cursor.c

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/* -*- C -*- */
/*
 * Copyright (c) 2011-2020 Seagate Technology LLC and/or its Affiliates
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * For any questions about this software or licensing,
 * please email opensource@seagate.com or cortx-questions@seagate.com.
 *
 */


#include "lib/assert.h"

#include "xcode/xcode.h"

M0_INTERNAL void m0_xcode_cursor_init(struct m0_xcode_cursor *it,
                                      const struct m0_xcode_obj *obj)
{
        M0_SET0(it);
        m0_xcode_cursor_top(it)->s_obj = *obj;
}

M0_INTERNAL struct m0_xcode_cursor_frame *
m0_xcode_cursor_top(struct m0_xcode_cursor *it)
{
        M0_PRE(IS_IN_ARRAY(it->xcu_depth, it->xcu_stack));
        return &it->xcu_stack[it->xcu_depth];
}

M0_INTERNAL const struct m0_xcode_field *
m0_xcode_cursor_field(const struct m0_xcode_cursor *it)
{
        if (it->xcu_depth > 0) {
                const struct m0_xcode_cursor_frame *pre =
                        m0_xcode_cursor_top((void *)it) - 1; /* Drop const. */
                return &pre->s_obj.xo_type->xct_child[pre->s_fieldno];
        } else
                return NULL;
}


M0_INTERNAL int m0_xcode_next(struct m0_xcode_cursor *it)
{
        struct m0_xcode_cursor_frame *top;
        struct m0_xcode_cursor_frame *next;
        const struct m0_xcode_type   *xt;
        int                           nr;

        M0_PRE(it->xcu_depth >= 0);

        top = m0_xcode_cursor_top(it);
        xt  = top->s_obj.xo_type;
        nr  = xt->xct_nr;

        M0_ASSERT_INFO_EX(m0_xcode_type_invariant(xt),
                          "xct_name: %s", xt->xct_name);
        switch (top->s_flag) {
        case M0_XCODE_CURSOR_NONE:
                top->s_flag = M0_XCODE_CURSOR_PRE;
                break;
        case M0_XCODE_CURSOR_IN:
                switch (xt->xct_aggr) {
                case M0_XA_RECORD:
                case M0_XA_TYPEDEF:
                        ++top->s_fieldno;
                        break;
                case M0_XA_SEQUENCE:
                        if (top->s_fieldno == 0) {
                                top->s_elno = 0;
                                top->s_fieldno = 1;
                        } else {
                case M0_XA_ARRAY: /* sic. All hail C. */
                                ++top->s_elno;
                        }
                        if (top->s_elno >= m0_xcode_tag(&top->s_obj)) {
                                top->s_elno = 0;
                                top->s_fieldno = 2;
                        }
                        break;
                case M0_XA_UNION:
                        if (top->s_fieldno != 0) {
                                top->s_fieldno = nr;
                                break;
                        }
                        while (++top->s_fieldno < nr &&
                               m0_xcode_tag(&top->s_obj) !=
                               xt->xct_child[top->s_fieldno].xf_tag) {
                                ;
                        }
                        break;
                case M0_XA_OPAQUE:
                default:
                        M0_IMPOSSIBLE("wrong aggregation type");
                }
                /* fall through */
        case M0_XCODE_CURSOR_PRE:
                if (top->s_fieldno < nr) {
                        top->s_flag = M0_XCODE_CURSOR_IN;
                        if (xt->xct_aggr != M0_XA_ATOM) {
                                int result;

                                ++it->xcu_depth;
                                next = m0_xcode_cursor_top(it);
                                result = m0_xcode_subobj(&next->s_obj,
                                                         &top->s_obj,
                                                         top->s_fieldno,
                                                         top->s_elno);
                                if (result != 0)
                                        return result;
                                next->s_fieldno = 0;
                                next->s_elno    = 0;
                                next->s_flag    = M0_XCODE_CURSOR_PRE;
                                next->s_datum   = 0;
                        }
                } else
                        top->s_flag = M0_XCODE_CURSOR_POST;
                break;
        case M0_XCODE_CURSOR_POST:
                if (--it->xcu_depth < 0)
                        return 0;
                top = m0_xcode_cursor_top(it);
                M0_ASSERT(top->s_flag < M0_XCODE_CURSOR_POST);
                top->s_flag = M0_XCODE_CURSOR_IN;
                break;
        default:
                M0_IMPOSSIBLE("wrong order");
        }
        return +1;
}

M0_INTERNAL void m0_xcode_skip(struct m0_xcode_cursor *it)
{
        m0_xcode_cursor_top(it)->s_flag = M0_XCODE_CURSOR_POST;
}

/*
 *  Local variables:
 *  c-indentation-style: "K&R"
 *  c-basic-offset: 8
 *  tab-width: 8
 *  fill-column: 80
 *  scroll-step: 1
 *  End:
 */