The long option parser for subcommands (lopsub).

[lopsub.git] / lopsub.h.m4

VERBATIM_C(«
/*
 * Copyright (C) 2016 Andre Noll <maan@tuebingen.mpg.de>
 *
 * Licensed under the LGPL v3, see http://www.gnu.org/licenses/lgpl-3.0.html
 */

#include <string.h>
#include <inttypes.h>
#include <stdbool.h>

#ifndef _LOPSUB_H
#define _LOPSUB_H
»)

STATEMENT(
        «struct lls_suite»,
        «Opaque structure which describes a lopsub suite.»,
«
        This structure is defined in the .c file which is generated by
        lopsubgen(1). The corresponding header file exposes a const pointer
        to a this structure for use in the application.

        Applications can not de-reference this pointer or access its content
        directly. They must call one of the accessor functions described below.
»)

STATEMENT(
        «struct lls_command»,
        «Represents one command of a suite.»,
«
        A command is identified by a suite and a command number. The symbolic
        names of all commands defined in a suite are exposed in the enumeration
        defined in the header file which is generated by lopsubgen(1),

        Applications can obtain an opaque pointer to a command by calling
        lls_cmd(), providing the command number and the suite pointer as
        arguments.
»)

STATEMENT(
        «struct lls_option»,
        «Represents one option of a command.»,
«
        Similar to a command, an option is identified by a command and an
        option number. The header file created by the lopsubgen(1) utility
        provides an enumeration for all options of each command.

        The lls_opt() function returns an opaque pointer to an option, given
        a command pointer and an option number.
»)

STATEMENT(
        «struct lls_parse_result»,
        «An argument vector, fully parsed according to a lopsub command.»,
«
        A pointer to an opaque structure of this type is returned by
        lls_parse() if the argument vector was found valid for the given
        command.

        Several functions (described below) take a pointer to such a
        structure. This enables applications to obtain details about the
        options and arguments that were given in the argument vector, for
        example whether an option was specified and how many non-options
        (aka inputs) were given.
»)

STATEMENT(
        «struct lls_opt_result»,
        «The part of a parse result related to a specific option»,
«
        Given an option and a parse result, the lls_opt_result() function
        returns an opaque pointer to a structure of this type which contains
        information about the option in the argument vector that was used to
        create the parse result.

        A pointer to a structure of this type can be passed to the various
        accessor functions described below. These functions return information
        about the option in the argument vector, for example how many times
        the option was given.
»)

DECLARE_FUNCTION(
        «lls_strerror»,
        «A strerror-like function for lopsub error codes.»,
«
        This works just like strerror(3).
», «
        «int lss_errno», «positive error code returned from a lopsub library function»
», «
»,
        «const char *», «points to static memory, must not be freed by the caller»
)

DECLARE_FUNCTION(
        «lls_parse»,
        «Parse an argument vector according to a lopsub command.»,
«
        This function turns a broken-up command line into a parse result,
        completely parsing all arguments according to the options defined
        in the given a lopsub command. As usual, options may be given in any
        order and the special argument "--" forces an end of option-scanning.

        For each option defined in the suite, if the multiple flag is set
        for the option, the parse result contains an array of values, with
        one value for each time the option was given. Conversely, if the
        multiple flag is not set, only a single value is stored in the parse
        result. Those options may still be given multiple times, but only
        the last given argument is stored while all previous arguments are
        discarded.

        For options which take an integer value, conversion is performed in
        a way that recognizes an optional base prefix like "0x". The empty
        string and strings with trailing non-digit characters result in a
        parse error. Range violations are detected and also cause the function
        to fail.
», «
        «int argc», «Usual argument counter.»,
        «char **argv», «Usual argument vector to parse.»,
        «const struct lls_command *cmd», «Contains names and characteristics of all allowed options.»,
        «struct lls_parse_result **lprp», «Result pointer.»,
        «char **errctx», «Optional error context string, only set on failure»
», «
        The parse_result pointer returned through lprp can be passed to several
        accessor functions described below in order to obtain information
        about the options and arguments in argv[].
»,
        «int», «Standard (negative error code on failure, non-negative on success).»,
«
        On success lprp is initialized according to the options that have been
        parsed successfully. In this case either errctx or *errctx is NULL,
        so no cleanup needs to be performed in the caller. However, when the
        caller is no longer interested in the parse result, it should call
        lls_free_parse_result() to release the memory that was allocated
        during the call to lls_parse().

