skullbrain-parser 0.1.0

use cstree::{
    interning::{Resolver, TokenKey},
    text::TextRange,
};

mod _ast;
mod span;

pub use span::Span;

/// Converts a concrete syntax tree (CST) node to its corresponding abstract syntax tree (AST) representation.
pub trait ToAst {
    /// The target AST type that this CST node converts to.
    type Output;

    /// Attempts to convert this CST node to its corresponding AST representation.
    ///
    /// Returns `Some(ast_node)` if the conversion is successful, or `None` if the
    /// CST node cannot be represented in the AST (e.g., due to syntax errors or
    /// unsupported constructs).
    fn to_ast<I>(self, resolver: &I) -> Option<Self::Output>
    where
        I: Resolver<TokenKey> + ?Sized;
}

/// Core AST expression enum - simplified and semantic.
#[derive(Debug, Clone, PartialEq)]
pub enum Expr {
    // Literals and identifiers
    /// Literal value (numbers, strings, booleans)
    Literal(Literal),
    /// Variable or function identifier
    Ident(Ident),

    // Operators
    /// Binary operation between two expressions (e.g., `a + b`, `x == y`)
    Binary(BinaryExpr),
    /// Unary operation on a single expression (e.g., `-x`, `!condition`)
    Unary(UnaryExpr),

    // Method chaining
    /// Method call or property access (e.g., `obj.method()`, `obj.field`)
    Chain(ChainExpr),

    // Grouping
    /// Parenthesized expression for precedence (e.g., `(a + b)`)
    Paren(ParenExpr),
    /// Block of statements/expressions (e.g., `{ stmt1; stmt2; expr }`)
    Block(BlockExpr),

    // Control flow
    /// Break statement, optionally with a value (e.g., `break;`, `break value;`)
    Break(Break),
    /// Continue statement (e.g., `continue;`)
    Continue(Continue),
    /// Return statement, optionally with a value (e.g., `return;`, `return value;`)
    Return(Return),
    /// Throw statement with an exception value (e.g., `throw error;`)
    Throw(Throw),

    // Loops
    /// While loop with condition and body (e.g., `while (condition) { body }`)
    While(While),
    /// For loop with iterator and body (e.g., `for (iterator) { body }`)
    For(ForLoop),

    // Conditionals
    /// If/else conditional expression (e.g., `if (cond) { then } else { else }`)
    If(IfElse),
    /// MatchPat matching expression (e.g., `match expr { MatchPat => body }`)
    Match(Match),

    // Exception handling
    /// Try-catch expression for exception handling (e.g., `try { code } catch (e) { handler }`)
    TryCatch(TryCatch),

    // Declarations (when used as expressions)
    /// Variable declaration/definition (e.g., `let x: int = value;`)
    Variable(VariableStmt),
    /// Function declaration/definition (e.g., `fn add(a: int, b: int) -> int { a + b }`)
    Function(Function),
    /// Class declaration/definition (e.g., `class MyClass { fields, methods }`)
    Class(Class),
    /// Trait declaration/definition (e.g., `trait Drawable { fn draw(&self); }`)
    Trait(Trait),
    /// Trait implementation block (e.g., `impl Drawable for MyClass { ... }`)
    TraitImpl(TraitImpl),
    /// Enum declaration/definition (e.g., `enum Option<T> { Some(T), None }`)
    Enum(Enum),
    /// Type alias declaration (e.g., `type UserId = u64;`)
    TypeAlias(TypeAlias),
    /// Import statement (e.g., `import { items } from "module";`)
    Import(ImportStmt),
}

/// Simplified literal representation in the abstract syntax tree.
///
/// Represents the basic literal values that can appear in expressions,
#[derive(Debug, Clone, PartialEq)]
pub struct Literal {
    ///
    span: TextRange,
    ///
    pub value: Value,
}

///
#[derive(Debug, Clone, PartialEq)]
pub enum Value {
    /// Boolean literal (`true` or `false`)
    Bool(bool),
    /// Signed integer literal
    Int(i64),
    /// Double-precision floating point literal
    Double(f64),
    /// String literal
    Str(String),
}
/// An identifier in the abstract syntax tree.
///
/// Represents a named identifier such as variable names, function names,
/// or other symbolic references in the source code.
#[derive(Debug, Clone, PartialEq)]
pub struct Ident {
    ///
    span: TextRange,
    /// The name of the identifier
    pub name: String,
}

