fish-shell/src/parse_productions.cpp

#include "parse_productions.h"
#include <assert.h>
#include <stdio.h>
#include "parse_tree.h"

using namespace parse_productions;

#define NO_PRODUCTION NULL

/* Herein are encoded the productions for our LL2 fish grammar.
 Each symbol (e.g. symbol_job_list) has a corresponding function (e.g. resolve_job_lits).
 The function accepts two tokens, representing the first and second lookahead, and returns
 returns a production representing the rule, or NULL on error. There is also a tag value
 which is returned by reference; the tag is a sort of node annotation.
 
 Productions are generally a static const array, and we return a pointer to the array (yes, really).
 */

#define RESOLVE(sym) static const production_t * resolve_##sym (const parse_token_t &token1, const parse_token_t &token2, parse_node_tag_t *out_tag)

/* Hacktastic? */
#define RESOLVE_ONLY(sym) \
    extern const production_t sym##_only; \
    static const production_t * resolve_##sym (const parse_token_t &token1, const parse_token_t &token2, parse_node_tag_t *out_tag) { return &sym ## _only ; } \
    const production_t sym ## _only

#define KEYWORD(x) ((x) + LAST_TOKEN_OR_SYMBOL + 1)

/* Helper macro to define an array */
#define P static const production_t

/* A job_list is a list of jobs, separated by semicolons or newlines */
RESOLVE(job_list)
{
    P list_end = {};
    P normal = {symbol_job, symbol_job_list};
    P empty_line = {parse_token_type_end, symbol_job_list};
    switch (token1.type)
    {
        case parse_token_type_string:
            // some keywords are special
            switch (token1.keyword)
            {
                case parse_keyword_end:
                case parse_keyword_else:
                case parse_keyword_case:
                    // End this job list
                    return &list_end;

                default:
                    // Normal string
                    return &normal;
            }

        case parse_token_type_pipe:
        case parse_token_type_redirection:
        case parse_token_type_background:
            return &normal;

        case parse_token_type_end:
            return &empty_line;

        case parse_token_type_terminate:
            // no more commands, just transition to empty
            return &list_end;

        default:
            return NO_PRODUCTION;
    }
}

/* A job is a non-empty list of statements, separated by pipes. (Non-empty is useful for cases like if statements, where we require a command). To represent "non-empty", we require a statement, followed by a possibly empty job_continuation */

RESOLVE_ONLY(job) = {symbol_statement, symbol_job_continuation, symbol_optional_background};

RESOLVE(job_continuation)
{
    P empty = {};
    P piped = {parse_token_type_pipe, symbol_statement, symbol_job_continuation};
    switch (token1.type)
    {
        case parse_token_type_pipe:
            // Pipe, continuation
            return &piped;

        default:
            // Not a pipe, no job continuation
            return &empty;
    }
}

/* A statement is a normal command, or an if / while / and etc */
RESOLVE(statement)
{
    P boolean = {symbol_boolean_statement};
    P block = {symbol_block_statement};
    P ifs = {symbol_if_statement};
    P switchs = {symbol_switch_statement};
    P decorated = {symbol_decorated_statement};
    /* The only block-like builtin that takes any parameters is 'function' So go to decorated statements if the subsequent token looks like '--'.
        The logic here is subtle:
            If we are 'begin', then we expect to be invoked with no arguments.
            If we are 'function', then we are a non-block if we are invoked with -h or --help
            If we are anything else, we require an argument, so do the same thing if the subsequent token is a statement terminator.
    */

    if (token1.type == parse_token_type_string)
    {
        // If we are a function, then look for help arguments
        // Otherwise, if the next token looks like an option (starts with a dash), then parse it as a decorated statement
        if (token1.keyword == parse_keyword_function && token2.is_help_argument)
        {
            return &decorated;
        }
        else if (token1.keyword != parse_keyword_function && token2.has_dash_prefix)
        {
            return &decorated;
        }

        // Likewise if the next token doesn't look like an argument at all. This corresponds to e.g. a "naked if".
        bool naked_invocation_invokes_help = (token1.keyword != parse_keyword_begin && token1.keyword != parse_keyword_end);
        if (naked_invocation_invokes_help && (token2.type == parse_token_type_end || token2.type == parse_token_type_terminate))
        {
            return &decorated;
        }

    }

    switch (token1.type)
    {
        case parse_token_type_string:
            switch (token1.keyword)
            {
                case parse_keyword_and:
                case parse_keyword_or:
                case parse_keyword_not:
                    return &boolean;

                case parse_keyword_for:
                case parse_keyword_while:
                case parse_keyword_function:
                case parse_keyword_begin:
                    return &block;

                case parse_keyword_if:
                    return &ifs;

                case parse_keyword_else:
                    return NO_PRODUCTION;

                case parse_keyword_switch:
                    return &switchs;

                case parse_keyword_end:
                    return NO_PRODUCTION;

