Logo

Programming-Idioms

  • Pascal
  • C++

Idiom #313 Test for map equality

Set b to true if the maps m and n have the same key/value entries, false otherwise.

#include <map>
b = m == n;
fgl
type
  TMap = specialize TFPGMap<TKey, TData>;

function ContentEquals(m,n : TMap): Boolean;
var
  key: TKey;
  data, data2: TData;
  idx: integer;
begin
  Result := False;
  if m.count <> n.count then
    Exit;
  for idx := 0 to m.count-1 do
  begin
    key := m.keys[idx];
    Result := n.TryGetData(key, data2);
    if Result then
    begin
      data := m.data[idx];
      Result := data2 = data;
    end;
    if not Result then
      Exit;
  end;
end;

begin  
  ...
  b := ContentEquals(m,n);

TKey and TData can be of any kind (except a class).
import "maps"
b := maps.Equal(m, n)

maps.Equal is generic and type-safe at compile time.
New implementation...
< > ⌨
programming-idioms.org 
b = m == n;
type
  TMap = specialize TFPGMap<TKey, TData>;

function ContentEquals(m,n : TMap): Boolean;
var
  key: TKey;
  data, data2: TData;
  idx: integer;
begin
  Result := False;
  if m.count <> n.count then
    Exit;
  for idx := 0 to m.count-1 do
  begin
    key := m.keys[idx];
    Result := n.TryGetData(key, data2);
    if Result then
    begin
      data := m.data[idx];
      Result := data2 = data;
    end;
    if not Result then
      Exit;
  end;
end;

begin  
  ...
  b := ContentEquals(m,n);
b := maps.Equal(m, n)
boolean b = m.equals(n);
$b = Compare( \%hash1, \%hash2 );
sub hcmp_numeric {
    my ($h, $g) = @_;

    my $hc = keys %$h;
    my $gc = keys %$g;

    return 0 unless $hc == $gc;
    return 0 unless $hc == grep { exists $g->{$_} } keys %$h;
    die 'non-scalar value detected' 
        if 0 < grep { ref $h->{$_} or ref $g->{$_} } keys %$h;
    return 0 unless $hc == grep { $h->{$_} == $g->{$_} } keys %$h;
    return 1;
}

b = m == n
b = m == n