        On errors, *lprp is set to NULL and the function returns a negative
        error code. This can happen for various reasons, for example if an
        invalid option or argument was given. Another possible reason is worth
        mentioning: when the non-opts-name directive was not specified in the
        suite, the subcommand is assumed to take no non-option arguments. In
        this case, lls_parse() fails if the argument vector does contain any
        non-option arguments.

        In the error case, if errctx is not NULL, *errctx points to a
        zero-terminated string which describes the context of the error
        condition, for example the problematic element of argv[]. The only
        exception is when an out of memory condition occurs. In this case
        *errctx may be NULL because the function was unable to allocate
        the memory needed for the error context. If *errctx is not NULL,
        the memory it points to should be freed by the caller. However,
        lls_free_parse_result() need not be called in this case.
»)

DECLARE_FUNCTION(
        «lls_free_parse_result»,
        «Deallocate a parse result.»,
«
        This frees the memory space allocated by lls_parse().
», «
        «struct lls_parse_result *lpr», «As returned by lls_parse().»,
        «const struct lls_command *cmd»,
                «This must match the pointer passed earlier to lls_parse().»
», «
        The parse result pointer must have been returned by a previous
        call to lls_parse() or lls_serialize_parse_result(). Otherwise, or
        if lls_free_parse_result has already been called before, undefined
        behavior occurs. It's OK to pass a NULL pointer though. In this case
        no action is performed.
»,
        «void»
)

DECLARE_FUNCTION(
        «lls_long_help»,
        «Return the long help text of a command.»,
«
        The long help text contains the synopsis, the purpose and the help
        text of the command, followed by the option list including descriptions
        and help for each option.
», «
        «const struct lls_command *cmd», «As returned from lls_cmd().»
», «
»,
        «char *», «A dynamically allocated string that must be freed by the caller.»
)

DECLARE_FUNCTION(
        «lls_short_help»,
        «Return the short help text of a command.»,
«
        This is similar to lls_long_help() but help texts are omitted from
        the output.
», «
        «const struct lls_command *cmd», «See lls_long_help().»
», «
»,
        «char *», «See lls_long_help().»
)

DECLARE_FUNCTION(
        «lls_lookup_subcmd»,
        «Tell whether the given string is the name of a subcommand.»,
«
        This tries to match the given string against the subcommands of the
        suite. Exact matches and unique partial matches count as success.
», «
        «const char *string», «The name to look up.»,
        «const struct lls_suite *suite», «Contains the command list.»,
        «char **errctx», «Contains lookup string and the name of the suite.»
», «
»,
        «int», «The command number on success, negative error code on failure.»,
«
        The lookup fails if (a) the given string pointer is NULL, or (b) if
        the string is no prefix of any subcommand of the suite, or (c) if it
        is a proper prefix of more than one subcommand.

        On success the error context pointer is set to NULL. In the error case,
        if errctx is not NULL, *errctx is pointed to a string that must be
        freed by the caller.
»)

DECLARE_FUNCTION(
        «lls_cmd»,
        «Return a pointer to a command structure.»,
«
        Applications usually call this at the beginning of each function that
        implements a lopsub command (aka command handler). The returned
        pointer serves as an abstract reference to the command. This
        reference is needed to call other functions of the lopsub library,
        notably lls_parse().
», «
        «unsigned cmd_num», «Appropriate enum value from the header file.»,
        «const struct lls_suite *suite», «Also declared in the header file.»
», «
        The suite pointer and all valid command numbers are defined in the
        header file which is generated by lopsubgen(1). Hence this header
        file must be included from the application to get the name of the
        suite pointer variable and the command numbers.
»,
        «const struct lls_command *», «Never returns NULL.»,
«
        This function always succeeds if both arguments are valid. That is,
        the command number is a symbolic constant from the LSG_XXX_COMMANDS
        enumeration of the header file generated by lopsubgen(1), and the suite
        pointer equals the pointer that is declared in the same header file.