                    // All other keywords fall through to decorated statement
                default:
                    return &decorated;
            }
            break;

        case parse_token_type_pipe:
        case parse_token_type_redirection:
        case parse_token_type_background:
        case parse_token_type_terminate:
            return NO_PRODUCTION;
            //parse_error(L"statement", token);

        default:
            return NO_PRODUCTION;
    }
}

RESOLVE_ONLY(if_statement) = {symbol_if_clause, symbol_else_clause, symbol_end_command, symbol_arguments_or_redirections_list};
RESOLVE_ONLY(if_clause) = { KEYWORD(parse_keyword_if), symbol_job, parse_token_type_end, symbol_andor_job_list, symbol_job_list };

RESOLVE(else_clause)
{
    P empty = {};
    P else_cont = { KEYWORD(parse_keyword_else), symbol_else_continuation };
    switch (token1.keyword)
    {
        case parse_keyword_else:
            return &else_cont;
        default:
            return &empty;
    }
}

RESOLVE(else_continuation)
{
    P elseif = {symbol_if_clause, symbol_else_clause};
    P elseonly = {parse_token_type_end, symbol_job_list};

    switch (token1.keyword)
    {
        case parse_keyword_if:
            return &elseif;
        default:
            return &elseonly;
    }
}

RESOLVE_ONLY(switch_statement) = { KEYWORD(parse_keyword_switch), symbol_argument, parse_token_type_end, symbol_case_item_list, symbol_end_command, symbol_arguments_or_redirections_list};

RESOLVE(case_item_list)
{
    P empty = {};
    P case_item = {symbol_case_item, symbol_case_item_list};
    P blank_line = {parse_token_type_end, symbol_case_item_list};
    if (token1.keyword == parse_keyword_case) return &case_item;
    else if (token1.type == parse_token_type_end) return &blank_line;
    else return &empty;
}

RESOLVE_ONLY(case_item) = {KEYWORD(parse_keyword_case), symbol_argument_list, parse_token_type_end, symbol_job_list};

RESOLVE(andor_job_list)
{
    P list_end = {};
    P andor_job = {symbol_job, symbol_andor_job_list};
    P empty_line = {parse_token_type_end, symbol_andor_job_list};
    
    if (token1.type == parse_token_type_end)
    {
        return &empty_line;
    }
    else if (token1.keyword == parse_keyword_and || token1.keyword == parse_keyword_or)
    {
        // Check that the argument to and/or is a string that's not help
        // Otherwise it's either 'and --help' or a naked 'and', and not part of this list
        if (token2.type == parse_token_type_string && !token2.is_help_argument)
        {
            return &andor_job;
        }
    }
    // All other cases end the list
    return &list_end;
}

RESOLVE(argument_list)
{
    P empty = {};
    P arg = {symbol_argument, symbol_argument_list};
    switch (token1.type)
    {
        case parse_token_type_string:
            return &arg;
        default:
            return &empty;
    }
}

RESOLVE(freestanding_argument_list)
{
    P empty = {};
    P arg = {symbol_argument, symbol_freestanding_argument_list};
    P semicolon = {parse_token_type_end, symbol_freestanding_argument_list};

    switch (token1.type)
    {
        case parse_token_type_string:
            return &arg;
        case parse_token_type_end:
            return &semicolon;
        default:
            return &empty;
    }
}

RESOLVE_ONLY(block_statement) = {symbol_block_header, symbol_job_list, symbol_end_command, symbol_arguments_or_redirections_list};

RESOLVE(block_header)
{
    P forh = {symbol_for_header};
    P whileh = {symbol_while_header};
    P funch = {symbol_function_header};
    P beginh = {symbol_begin_header};

    switch (token1.keyword)
    {
        case parse_keyword_for:
            return &forh;
        case parse_keyword_while:
            return &whileh;
        case parse_keyword_function:
            return &funch;
        case parse_keyword_begin:
            return &beginh;
        default:
            return NO_PRODUCTION;
    }
}

RESOLVE_ONLY(for_header) = {KEYWORD(parse_keyword_for), parse_token_type_string, KEYWORD
    (parse_keyword_in), symbol_argument_list, parse_token_type_end};
RESOLVE_ONLY(while_header) = {KEYWORD(parse_keyword_while), symbol_job, parse_token_type_end, symbol_andor_job_list};
RESOLVE_ONLY(begin_header) = {KEYWORD(parse_keyword_begin)};
RESOLVE_ONLY(function_header) = {KEYWORD(parse_keyword_function), symbol_argument, symbol_argument_list, parse_token_type_end};

/* A boolean statement is AND or OR or NOT */
RESOLVE(boolean_statement)
{
    P ands = {KEYWORD(parse_keyword_and), symbol_statement};
    P ors = {KEYWORD(parse_keyword_or), symbol_statement};
    P nots = {KEYWORD(parse_keyword_not), symbol_statement};

    switch (token1.keyword)
    {
        case parse_keyword_and:
            *out_tag = parse_bool_and;
            return &ands;
        case parse_keyword_or:
            *out_tag = parse_bool_or;
            return &ors;
        case parse_keyword_not:
            *out_tag = parse_bool_not;
            return &nots;
        default:
            return NO_PRODUCTION;
    }
}

