gherkin-cpp-parser.razor

@using Berp;
@functions {
public static string ToSnakeCase(string str)
{
    return
        string.Concat(
            str.Select(
                (x, i) => i > 0 && char.IsUpper(x)
                ? "_" + x
                : x.ToString()
            )
        ).ToLower();
}

public static string NameOf(Rule rule)
{ return ToSnakeCase(rule.Name.Replace("#", "")); }
}
@helper CallProduction(ProductionRule production)
{
  var rname = ToSnakeCase(production.RuleName);

  switch(production.Type)
  {
    case ProductionRuleType.Start:
      @:  start_rule(context, rule_type::@rname);
      break;
    case ProductionRuleType.End:
      @:  end_rule(context, rule_type::@rname);
      break;
    case ProductionRuleType.Process:
      @:  build(context, token);
      break;
  }
}
@helper HandleParserError(IEnumerable<string> expectedTokens, State state)
{<text>
        std::string state_comment = "State: @state.Id - @Raw(state.Comment)";
        std::string expected_tokens = "@Raw(string.Join(", ", expectedTokens))";

        auto ep =
            token.is_eof()
            ? new_parser_error<unexpected_eof>(
                token, expected_tokens, state_comment
            )
            : new_parser_error<unexpected_token>(
                token, expected_tokens, state_comment
            )
            ;

        if (context.stop_at_first_error) {
            throw *ep;
        }

        context.add_error(std::move(ep));

        return @state.Id;
</text>}
@helper MatchToken(TokenType tokenType)
{<text>match_@(ToSnakeCase(tokenType.Name))(context, token)</text>}
// This file is generated. Do not edit! Edit gherkin-cpp-parser.razor instead.
#include <cucumber/gherkin/parser_base.hpp>
#include <cucumber/gherkin/rule_type.hpp>

namespace cucumber::gherkin {

template <
    typename Builder = ast_builder,
    typename Scanner = token_scanner,
    typename Matcher = token_matcher
>
class parser : public parser_base<Builder, Scanner, Matcher>
{
public:
    using parent = parser_base<Builder, Scanner, Matcher>;
    using parent::parent;
    using parent::parse;
    using context_type = typename parent::context_type;

protected:
    void parse(context_type& context) override
    {
        start_rule(context, rule_type::@NameOf(Model.RuleSet.StartRule));

        std::size_t state = 0;

        while (true) {
            auto token = context.read_token();
            state = match_token(state, token, context);

            if (token.is_eof()) {
                break;
            }
        }

        end_rule(context, rule_type::@NameOf(Model.RuleSet.StartRule));

        if (context.has_errors()) {
            throw composite_parser_error(context.eptrs);
        }
    }

    void build(context_type& context, token& token)
    { context.builder.build(token); }

    void start_rule(context_type& context, rule_type rule_type)
    {
        handle_ast_error(
            context,
            rule_type,
            [&context](auto rtype) {
                context.builder.start_rule(rtype);
            }
        );
    }

    void end_rule(context_type& context, rule_type rule_type)
    {
        handle_ast_error(
            context,
            rule_type,
            [&context](auto rtype) {
                context.builder.end_rule(rtype);
            }
        );
    }

    template <typename Argument, typename Action>
    bool handle_external_error(
        context_type& context,
        bool default_value,
        Argument&& argument,
        Action&& action
    )
    {
        using ret_type = decltype(action(argument));

        try {
            if constexpr (std::is_same_v<ret_type, void>) {
                action(argument);
                return default_value;
            } else {
                return action(argument);
            }
        } catch (const composite_parser_error& e) {
            for (const auto& ep : e.errors()) {
                context.add_error(ep);
            }
        } catch (const parser_error& e) {
            auto ep = new_parser_error<parser_error>(e);
            context.add_error(ep);
        }

        return default_value;
    }

    template <typename Argument, typename Action>
    void handle_ast_error(
        context_type& context,
        Argument&& argument,
        Action&& action
    )
    { handle_external_error(context, true, argument, action); }

@foreach(var rule in Model.RuleSet.TokenRules)
{
<text>
    bool match_@(NameOf(rule))(context_type& context, token& token)
    {
    @if (rule.Name != "#EOF")
    {
        @:if (token.is_eof()) {
        @:    return false;
        @:}
        @:
    }
        return
            handle_external_error(
                context,
                false,
                token,
                [&context](auto& t) {
                    return context.matcher.match_@(NameOf(rule))(t);
                }
            );
    }
</text>
}

@foreach(var lookAheadHint in Model.RuleSet.LookAheadHints)
{
<text>
    bool lookahead_@(lookAheadHint.Id)(context_type& context, token& current_token)
    {
        current_token.detach();
        token token;
        token_queue queue;
        bool match = false;

        while (true) {
            token = context.read_token();
            token.detach();
            queue.push_back(token);

            if (@foreach(var tokenType in lookAheadHint.ExpectedTokens) {<text>@MatchToken(tokenType) || </text>}false) {
                match = true;
                break;
            }

            if (!(@foreach(var tokenType in lookAheadHint.Skip) {<text>@MatchToken(tokenType) || </text>}false)) {
                break;
            }
        }

        context.push_tokens(queue);

        return match;
    }
</text>
}

@foreach(var state in Model.States.Values.Where(s => !s.IsEndState))
{<text>
    // @Raw(state.Comment)
    std::size_t match_token_at_@(state.Id)(token& token, context_type& context)
    {
@{var indent = "    ";}
    @foreach(var transition in state.Transitions)
    {
        @:if (@MatchToken(transition.TokenType)) {
            if (transition.LookAheadHint != null)
            {
            @:if (lookahead_@(transition.LookAheadHint.Id)(context, token)) {
                indent = "        ";
            }
            foreach(var production in transition.Productions)
            {
                @indent@CallProduction(production)
            }
        @:@(indent)return @transition.TargetState;
            if (transition.LookAheadHint != null)
            {
                indent = "    ";
            @:}
            }
        @:}
    }
        @HandleParserError(state.Transitions.Select(t => "#" + t.TokenType.ToString()).Distinct(), state)
    }
</text>
}

    std::size_t match_token(std::size_t state, token& token, context_type& context)
    {
        switch (state) {
    @foreach(var state in Model.States.Values.Where(s => !s.IsEndState))
    {
        @:case @state.Id:
            @:return match_token_at_@(state.Id)(token, context);
    }
        default:
            throw
                std::runtime_error(
                    "invalid operation: " + std::to_string(state)
                );

            return -1;
        }
    }
};

}