ExtUtils::ParseXS::Utilities(3)

NAME
ExtUtils::ParseXS::Utilities - Subroutines used with ExtUtils::ParseXS

SYNOPSIS
  use ExtUtils::ParseXS::Utilities qw(
    standard_typemap_locations
    trim_whitespace
    C_string
    valid_proto_string
    process_typemaps
    map_type
    standard_XS_defs
    analyze_preprocessor_statement
    set_cond
    Warn
    blurt
    death
    check_conditional_preprocessor_statements
    escape_file_for_line_directive
    report_typemap_failure
  );

SUBROUTINES
The following functions are not considered to be part of the public interface. They are documented here for the benefit of future maintainers of this module.

  standard_typemap_locations()

•   Purpose

    Provide a list of filepaths where typemap files may be found. The filepaths -- relative paths to files (not just directory paths) -- appear in this list in lowest-to-highest priority.

    The highest priority is to look in the current directory.

      'typemap'

    The second and third highest priorities are to look in the parent of the current directory and a directory called lib/ExtUtils underneath the parent directory.

      '../typemap',
      '../lib/ExtUtils/typemap',

    The fourth through ninth highest priorities are to look in the corresponding grandparent, great-grandparent and great-great-grandparent directories.

      '../../typemap',
      '../../lib/ExtUtils/typemap',
      '../../../typemap',
      '../../../lib/ExtUtils/typemap',
      '../../../../typemap',
      '../../../../lib/ExtUtils/typemap',

    The tenth and subsequent priorities are to look in directories named ExtUtils which are subdirectories of directories found in @INC -- provided a file named typemap actually exists in such a directory. Example:

      '/usr/local/lib/perl5/5.10.1/ExtUtils/typemap',

    However, these filepaths appear in the list returned by standard_typemap_locations() in reverse order, i.e., lowest-to-highest.

      '/usr/local/lib/perl5/5.10.1/ExtUtils/typemap',
      '../../../../lib/ExtUtils/typemap',
      '../../../../typemap',
      '../../../lib/ExtUtils/typemap',
      '../../../typemap',
      '../../lib/ExtUtils/typemap',
      '../../typemap',
      '../lib/ExtUtils/typemap',
      '../typemap',
      'typemap'

•   Arguments

      my @stl = standard_typemap_locations( \@INC );

    Reference to @INC.

•   Return Value

    Array holding list of directories to be searched for typemap files.

  trim_whitespace()

•   Purpose

    Perform an in-place trimming of leading and trailing whitespace from the first argument provided to the function.

•   Argument

      trim_whitespace($arg);

•   Return Value

    None. Remember: this is an in-place modification of the argument.

  C_string()

•   Purpose

    Escape backslashes ("\") in prototype strings.

•   Arguments

          $ProtoThisXSUB = C_string($_);

    String needing escaping.

•   Return Value

    Properly escaped string.

  valid_proto_string()

•   Purpose

    Validate prototype string.

•   Arguments

    String needing checking.

•   Return Value

    Upon success, returns the same string passed as argument.

    Upon failure, returns 0.

  process_typemaps()

•   Purpose

    Process all typemap files.

•   Arguments

      my $typemaps_object = process_typemaps( $args{typemap}, $pwd );

    List of two elements: "typemap" element from %args; current working directory.

•   Return Value

    Upon success, returns an ExtUtils::Typemaps object.

  "map_type($self, $type, $varname)"
Returns a mapped version of the C type $type. In particular, it converts "Foo::bar" to "Foo__bar", converts the special "array(type,n)" into "type *", and inserts $varname (if present) into any function pointer type. So "...(*)..." becomes "...(* foo)...".

  standard_XS_defs()

•   Purpose

    Writes to the ".c" output file certain preprocessor directives and function headers needed in all such files.

•   Arguments

    None.

•   Return Value

    Returns true.

  analyze_preprocessor_statement()

•   Purpose

    Process a CPP conditional line ("#if" etc), to keep track of conditional nesting. In particular, it updates "@{$self->{XS_parse_stack}}" which contains the current list of nested conditions, and "$self->{XS_parse_stack_top_if_idx}" which indicates the most recent "if" in that stack. So an "#if" pushes, an "#endif" pops, an "#else" modifies etc. Each element is a hash of the form:

      {
        type      => 'if',
        varname   => 'XSubPPtmpAAAA', # maintained by caller

                      # XS functions defined within this branch of the
                      # conditional (maintained by caller)
        functions =>  {
                        'Foo::Bar::baz' => 1,
                        ...
                      }
                      # XS functions seen within any previous branch
        other_functions => {... }

    It also updates "$self->{bootcode_early}" and "$self->{bootcode_late}" with extra CPP directives.

•   Arguments

          $self->analyze_preprocessor_statement($statement);

  set_cond()

•   Purpose

    Return a string containing a snippet of C code which tests for the 'wrong number of arguments passed' condition, depending on whether there are default arguments or ellipsis.

•   Arguments

    "ellipsis" true if the xsub's signature has a trailing ", ...".

    $min_args the smallest number of args which may be passed.

    $num_args the number of parameters in the signature.

•   Return Value

    The text of a short C code snippet.

  current_line_number()

•   Purpose

    Figures out the current line number in the XS file.

•   Arguments

    $self

•   Return Value

    The current line number.

  Error handling methods
There are four main methods for reporting warnings and errors.

"$self->Warn(@messages)"
    This is equivalent to:

      warn "@messages in foo.xs, line 123\n";

    The file and line number are based on the file currently being parsed. It is intended for use where you wish to warn, but can continue parsing and still generate a correct C output file.

"$self->blurt(@messages)"
    This is equivalent to "Warn", except that it also increments the internal error count (which can be retrieved with report_error_count()). It is used to report an error, but where parsing can continue (so typically for a semantic error rather than a syntax error). It is expected that the caller will eventually signal failure in some fashion. For example, "xsubpp" has this as its last line:

      exit($self->report_error_count() ? 1 : 0);

"$self->death(@messages)"
    This normally equivalent to:

      $self->Warn(@messages);
      exit(1);

    It is used for something like a syntax error, where parsing can't continue. However, this is inconvenient for testing purposes, as the error can't be trapped. So if $self is created with the "die_on_error" flag, or if $ExtUtils::ParseXS::DIE_ON_ERROR is true when process_file() is called, then instead it will die() with that message.

"$self->WarnHint(@messages, $hints)"
    This is a more obscure twin to "Warn", which does the same as "Warn", but afterwards, outputs any lines contained in the $hints string, with each line wrapped in parentheses. For example:

      $self->WarnHint(@messages,
        "Have you set the foo switch?\nSee the manual for further info");

  check_conditional_preprocessor_statements()

•   Purpose

    Warn if the lines in "@{ $self->{line} }" don't have balanced "#if", "endif" etc.

•   Arguments

    None

•   Return Value

    None

  escape_file_for_line_directive()

•   Purpose

    Escapes a given code source name (typically a file name but can also be a command that was read from) so that double-quotes and backslashes are escaped.

•   Arguments

    A string.

•   Return Value

    A string with escapes for double-quotes and backslashes.

  "report_typemap_failure"

•   Purpose

    Do error reporting for missing typemaps.

•   Arguments

    The "ExtUtils::ParseXS" object.

    An "ExtUtils::Typemaps" object.

    The string that represents the C type that was not found in the typemap.

    Optionally, the string "death" or "blurt" to choose whether the error is immediately fatal or not. Default: "blurt"

•   Return Value

    Returns nothing. Depending on the arguments, this may call "death" or "blurt", the former of which is fatal.