luaur-ast 0.1.3

Lexer, parser, and AST for Luau (faithful Rust port).
Documentation 
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//! Node: `cxx:Method:Luau.Ast:Ast/src/Parser.cpp:2004:parseAssignment`
//!
//! Faithful port of `Parser::parseAssignment` — `var {, var} = expr {, expr}`.
//! Each assignment target is validated as an l-value (a non-l-value is replaced
//! by an error node, gated on the export-value flag pair like the C++). The
//! target and value lists are gathered in scratch arenas (vars/values share the
//! comma-position arena, stack-disciplined) and copied into the node.

use crate::functions::is_expr_l_value::is_expr_l_value;
use crate::records::ast_expr::AstExpr;
use crate::records::ast_node::AstNode;
use crate::records::ast_stat::AstStat;
use crate::records::ast_stat_assign::AstStatAssign;
use crate::records::cst_node::CstNode;
use crate::records::cst_stat_assign::CstStatAssign;
use crate::records::lexeme::Type;
use crate::records::location::Location;
use crate::records::parser::Parser;
use crate::records::position::Position;
use crate::records::temp_vector::TempVector;

impl Parser {
    pub fn parse_assignment(&mut self, mut initial: *mut AstExpr) -> *mut AstStat {
        if !is_expr_l_value(initial) {
            initial = if luaur_common::FFlag::LuauExportValueSyntax.get()
                && luaur_common::FFlag::LuauConst2.get()
            {
                self.report_l_value_error(initial) as *mut AstExpr
            } else {
                let expressions = self.copy_initializer_list_t(&[initial]);
                self.report_expr_error(
                    unsafe { (*initial).base.location },
                    expressions,
                    format_args!("Assigned expression must be a variable or a field"),
                ) as *mut AstExpr
            };
        }

        let mut vars = TempVector::new(&mut self.scratch_expr);
        let mut vars_comma_positions = TempVector::new(&mut self.scratch_position);
        vars.push_back(initial);

        while self.lexer.current().r#type == Type(b',' as i32) {
            if self.options.store_cst_data {
                vars_comma_positions.push_back(self.lexer.current().location.begin);
            }
            self.next_lexeme();

            let mut expr = self.parse_primary_expr(true);

            if !is_expr_l_value(expr) {
                expr = if luaur_common::FFlag::LuauExportValueSyntax.get()
                    && luaur_common::FFlag::LuauConst2.get()
                {
                    self.report_l_value_error(expr) as *mut AstExpr
                } else {
                    let expressions = self.copy_initializer_list_t(&[expr]);
                    self.report_expr_error(
                        unsafe { (*expr).base.location },
                        expressions,
                        format_args!("Assigned expression must be a variable or a field"),
                    ) as *mut AstExpr
                };
            }

            vars.push_back(expr);
        }

        let equals_found = self.expect_and_consume_char('=', "assignment");
        let equals_position = if equals_found {
            self.lexer.previous_location().begin
        } else {
            Position::missing()
        };

        let mut values = TempVector::new(&mut self.scratch_expr_aux);
        let mut values_comma_positions = TempVector::new(&mut self.scratch_position);
        self.parse_expr_list(
            &mut values,
            if self.options.store_cst_data {
                Some(&mut values_comma_positions)
            } else {
                None
            },
        );

        let vars_array = self.copy_temp_vector_t(&vars);
        let values_array = self.copy_temp_vector_t(&values);

        let node = unsafe {
            (*self.allocator).alloc(AstStatAssign::new(
                Location::new(
                    (*initial).base.location.begin,
                    (**values.back()).base.location.end,
                ),
                vars_array,
                values_array,
            ))
        };

        if self.options.store_cst_data {
            let vars_comma = self.copy_temp_vector_t(&vars_comma_positions);
            let values_comma = self.copy_temp_vector_t(&values_comma_positions);
            let cst_node = unsafe {
                (*self.allocator).alloc(CstStatAssign::new(
                    vars_comma,
                    equals_position,
                    values_comma,
                ))
            };
            self.cst_node_map
                .try_insert(node as *mut AstNode, cst_node as *mut CstNode);
        }

        node as *mut AstStat
    }
}