Utilities

CORE_PP_EMPTY()

Expands to nothing.

CORE_PP_COMMA()

Expands to a literal comma character

CORE_PP_LPAREN()

Expands to a literal left parenthesis character.

CORE_PP_RPAREN()

Expands to a literal right parenthesis character.

CORE_PP_PASS(...)

Expands to the zero-or-more passed arguments.

CORE_PP_HAS_ARGS(...)

Expands to 1 if the macro is passed arguments, 0 otherwise.

CORE_PP_HAS_ARGS()      // 0
CORE_PP_HAS_ARGS(a)     // 1
CORE_PP_HAS_ARGS(a,b)   // 1
CORE_PP_HAS_ARGS((a,b)) // 1

CORE_PP_STRINGIZE(...)

CORE_PP_UNPAREN(...)

Expands to its arguments removing a pair of enclosing parentheses if possible.

Invoking this macro on a sequence produces a list.

CORE_PP_UNPAREN(a)     // a
CORE_PP_UNPAREN((a))   // a
CORE_PP_UNPAREN((a,b)) // a,b

CORE_PP_EVAL(...)

Force the preprocessor to recursively expand the given arguments.

Left to its own devices, the preprocessor will not recursively expand macros, but will do a single-pass substitution. CORE_PP_EVAL recursivley expands its arguments up to 1024 levels.

#define A(x) x+1
#define EMPTY
#define NEEDS_TWO_PASSES(x) A EMPTY (x)
NEEDS_TWO_PASSES(2)                // A (2)
CORE_PP_EVAL(NEEDS_TWO_PASSES(2))  // 2 +1

CORE_PP_DEFER1(id)

Defers the expansion of its argument for a single pass.

CORE_PP_DEFER2(id)

Defers the expansion of its argument for two passes.

CORE_PP_DEFER3(id)

Defers the expansion of its argument for three passes.

CORE_PP_DEFER4(id)

Defers the expansion of its argument for four substitution passes.