [
            name IdentToken => SyntaxKind::Ident,
            colon_token ColonToken => SyntaxKind::Colon
        ],
    }
}

impl Parameter {
    fn forward_name_from(syntax: &SyntaxNode) -> Option<IdentToken> {
        utils::child::<Parameter>(&syntax)?.name()
    }

    fn forward_type_from(syntax: &SyntaxNode) -> Option<Type> {
        utils::child::<Parameter>(&syntax)?.ty()
    }
}

define_cst_node! {
    ///
    pub struct BinaryExpr {
        forward: [
            lhs SyntaxKind::Lhs => Expr,
            rhs SyntaxKind::Rhs => Expr
        ],
    }
}

define_cst_token! {
    ///
    pub struct BinaryOp {}
}

impl BinaryExpr {
    ///
    pub fn operator(&self) -> BinaryOp {
        use SyntaxKind::*;
        const fn is_op(it: SyntaxKind) -> bool {
            matches!(
                it,
                OpEq | OpNotEq
                    | OpLt
                    | OpGt
                    | OpLtEq
                    | OpGtEq
                    | OpAnd
                    | OpOr
                    | OpMinus
                    | OpPlus
                    | OpMul
                    | OpDivide
                    | OpMod
            )
        }

        let Some(tok) = utils::token_with(&self.syntax, is_op) else {
            unreachable!()
        };

        BinaryOp { token: tok.clone() }
    }
}

define_cst_node! {
    ///
    pub struct UnaryExpr {
        forward: [
            expr SyntaxKind::Rhs => Expr
        ],
    }
}

define_cst_token! {
    ///
    pub struct UnaryOp {}
}

impl UnaryExpr {
    ///
    pub fn operator(&self) -> UnaryOp {
        use SyntaxKind::*;
        const fn is_op(it: SyntaxKind) -> bool {
            matches!(it, OpMinus | OpNot)
        }

        let Some(tok) = utils::token_with(&self.syntax, is_op) else {
            unreachable!()
        };

        UnaryOp { token: tok.clone() }
    }
}

define_cst_node! {
    ///
    pub struct ChainExpr {
        tokens : [
            /// A `.` token
            chaining_token ChainingToken => SyntaxKind::OpMethodChaining
        ],
        forward: [
            object SyntaxKind::Lhs => Expr,
            method SyntaxKind::Rhs => Expr
        ],
    }
}

define_cst_node! {
    /// An `if (cond) { … }` statement.
    pub struct IfElse {
        kind: SyntaxKind::IfElse,
        child : [if_arm => IfArm],
    }
}

define_cst_node! {
    /// A `if (cond) { ... }  arm.
    pub struct IfArm {
        kind : SyntaxKind::If,
        tokens:[
            /// A 'if' token
            if_token IfToken => SyntaxKind::Keyword],
        forward: [
            body SyntaxKind::Body => BlockExpr,
            condition SyntaxKind::Condition => ParenExpr
        ],
    }
}

define_cst_node! {
    /// A `else { .. }` arm.
    pub struct ElseArm {
        tokens:[
            /// A `else` token
            else_token ElseToken => SyntaxKind::Keyword],
        forward: [
            body SyntaxKind::Body => BlockExpr
        ],
    }
}

define_cst_node! {
    /// A `else if (..) { … }` arm.
    pub struct ElseIfArm {
        forward: [
            body SyntaxKind::Body => BlockExpr,
            condition SyntaxKind::Condition => ParenExpr
        ],
    }
}

///
pub enum ElseBranch {
    ///
    Else(ElseArm),
    ///
    ElseIf(ElseIfArm),
}

impl IfElse {
    ///
    pub fn else_branches(&self) -> impl Iterator<Item = ElseBranch> + use<'_> {
        utils::children::<ElseBranch>(&self.syntax)
    }
}

impl ElseIfArm {
    ///
    pub fn contains_else_if(&self) -> Option<()> {
        let count_of_keywords = self
            .syntax
            .children_with_tokens()
            .filter_map(|it| it.into_token())
            .filter(|n| IdentToken::can_cast(n.kind()))
            .count();