RESOLVE(decorated_statement)
{
    P plains = {symbol_plain_statement};
    P cmds = {KEYWORD(parse_keyword_command), symbol_plain_statement};
    P builtins = {KEYWORD(parse_keyword_builtin), symbol_plain_statement};
    P execs = {KEYWORD(parse_keyword_exec), symbol_plain_statement};

    /* If this is e.g. 'command --help' then the command is 'command' and not a decoration. If the second token is not a string, then this is a naked 'command' and we should execute it as undecorated. */
    if (token2.type != parse_token_type_string || token2.has_dash_prefix)
    {
        return &plains;
    }

    switch (token1.keyword)
    {
        default:
            *out_tag = parse_statement_decoration_none;
            return &plains;
        case parse_keyword_command:
            *out_tag = parse_statement_decoration_command;
            return &cmds;
        case parse_keyword_builtin:
            *out_tag = parse_statement_decoration_builtin;
            return &builtins;
        case parse_keyword_exec:
            *out_tag = parse_statement_decoration_exec;
            return &execs;
    }
}

RESOLVE_ONLY(plain_statement) = {parse_token_type_string, symbol_arguments_or_redirections_list};

RESOLVE(arguments_or_redirections_list)
{
    P empty = {};
    P value = {symbol_argument_or_redirection, symbol_arguments_or_redirections_list};
    switch (token1.type)
    {
        case parse_token_type_string:
        case parse_token_type_redirection:
            return &value;
        default:
            return &empty;
    }
}

RESOLVE(argument_or_redirection)
{
    P arg = {symbol_argument};
    P redir = {symbol_redirection};
    switch (token1.type)
    {
        case parse_token_type_string:
            return &arg;
        case parse_token_type_redirection:
            return &redir;
        default:
            return NO_PRODUCTION;
    }
}

RESOLVE_ONLY(argument) = {parse_token_type_string};
RESOLVE_ONLY(redirection) = {parse_token_type_redirection, parse_token_type_string};

RESOLVE(optional_background)
{
    P empty = {};
    P background = { parse_token_type_background };
    switch (token1.type)
    {
        case parse_token_type_background:
            *out_tag = parse_background;
            return &background;
        default:
            *out_tag = parse_no_background;
            return &empty;
    }
}

RESOLVE_ONLY(end_command) = {KEYWORD(parse_keyword_end)};

#define TEST(sym) case (symbol_##sym): resolver = resolve_ ## sym ; break;
const production_t *parse_productions::production_for_token(parse_token_type_t node_type, const parse_token_t &input1, const parse_token_t &input2, parse_node_tag_t *out_tag)
{
    const bool log_it = false;
    if (log_it)
    {
        fprintf(stderr, "Resolving production for %ls with input token <%ls>\n", token_type_description(node_type).c_str(), input1.describe().c_str());
    }

    /* Fetch the function to resolve the list of productions */
    const production_t * (*resolver)(const parse_token_t &input1, const parse_token_t &input2, parse_node_tag_t *out_tag) = NULL;
    switch (node_type)
    {
            TEST(job_list)
            TEST(job)
            TEST(statement)
            TEST(job_continuation)
            TEST(boolean_statement)
            TEST(block_statement)
            TEST(if_statement)
            TEST(if_clause)
            TEST(else_clause)
            TEST(else_continuation)
            TEST(switch_statement)
            TEST(decorated_statement)
            TEST(case_item_list)
            TEST(case_item)
            TEST(argument_list)
            TEST(freestanding_argument_list)
            TEST(block_header)
            TEST(for_header)
            TEST(while_header)
            TEST(begin_header)
            TEST(function_header)
            TEST(plain_statement)
            TEST(andor_job_list)
            TEST(arguments_or_redirections_list)
            TEST(argument_or_redirection)
            TEST(argument)
            TEST(redirection)
            TEST(optional_background)
            TEST(end_command)

        case parse_token_type_string:
        case parse_token_type_pipe:
        case parse_token_type_redirection:
        case parse_token_type_background:
        case parse_token_type_end:
        case parse_token_type_terminate:
            fprintf(stderr, "Terminal token type %ls passed to %s\n", token_type_description(node_type).c_str(), __FUNCTION__);
            PARSER_DIE();
            break;

        case parse_special_type_parse_error:
        case parse_special_type_tokenizer_error:
        case parse_special_type_comment:
            fprintf(stderr, "Special type %ls passed to %s\n", token_type_description(node_type).c_str(), __FUNCTION__);
            PARSER_DIE();
            break;


        case token_type_invalid:
            fprintf(stderr, "token_type_invalid passed to %s\n", __FUNCTION__);
            PARSER_DIE();
            break;

    }
    PARSE_ASSERT(resolver != NULL);

    const production_t *result = resolver(input1, input2, out_tag);
    if (result == NULL)
    {
        if (log_it)
        {
            fprintf(stderr, "Node type '%ls' has no production for input '%ls' (in %s)\n", token_type_description(node_type).c_str(), input1.describe().c_str(), __FUNCTION__);
        }
    }

    return result;
}