        If at least one of the arguments are invalid, the behavior is
        undefined.
»)

DECLARE_FUNCTION(
        «lls_command_name»,
        «Obtain the name of the command, given a command pointer.»,
«
        Even in situations where the application knows the name of the command,
        it is less error-prone to call this function rather than to duplicate
        the command name in the application.
», «
        «const struct lls_command *cmd», «As obtained from lls_cmd().»
», «
»,
        «const char *», «Never returns NULL.»,
«
        This function succeeds unless the given command pointer is invalid
        (was not obtained through an earlier call to lls_cmd() or is NULL),
        in which case the behavior is undefined. The return pointer refers
        to static storage that must not be freed by the caller.
»)

DECLARE_FUNCTION(
        «lls_user_data»,
        «Obtain the application-specific data pointer.»,
«
        Some applications need to store further information for each subcommand,
        for example a function pointer which refers to the implementation of
        the subcommand. The optional user data feature allows to define one
        application defined pointer that can be retrieved by calling this
        function.

        Of course storing one function pointer per command could simply be
        done by defining a suitable array in the application which contains
        one pointer per (sub)command. However, this approach has the disadvantage
        that it effectively creates two command lists (one in the suite
        file and one for the array) that need to be maintained and kept in
        sync. Moreover, functions can not be declared as static if they are
        defined in a different source file than the one that defines the array.

        Therefore, lopsub offers an alternative: The .c file generated by
        lopsubgen(1) declares one const void * pointer per command. These
        pointers are marked with the "weak" attribute (a gcc extension, but
        also available for clang). This instructs the compiler to store the
        declaration as a weak symbol in the object file. Since the linker
        does not require weak symbols to be defined, linking succeeds even
        if the application chooses to not employ the user data feature.

        To make use of the user data feature, the application needs to define
        one pointer for each command called lsg_xxx_com_yyy_user_data, where
        xxx is the name of the suite and yyy the name of the command. A
        suitable preprocessor macro can make this as simple as EXPORT_CMD(foo).
», «
        «const struct lls_command *cmd», «As obtained from lls_cmd().»
», «
»,
        «const void *», «The user data pointer defined in the application.»,
«
        If the application did not define a user data pointer for the given
        command, the function returns NULL.
»)

DECLARE_FUNCTION(
        «lls_opt_result»,
        «Extract information about one option from a parse result.»,
«
        The returned pointer can be passed to the accessor functions described
        below. Those functions let the applications tell how many times the
        option was given and retrieve any argument(s) for the option.
», «
        «unsigned opt_num», «As declared in the header file.»,
        «const struct lls_parse_result *lpr», «As returned from lls_parse().»
», «
        The header file generated by lopsubgen(1) generates for each command
        an enumeration which declares one option number per option as a
        symbolic constant.
»,
        «const struct lls_opt_result *», «Never returns NULL.»,
«
        If the parse result pointer is invalid (was not returned by
        lls_parse(), or is NULL), or the option number does not correspond to
        the command that was used to create the parse result, the behaviour
        is undefined. Otherwise this function succeeds.
»)

DECLARE_FUNCTION(
        «lls_opt»,
        «Get a reference to an option, given a command and an option number.»,
«
        While an opt_result pointer described above is used to obtain
        information in an argument vector, the pointer returned by this
        function allows to obtain information about the option itself.