        (count_of_keywords == 2).then_some(())
    }
}

impl CstNode for ElseBranch {
    fn can_cast(kind: SyntaxKind) -> bool {
        matches!(kind, SyntaxKind::Else)
    }

    fn cast(syntax: SyntaxNode) -> Option<Self> {
        if Self::can_cast(syntax.kind()) {
            let count_of_keywords = syntax
                .children_with_tokens()
                .filter_map(|it| it.into_token())
                .filter(|n| IdentToken::can_cast(n.kind()))
                .count();

            let res = match count_of_keywords {
                1 => ElseBranch::Else(ElseArm { syntax }),
                2 => ElseBranch::ElseIf(ElseIfArm { syntax }),
                _ => unreachable!(),
            };

            Some(res)
        } else {
            None
        }
    }

    fn syntax(&self) -> &SyntaxNode {
        match self {
            ElseBranch::Else(else_arm) => &else_arm.syntax,
            ElseBranch::ElseIf(else_if_arm) => &else_if_arm.syntax,
        }
    }
}

define_cst_node! {
    /// A `match` expression.
    pub struct Match {
        kind: SyntaxKind::Match,
        tokens: [
            /// A `match` token
            match_token MatchToken => SyntaxKind::Keyword
        ],
    }
}

define_cst_node! {
    /// A match-arm condition.
    pub struct MatchArmWithCondition {
        kind: SyntaxKind::MatchCondition,
        tokens:[arrow ArrowToken => SyntaxKind::Arrow],
        forward: [
            pat SyntaxKind::Condition => MatchPat,
            body SyntaxKind::DelimitedRange => BlockExpr
        ],
    }
}

define_cst_node! {
    /// A match-arm pattern
    pub struct MatchPat {
        nogen tokens:[
            ident IdentToken => SyntaxKind::Ident,
            lit LiteralToken => SyntaxKind::Literal
        ],
    }
}

define_cst_node! {
    /// A match-arm default case (`_ => …`).
    pub struct MatchArmDefault {
        kind: SyntaxKind::MatchConditionDefault,
        nogen tokens:[arrow ArrowToken => SyntaxKind::Arrow],
        forward: [
            body SyntaxKind::DelimitedRange => BlockExpr
        ],
    }
}

///
pub enum MatchArm {
    /// A match-arm condition.
    WithCondition(MatchArmWithCondition),
    /// A match-arm default case (`_ => …`).
    Default(MatchArmDefault),
}

impl Match {
    ///
    pub fn expr(&self) -> Option<ParenExpr> {
        children(&self.syntax).next()
    }

    fn body(&self) -> Option<&SyntaxNode> {
        self.syntax
            .children()
            .find(|i| BraceRange::can_cast(i.kind()))
    }

    ///
    pub fn body_open_token(&self) -> Option<OpenBraceToken> {
        utils::token(self.body()?, SyntaxKind::OpenBrace)
    }

    ///
    pub fn body_close_token(&self) -> Option<CloseBraceToken> {
        utils::token(self.body()?, SyntaxKind::CloseBrace)
    }

    ///
    pub fn match_arms(&self) -> Option<impl Iterator<Item = MatchArm> + use<'_>> {
        Some(children(self.body()?))
    }

    ///
    pub fn disallowed_exprs(&self) -> Option<impl Iterator<Item = Expr> + use<'_>> {
        Some(
            self.body()?
                .children_with_tokens()
                .filter(|it| {
                    matches!(
                        it.kind(),
                        SyntaxKind::MatchCondition | SyntaxKind::MatchConditionDefault
                    )
                })
                .map(|it| Expr::cast_element(it.clone())),
        )
    }
}

impl CstNode for MatchArm {
    fn can_cast(kind: SyntaxKind) -> bool {
        matches!(
            kind,
            SyntaxKind::MatchCondition | SyntaxKind::MatchConditionDefault
        )
    }

    fn syntax(&self) -> &SyntaxNode {
        match self {
            MatchArm::WithCondition(match_arm_with_condition) => &match_arm_with_condition.syntax,
            MatchArm::Default(match_arm_default) => &match_arm_default.syntax,
        }
    }

    fn cast(node: SyntaxNode) -> Option<Self> {
        let res = match node.kind() {
            SyntaxKind::MatchCondition => {
                let Some(arm) = MatchArmWithCondition::cast(node) else {
                    unreachable!()
                };

