System cleanup, part 2 (#13155)

* create basic_types, arithmetics, exceptions, comparisons
* create setops.nim
* create memalloc.nim
* create gc_interface.nim
* create iterators_1.nim

lib/system/gc_interface.nim

@@ -0,0 +1,100 @@
+# ----------------- GC interface ---------------------------------------------
+const
+  usesDestructors = defined(gcDestructors) or defined(gcHooks)
+
+when not usesDestructors:
+  {.pragma: nodestroy.}
+
+when hasAlloc:
+  type
+    GC_Strategy* = enum  ## The strategy the GC should use for the application.
+      gcThroughput,      ## optimize for throughput
+      gcResponsiveness,  ## optimize for responsiveness (default)
+      gcOptimizeTime,    ## optimize for speed
+      gcOptimizeSpace    ## optimize for memory footprint
+
+when hasAlloc and not defined(JS) and not usesDestructors:
+  proc GC_disable*() {.rtl, inl, benign.}
+    ## Disables the GC. If called `n` times, `n` calls to `GC_enable`
+    ## are needed to reactivate the GC.
+    ##
+    ## Note that in most circumstances one should only disable
+    ## the mark and sweep phase with
+    ## `GC_disableMarkAndSweep <#GC_disableMarkAndSweep>`_.
+
+  proc GC_enable*() {.rtl, inl, benign.}
+    ## Enables the GC again.
+
+  proc GC_fullCollect*() {.rtl, benign.}
+    ## Forces a full garbage collection pass.
+    ## Ordinary code does not need to call this (and should not).
+
+  proc GC_enableMarkAndSweep*() {.rtl, benign.}
+  proc GC_disableMarkAndSweep*() {.rtl, benign.}
+    ## The current implementation uses a reference counting garbage collector
+    ## with a seldomly run mark and sweep phase to free cycles. The mark and
+    ## sweep phase may take a long time and is not needed if the application
+    ## does not create cycles. Thus the mark and sweep phase can be deactivated
+    ## and activated separately from the rest of the GC.
+
+  proc GC_getStatistics*(): string {.rtl, benign.}
+    ## Returns an informative string about the GC's activity. This may be useful
+    ## for tweaking.
+
+  proc GC_ref*[T](x: ref T) {.magic: "GCref", benign.}
+  proc GC_ref*[T](x: seq[T]) {.magic: "GCref", benign.}
+  proc GC_ref*(x: string) {.magic: "GCref", benign.}
+    ## Marks the object `x` as referenced, so that it will not be freed until
+    ## it is unmarked via `GC_unref`.
+    ## If called n-times for the same object `x`,
+    ## n calls to `GC_unref` are needed to unmark `x`.
+
+  proc GC_unref*[T](x: ref T) {.magic: "GCunref", benign.}
+  proc GC_unref*[T](x: seq[T]) {.magic: "GCunref", benign.}
+  proc GC_unref*(x: string) {.magic: "GCunref", benign.}
+    ## See the documentation of `GC_ref <#GC_ref,string>`_.
+
+  proc nimGC_setStackBottom*(theStackBottom: pointer) {.compilerRtl, noinline, benign.}
+    ## Expands operating GC stack range to `theStackBottom`. Does nothing
+      ## if current stack bottom is already lower than `theStackBottom`.
+
+when hasAlloc and defined(JS):
+  template GC_disable* =
+    {.warning: "GC_disable is a no-op in JavaScript".}
+
+  template GC_enable* =
+    {.warning: "GC_enable is a no-op in JavaScript".}
+
+  template GC_fullCollect* =
+    {.warning: "GC_fullCollect is a no-op in JavaScript".}
+
+  template GC_setStrategy* =
+    {.warning: "GC_setStrategy is a no-op in JavaScript".}
+
+  template GC_enableMarkAndSweep* =
+    {.warning: "GC_enableMarkAndSweep is a no-op in JavaScript".}
+
+  template GC_disableMarkAndSweep* =
+    {.warning: "GC_disableMarkAndSweep is a no-op in JavaScript".}
+
+  template GC_ref*[T](x: ref T) =
+    {.warning: "GC_ref is a no-op in JavaScript".}
+
+  template GC_ref*[T](x: seq[T]) =
+    {.warning: "GC_ref is a no-op in JavaScript".}
+
+  template GC_ref*(x: string) =
+    {.warning: "GC_ref is a no-op in JavaScript".}
+
+  template GC_unref*[T](x: ref T) =
+    {.warning: "GC_unref is a no-op in JavaScript".}
+
+  template GC_unref*[T](x: seq[T]) =
+    {.warning: "GC_unref is a no-op in JavaScript".}
+
+  template GC_unref*(x: string) =
+    {.warning: "GC_unref is a no-op in JavaScript".}
+
+  template GC_getStatistics*(): string =
+    {.warning: "GC_getStatistics is a no-op in JavaScript".}
+    ""