Die

pub const Die = struct {
    tag_id: u64,
    has_children: bool,
    attrs: []Attr,

    const Attr = struct {
        id: u64,
        value: FormValue,
    };

    fn deinit(self: *Die, gpa: Allocator) void {
        gpa.free(self.attrs);
        self.* = undefined;
    }

    fn getAttr(self: *const Die, id: u64) ?*const FormValue {
        for (self.attrs) |*attr| {
            if (attr.id == id) return &attr.value;
        }
        return null;
    }

    fn getAttrAddr(
        self: *const Die,
        di: *const Dwarf,
        endian: Endian,
        id: u64,
        compile_unit: *const CompileUnit,
    ) error{ InvalidDebugInfo, MissingDebugInfo }!u64 {
        const form_value = self.getAttr(id) orelse return error.MissingDebugInfo;
        return switch (form_value.*) {
            .addr => |value| value,
            .addrx => |index| di.readDebugAddr(endian, compile_unit, index),
            else => bad(),
        };
    }

    fn getAttrSecOffset(self: *const Die, id: u64) !u64 {
        const form_value = self.getAttr(id) orelse return error.MissingDebugInfo;
        return form_value.getUInt(u64);
    }

    fn getAttrRef(self: *const Die, id: u64, unit_offset: u64, unit_len: u64) !u64 {
        const form_value = self.getAttr(id) orelse return error.MissingDebugInfo;
        return switch (form_value.*) {
            .ref => |offset| if (offset < unit_len) unit_offset + offset else bad(),
            .ref_addr => |addr| addr,
            else => bad(),
        };
    }

    pub fn getAttrString(
        self: *const Die,
        di: *Dwarf,
        endian: Endian,
        id: u64,
        opt_str: ?[]const u8,
        compile_unit: *const CompileUnit,
    ) error{ InvalidDebugInfo, MissingDebugInfo }![]const u8 {
        const form_value = self.getAttr(id) orelse return error.MissingDebugInfo;
        switch (form_value.*) {
            .string => |value| return value,
            .strp => |offset| return di.getString(offset),
            .strx => |index| {
                const debug_str_offsets = di.section(.debug_str_offsets) orelse return bad();
                if (compile_unit.str_offsets_base == 0) return bad();
                switch (compile_unit.format) {
                    .@"32" => {
                        const byte_offset = compile_unit.str_offsets_base + 4 * index;
                        if (byte_offset + 4 > debug_str_offsets.len) return bad();
                        const offset = mem.readInt(u32, debug_str_offsets[@intCast(byte_offset)..][0..4], endian);
                        return getStringGeneric(opt_str, offset);
                    },
                    .@"64" => {
                        const byte_offset = compile_unit.str_offsets_base + 8 * index;
                        if (byte_offset + 8 > debug_str_offsets.len) return bad();
                        const offset = mem.readInt(u64, debug_str_offsets[@intCast(byte_offset)..][0..8], endian);
                        return getStringGeneric(opt_str, offset);
                    },
                }
            },
            .line_strp => |offset| return di.getLineString(offset),
            else => return bad(),
        }
    }
}