        Applications rarely need to care about the option pointer. It
        is required to get the possible values of an enumeration option
        though. See lls_enum_string_val().
», «
        «unsigned opt_num», «See lls_opt_result()»,
        «const struct lls_command *cmd», «Obtained from lls_cmd().»
», «
»,
        «const struct lls_option *», «Never returns NULL.»,
«
        This function always succeeds if both arguments are
        valid. Otherwise the behavior is undefined.
»)

DECLARE_FUNCTION(
        «lls_opt_given»,
        «Return how many times an option was given.»,
«
        This is employed as follows. Applications first call lls_parse() to
        initialize the parse result, followed by lls_opt_result() to obtain a
        reference to those parts of the parse result that are related to one
        specific option. The reference can then be passed to this function
        to find out how many times the option was given.
», «
        «const struct lls_opt_result *r», «As returned from lls_opt_result().»
», «
»,
        «unsigned», «Zero means: Not given at all.»,
«
        Even if the multiple flag was not set for the option, the returned
        value may be greater than one because this flag only affects how many
        arguments are stored in the parse result.

        This function succeeds unless the opt_result pointer is invalid
        (was not returned by lls_opt_result(), or is NULL), in which case
        the behaviour is undefined.
»)

DECLARE_FUNCTION(
        «lls_string_val»,
        «Retrieve one argument to a string option.»,
«
        This function may only be called for options which take an optional or
        required argument of string type. Enum options (which take as their
        argument one of a fixed, finite set of possible strings), however,
        are treated as if the option took an argument of uint32 type. Hence
        this function must not be called for these options.
», «
        «unsigned idx», «The index in the array of values.»,
        «const struct lls_opt_result *r», «As returned from lls_opt_result.»
», «
        The first argument must be zero if the multiple flag is not set for
        the option. Otherwise any number between zero and n - 1 (inclusively)
        may be passed, where n is the number of times the option was given,
        that is, the return value of lls_opt_given().

        As as special case, if the option was not given at all (i.e., n == 0),
        it is still OK to call this function with an index value of zero. In
        this case, the default value for the option will be returned, or NULL
        if no default value was specified in the suite.
»,
        «const char *», «The argument that corresponds to the given index.»,
«
        The memory referenced by the return pointer is part of the parse
        result and must not be freed by the caller. It will be freed when
        lls_free_parse_result() is called.

        Undefined behaviour occurs in all of the following cases: (a) the
        index is out of range, (b) the opt_result pointer is NULL or was
        not obtained through a previous call to lls_opt_result(), (c) the
        opt_result pointer corresponds to an option which takes an argument
        of different type or no argument at all. If none of these conditions
        apply, the function is guaranteed to succeed.
»)

DECLARE_FUNCTION(
        «lls_int32_val»,
        «Retrieve one argument to an option that takes an int32 argument.»,
«
        This is like lls_string_val(), but for options which take an optional
        or required argument of type int32.
», «
        «unsigned idx», «See lls_string_val()»,
        «const struct lls_opt_result *r», «See lls_string_val().»
», «
        As for lls_string_val(), a zero index value is considered a valid
        input even if the option was not given at all. In this case. the
        default value is returned, or zero if the option has no default value.
»,
        «int32_t», «The argument, converted to a 32 bit signed integer.»,
«
        Since conversion of the argument to int32_t takes place earlier during
        lls_parse(), no errors are possible unless the index parameter or the
        the opt result pointer (or both) are invalid. See above for details.
»)

DECLARE_FUNCTION(
        «lls_uint32_val»,
        «Retrieve one argument to an option that takes an uint32 argument.»,
«
        Identical to lls_int32_val(), except the argument type of the option
        and the return value are different.