                MatchArm::WithCondition(arm)
            }
            SyntaxKind::MatchConditionDefault => {
                let Some(arm) = MatchArmDefault::cast(node) else {
                    unreachable!()
                };

                MatchArm::Default(arm)
            }
            _ => return None,
        };

        Some(res)
    }
}

impl CstNode for MatchPat {
    fn syntax(&self) -> &SyntaxNode {
        &self.syntax
    }

    fn can_cast(kind: SyntaxKind) -> bool {
        matches!(kind, SyntaxKind::Literal | SyntaxKind::Ident)
    }

    fn cast(node: SyntaxNode) -> Option<Self> {
        Self::can_cast(node.kind()).then(|| Self { syntax: node })
    }
}

define_cst_node! {
    /// An import expression.
    pub struct ImportStmt {
        kind: SyntaxKind::Import,
        child : [
        source => ImportSource,
            items => ImportItems
        ],
        tokens: [
            import_token ImportToken => SyntaxKind::Keyword
        ],
        nogen tokens: [
            alias_token AliasToken=> SyntaxKind::ImportAlias
        ],
    }
}

define_cst_node! {
    /// An import expression.
    pub struct ImportItems {
        kind: SyntaxKind::ImportItem,
        nogen tokens: [
            open_token OpenBraceToken => SyntaxKind::OpenBrace,
            close_token CloseBraceToken => SyntaxKind::CloseBrace
        ],
    }
}

define_cst_node! {
    /// A import source
    pub struct ImportSource {
        kind : SyntaxKind::ImportSource,
        nogen tokens : [
            ident IdentToken => SyntaxKind::Ident,
            path StringToken => SyntaxKind::Literal
        ],
    }
}

impl ImportItems {
    ///
    pub fn idents(&self) -> impl Iterator<Item = IdentToken> + use<'_> {
        self.syntax
            .children_with_tokens()
            .filter_map(|it| it.into_token())
            .filter_map(|i| IdentToken::cast(i.clone()))
    }
}

define_cst_node! {
    /// A list of modifiers (e.g. `pub`, `static`).
    pub struct Modifiers {
        kind: SyntaxKind::Modifiers,
    }
}

impl Modifiers {
    ///
    pub fn iter(&self) -> impl Iterator<Item = ModifierToken> + '_ {
        self.syntax
            .children_with_tokens()
            .filter_map(|it| it.into_token())
            .filter(|token| matches!(token.kind(), SyntaxKind::Keyword))
            .map(|it| ModifierToken { token: it.clone() })
    }
}

define_cst_token! {
    ///
    pub struct ModifierToken {}
}

impl ModifierToken {
    ///
    pub fn kind<I>(&self, resolver: &I) -> ModifierKind
    where
        I: Resolver<TokenKey> + ?Sized,
    {
        let text = self.token.resolve_text(resolver);
        let Some(kind) = ModifierKind::from_token_repr(text) else {
            unreachable!()
        };

        kind
    }
}

define_cst_node! {
    /// A class declaration.
    pub struct Class {
        kind: SyntaxKind::Class,
        child:[modifiers => Modifiers],
        tokens: [
            class_token ClassToken => SyntaxKind::Keyword
        ],
        nogen tokens :[
            name IdentToken => SyntaxKind::Ident
        ],
    }
}

impl Class {
    fn body(&self) -> Option<&SyntaxNode> {
        self.syntax
            .children()
            .find(|i| BraceRange::can_cast(i.kind()))
    }

    ///
    pub fn body_open_tok(&self) -> Option<OpenBraceToken> {
        utils::token(self.body()?, SyntaxKind::OpenBrace)
    }

