path_parser.cc

#include <internal/path_parser.hpp>
#include <internal/tokens.hpp>
#include <sstream>
#include <internal/values/config_string.hpp>
#include <boost/algorithm/string.hpp>
#include <leatherman/locale/locale.hpp>

// Mark string for translation (alias for leatherman::locale::format)
using leatherman::locale::_;

using namespace std;
using namespace boost::algorithm;

namespace hocon {

    /** Element */
    path_parser::element::element(string initial, bool can_be_empty) : _value(move(initial)),
                                                                       _can_be_empty(can_be_empty) { }

    string path_parser::element::to_string() const {
        return "Element(" + _value + "," + std::to_string(_can_be_empty) + ")";
    }

    /** Path parser */
    const shared_origin path_parser::api_origin = make_shared<simple_config_origin>("path parameter");

    config_node_path path_parser::parse_path_node(string const& path_string, config_syntax flavor) {
        token_iterator tokens = token_iterator(api_origin,
                                               unique_ptr<istringstream>(new istringstream(path_string)),
                                               (flavor != config_syntax::JSON));

        tokens.next();  // drop start token
        return parse_path_node_expression(tokens, api_origin, path_string, flavor);
    }

    path path_parser::parse_path(string const& path_string) {
        path speculated = speculative_fast_parse_path(path_string);
        if (speculated != path()) {
            return speculated;
        }

        token_iterator tokens = token_iterator(api_origin,
                                               unique_ptr<istringstream>(new istringstream(path_string)),
                                               true);
        tokens.next();  // drop start token
        return parse_path_expression(tokens, api_origin, path_string);
    }

    config_node_path path_parser::parse_path_node_expression(iterator& expression,
                                                             shared_origin origin,
                                                             string const& original_text,
                                                             config_syntax flavor)
    {
        token_list tokens;
        path path = parse_path_expression(expression, origin, original_text, &tokens, flavor);
        return config_node_path(path, tokens);
    }

    path path_parser::parse_path_expression(iterator& expression, shared_origin origin,
                                            string const& original_text, token_list* path_tokens,
                                            config_syntax flavor)
    {
        vector<element> elements = { element("", false) };

        if (!expression.has_next()) {
            throw bad_path_exception(*origin, original_text,
                                     _("Expecting a field name or path here, but got nothing"));
        }

        while (expression.has_next()) {
            shared_token t = expression.next();

            if (path_tokens != nullptr) {
                path_tokens->push_back(t);
            }

            if (t->get_token_type() == token_type::IGNORED_WHITESPACE) {
                continue;
            }

            if (tokens::is_value_with_type(t, config_value::type::STRING)) {
                auto value = tokens::get_value(t);
                // this is a quoted string, so any periods in here don't count as path separators
                string s = value->transform_to_string();
                add_path_text(elements, true, s);
            } else if (t == tokens::end_token()) {
                // ignore this; when parsing a file, it should not happen
                // since we're parsing a token list rather than the main
                // token iterator, and when parsing a path expression from the
                // API, it's expected to have an END.
            } else {
                // any periods outside of a quoted string count as separators
                string text;
                if (t->get_token_type() == token_type::VALUE) {
                    // appending a number here may add a period, but we _do_ count those as path
                    // separators, because we basically want "foo 3.0bar" to parse as a string even
                    // though there's a number in it. The fact that we tokenize non-string values
                    // is largely an implementation detail.
                    auto value = tokens::get_value(t);

                    // We need to split the tokens on a . so that we can get sub-paths but still preserve
                    // the original path text when doing an insertion
                    if (path_tokens != nullptr) {
                        path_tokens->pop_back();
                        token_list split_tokens = split_token_on_period(t, flavor);
                        path_tokens->insert(path_tokens->end(), split_tokens.begin(), split_tokens.end());
                    }
                    text = value->render();
                } else if (t->get_token_type() == token_type::UNQUOTED_TEXT) {
                    // We need to split the tokens on a . so that we can get sub-paths but still preserve
                    // the original path text when doing an insertion on config_nodeObjects
                    if (path_tokens != nullptr) {
                        path_tokens->pop_back();
                        token_list split_tokens = split_token_on_period(t, flavor);
                        path_tokens->insert(path_tokens->end(), split_tokens.begin(), split_tokens.end());
                    }
                    text = t->token_text();
                } else {
                    throw bad_path_exception(*origin, original_text,
                                             _("Token not allowed in path expression: {1} (you can double-quote this token if you really want it here)", t->to_string()));
                }

