Commit | Line | Data |
0446ca9c |
1 | package Data::Query::Renderer::SQL::Slice::FetchFirst; |
2 | |
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3 | use Data::Query::ExprHelpers; |
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4 | use Moo::Role; |
5 | |
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6 | sub _render_slice_limit { |
7 | my ($self, $dq) = @_; |
8 | return [ |
9 | ($dq->{from} ? $self->_render($dq->{from}) : ()), |
10 | $self->_format_keyword('FETCH FIRST'), |
11 | sprintf("%i", $dq->{limit}{value}), |
12 | $self->_format_keyword('ROWS ONLY') |
13 | ]; |
14 | } |
15 | |
16 | sub _slice_type { 'FetchFirst' } |
17 | |
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18 | sub _render_slice { |
19 | my ($self, $dq) = @_; |
20 | unless ($dq->{offset}) { |
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21 | return $self->_render_slice_limit($dq); |
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22 | } |
23 | unless ($dq->{order_is_stable}) { |
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24 | die $self->_slice_type." limit style requires a stable order"; |
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25 | } |
26 | die "Slice's inner is not a Select" |
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27 | unless is_Select my $orig_select = $dq->{from}; |
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28 | my %alias_map; |
29 | my $gensym_count; |
30 | my (@inside_select_list, @outside_select_list); |
31 | my $default_inside_alias; |
32 | SELECT: foreach my $s (@{$orig_select->{select}}) { |
33 | my $name; |
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34 | if (is_Alias $s) { |
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35 | $name = $s->{to}; |
36 | $s = $s->{from}; |
37 | } |
38 | my $key; |
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39 | if (is_Identifier $s) { |
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40 | if (!$name and @{$s->{elements}} == 2) { |
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41 | $default_inside_alias ||= $s->{elements}[0]; |
42 | if ($s->{elements}[0] eq $default_inside_alias) { |
43 | $alias_map{join('.',@{$s->{elements}})} = $s; |
44 | push @inside_select_list, $s; |
45 | push @outside_select_list, $s; |
46 | next SELECT; |
47 | } |
48 | } |
49 | $name ||= join('__', @{$s->{elements}}); |
50 | $key = join('.', @{$s->{elements}}); |
51 | } else { |
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52 | die "XXX not implemented yet" unless $name; |
53 | $key = "$s"; |
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54 | } |
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55 | $name ||= sprintf("GENSYM__%03i",++$gensym_count); |
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56 | push @inside_select_list, Alias($name, $s); |
57 | push @outside_select_list, $alias_map{$key} = Identifier($name); |
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58 | } |
59 | my $order = $orig_select->{from}; |
60 | my $order_gensym_count; |
61 | die "Slice's Select not followed by Order but order_is_stable set" |
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62 | unless is_Order $order; |
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63 | my (@order_nodes, %order_map); |
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64 | while (is_Order $order) { |
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65 | my $by = $order->{by}; |
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66 | if (is_Identifier $by) { |
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67 | $default_inside_alias ||= $by->{elements}[0] |
68 | if @{$by->{elements}} == 2; |
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69 | $order_map{$by} |
70 | = $alias_map{join('.', @{$by->{elements}})} |
71 | ||= do { |
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72 | if ( |
73 | @{$by->{elements}} == 2 |
74 | and $by->{elements}[0] eq $default_inside_alias |
75 | ) { |
76 | $by; |
77 | } else { |
78 | my $name = sprintf("ORDER__BY__%03i",++$order_gensym_count); |
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79 | push @inside_select_list, Alias($name, $by); |
80 | Identifier($name); |
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81 | } |
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82 | }; |
83 | } else { |
84 | die "XXX not implemented yet"; |
85 | } |
86 | push @order_nodes, $order; |
87 | $order = $order->{from}; |
88 | } |
89 | my $inside_order = $order; |
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90 | $inside_order = Order($_->{by}, $_->{reverse}, $inside_order) |
91 | for reverse @order_nodes; |
92 | my $inside_select = Select(\@inside_select_list, $inside_order); |
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93 | my $limit_plus_offset = +{ |
94 | %{$dq->{limit}}, value => $dq->{limit}{value} + $dq->{offset}{value} |
95 | }; |
96 | $default_inside_alias ||= 'me'; |
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97 | my $bridge_from = Alias( |
98 | $default_inside_alias, |
99 | Slice(undef, $limit_plus_offset, $inside_select) |
100 | ); |
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101 | my $outside_order = $bridge_from; |
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102 | $outside_order = Order($order_map{$_->{by}}, !$_->{reverse}, $outside_order) |
103 | for reverse @order_nodes; |
104 | my $outside_select = Select( |
105 | ( |
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106 | $dq->{preserve_order} |
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107 | ? [ |
108 | @outside_select_list, |
109 | grep @{$_->{elements}} == 1, @order_map{map $_->{by}, @order_nodes} |
110 | ] |
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111 | : \@outside_select_list, |
112 | ), |
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113 | $outside_order, |
114 | ); |
115 | my $final = Slice(undef, $dq->{limit}, $outside_select); |
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116 | if ($dq->{preserve_order}) { |
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117 | $final = Alias($default_inside_alias, $final); |
118 | $final = Order($order_map{$_->{by}}, $_->{reverse}, $final) |
119 | for reverse @order_nodes; |
120 | $final = Select(\@outside_select_list, $final); |
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121 | } |
122 | return $self->_render($final); |
123 | } |
124 | |
125 | 1; |