56 lines
1.7 KiB
C
56 lines
1.7 KiB
C
#pragma once
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/* Example:
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int multiplier = 5;
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DECL_LAMBDA(l, int, (int a), {
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return a * multiplier;
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})
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assert(l.func(l.arg, 4) == 20);
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The point of this is to work on both iOS, where GCC inline
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functions don't work, and Linux, where Apple blocks generally
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aren't available.
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*/
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#ifdef __BLOCKS__
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struct _blk {
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void *isa;
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int flags;
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int reserved;
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void *invoke;
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};
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#define LAMBDA_BODY(typ, ret, args, body) \
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({ union { \
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ret (^blk) args; \
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struct _blk *_blk; \
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} u = { ^ret args body }; \
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(typ) {u._blk->invoke, u._blk}; \
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})
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#else
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#define LAMBDA_BODY_(typ, ret, args, body) \
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({ ret func args body; \
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(typ) {&func, 0}; \
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})
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#define LAMBDA_BODY(typ, ret, args, body) \
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LAMBDA_BODY_(typ, ret, LAMBDA_UNPAREN args, body)
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#endif
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// based on http://lefteris.realintelligence.net/?p=593
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#define LAMBDA_YUP() LAMBDA_NOPE
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#define LAMBDA_CHECK_LAMBDA_YUP_() ,
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#define LAMBDA_CHECK_LAMBDA_NOPE_()
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#define LAMBDA_CHECK_LAMBDA_YUP LAMBDA_CHECK_LAMBDA_YUP_,
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#define LAMBDA_CHECK_LAMBDA_NOPE LAMBDA_CHECK_LAMBDA_NOPE_,
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#define LAMBDA_APPLY_FIRST_ARG(a, ...) a()
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#define LAMBDA_COMMA_IF_NONEMPTY___(a...) LAMBDA_APPLY_FIRST_ARG(a)
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#define LAMBDA_COMMA_IF_NONEMPTY__(a) LAMBDA_COMMA_IF_NONEMPTY___(LAMBDA_CHECK_##a)
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#define LAMBDA_COMMA_IF_NONEMPTY_(a) LAMBDA_COMMA_IF_NONEMPTY__(a)
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#define LAMBDA_COMMA_IF_NONEMPTY(a, ...) LAMBDA_COMMA_IF_NONEMPTY_(LAMBDA_YUP a ())
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#define LAMBDA_UNPAREN(args...) (void *_lambda_ignored LAMBDA_COMMA_IF_NONEMPTY(args) args)
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#define DECL_LAMBDA(name, ret, args, body) \
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struct __lambda_##name { \
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ret (*func) LAMBDA_UNPAREN args; \
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void *arg; \
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} name = LAMBDA_BODY(struct __lambda_##name, ret, args, body);
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