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Expose public garbage collector API for C language

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You can now do epic things like this:

    puts(_gc(xasprintf("%d", 123)));

The _gc() API is shorthand for _defer() which works like Go's keyword:

    const char *s = xasprintf("%d", 123);
    _defer(free, s);
    puts(s);

Be sure to always use -fno-omit-frame-pointer which makes code fast too.

Enjoy! See also #114
This commit is contained in:
Justine Tunney 2021-03-08 10:56:09 -08:00
parent 0ad609268f
commit 33e8fc8687
26 changed files with 192 additions and 182 deletions
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51
libc/runtime/gc.internal.h
View file

@ -1,49 +1,10 @@
#ifndef COSMOPOLITAN_LIBC_RUNTIME_GC_H_
#define COSMOPOLITAN_LIBC_RUNTIME_GC_H_
#include "libc/calls/calls.h"
#include "libc/nexgen32e/stackframe.h"
#include "libc/runtime/runtime.h"
#ifndef COSMOPOLITAN_LIBC_RUNTIME_GC_INTERNAL_H_
#define COSMOPOLITAN_LIBC_RUNTIME_GC_INTERNAL_H_
#include "libc/runtime/gc.h"
#if !(__ASSEMBLER__ + __LINKER__ + 0)
COSMOPOLITAN_C_START_
/**
* @fileoverview Cosmopolitan Return-Oriented Garbage Collector.
*
* This is the same thing as {@code std::unique_ptr<>} in C++ or the
* {@code defer} keyword in Go. We harness the power of ROP for good
* using very few lines of code.
*/
#define gc(THING) _gc(THING)
#define defer(FN, ARG) _defer(FN, ARG)
/**
* Releases resource when function returns.
*
* @warning do not return a gc()'d pointer
* @warning do not realloc() with gc()'d pointer
*/
#define gc(THING) defer((void *)weakfree, (void *)(THING))
/**
* Same as longjmp() but runs gc() / defer() destructors.
*/
void gclongjmp(jmp_buf, int) nothrow wontreturn paramsnonnull();
/**
* Calls FN(ARG) when function returns.
*/
#ifndef __VSCODE_INTELLISENSE__
#define defer(FN, ARG) \
({ \
autotype(ARG) Arg = (ARG); \
/* prevent weird opts like tail call */ \
asm volatile("" : "+g"(Arg) : : "memory"); \
__defer((struct StackFrame *)__builtin_frame_address(0), FN, Arg); \
asm volatile("" : "+g"(Arg) : : "memory"); \
Arg; \
})
#endif /* __VSCODE_INTELLISENSE__ */
void __defer(struct StackFrame *, void *, void *) hidden paramsnonnull((1, 2));
COSMOPOLITAN_C_END_
#endif /* !(__ASSEMBLER__ + __LINKER__ + 0) */
#endif /* COSMOPOLITAN_LIBC_RUNTIME_GC_H_ */
#endif /* COSMOPOLITAN_LIBC_RUNTIME_GC_INTERNAL_H_ */