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Introduction

In this module, we implement two types of stack, istack and gstack. The istack type was designed to deal with integer numbers only. However, gstack is a generic type stack. More specifically, it supports the following four data types:

  • integer,
  • logical,
  • real(dp),
  • complex(dp).

The usages and subroutine's parameters for these two stack types are almost identical. To implement the gstack type, we generally use the unlimited polymorphic features in Fortran 2003/2008 standard. Noted that not all Fortran compilers can support these features. This module was tested using Intel Fortran compiler only. We do not guarantee it can work/be compiled correctly for using the other Fortran compilers. So please use it carefully. In the iQIST project, so far we only use the istack type. However, in the future, we will turn to the gstack type.

Type

module

Source

src/m_stack.f90

Usage

(1) Import stack module support.

use stack

(2) Declare stack type.

type (istack) :: is
type (gstack) :: gs

(3) Create stack struct.

call istack_create(is, 1024)
call gstack_create(gs, 1, 1024)                ! create stack to support integer
call gstack_create(gs, .true., 1024)           ! create stack to support logical
call gstack_create(gs, 1.0_dp, 1024)           ! create stack to support real(dp)
call gstack_create(gs, (1.0_dp, 1.0_dp), 1024) ! create stack to support complex(dp)
Note

In istack_create(), the second parameter is the capacity of the stack. However, in gstack_create(), the second parameter means the data type that gstack will manipulate, and the third parameter will be used to determine the capacity. It is an optional parameter.

(4) Push element into stack.

call istack_push(is, 1)
call gstack_push(gs, 1)
call gstack_push(gs, .true.)
call gstack_push(gs, 2.0_dp)
call gstack_push(gs, (1.0_dp, 1.0_dp))

(5) Pop element from stack.

call istack_pop(is, i) ! i is an integer
call gstack_pop(is, j) ! j can be integer, logical, real(dp), and complex(dp)

(6) Check status of stack.

print *, istack_isfull(is)
print *, istack_isempty(is)
print *, istack_getsize(is)
print *, istack_getrest(is)

print *, gstack_isfull(gs)
print *, gstack_isempty(gs)
print *, gstack_getsize(gs)
print *, gstack_getrest(gs)

The above three function calls will tell you whether the stack is full, whether it is empty, and its capacity.

(7) Clean the stack.

call istack_clean(is)
call gstack_clean(gs)
Note

This operation will reset the top position of the stack, instead of releasing the memory of it. So you can still use the stack after that.

(8) Destroy the stack.

call istack_destroy(is)
call gstack_destroy(gs)
Note

When the stack was destroyed, you can not use it any more.