    ///
    pub fn body_close_tok(&self) -> Option<CloseBraceToken> {
        utils::token(self.body()?, SyntaxKind::CloseBrace)
    }

    /// All the methods (function declarations) in this class.
    pub fn methods(&self) -> Option<impl Iterator<Item = Function> + use<'_>> {
        self.body().map(|syn| utils::children(&syn))
    }

    ///
    pub fn ty_aliasz(&self) -> Option<impl Iterator<Item = TypeAlias> + use<'_>> {
        self.body().map(|syn| utils::children(&syn))
    }

    /// All the fields (variable declarations) in this class.
    pub fn variables(&self) -> Option<impl Iterator<Item = VariableStmt> + use<'_>> {
        self.body().map(|syn| utils::children(syn))
    }

    /// All the `impl` blocks nested inside this class
    pub fn nested_impls(&self) -> Option<impl Iterator<Item = TraitImpl> + use<'_>> {
        self.body().map(|syn| utils::children(syn))
    }

    ///
    pub fn implicit_init_exprs(&self) -> Option<impl Iterator<Item = Expr> + use<'_>> {
        self.body().map(|syn| implicit_init_exprs(syn))
    }
}

fn implicit_init_exprs<'a>(syntax: &'a SyntaxNode) -> impl Iterator<Item = Expr> + 'a {
    syntax
        .children_with_tokens()
        .filter(move |i| {
            matches!(
                i.kind(),
                SyntaxKind::Function
                    | SyntaxKind::VariableDeclaration
                    | SyntaxKind::Trait
                    | SyntaxKind::TraitImpl
                    | SyntaxKind::TypeAlias
                    | SyntaxKind::Enum
                    | SyntaxKind::EnumVariant
                    | SyntaxKind::Import
                    | SyntaxKind::ImportAlias
                    | SyntaxKind::ImportSource
                    | SyntaxKind::ImportItem
            )
        })
        .map(|element| Expr::cast_element(element))
}

define_cst_node! {
    /// A trait implementation.
    pub struct TraitImpl {
        kind: SyntaxKind::TraitImpl,
        child: [modifiers => Modifiers],
        tokens: [impl_token TraitImplToken => SyntaxKind::Keyword],
    }
}

impl TraitImpl {
    ///
    pub fn body_open_tok(&self) -> Option<OpenBraceToken> {
        utils::token(self.body()?, SyntaxKind::OpenBrace)
    }

    ///
    pub fn body_close_tok(&self) -> Option<CloseBraceToken> {
        utils::token(self.body()?, SyntaxKind::CloseBrace)
    }

    fn body(&self) -> Option<&SyntaxNode> {
        self.syntax
            .children()
            .find(|i| BraceRange::can_cast(i.kind()))
    }

    /// Iterate *all* function implementations in this impl block.
    pub fn methods(&self) -> Option<impl Iterator<Item = Function> + '_> {
        self.body().map(|syntax| utils::children(syntax))
    }

    /// Iterate *all* variable declarations in this impl (e.g., overrides of associated constants).
    pub fn var_decls(&self) -> Option<impl Iterator<Item = VariableStmt> + '_> {
        self.body().map(|syntax| utils::children(syntax))
    }

    /// All associated type overrides in this impl.
    pub fn type_aliases(&self) -> Option<impl Iterator<Item = TypeAlias> + '_> {
        self.body().map(|syntax| utils::children(syntax))
    }

    ///
    pub fn implicit_init_exprs(&self) -> Option<impl Iterator<Item = Expr> + use<'_>> {
        self.body().map(|syntax| implicit_init_exprs(syntax))
    }
}

define_cst_node! {
    /// An enum declaration.
    pub struct Enum {
        kind: SyntaxKind::Enum,
        child:[modifiers => Modifiers],
        tokens: [
            enum_token EnumToken => SyntaxKind::Keyword
        ],
        nogen tokens: [
            name IdentToken => SyntaxKind::Ident
        ],
    }
}

impl Enum {
    /// All the variants defined in this enum.
    pub fn variants(&self) -> impl Iterator<Item = EnumVariant> + use<'_> {
        utils::children::<EnumVariant>(&self.syntax)
    }

