Zero-length arrays (#277)

* When reading an empty JSON array it is now returned as an allocated array with zero length.
Fixes #276

* fixed unicode issues in last commit.

Author: jacobwilliams

src/json_value_module.F90

@@ -2965,6 +2965,8 @@ subroutine json_value_insert_after_child_by_index(json,p,idx,element)
     type(json_value),pointer       :: p       !! a JSON object or array.
     integer(IK),intent(in)         :: idx     !! the index of the child of `p` to
                                               !! insert the new element after
+                                              !! (this is a 1-based Fortran
+                                              !! style array index)
     type(json_value),pointer       :: element !! the element to insert
 
     type(json_value),pointer :: tmp  !! for getting the `idx`-th child of `p`
@@ -6228,6 +6230,15 @@ subroutine json_get_integer_vec(json, me, vec)
 
     logical(LK) :: initialized
 
+    ! check for 0-length arrays first:
+    select case (me%var_type)
+    case (json_array)
+        if (json%count(me)==0) then
+            allocate(vec(0))
+            return
+        end if
+    end select
+
     initialized = .false.
 
     !the callback function is called for each element of the array:
@@ -6440,6 +6451,15 @@ subroutine json_get_double_vec(json, me, vec)
 
     logical(LK) :: initialized
 
+    ! check for 0-length arrays first:
+    select case (me%var_type)
+    case (json_array)
+        if (json%count(me)==0) then
+            allocate(vec(0))
+            return
+        end if
+    end select
+
     initialized = .false.
 
     !the callback function is called for each element of the array:
@@ -6648,6 +6668,15 @@ subroutine json_get_logical_vec(json, me, vec)
 
     logical(LK) :: initialized
 
+    ! check for 0-length arrays first:
+    select case (me%var_type)
+    case (json_array)
+        if (json%count(me)==0) then
+            allocate(vec(0))
+            return
+        end if
+    end select
+
     initialized = .false.
 
     !the callback function is called for each element of the array:
@@ -6920,6 +6949,15 @@ subroutine json_get_string_vec(json, me, vec)
 
     logical(LK) :: initialized
 
+    ! check for 0-length arrays first:
+    select case (me%var_type)
+    case (json_array)
+        if (json%count(me)==0) then
+            allocate(vec(0))
+            return
+        end if
+    end select
+
     initialized = .false.
 
     !the callback function is called for each element of the array:
@@ -7043,6 +7081,16 @@ subroutine json_get_alloc_string_vec(json, me, vec, ilen)
     logical(LK) :: initialized !! if the output array has been sized
     integer(IK) :: max_len     !! the length of the longest string in the array
 
+    ! check for 0-length arrays first:
+    select case (me%var_type)
+    case (json_array)
+        if (json%count(me)==0) then
+            allocate(character(kind=CK,len=0) :: vec(0))
+            allocate(ilen(0))
+            return
+        end if
+    end select
+
     initialized = .false.
 
     call json%string_info(me,ilen=ilen,max_str_len=max_len)

src/tests/jf_test_1.f90

@@ -33,6 +33,12 @@ subroutine test_1(error_cnt)
     real(wp) :: rval
     logical :: found
     logical :: lval
+    integer,dimension(:),allocatable :: ivec
+    integer,dimension(:),allocatable :: ilen
+    real(wp),dimension(:),allocatable :: rvec
+    character(kind=json_CK,len=1),dimension(:),allocatable :: cvec
+    character(kind=json_CK,len=:),dimension(:),allocatable :: acvec
+    logical,dimension(:),allocatable :: lvec
 
     error_cnt = 0
     call json%initialize()
@@ -221,6 +227,20 @@ subroutine test_1(error_cnt)
         write(error_unit,'(A)') 'files[5] = '//trim(cval)
       end if
 
+      ! test empty array (each type):
+      write(error_unit,'(A)') ''
+                               call json%get('empty_array', ivec  )
+      if (.not. json%failed()) call json%get('empty_array', rvec  )
+      if (.not. json%failed()) call json%get('empty_array', cvec  )
+      if (.not. json%failed()) call json%get('empty_array', acvec, ilen )
+      if (.not. json%failed()) call json%get('empty_array', lvec  )
+      if (json%failed()) then
+        call json%print_error_message(error_unit)
+        error_cnt = error_cnt + 1
+      else
+        write(error_unit,'(A)') 'empty_array = ',ivec
+      end if
+
       !
       ! Test of values that aren't there:
       ! Note: when using the "found" output, the exceptions are cleared automatically.