/// Binary operation expression in the abstract syntax tree.
///
/// Represents an expression with two operands and a binary operator,
/// such as `a + b`, `x == y`, or `foo && bar`.
#[derive(Debug, Clone, PartialEq)]
pub struct BinaryExpr {
    /// The left and right operands, boxed to reduce memory usage
    operand: Box<(Expr, Expr)>,
    /// The binary operator applied to the operands
    pub op: BinaryOp,
}

impl BinaryExpr {
    /// Returns a reference to the left operand of the binary expression.
    pub const fn left(&self) -> &Expr {
        &self.operand.0
    }

    /// Returns a reference to the right operand of the binary expression.
    pub const fn right(&self) -> &Expr {
        &self.operand.1 // Note: This should be .1, not .0
    }

    /// Returns a mutable reference to the left operand of the binary expression.
    pub const fn left_mut(&mut self) -> &mut Expr {
        &mut self.operand.0
    }

    /// Returns a mutable reference to the right operand of the binary expression.
    pub const fn right_mut(&mut self) -> &mut Expr {
        &mut self.operand.1
    }
}
/// Binary operators available in expressions.
///
/// Represents the various binary operations that can be performed between two operands,
/// organized by category for clarity.
#[derive(Debug, Clone, PartialEq)]
pub enum BinaryOp {
    // Arithmetic operators
    /// Addition operator (`+`)
    Add,
    /// Subtraction operator (`-`)
    Sub,
    /// Multiplication operator (`*`)
    Mul,
    /// Division operator (`/`)
    Div,
    /// Modulo operator (`%`)
    Mod,

    // Comparison operators
    /// Equality operator (`==`)
    Eq,
    /// Inequality operator (`!=`)
    NotEq,
    /// Less than operator (`<`)
    Lt,
    /// Greater than operator (`>`)
    Gt,
    /// Less than or equal operator (`<=`)
    LtEq,
    /// Greater than or equal operator (`>=`)
    GtEq,

    // Logical operators
    /// Logical AND operator (`&&`)
    And,
    /// Logical OR operator (`||`)
    Or,
}

/// Unary operation expression in the abstract syntax tree.
///
/// Represents an expression with a single operand and a unary operator,
/// such as `-x` (negation) or `!condition` (logical not).
#[derive(Debug, Clone, PartialEq)]
pub struct UnaryExpr {
    /// The unary operator to apply
    pub op: UnaryOp,
    /// The operand expression, boxed to reduce memory usage
    pub expr: Box<Expr>,
}

/// Unary operators available in expressions.
///
/// Represents the unary operations that can be performed on a single operand.
#[derive(Debug, Clone, PartialEq)]
pub enum UnaryOp {
    /// Arithmetic negation operator (`-`)
    Minus,
    /// Logical NOT operator (`!`)
    Not,
}

/// Method chaining expression in the abstract syntax tree.
///
/// Represents method invocation or property access on an object,
/// such as `obj.method()` or `obj.property`.
#[derive(Debug, Clone, PartialEq)]
pub struct ChainExpr {
    /// The object and method/property pair, boxed to reduce memory usage
    data: Box<(Expr, Expr)>,
}

impl ChainExpr {
    /// Returns a reference to the object being accessed.
    pub const fn object(&self) -> &Expr {
        &self.data.0
    }

    /// Returns a reference to the method or property being accessed.
    pub const fn method(&self) -> &Expr {
        &self.data.1 // Note: This should be .1, not .0
    }

    /// Returns a mutable reference to the object being accessed.
    pub const fn object_mut(&mut self) -> &mut Expr {
        &mut self.data.0
    }

    /// Returns a mutable reference to the method or property being accessed.
    pub const fn method_mut(&mut self) -> &mut Expr {
        &mut self.data.1 // Note: This should be .1, not .0
    }
}
/// Parenthesized expression in the abstract syntax tree.
///
/// Represents an expression wrapped in parentheses, such as `(x + y)`.
/// While parentheses don't change the semantic meaning, they can affect
/// operator precedence and are sometimes preserved for clarity.
#[derive(Debug, Clone, PartialEq)]
pub struct ParenExpr {
    ///
    span: TextRange,

    /// The expression contained within the parentheses
    pub expr: Box<Expr>,
}

/// Block expression in the abstract syntax tree.
///
/// Represents a sequence of statements or expressions enclosed in braces,
/// such as `{ stmt1; stmt2; expr }`. The last expression in the block
/// is typically the block's value.
#[derive(Debug, Clone, PartialEq)]
pub struct BlockExpr {
    ///
    pub span: TextRange,
    /// The statements and expressions within the block
    pub statements: Box<[Expr]>,
}

