luaur-analysis 0.1.3

Luau type checker and type inference (Rust).
Documentation 
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use crate::functions::as_mutable_type_pack::as_mutable_type_pack;
use crate::functions::flatten_type_pack::flatten_type_pack_id;
use crate::functions::parse_pattern_string::parse_pattern_string;
use crate::records::builtin_types::BuiltinTypes;
use crate::records::magic_find::MagicFind;
use crate::records::magic_function_call_context::MagicFunctionCallContext;
use crate::records::type_arena::TypeArena;
use crate::records::union_type::UnionType;
use crate::type_aliases::type_id::TypeId;
use crate::type_aliases::type_pack_id::TypePackId;
use alloc::vec;
use luaur_ast::records::ast_expr_constant_bool::AstExprConstantBool;
use luaur_ast::records::ast_expr_constant_string::AstExprConstantString;
use luaur_ast::records::ast_node::AstNode;
use luaur_ast::rtti::ast_node_as;

impl MagicFind {
    pub fn infer(&self, context: &MagicFunctionCallContext) -> bool {
        let (params, _tail) = flatten_type_pack_id(context.arguments);

        if params.len() < 2 || params.len() > 4 {
            return false;
        }

        let solver = unsafe { context.solver.as_ref() };
        let arena = unsafe { &mut *solver.arena };
        let builtin_types = unsafe { &*solver.builtin_types };
        let call_site = unsafe { context.call_site.as_ref() };

        let pattern_index = if call_site.self_ { 0 } else { 1 };
        let pattern = if call_site.args.size > pattern_index {
            let expr = unsafe { *call_site.args.data.add(pattern_index) };
            unsafe { ast_node_as::<AstExprConstantString>(expr as *mut AstNode) }
        } else {
            core::ptr::null_mut()
        };

        if pattern.is_null() {
            return false;
        }

        let mut plain = false;
        let plain_index = if call_site.self_ { 2 } else { 3 };
        if call_site.args.size > plain_index {
            let expr = unsafe { *call_site.args.data.add(plain_index) };
            let bool_expr = unsafe { ast_node_as::<AstExprConstantBool>(expr as *mut AstNode) };
            if !bool_expr.is_null() {
                plain = unsafe { &*bool_expr }.value;
            }
        }

        let mut return_types: Vec<TypeId> = Vec::new();
        if !plain {
            return_types = unsafe {
                parse_pattern_string(
                    core::ptr::NonNull::new_unchecked(solver.builtin_types),
                    unsafe { &*pattern }.value.data,
                    unsafe { &*pattern }.value.size,
                )
            };

            if return_types.is_empty() {
                return false;
            }
        }

        unsafe {
            (*context.solver.as_ptr()).constraint_solver_unify(
                context.constraint.as_ptr(),
                params[0],
                builtin_types.stringType,
            );
        }

        let optional_number = arena.add_type(UnionType {
            options: vec![builtin_types.nilType, builtin_types.numberType],
        });
        let optional_boolean = arena.add_type(UnionType {
            options: vec![builtin_types.nilType, builtin_types.booleanType],
        });

        let init_index = if call_site.self_ { 1 } else { 2 };
        if params.len() >= 3 && call_site.args.size > init_index {
            unsafe {
                (*context.solver.as_ptr()).constraint_solver_unify(
                    context.constraint.as_ptr(),
                    params[2],
                    optional_number,
                );
            }
        }

        if params.len() == 4 && call_site.args.size > plain_index {
            unsafe {
                (*context.solver.as_ptr()).constraint_solver_unify(
                    context.constraint.as_ptr(),
                    params[3],
                    optional_boolean,
                );
            }
        }

        return_types.insert(0, optional_number);
        return_types.insert(1, optional_number);

        let return_list =
            arena.add_type_pack_vector_type_id_optional_type_pack_id(return_types, None);
        let result_mut = as_mutable_type_pack(context.result);
        unsafe {
            (*result_mut).ty =
                crate::type_aliases::type_pack_variant::TypePackVariant::Bound(return_list);
        }

        true
    }
}