    ///
    pub fn body_open_tok(&self) -> Option<OpenBraceToken> {
        utils::token(self.body()?, SyntaxKind::OpenBrace)
    }

    ///
    pub fn body_close_tok(&self) -> Option<CloseBraceToken> {
        utils::token(self.body()?, SyntaxKind::CloseBrace)
    }

    fn body(&self) -> Option<&SyntaxNode> {
        self.syntax
            .children()
            .find(|i| BraceRange::can_cast(i.kind()))
    }

    /// Any “implicit initializer” expressions attached directly under the enum
    pub fn implicit_init_exprs(&self) -> Option<impl Iterator<Item = Expr> + use<'_>> {
        self.body().map(|syntax| implicit_init_exprs(syntax))
    }

    /// All the methods (function declarations) in this enum.
    pub fn methods(&self) -> Option<impl Iterator<Item = Function> + use<'_>> {
        self.body().map(|syntax| utils::children(syntax))
    }

    /// All the fields (variable declarations) in this enum.
    pub fn variables(&self) -> Option<impl Iterator<Item = VariableStmt> + use<'_>> {
        self.body().map(|syntax| utils::children(syntax))
    }

    /// All the `impl` blocks nested inside this class
    pub fn nested_impls(&self) -> Option<impl Iterator<Item = TraitImpl> + use<'_>> {
        self.body().map(|syntax| utils::children(syntax))
    }
    ///
    pub fn ty_aliasz(&self) -> Option<impl Iterator<Item = TypeAlias> + use<'_>> {
        self.body().map(|syn| utils::children(&syn))
    }
}

define_cst_node! {
    /// A single enum variant.
    pub struct EnumVariant {
        kind: SyntaxKind::EnumVariant,
        child:[modifiers => Modifiers],
        nogen tokens: [name IdentToken => SyntaxKind::Ident],
    }
}

define_cst_node! {
    /// A single field/parameter of the enum variant.
    pub struct EnumVariantField {
        kind: SyntaxKind::Parameter,
        child :[ty => Type],
        nogen tokens: [name IdentToken => SyntaxKind::Ident,colon_token ColonToken => SyntaxKind::Colon ],
    }
}

impl EnumVariant {
    /// If this variant has associated fields (a brace‐delimited block of variable declarations),
    /// iterate them here.
    pub fn fields(&self) -> Option<impl Iterator<Item = EnumVariantField> + use<'_>> {
        let syntax = self
            .syntax
            .children()
            .find(|i| ParenRange::can_cast(i.kind()))?;
        let children = children(syntax);
        Some(children)
    }

    ///
    pub fn open_brace_token(&self) -> Option<OpenParenToken> {
        utils::child::<ParenRange>(&self.syntax)?.open_token()
    }

    ///
    pub fn close_brace_token(&self) -> Option<CloseParenToken> {
        utils::child::<ParenRange>(&self.syntax)?.close_token()
    }

    /// Does this variant carry no payload (i.e. a plain C‐style variant)?
    pub fn is_unit(&self) -> bool {
        self.fields().is_some()
    }
}

define_cst_node! {
    pub(super) struct ParenRange {
        kind: SyntaxKind::DelimitedRange,
        nogen tokens: [
            open_token OpenParenToken => SyntaxKind::OpenParen,
            close_token CloseParenToken => SyntaxKind::CloseParen
        ],
    }
}

define_cst_node! {
    struct BraceRange {
        kind: SyntaxKind::DelimitedRange,
    }
}

define_cst_node! {
    /// A trait declaration.
    pub struct Trait {
        kind: SyntaxKind::Trait,
        child: [
            modifiers => Modifiers
        ],
        tokens: [
            trait_token TraitToken => SyntaxKind::Keyword
        ],
        nogen tokens: [
            name IdentToken => SyntaxKind::Ident
        ],
    }
}

impl Trait {
    fn body(&self) -> Option<&SyntaxNode> {
        self.syntax
            .children()
            .find(|i| BraceRange::can_cast(i.kind()))
    }