/// Break statement in the abstract syntax tree.
///
/// Represents a break statement that exits from a loop, optionally
/// with a value, such as `break;` or `break value;`.
#[derive(Debug, Clone, PartialEq)]
pub struct Break {
    ///
    span: TextRange,
    /// Optional value to break with
    pub value: Option<Box<Expr>>,
}

/// Continue statement in the abstract syntax tree.
///
/// Represents a continue statement that skips to the next iteration
/// of a loop, such as `continue;`.
#[derive(Debug, Clone, PartialEq)]
pub struct Continue {
    ///
    span: TextRange,
}

/// Return statement in the abstract syntax tree.
///
/// Represents a return statement that exits from a function, optionally
/// with a value, such as `return;` or `return value;`.
#[derive(Debug, Clone, PartialEq)]
pub struct Return {
    ///
    span: TextRange,
    /// Optional value to return
    pub value: Option<Box<Expr>>,
}

/// Throw statement in the abstract syntax tree.
///
/// Represents a throw statement that raises an exception with the given value,
/// such as `throw error;`.
#[derive(Debug, Clone, PartialEq)]
pub struct Throw {
    ///
    span: TextRange,
    /// The value/exception to throw
    pub value: Box<Expr>,
}

/// While loop expression in the abstract syntax tree.
///
/// Represents a while loop with a condition and body, such as
/// `while (condition) { body }`.
#[derive(Debug, Clone, PartialEq)]
pub struct While {
    ///
    span: TextRange,
    /// The loop condition wrapped in parentheses
    pub condition: ParenExpr,
    /// The loop body
    pub body: BlockExpr,
}

/// For loop expression in the abstract syntax tree.
///
/// Represents a for loop with an iterator expression and body, such as
/// `for (iterator) { body }`.
#[derive(Debug, Clone, PartialEq)]
pub struct ForLoop {
    ///
    span: TextRange,
    /// The iterator expression wrapped in parentheses
    pub iterator: ParenExpr,
    /// The loop body
    pub body: BlockExpr,
}

/// If expression in the abstract syntax tree.
///
/// Represents conditional branching with if/else if/else chains, such as
/// `if (condition) { then_branch } else if (condition2) { branch2 } else { final_branch }`.
#[derive(Debug, Clone, PartialEq)]
pub struct IfElse {
    ///
    span: TextRange,

    /// The primary condition wrapped in parentheses
    pub condition: ParenExpr,
    /// The block to execute when the condition is true
    pub then_branch: BlockExpr,
    /// Optional chain of else-if and else branches
    pub else_branches: Option<Box<[ElseBranch]>>,
}

/// A single else or else-if branch in an if expression.
///
/// Represents either an `else if (condition) { block }` branch (when condition is Some)
/// or a final `else { block }` branch (when condition is None).
#[derive(Debug, Clone, PartialEq)]
pub struct ElseBranch {
    ///
    span: TextRange,

    /// The condition for else-if branches, None for final else branch
    pub condition: Option<ParenExpr>,
    /// The block to execute for this branch
    pub then_branch: BlockExpr,
}

/// Match expression in the abstract syntax tree.
///
/// Represents MatchPat matching against an expression with multiple arms,
/// such as `match expr { MatchPat1 => body1, MatchPat2 => body2 }`.
#[derive(Debug, Clone, PartialEq)]
pub struct Match {
    ///
    span: TextRange,

    /// The expression being matched against
    pub expr: ParenExpr,
    /// The match arms containing MatchPats and their corresponding bodies
    pub arms: Box<[MatchArm]>,
}

/// A single arm in a match expression.
///
/// Represents one MatchPat-body pair in a match expression,
/// such as `MatchPat => body`.
#[derive(Debug, Clone, PartialEq)]
pub struct MatchArm {
    /// The MatchPat to match against
    pub pat: Option<MatchPat>,
    /// The expression to evaluate when the MatchPat matches
    pub body: BlockExpr,
}
/// MatchPat for matching in match expressions and other MatchPat contexts.
///
/// Represents the various MatchPats that can be used to match against values
/// in MatchPat matching constructs like match expressions.
#[derive(Debug, Clone, PartialEq)]
pub enum MatchPat {
    /// Literal MatchPat that matches a specific literal value
    Literal(Literal),
    ///
    Ident(Ident),
}

