chore: import upstream snapshot with attribution

vendored/tre/tre-stack.h

@@ -0,0 +1,76 @@
+/*
+  tre-stack.h: Stack definitions
+
+  This software is released under a BSD-style license.
+  See the file LICENSE for details and copyright.
+
+*/
+
+
+#ifndef TRE_STACK_H
+#define TRE_STACK_H 1
+
+#include "tre.h"
+
+typedef struct tre_stack_rec tre_stack_t;
+
+/* Creates a new stack object with initial size `size' and maximum size
+   `max_size'. Pushing an additional item onto a full stack will resize
+   the stack to double its capacity until the maximum is reached. Returns
+   the stack object or NULL if out of memory. */
+tre_stack_t *
+tre_stack_new(size_t size, size_t max_size);
+
+/* Frees the stack object. */
+void
+tre_stack_destroy(tre_stack_t *s);
+
+/* Returns the current number of items on the stack. */
+size_t
+tre_stack_num_items(tre_stack_t *s);
+
+/* Each tre_stack_push_*(tre_stack_t *s, <type> value) function pushes
+   `value' on top of stack `s'.  Returns REG_ESPACE if out of memory.
+   This tries to realloc() more space before failing if maximum size
+   has not yet been reached.  Returns REG_OK if successful. */
+#define declare_pushf(typetag, type)					      \
+  reg_errcode_t tre_stack_push_ ## typetag(tre_stack_t *s, type value)
+
+declare_pushf(voidptr, void *);
+declare_pushf(int, int);
+
+/* Each tre_stack_pop_*(tre_stack_t *s) function pops the topmost
+   element off of stack `s' and returns it.  The stack must not be
+   empty. */
+#define declare_popf(typetag, type)		  \
+  type tre_stack_pop_ ## typetag(tre_stack_t *s)
+
+declare_popf(voidptr, void *);
+declare_popf(int, int);
+
+/* Just to save some typing. */
+#define STACK_PUSH(s, typetag, value)					      \
+  do									      \
+    {									      \
+      status = tre_stack_push_ ## typetag(s, value);			      \
+    }									      \
+  while (/*CONSTCOND*/(void)0,0)
+
+#define STACK_PUSHX(s, typetag, value)					      \
+  {									      \
+    status = tre_stack_push_ ## typetag(s, value);			      \
+    if (status != REG_OK)						      \
+      break;								      \
+  }
+
+#define STACK_PUSHR(s, typetag, value)					      \
+  {									      \
+    reg_errcode_t _status;						      \
+    _status = tre_stack_push_ ## typetag(s, value);			      \
+    if (_status != REG_OK)						      \
+      return _status;							      \
+  }
+
+#endif /* TRE_STACK_H */
+
+/* EOF */