        For enum options, this is the correct function to call in order
        to obtain the index into the array of possible values, see
        lls_enum_string_val() below.
», «
        «unsigned idx», «See lls_int32_val().»,
        «const struct lls_opt_result *r», «See lls_int32_val().»
», «
»,
        «uint32_t», «See lls_int32_val().»
)

DECLARE_FUNCTION(
        «lls_int64_val»,
        «Retrieve one argument to an option that takes an int64 argument.»,
«
        Identical to lls_int32_val(), except that this function must be used
        for options which take a 64 bit signed integer argument.
», «
        «unsigned idx», «See lls_int32_val().»,
        «const struct lls_opt_result *r», «See lls_int32_val().»
», «
»,
        «int64_t», «See lls_int32_val().»
)

DECLARE_FUNCTION(
        «lls_uint64_val»,
        «Retrieve one argument to an option that takes an uint64 argument.»,
«
        Identical to lls_int32_val(), except that this function must be used
        for options which take a 64 bit unsigned integer argument.
», «
        «unsigned idx», «See lls_int32_val().»,
        «const struct lls_opt_result *r», «See lls_int32_val().»
», «
»,
        «uint64_t», «See lls_int32_val().»
)

DECLARE_FUNCTION(
        «lls_enum_string_val»,
        «Get one possible argument value for an option.»,
«
        This function must only be called for enum options. That is, options
        for which the set of possible arguments was defined through the values
        directive in the suite.
», «
        «unsigned idx», «Determines which of the possible values to get.»,
        «const struct lls_option *opt», «As returned by lls_opt().»
», «
        The possible values of an enum option are a property of the option
        itself and are thus independent of the command line. Therefore this
        function expects an option pointer rather than a pointer to an opt
        result.

        The index parameter must be a value between zero and the number of
        possible values minus one, inclusively. This number is declared as
        the last member of the enumeration for the option, which is defined
        of the generated header file.
»,
        «const char *», «Static memory, must not be freed.»,
«
        Behavior is undefined if the given option is not an enum option, a
        NULL pointer is passed, or if the index value is out of range.
»
)

DECLARE_FUNCTION(
        «lls_num_inputs»,
        «Get the number of non-option arguments.»,
«
        In addition to options and their arguments, subcommands may accept
        any number of additional arguments which are not related to any
        particular option. For example, file names are frequently passed
        as such non-option arguments (aka inputs).
», «
        «const struct lls_parse_result *lpr», «As returned from lls_parse().»
», «
        Passing a NULL pointer to this function results in undefined behaviour.
»,
        «unsigned», «Number of non-option arguments.»,
«
        This function never fails. See also lls_input(), lls_check_arg_count().
»)

DECLARE_FUNCTION(
        «lls_input»,
        «Get a reference to one non-option argument.»,
«
        If the argument vector passed to lls_parse() contained non-option
        arguments, the value of each of them can be obtained by calling
        this function.
», «
        «unsigned idx», «The index into the array of non-option arguments.»,
        «const struct lls_parse_result *lpr», «As returned from lls_parse().»
», «
        The index must be between zero and n-1, inclusively, where n is the
        number returned by lls_num_inputs(). The parse_result pointer must have
        been obtained by an earlier call to lls_parse().
»,
        «const char *», «Pointer to the corresponding non-option argument.»,
«
        If the conditions described above are met, the function is guaranteed
        to succeed. It will never return a NULL pointer in this case.
»
)

DECLARE_FUNCTION(
        «lls_version»,
        «Get the version string of the lopsub library.»,
«
        The version string is determined at build time from the sha1 of the
        HEAD git commit or from the name of the top level directory for compiling
        from a gitweb snapshot.
», «
        «void»,
», «
»,
        «const char *», «Static storage, must not be freed by the caller.»,
«
        The returned string is of the form <tag>-<d>-g<sha1>, where <tag>
        is the name of the last tagged commit contained in the HEAD commit,
        <d> is the number of commits between <tag> and HEAD, and <sha1> is the
        first four hex digits of the hash of the HEAD commit. If the working
        tree was dirty at compile time, the string "-dirty" is appended to
        the version string.

