Macro

Definition

Macro management and expansion core of the fpx Fortran preprocessor.

This module implements a complete, standards-inspired macro system supporting:

• Object-like and function-like macros
• Variadic macros (... and __VA_ARGS__)
• Parameter stringification (#param) and token pasting (##)
• Built-in predefined macros: __FILE__, __FILENAME__, __LINE__, __DATE__, __TIME__, __TIMESTAMP__
• Recursive expansion with circular dependency detection via digraph analysis
• Dynamic macro table of macro objects with efficient addition, lookup, removal
• Full support for nested macro calls and proper argument handling

The design allows safe, repeated expansion while preventing infinite recursion. All operations are container-agnostic using allocatable dynamic arrays.

Examples

1. Define and use simple macros:

   type(macro), allocatable :: macros(:)
   call add(macros, macro('PI', '3.1415926535'))
   call add(macros, macro('MSG(x)', 'print *, ″Hello ″, x'))
   print *, expand_all(context('area = PI * r**2', 10, './circle.F90', 'circle'), macros, stitch, .false., .false.)
   !> prints: area = 3.1415926535 * r**2

2. Variadic macro with stringification and pasting:

   call add(macros, macro('DEBUG_PRINT(...)', 'print *, ″DEBUG[″, __FILE__, ″:″, __LINE__, ″]: ″, __VA_ARGS__'))
   print *, expand_all(context('DEBUG_PRINT(″value =″, x)', 42, 'test.F90', 'text'), macros, stitch, .false., false)
   !> prints: print *, 'DEBUG[', 'test.F90', ':', 42, ']: ', 'value =', x

3. Token pasting with ##:

   call add(macros, macro('MAKE_VAR(name,num)', 'var_name_##num'))
   print *, expand_all(context('real :: MAKE_VAR(temp,42)', 5, 'file.F90', 'file'), macros, stitch, .false., .false.)
   !> prints: real :: var_name_42

Data Types
interface	macro
	Derived type representing a single preprocessor macro Extends string with macro-specific fields: replacement value, parameters, variadic flag, and cyclic self-reference detection. More...
interface	add
	Add one or more macros to a dynamic table. More...
interface	clear
	Remove all macros from a table. More...
interface	get
	Retrieve a macro by index. More...
interface	insert
	Insert more macro to a dynamic table. More...
interface	remove
	Remove a macro at given index. More...
interface	sizeof
	Return current number of stored macros. More...

Variables

buffer_size

integer, parameter buffer_size = 256

private

Default buffer size.

Definition at line 67 of file macro.f90.

Methods

expand_all()

character(:) function, allocatable, public expand_all	(	type(context), intent(in)	ctx,
		type(macro), dimension(:), intent(in)	macros,
		logical, intent(out)	stitch,
		logical, intent(in)	has_extra,
		logical, intent(in)	implicit_conti )

Fully expand a line including predefined macros (FILE, LINE, etc.) First performs normal macro expansion via expand_macros(), then substitutes standard predefined tokens with current file/line/date information.

Parameters

[in]	ctx	Context
[in]	macros	Current macro table
[out]	stitch	Set to .true.true. if result ends with '&' (Fortran continuation)
[in]	has_extra	Has extra macros (non-standard) like FILENAME and TIMESTAMP
[in]	implicit_conti	If .true., implicit continuation is permitted

Returns

Expanded line with all macros and predefined tokens replaced

Remarks

Definition at line 195 of file macro.f90.

expand_macros()

character(:) function, allocatable, public expand_macros	(	character(*), intent(in)	line,
		type(macro), dimension(:), intent(in)	macros,
		logical, intent(out)	stitch,
		logical, intent(in)	implicit_conti,
		type(context), intent(in)	ctx )

Core recursive macro expander (handles function-like, variadic, #, ##).

Performs actual macro replacement with full support for:

• Function-like macros with argument collection
• Stringification (#param)
• Token pasting (##)
• Variadic macros and __VA_ARGS__, __VA_OPT__
• Recursion with cycle detection via digraph
• Proper handling of nested parentheses and quoted strings

Parameters

[in]	line	Line to be expanded
[in]	macros	Current macro table
[out]	stitch	.true. if final line ends with '&'
[in]	implicit_conti	If .true., implicit continuation is permitted
[in]	ctx	Context

Returns

Line with user-defined macros expanded (predefined tokens untouched)

Remarks

Definition at line 299 of file macro.f90.

is_defined()

logical function, public is_defined	(	character(*), intent(in)	name,
		type(macro), dimension(:), intent(in)	macros,
		integer, intent(inout), optional	idx )

Check if a macro with given name exists in table.

Parameters

[in]	name	Macro name to test
[in]	macros	Current macro table
[in,out]	idx	Optional: returns index (1-based) if found

Returns

.true. if macro is defined

Remarks

Definition at line 624 of file macro.f90.

tostring()

character(:) function, allocatable tostring ( class(*), intent(in) any )

private

Generic conversion of polymorphic value to string Used internally during macro argument stringification and debugging. Supports integers, reals, logicals, characters, and complex.

Remarks

Definition at line 647 of file macro.f90.