added a new routine to remove an item from a json structure.

added a test case for it.

Author: jacobwilliams

src/json_example.f90

@@ -10,7 +10,7 @@ program json_test
 !    Unit tests for the json_module.
 !
 !  USES
-!	json_module
+!    json_module
 !
 !  HISTORY
 !    Jacob Williams : 2/8/2014 : Created
@@ -472,6 +472,7 @@ subroutine test_1()
     character(len=:),allocatable :: cval
     real(wp) :: rval
     logical :: found
+    type(json_value),pointer :: p
 
     write(*,'(A)') ''
     write(*,'(A)') '================================='
@@ -584,7 +585,23 @@ subroutine test_1()
         else
             write(*,'(A)') 'version.blah = ',ival
         end if
-
+        
+        write(*,'(A)') ''
+        write(*,'(A)') ' Test removing data from the json structure:'
+        
+        call json%get('files', p)           !in the middle of a list
+        call json_remove(p)
+        
+        call json%get('data(1).array', p)   !at the end of a list
+        call json_remove(p)
+        
+        call json%get('data(2).number', p)  !at the beginning of a list
+        call json_remove(p)
+        
+        write(*,'(A)') ''
+        write(*,'(A)') 'printing the modified structure...'
+        call json%print_file()       
+        
     end if
 
     ! clean up

src/json_module.f90

@@ -171,6 +171,7 @@ module json_module
         type(json_data_non_polymorphic) :: data
 
         !for the linked list:
+        type(json_value), pointer :: previous => null()
         type(json_value), pointer :: next => null()
         type(json_value), pointer :: parent => null()
         type(json_value), pointer :: children => null()
@@ -283,10 +284,15 @@ end subroutine array_callback_func
     interface json_destroy
         module procedure :: json_value_destroy
     end interface
+    
+    interface json_remove
+        module procedure :: json_value_remove
+    end interface
 
     !public routines:
     public :: json_initialize            !to initialize the module
     public :: json_destroy               !clear a JSON structure (destructor)
+    public :: json_remove                !remove from a JSON structure
     public :: json_parse                 !read a JSON file and populate the structure
     public :: json_clear_exceptions      !clear exceptions
     public :: json_check_for_errors      !check for error and get error message
@@ -1055,6 +1061,73 @@ recursive subroutine json_value_destroy(this)
     end subroutine json_value_destroy
 !*****************************************************************************************
 
+!*****************************************************************************************
+!****f* json_module/json_value_remove
+!
+!  NAME
+!    json_value_destroy
+!
+!  DESCRIPTION
+!    Remove and destroy a json_value (and all its children) 
+!        from a linked-list structure.
+!
+!  AUTHOR
+!    Jacob Williams : 9/9/2014
+!
+!  SOURCE
+
+    subroutine json_value_remove(me)
+
+    implicit none
+
+    type(json_value),pointer :: me
+    
+    type(json_value),pointer :: parent,previous,next
+    
+    if (associated(me)) then
+        if (associated(me%parent)) then
+            if (associated(me%next)) then
+        
+                !there are later items in the list:
+            
+                next => me%next
+                nullify(me%next)
+            
+                if (associated(me%previous)) then           
+                    !there are earlier items in the list
+                    previous => me%previous                
+                    previous%next => next
+                    next%previous => previous
+                else
+                    !this is the first item in the list
+                    parent => me%parent                    
+                    parent%children => next
+                    next%previous => null()
+                end if
+                
+            else
+            
+                if (associated(me%previous)) then
+                	!there are earlier items in the list:
+                    previous => me%previous 
+                    previous%next => null()  
+                else
+                	!this is the only item in the list:
+                    parent => me%parent 
+                    parent%children => null()                   
+                end if
+                
+            end if     
+                   
+        end if
+            
+        call json_value_destroy(me)
+
+    end if
+
+    end subroutine json_value_remove
+!*****************************************************************************************
+
 !*****************************************************************************************
 !****f* json_module/json_value_add_member
 !
@@ -1090,13 +1163,15 @@ subroutine json_value_add_member(this, member)
                 p => p % next
             end do
 
-            p % next => member
+            p%next => member
+            member%previous => p
 
             nullify(p)    !cleanup
 
         else
 
-            this % children => member
+            this%children => member
+            member%previous => null()
 
         end if