    ///
    pub fn open_brace_token(&self) -> Option<OpenParenToken> {
        utils::child::<ParenRange>(self.body()?)?.open_token()
    }

    ///
    pub fn close_brace_token(&self) -> Option<CloseParenToken> {
        utils::child::<ParenRange>(self.body()?)?.close_token()
    }

    /// Iterate *all* function declarations inside this trait (both required and default-implemented).
    pub fn functions(&self) -> Option<impl Iterator<Item = FunctionItem> + use<'_>> {
        // Any Function child under the trait node
        self.body().map(|syntax| children(syntax))
    }

    /// Iterate *all* variable declarations in this trait (e.g., associated constants or properties).
    pub fn var_decls(&self) -> Option<impl Iterator<Item = VariableStmt> + use<'_>> {
        self.body().map(|syntax| children(syntax))
    }

    /// All associated type aliases in this trait.
    pub fn type_aliases(&self) -> Option<impl Iterator<Item = TypeAlias> + '_> {
        self.body().map(|syntax| children(syntax))
    }

    ///
    pub fn implicit_init_exprs(&self) -> Option<impl Iterator<Item = Expr> + use<'_>> {
        self.body().map(|syntax| implicit_init_exprs(syntax))
    }
}

define_cst_node! {
    /// A function declaration.
    pub struct Function {
        kind: SyntaxKind::Function,
        child: [modifiers => Modifiers,body => BlockExpr],
        tokens: [
            fn_token FnToken => SyntaxKind::Keyword
        ],
        nogen tokens: [
            name IdentToken=> SyntaxKind::Ident
        ],
        forward: [
            signature SyntaxKind::FunctionSignature => FunctionSignature
        ],
    }
}

define_cst_node! {
    /// A function without a body in context of traits
    pub struct PartialFunction {
        child: [modifiers => Modifiers],
        nogen tokens: [
            name IdentToken=> SyntaxKind::Ident,
            fn_token FnToken => SyntaxKind::Keyword
        ],
        forward: [
            signature SyntaxKind::FunctionSignature => FunctionSignature
        ],
    }
}

///
pub enum FunctionItem {
    ///
    Full(Function),
    ///
    Partial(PartialFunction),
}

impl FunctionItem {
    ///
    pub fn modifiers(&self) -> Option<Modifiers> {
        match self {
            FunctionItem::Full(function) => function.modifiers(),
            FunctionItem::Partial(partial_function) => partial_function.modifiers(),
        }
    }

    ///
    pub fn name(&self) -> Option<IdentToken> {
        match self {
            FunctionItem::Full(function) => function.name(),
            FunctionItem::Partial(partial_function) => partial_function.name(),
        }
    }

    ///
    pub fn signature(&self) -> Option<FunctionSignature> {
        match self {
            FunctionItem::Full(function) => function.signature(),
            FunctionItem::Partial(partial_function) => partial_function.signature(),
        }
    }
}

impl CstNode for FunctionItem {
    fn can_cast(kind: SyntaxKind) -> bool {
        Function::can_cast(kind)
    }

    fn cast(node: SyntaxNode) -> Option<Self> {
        Self::can_cast(node.kind()).then(|| {
            let function = Function { syntax: node };
            match function.body() {
                Some(_) => Self::Full(function),
                None => Self::Partial(PartialFunction {
                    syntax: function.syntax,
                }),
            }
        })
    }

    fn syntax(&self) -> &SyntaxNode {
        match self {
            FunctionItem::Full(function) => &function.syntax,
            FunctionItem::Partial(partial_function) => &partial_function.syntax,
        }
    }
}

///
pub enum Fragment {
    ///
    EnumVariant(EnumVariant),

    /// Modifiers (if used inline).
    Modifiers(Modifiers),

    /// Unknown or error node.
    Unknown(UnknownToken),

    ///
    MatchArm(MatchArm),
    ///
    Generic {
        ///
        syntax: SyntaxNode,
    },
}