/// Try-catch expression in the abstract syntax tree.
///
/// Represents exception handling with a try block and optional catch arms,
/// such as `try { risky_code } catch (ErrorType e) { handle_error }`.
#[derive(Debug, Clone, PartialEq)]
pub struct TryCatch {
    ///
    span: TextRange,
    /// The block of code that might throw an exception
    pub try_block: BlockExpr,
    /// Optional catch arms for handling different exception types
    pub catch_arms: Option<Box<[CatchArm]>>,
}

/// A single catch arm in a try-catch expression.
///
/// Represents one exception handler that catches a specific type of exception
/// and executes a corresponding block of code.
#[derive(Debug, Clone, PartialEq)]
pub struct CatchArm {
    ///
    span: TextRange,
    /// The type of exception this arm catches
    pub catch_ty: Option<CatchType>,
    /// The block of code to execute when this exception is caught
    pub body: BlockExpr,
}

/// Exception type specification for catch arms.
///
/// Specifies both the type of exception to catch and the variable name
/// to bind the caught exception to within the catch block.
#[derive(Debug, Clone, PartialEq)]
pub struct CatchType {
    ///
    span: TextRange,
    /// The type of exception to catch
    pub ty: Type,
    /// The variable name to bind the caught exception to
    pub name: Ident,
}

/// Type representation in the abstract syntax tree.
///
/// Represents the various types that can appear in type annotations,
/// function signatures, and other type contexts.
#[derive(Debug, Clone, PartialEq)]
pub enum Type {
    /// A simple identifier type (e.g., `String`, `MyClass`)
    Ident(Ident),
    /// A function type with its signature (e.g., `(int, string) -> bool`)
    Function(FunctionSignature),
}

/// Variable declaration/expression in the abstract syntax tree.
///
/// Represents variable declarations with optional type annotations and initializers,
/// such as `let mut x: int = { compute_value() }`.
#[derive(Debug, Clone, PartialEq)]
pub struct VariableStmt {
    ///
    span: TextRange,

    /// Whether the variable is mutable
    pub is_mutable: bool,
    /// Access modifiers (public, private, etc.)
    pub modifiers: Modifiers,
    /// The variable name
    pub name: Ident,
    /// Optional type annotation
    pub ty_annotation: Option<Type>,
    /// The initialization expression
    pub initializer: BlockExpr,
}

/// Function declaration/expression in the abstract syntax tree.
///
/// Represents function definitions with their signature, modifiers, and body,
/// such as `pub fn add(a: int, b: int) -> int { a + b }`.
#[derive(Debug, Clone, PartialEq)]
pub struct Function {
    ///
    span: TextRange,

    /// Access modifiers (public, private, static, etc.)
    pub modifiers: Modifiers,
    /// The function name
    pub name: Ident,
    /// The function signature (parameters and return type)
    pub signature: FunctionSignature,
    /// The function body
    pub body: BlockExpr,
}

/// Function signature specification.
///
/// Defines the parameters and return type of a function without the body.
#[derive(Debug, Clone, PartialEq)]
pub struct FunctionSignature {
    ///
    span: TextRange,
    /// The function parameters
    pub parameters: Box<[Parameter]>,
    /// Optional return type (None for void functions)
    pub return_type: Option<Box<Type>>,
}

/// Function parameter specification.
///
/// Represents a single parameter in a function signature with its name and type.
#[derive(Debug, Clone, PartialEq)]
pub struct Parameter {
    /// The parameter name
    pub name: Ident,
    /// The parameter type
    pub ty: Type,
}

/// Class declaration/expression in the abstract syntax tree.
///
/// Represents class definitions with their members and nested implementations,
/// such as `pub class MyClass { fields, methods, etc. }`.
#[derive(Debug, Clone, PartialEq)]
pub struct Class {
    ///
    span: TextRange,

    /// Access modifiers (public, abstract, etc.)
    pub modifiers: Modifiers,
    /// The class name
    pub name: Ident,
    /// The class members (fields, methods, etc.)
    pub members: MemberConstructions,
    /// Nested trait implementations within the class
    pub nested_impls: Box<[TraitImpl]>,
}

