CONTENTS

• NAME
• SYNOPSIS
• SUBROUTINES
  • standard_typemap_locations()
  • trim_whitespace()
  • C_string()
  • valid_proto_string()
  • process_typemaps()
  • map_type($self, $type, $varname)
  • standard_XS_defs()
  • analyze_preprocessor_statement()
  • set_cond()
  • current_line_number()
  • Error handling methods
  • check_conditional_preprocessor_statements()
  • escape_file_for_line_directive()
  • report_typemap_failure

#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

  Returns a standard list of filepaths where typemap files may be found. This will typically be something like:

  map("$_/ExtUtils/typemap", reverse @INC),
  qw(
      ../../../../lib/ExtUtils/typemap
      ../../../../typemap
      ../../../lib/ExtUtils/typemap
      ../../../typemap
      ../../lib/ExtUtils/typemap
      ../../typemap
      ../lib/ExtUtils/typemap
      ../typemap
      typemap
  )

  but the style of the pathnames may vary with OS. Note that the value to use for @INC is passed as an array reference, and can be something other than @INC itself.

  Pathnames are returned in the order they are expected to be processed; this means that later files will update or override entries found in earlier files. So in particular, typemap in the current directory has highest priority. @INC is searched in reverse order so that earlier entries in @INC are processed later and so have higher priority.

  The values of -typemap switches are not used here; they should be added by the caller to the list of pathnames returned by this function.

• Arguments

  my @stl = standard_typemap_locations(\@INC);

  A single argument: a reference to an array to use as if it were @INC.

• Return Value

  A list of typemap pathnames.

#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. Reads in any typemap files specified explicitly with -typemap switches or similar, plus any typemap files found in standard locations relative to @INC and the current directory.

• Arguments

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

  The first argument is the typemap element from %args; the second is the current working directory (which is only needed for error messages).

• Return Value

  Upon success, returns an ExtUtils::Typemaps object which contains the accumulated results of all processed typemap files.

#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.

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