validate.h

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/*
 * XMLTree - An XML Parser-Helper Library
 * Copyright (C) 2025  Marcus Harrison
 * 
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */
 
#ifndef DESCENT_XML_VALIDATE
#define DESCENT_XML_VALIDATE
 
#ifdef __cplusplus
extern "C" {
#endif
 
#include <stdbool.h>
 
#include <libadt/lptr.h>
#include <libadt/str.h>
 
#include "parse.h"
 
inline struct descent_xml_lex _descent_xml_validate_element_handler(
    struct descent_xml_lex token,
    struct libadt_const_lptr element_name,
    struct libadt_const_lptr attributes,
    bool empty,
    void *context_p
)
{
    (void)attributes;
    struct {
        bool valid;
        int depth;
    } *context = context_p;
    if (context->depth == 0) {
        context->valid = false;
        return token;
    }
    context->depth--;
 
    const struct libadt_const_lptr xmldecl = libadt_str_literal("?xml");
 
    if (libadt_const_lptr_equal(element_name, xmldecl)) {
        context->valid = false;
        return token;
    }
 
    if (empty)
        return token;
 
    while (token.type != descent_xml_classifier_element_close_name) {
        if (
            token.type == descent_xml_classifier_unexpected
            || token.type == descent_xml_classifier_eof
            || token.type == descent_xml_lex_xmldecl
            || token.type == descent_xml_lex_doctype
            || !context->valid
        ) {
            context->valid = false;
            return token;
        }
        token = descent_xml_parse(
            token,
            _descent_xml_validate_element_handler,
            NULL,
            context
        );
    }
 
    context->valid = libadt_const_lptr_equal(
        token.value,
        element_name
    );
    context->depth++;
    token = descent_xml_parse(token, NULL, NULL, NULL);
    return token;
}
 
inline bool descent_xml_validate_element_depth(
    struct descent_xml_lex token,
    int depth
)
{
    struct {
        bool valid;
        int depth;
    } context = { true, depth };
    while (token.type != descent_xml_classifier_element) {
        if (
            token.type == descent_xml_classifier_unexpected
            || token.type == descent_xml_classifier_eof
        )
            return false;
        token = descent_xml_lex_next_raw(token);
    }
    token = descent_xml_parse(
        token,
        _descent_xml_validate_element_handler,
        NULL,
        &context
    );
 
    // We have to check for unexpected/eof here in case the
    // element handler never runs
    return
        context.valid
        && token.type != descent_xml_classifier_unexpected
        && token.type != descent_xml_classifier_eof;
}
 
inline bool descent_xml_validate_element(struct descent_xml_lex token)
{
    return descent_xml_validate_element_depth(token, 10000);
}
 
inline bool _descent_xml_non_space_text(struct descent_xml_lex token)
{
    return token.type == descent_xml_classifier_text
        || token.type == descent_xml_classifier_text_entity_start
        || token.type == descent_xml_classifier_text_entity
        || token.type == descent_xml_lex_cdata;
}
 
inline struct descent_xml_lex _descent_xml_validate_prolog_goto_element(
    struct descent_xml_lex token
)
{
    while (token.type != descent_xml_classifier_element) {
        if (
            token.type == descent_xml_classifier_unexpected
            || token.type == descent_xml_classifier_eof
            || _descent_xml_non_space_text(token)
        )
            return token;
        token = descent_xml_lex_next_raw(token);
    }
    return token;
}
 
inline struct descent_xml_lex _descent_xml_validate_prolog_comments(
    struct descent_xml_lex token
)
{
    if (token.type != descent_xml_classifier_element) {
        token.type = descent_xml_classifier_unexpected;
        return token;
    }
 
    struct descent_xml_lex next = descent_xml_lex_next_raw(token);
    if (next.type == descent_xml_lex_comment) {
        token = descent_xml_lex_then(
            next,
            _descent_xml_validate_prolog_goto_element
        );
        token = descent_xml_lex_optional(
            token,
            _descent_xml_validate_prolog_comments
        );
    }
    return token;
}
 
inline struct descent_xml_lex _descent_xml_validate_xmldecl(
    struct descent_xml_lex token
)
{
    struct descent_xml_lex next = descent_xml_lex_next_raw(token);
 
    if (next.type == descent_xml_lex_xmldecl) {
        token = descent_xml_lex_then(
            next,
            _descent_xml_validate_prolog_goto_element
        );
    }
 
    return token;
}
 
inline struct descent_xml_lex _descent_xml_validate_doctype(
    struct descent_xml_lex token
)
{
    struct descent_xml_lex next = descent_xml_lex_next_raw(token);
 
    if (next.type == descent_xml_lex_doctype) {
        token = descent_xml_lex_then(
            next,
            _descent_xml_validate_prolog_goto_element
        );
    }
 
    return token;
}
 
inline struct descent_xml_lex _descent_xml_validate_parse_prolog(
    struct descent_xml_lex token
)
{
    token = descent_xml_lex_then(
        token,
        _descent_xml_validate_prolog_goto_element
    );
    token = descent_xml_lex_optional(
        token,
        _descent_xml_validate_xmldecl
    );
    token = descent_xml_lex_optional(
        token,
        _descent_xml_validate_prolog_comments
    );
    token = descent_xml_lex_optional(
        token,
        _descent_xml_validate_doctype
    );
    token = descent_xml_lex_optional(
        token,
        _descent_xml_validate_prolog_comments
    );
    return token;
}
 
inline bool descent_xml_validate_document_depth(
    struct descent_xml_lex token,
    int depth
)
{
    struct {
        bool valid;
        int depth;
    } context = {true, depth};
 
    token = _descent_xml_validate_parse_prolog(token);
    if (
        token.type == descent_xml_classifier_unexpected
        || token.type == descent_xml_classifier_eof
    )
        return false;
 
    token = descent_xml_parse(
        token,
        _descent_xml_validate_element_handler,
        NULL,
        &context
    );
 
    if (!context.valid)
        return false;
 
    // check that there's only one element node in the root
    while (token.type != descent_xml_classifier_element) {
        if (token.type == descent_xml_classifier_eof)
            return true;
        if (token.type == descent_xml_classifier_unexpected)
            return false;
        if (token.type == descent_xml_classifier_text)
            return false;
        token = descent_xml_lex_next_raw(token);
    }
 
    return false;
}
 
inline bool descent_xml_validate_document(
    struct descent_xml_lex token
)
{
    return descent_xml_validate_document_depth(token, 1000);
}
 
#ifdef __cplusplus
} // extern "C"
#endif
 
#endif // DESCENT_XML_VALIDATE