        This function always succeeds.
»
)

DECLARE_FUNCTION(
        «lls_purpose»,
        «Get the line which describes the purpose of a command.»,
«
        This function is useful for applications which need to print
        their own command summary rather than employ lls_short_help() and
        lls_long_help(). One reason for this could be that the application
        has additional per-command informations which should be included in
        the command summary.
», «
        «const struct lls_command *cmd», «Obtained from lls_cmd().»
», «
»,
        «const char *», «Static storage, must not be freed.»,
«
        The returned string is the content of the corresponding directive of
        the suite file, with leading and trailing whitespace removed.
»
)

DECLARE_FUNCTION(
        «lls_convert_config»,
        «Transform the contents of a config file into an argument vector.»,
«
        This function scans the given input buffer to compute an (argc,
        argv) pair which is suitable to be fed to lls_parse(). The function
        is config-agnostic. That is, it does not know anything about option
        names and their type.

        Arguments are separated from the option by whitespace and an optional
        '=' character. Arguments to string options should be enclosed in double
        quotes and must not spawn multiple lines. Newline or tab characters
        may be embedded into the argument string with '\n' and '\t'. To embed
        a backslash, double it. To embed a quote, prefix it with a backslash.
», «
        «const char *buf», «Input buffer (content of the config file).»,
        «size_t nbytes», «The buffer size.»,
        «const char *subcmd», «NULL means supercommand.»,
        «char ***result», «Argument vector is returned here.»,
        «char **errctx», «Error context, see lls_parse().»
», «
        If a subcommand is specified, only the part of the input buffer which
        is started by a [subcmd] marker is taken into account. Conversely,
        if a NULL pointer is passed, only the beginning part until the first
        section marker will be considered. This allows config files to contain
        options for the supercommand and subcommands.
»,
        «int», «Length of the argument vector.»,
«
        On success, the number of elements in the computed argument vector
        is returned. Slot zero of the argument vector is initialized to a
        dummy value while the remaining values correspond to the options and
        arguments found in the input buffer. The argument vector should be
        freed with lls_free_argv() when it is no longer needed.

        On failure a negative error code is returned and *result is set to
        NULL. Several types of failure are possible, including allocation
        failure, errors from the lexer and various syntax errors.
»
)

DECLARE_FUNCTION(
        «lls_free_argv»,
        «Deallocate an argument vector.»,
«
        lls_convert_config() dynamically allocates memory for the argument
        and for each of its elements. This function frees this memory.
», «
        «char **argv», «The argument vector to free.»
», «
        It's OK to pass a NULL pointer, in which case the function does
        nothing.
»,
        «void»
)

DECLARE_FUNCTION(
        «lls_check_arg_count»,
        «Check the number of non-option arguments.»,
«
        This helper verifies that the number of non-option arguments lies
        within the specified range. Although this function is kind of trivial,
        it can help applications to provide nice and consistent error messages.
», «
        «const struct lls_parse_result *lpr», «As obtained from lls_parse().»,
        «int min_argc», «Lower bound on the number of non-option arguments.»,
        «int max_argc», «Upper bound on the number of non-option arguments.»,
        «char **errctx», «Describes the range violation, only set on failure.»
», «
        For the function to succeed, the number of non-option arguments (as
        returned by lls_num_inputs()) must be greater or equal to min_argc
        and less or equal to max_argc.

        Both min_argc and max_argc may be zero (but not negative), and min_argc
        must be less or equal to max_argc. The value INT_MAX for max_argc
        indicates that the number of allowed non-option arguments is unbounded.
»,
        «int», «Standard. The only possible error is -LLS_E_BAD_ARG_COUNT.»,
«
        Examples:

        min_argc = 0, max_argc = 0: no non-option argument may be given.

        min_argc = 0, max_argc = INT_MAX: any number of non-option arguments OK.

        min_argc = 1, max_argc = 2: either one or two non-option arguments OK.