/// Collection of member constructions for classes, traits, and enums.
///
/// Groups together all the different types of members that can appear
/// within a class, trait, or enum definition.
#[derive(Debug, Clone, PartialEq)]
pub struct MemberConstructions<T = Function> {
    /// Implicit initialization expressions
    pub implicit_inits: Box<[Expr]>,
    /// Method definitions
    pub methods: Box<[T]>,
    /// Field declarations
    pub fields: Box<[VariableStmt]>,
    /// Type aliases defined within this scope
    pub aliasz: Box<[TypeAlias]>,
}

/// Trait declaration/expression in the abstract syntax tree.
///
/// Represents trait definitions that specify a contract of methods and types,
/// such as `pub trait Drawable { fn draw(&self); }`.
#[derive(Debug, Clone, PartialEq)]
pub struct Trait {
    ///
    span: TextRange,

    /// Access modifiers (public, etc.)
    pub modifiers: Modifiers,
    /// The trait name
    pub name: Ident,
    /// The trait members (method signatures, associated types, etc.)
    pub members: MemberConstructions<FunctionItem>,
}

/// Function declaration/expression in the abstract syntax tree.
#[derive(Debug, Clone, PartialEq)]
pub struct FunctionItem {
    ///
    span: TextRange,

    /// Access modifiers (public, private, static, etc.)
    pub modifiers: Modifiers,
    /// The function name
    pub name: Ident,
    /// The function signature (parameters and return type)
    pub signature: FunctionSignature,
    /// The function body
    pub body: Option<BlockExpr>,
}

/// Trait implementation block.
///
/// Represents the implementation of trait methods and associated items,
/// providing concrete implementations for trait requirements.
#[derive(Debug, Clone, PartialEq)]
pub struct TraitImpl {
    ///
    span: TextRange,

    /// The implemented members (method bodies, type definitions, etc.)
    pub members: MemberConstructions,
}

/// Enum declaration/expression in the abstract syntax tree.
///
/// Represents enumeration types with variants and associated members,
/// such as `pub enum Option<T> { Some(T), None }`.
#[derive(Debug, Clone, PartialEq)]
pub struct Enum {
    ///
    span: TextRange,

    /// Access modifiers (public, etc.)
    pub modifiers: Modifiers,
    /// The enum name
    pub name: Ident,
    /// The enum variants
    pub variants: Box<[EnumVariant]>,
    /// Associated members (methods, constants, etc.)
    pub members: MemberConstructions,
    /// Nested trait implementations for the enum
    pub nested_impls: Box<[TraitImpl]>,
}

/// A single variant in an enum definition.
///
/// Represents one possible value of an enumeration, optionally with associated data,
/// such as `Some(T)` or `Error { code: int, message: string }`.
#[derive(Debug, Clone, PartialEq)]
pub struct EnumVariant {
    /// The variant name
    pub name: Ident,
    /// Optional fields associated with this variant
    pub fields: Option<Box<[EnumVariantField]>>,
}

/// A named field within an enum variant.
#[derive(Debug, Clone, PartialEq)]
pub struct EnumVariantField {
    /// The name of the field
    pub name: Ident,
    /// The type of the field
    pub ty: Type,
}

/// Type alias declaration/expression in the abstract syntax tree.
///
/// Represents type aliases that create alternative names for existing types,
/// such as `pub type UserId = u64;`.
#[derive(Debug, Clone, PartialEq)]
pub struct TypeAlias {
    ///
    span: TextRange,

    /// Access modifiers (public, etc.)
    pub modifiers: Modifiers,
    /// The alias name
    pub name: Ident,
    /// The type being aliased
    pub aliased_type: Type,
}

/// Import statement in the abstract syntax tree.
///
/// Represents module imports that bring external items into scope,
/// such as `import { foo, bar } from "module";`.
#[derive(Debug, Clone, PartialEq)]
pub struct ImportStmt {
    ///
    span: TextRange,

    /// The source module or file path
    pub source: String,
    /// The specific items to import from the source
    pub items: Box<[Ident]>,
}

bitflags::bitflags! {
    /// Represents various modifiers that can be applied to functions, classes, variables,
    /// and other declarations to control their visibility, accessibility, and behavior.

    #[derive(Debug, Clone, PartialEq)]
    pub struct Modifiers : u8 {
        /// Public visibility modifier.
        ///
        /// Makes the declaration accessible from outside its defining module
        const Public = 0b00000001;

          /// Instance access modifier.
        ///
        /// Indicates that the declaration requires instance access (non-static).
        const InstanceAccess = 0b00000010;
    }
}