Preprocessor

The preprocessor is a compilation stage that operates on lexer tokens, before the parser. It resolves #-directives and macro references.

All preprocessor directives begin with #.

#include

#include inserts the contents of another file at the point of the directive.

#include "sum.gof"

func void main[]
    2 2 sum    // `sum` is defined in sum.gof
end

Inclusion is recursive: definitions from the included file are available at the include site, and the included file may itself #include other files.

Module include

Including a directory includes the file with the same name inside it:

#include "dir"    // includes `dir/dir.gof`

This simplifies library layout: a library foo is a directory foo/ with foo/foo.gof as its entry point.

Include-once

Each file is included at most once per compilation, even if it is #included from multiple places.

Search strategy

When resolving #include, Gofra searches in this order:

1. The directory of the including file.
2. The directory of the main file.
3. Include search directories (-isd / --include-search-dir).

#define and #undef

#define creates a macro. #undef removes it.

#define MACRO 2

The macro can be used anywhere in the code after its definition:

MACRO MACRO +    // 2 2 + = 4

From the command line

Macros can be defined from the CLI with -D:

gofra build -Ddebug=1 main.gof

This is useful for debug flags and feature toggles.

#ifdef, #ifndef, #endif

Conditional compilation based on macro definition:

#ifdef DEBUG
    // compiled only if DEBUG is defined
#endif

#ifndef DEBUG
    // compiled only if DEBUG is not defined
#endif

Built-in macros

Gofra defines two macros for the target:

Macro	Example	Meaning
OS_{NAME}	OS_LINUX, OS_DARWIN	Target operating system
ARCH_{NAME}	ARCH_AMD64, ARCH_AARCH64	Target architecture
IS_{ENDIANNES}_ENDIAN	IS_LITTLE_ENDIAN, IS_BIG_ENDIAN	...

For example, compiling for Darwin on ARM64 defines OS_DARWIN and ARCH_AARCH64.