        Behaviour is undefined if min_argc or max_argc is negative, if min_argc
        is greater than max_argc, or if lpr is invalid.
»
)

DECLARE_FUNCTION(
        «lls_serialize_parse_result»,
        «Create a buffer from a parse result.»,
«
        This function is handy for passing the result from lls_parse() to a
        different process.
», «
        «const struct lls_parse_result *lpr», «The parse result to serialize.»,
        «const struct lls_command *cmd», «Must point to the command used to create the parse result.»,
        «char **result», «The serialized parse result.»,
        «size_t *nbytes», «The size of the serialized buffer.»
», «
        Depending on the initial value of the result pointer, the function
        behaves as follows.

        (a) If result is NULL, the size required to store the serialized
        buffer is computed and returned through the nbytes argument, but no
        serialization takes place.

        (b) If result is not NULL, but *result is NULL, a suitable buffer is
        allocated with malloc() and *result is pointed at this buffer. The
        caller is responsible for freeing this buffer when it is no longer
        needed.

        (c) If *result is not NULL, the buffer pointed at by *result is assumed
        be be large enough for the serialized parse result, and this buffer
        is used to store the result.
»,
        «int», «Standard.»,
«
        See also: lls_deserialize_parse_result().
»
)

DECLARE_FUNCTION(
        «lls_deserialize_parse_result»,
        «Initialize a parse result from a buffer.»,
«
        This is the counterpart to lls_serialize_parse_result().
», «
        «const char *buf», «The buffer to de-serialize.»,
        «const struct lls_command *cmd», «Must match the pointer used for serializing.»,
        «struct lls_parse_result **lprp», «Result pointer.»
», «
        The input buffer should have been obtained through an earlier call
        to lls_serialize_parse_result().
»,
        «int», «Standard.»,
«
        On success all fields of lpr match the original values. After the
        call, no fields of *lprp contain references to buf, so buf may safely
        be freed.
»
)

DECLARE_FUNCTION(
        «lls_merge»,
        «Combine two parse results, creating an effective configuration.»,
«
        This is useful for applications which receive options from the command
        line and the configuration file.
», «
        «const struct lls_parse_result *primary», «From command line options.»,
        «const struct lls_parse_result *secondary», «From config file.»,
        «const struct lls_command *cmd», «Common command for both parse results.»,
        «struct lls_parse_result **lprp», «Effective configuration is returned here.»,
        «char **errctx», «Error context, see lls_parse().»
», «
        Merging works on a per-option basis as follows. If the multiple flag
        is set for the option, the argument arrays of the primary and the
        secondary parse result are concatenated and the concatenation is the
        argument array for the merge result. It the multiple flag is not set,
        the value of the primary parse result becomes the argument for the
        merge result.

        The two non-option argument arrays are concatenated in the same way
        as the arguments to options with the multiple flag set.

        All arguments are copied from the two input parse results. It is safe
        to free them after the function returns. The merge result should be
        freed with lls_parse_result() when it is no longer needed.
»,
        «int», «Standard.»,
«
        The only possible error is an out of memory condition. However,
        behaviour is undefined if the primary or secondary parse result is
        NULL, or was not obtained from the given command.
»
)

DECLARE_FUNCTION(
        «lls_dump_parse_result»,
        «Create contents of a configuration file from a parse result.»,
«
        The subcommand marker ([subcommand]) is not included in the output.
», «
        «const struct lls_parse_result *lpr», «As obtained from lls_parse() or lls_merge().»,
        «const struct lls_command *cmd», «Subcommand or supercommand.»,
        «bool non_default_only», «Only include option values that differ from the default.»
»,«
        If non_default_only is false, options are included in the dump even
        if they are not given in the parse result. However, flag options are
        excluded in this case as well as options which take an argument for
        which no default value has been defined.
»,
        «char *», «Must be freed by the caller.»,
«
        If no options are given, or if every option argument of the parse
        result matches the default value of the option and non_default_only
        is true, the function returns the empty string.

        The only possible error is an out of memory condition, in which case
        the NULL pointer is returned. Behaviour is undefined if any of the
        pointer arguments is NULL, or if the parse result does not match the
        given command.
»
)
VERBATIM_C(«#endif /* _LOPSUB_H */»)