                add_path_text(elements, false, text);
            }
        }

        path_builder builder;
        for (element e : elements) {
            if (e._value.length() == 0 && !e._can_be_empty) {
                throw bad_path_exception(*origin, original_text,
                                         _("path has a leading, trailing, or two adjacent '.' (use quoted \"\" empty string if you want an empty element)"));
            } else {
                builder.append_key(e._value);
            }
        }

        return builder.result();
    }

    token_list path_parser::split_token_on_period(shared_token t, config_syntax flavor) {
        string token_text = t->token_text();
        if (token_text == ".") {
            return token_list { t };
        }

        bool ends_in_period = token_text.back() == '.';

        // The split iterator tacks an empty string onto the end of the iterator if the string
        // ends in the split character; so we need to remove trailing '.'
        boost::trim_right_if(token_text, is_any_of("."));

        vector<string> token_it;
        boost::split(token_it, token_text, is_any_of("."));

        token_list split_tokens;
        for (auto& s : token_it) {
            // string token_string { s.begin(), s.end() };
            if (flavor == config_syntax::CONF) {
                split_tokens.push_back(make_shared<unquoted_text>(t->origin(), move(s)));
            } else {
                split_tokens.push_back(make_shared<value>(
                        make_shared<config_string>(
                                t->origin(), "\"" + s + "\"", config_string_type::UNQUOTED)));
            }
            split_tokens.push_back(make_shared<unquoted_text>(t->origin(), "."));
        }

        // If the token text does not end in a period, we have reached the end of a path,
        // and we want to treat the last element differently
        if (!ends_in_period) {
            split_tokens.pop_back();
        }
        return split_tokens;
    }

    void path_parser::add_path_text(std::vector<element>& buff, bool was_quoted, std::string new_text) {
        size_t i = was_quoted ? string::npos : new_text.find('.');
        element& current = buff.back();
        if (i == string::npos) {
            // add the current path element
            current._value += new_text;
            // any empty quoted string means this element can now be empty
            if (was_quoted && current._value.empty()) {
                current._can_be_empty = true;
            }
        } else {
            // buff plus up to the period is an element
            current._value += new_text.substr(0, i);
            // then start a new element
            buff.push_back(element("", false));
            // recurse to consume the remainder of new_text
            add_path_text(buff, false, new_text.substr(i + 1));
        }
    }

    bool path_parser::looks_unsafe_for_fast_parser(std::string s) {
        bool last_was_dot = true;  // start of a path is also a "dot"
        size_t len = s.length();
        if (s.empty()) {
            return true;
        }
        if (s[0] == '.') {
            return true;
        }
        if (s[len - 1] == '.') {
            return true;
        }

        for (char c : s) {
            if ((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') || c == '_') {
                last_was_dot = false;
                continue;
            } else if (c == '.') {
                if (last_was_dot) {
                    return true;  // ".." means we need to throw an error
                }
                last_was_dot = true;
            } else if (c == '-') {
                if (last_was_dot) {
                    return true;
                }
                continue;
            } else {
                return true;
            }
        }

        return last_was_dot;
    }

    path path_parser::fast_path_build(path tail, string s) {
        size_t split_at = s.find_last_of('.');
        token_list tokens;
        tokens.push_back(make_shared<unquoted_text>(nullptr, s));
        path with_one_more_element = path(s.substr(split_at + 1), tail);
        if (split_at == string::npos) {
            return with_one_more_element;
        } else {
            return fast_path_build(with_one_more_element, s.substr(0, split_at));
        }
    }

    path path_parser::speculative_fast_parse_path(std::string const& path_string) {
        string s = path_string;
        boost::trim(s);
        if (looks_unsafe_for_fast_parser(s)) {
            return path { };
        }

        return fast_path_build(path(), s);
    }

}  // namespace hocon