parseExprPrecedence

fn parseExprPrecedence(p: *Parse, min_prec: i32) Error!?Node.Index

File

Code

fn parseExprPrecedence(p: *Parse, min_prec: i32) Error!?Node.Index {
    assert(min_prec >= 0);
    var node = try p.parsePrefixExpr() orelse return null;

    var banned_prec: i8 = -1;

    while (true) {
        const tok_tag = p.tokenTag(p.tok_i);
        const info = operTable[@as(usize, @intCast(@backingInt(tok_tag)))];
        if (info.prec < min_prec) {
            break;
        }
        if (info.prec == banned_prec) {
            return p.fail(.chained_comparison_operators);
        }

        const oper_token = p.nextToken();
        // Special-case handling for "catch"
        if (tok_tag == .keyword_catch) {
            _ = try p.parsePayload();
        }

        // Check for whitespace error before parsing the rhs to facilitate fuzzing.
        // Consider the case where there is a mismatched whitespace error but the rhs
        // expression triggers stack overflow when parsing is attempted. In this case
        // we want to return with an error rather than crashing on stack overflow.
        {
            const tok_len = tok_tag.lexeme().?.len;
            if (p.tokenStart(oper_token) + tok_len >= p.source.len) {
                try p.warn(.expected_expr);
                return node;
            }
            const char_before = p.source[p.tokenStart(oper_token) - 1];
            const char_after = p.source[p.tokenStart(oper_token) + tok_len];
            if (tok_tag == .ampersand and char_after == '&') {
                // without types we don't know if '&&' was intended as 'bitwise_and address_of', or a c-style logical_and
                // The best the parser can do is recommend changing it to 'and' or ' & &'
                try p.warnMsg(.{ .tag = .invalid_ampersand_ampersand, .token = oper_token });
            } else if (std.ascii.isWhitespace(char_before) != std.ascii.isWhitespace(char_after)) {
                try p.warnMsg(.{ .tag = .mismatched_binary_op_whitespace, .token = oper_token });
            }
        }

        const rhs = try p.parseExprPrecedence(info.prec + 1) orelse {
            try p.warn(.expected_expr);
            return node;
        };

        node = try p.addNode(.{
            .tag = info.tag,
            .main_token = oper_token,
            .data = .{ .node_and_node = .{ node, rhs } },
        });

        if (info.assoc == Assoc.none) {
            banned_prec = info.prec;
        }
    }

    return node;
}