tidy up as/alias expansion

[scpubgit/Q-Branch.git] / lib / SQL / Abstract / ExtraClauses.pm

diff --git a/lib/SQL/Abstract/ExtraClauses.pm b/lib/SQL/Abstract/ExtraClauses.pm
index 358cdf1..9c27845 100644 (file)
--- a/lib/SQL/Abstract/ExtraClauses.pm
+++ b/lib/SQL/Abstract/ExtraClauses.pm
@@ -167,6 +167,7 @@ sub _expand_from_list {
     }
     push @list, $aqt;
   }
+  return $list[0] if @list == 1;
   return { -from_list => \@list };
 }
 
@@ -175,10 +176,12 @@ sub _expand_join {
   my %proto = (
     ref($args) eq 'HASH'
       ? %$args
-      : (to => $args->[0], @{$args}[1..$#$args])
+      : (to => @$args)
   );
   if (my $as = delete $proto{as}) {
-    $proto{to} = $self->expand_expr({ -as => [ $proto{to}, $as ] });
+    $proto{to} = $self->expand_expr(
+                   { -as => [ { -from_list => $proto{to} }, $as ] }
+                 );
   }
   if (defined($proto{using}) and ref(my $using = $proto{using}) ne 'HASH') {
     $proto{using} = [
@@ -186,8 +189,14 @@ sub _expand_join {
         ref($using) eq 'ARRAY' ? @$using: $using
     ];
   }
-  my %ret = map +($_ => $self->expand_expr($proto{$_}, -ident)),
-              sort keys %proto;
+  my %ret = (
+    type => delete $proto{type},
+    to => $self->expand_expr({ -from_list => delete $proto{to} }, -ident)
+  );
+  %ret = (%ret,
+    map +($_ => $self->expand_expr($proto{$_}, -ident)),
+      sort keys %proto
+  );
   return +{ -join => \%ret };
 }
 
@@ -202,7 +211,12 @@ sub _render_join {
   my @parts = (
     $args->{from},
     { -keyword => join '_', ($args->{type}||()), 'join' },
-    (map +($_->{-ident} || $_->{-as} ? $_ : ('(', $_, ')')), $args->{to}),
+    (map +($_->{-ident} || $_->{-as}
+      ? $_
+      : ('(', $self->render_aqt($_, 1), ')')),
+        map +(@{$_->{-from_list}||[]} == 1 ? $_->{-from_list}[0] : $_),
+          $args->{to}
+    ),
     ($args->{on} ? (
       { -keyword => 'on' },
       $args->{on},
@@ -219,11 +233,11 @@ sub _expand_op_as {
   my ($self, undef, $vv, $k) = @_;
   my @vv = (ref($vv) eq 'ARRAY' ? @$vv : $vv);
   my $ik = $self->expand_expr($k, -ident);
-  return +{ -as => [ $ik, $self->expand_expr($vv[0], -alias) ] }
+  return +{ -as => [ $ik, $self->expand_expr($vv[0], -ident) ] }
     if @vv == 1 and ref($vv[0]) eq 'HASH';
 
   my @as = map $self->expand_expr($_, -ident), @vv;
-  return { -as => [ $ik, { -alias => \@as } ] };
+  return { -as => [ $ik, $self->expand_expr({ -alias => \@as }) ] };
 }
 
 sub _render_as {
@@ -274,11 +288,10 @@ sub _expand_alias {
   if (ref($args) eq 'HASH' and my $alias = $args->{-alias}) {
     $args = $alias;
   }
-  +{ -alias => [
-      map $self->expand_expr($_, -ident),
-      ref($args) eq 'ARRAY' ? @{$args} : $args
-    ]
-  }
+  my @parts = map $self->expand_expr($_, -ident),
+                ref($args) eq 'ARRAY' ? @{$args} : $args;
+  return $parts[0] if @parts == 1;
+  return { -alias => \@parts };
 }
 
 sub _expand_with {
@@ -415,12 +428,7 @@ as a list of arguments for the alias node.
   { foo => { -as => 'bar' } }
 
   # aqt
-  { -as =>
-      [
-        { -ident => [ 'foo' ] },
-        { -alias => [ { -ident => [ 'bar' ] } ] },
-      ]
-  }
+  { -as => [ { -ident => [ 'foo' ] }, { -ident => [ 'bar' ] } ] }
 
   # query
   foo AS bar
@@ -457,4 +465,114 @@ as a list of arguments for the alias node.
   CAST(birthday AS date)
   []
 
+=head2 join
+
+If given an arrayref, pretends it was given a hashref with the first
+element of the arrayref as the value for 'to' and the remaining pairs copied.
+
+Given a hashref, the 'as' key is if presented expanded to wrap the 'to'.
+
+If present the 'using' key is expanded as a list of idents.
+
+Known keys are: 'from' (the left hand side), 'type' ('left', 'right', or
+nothing), 'to' (the right hand side), 'on' and 'using'.
+
+  # expr
+  { -join => {
+      from => 'lft',
+      on => { 'lft.bloo' => { '>' => 'rgt.blee' } },
+      to => 'rgt',
+      type => 'left',
+  } }
+
+  # aqt
+  { -join => {
+      from => { -ident => [ 'lft' ] },
+      on => { -op => [
+          '>', { -ident => [ 'lft', 'bloo' ] },
+          { -ident => [ 'rgt', 'blee' ] },
+      ] },
+      to => { -ident => [ 'rgt' ] },
+      type => 'left',
+  } }
+
+  # query
+  lft LEFT JOIN rgt ON lft.bloo > rgt.blee
+  []
+
+=head2 from_list
+
+List of components of the FROM clause; -foo type elements indicate a pair
+with the next element; this is easiest if I show you:
+
+  # expr
+  { -from_list => [
+      't1', -as => 'table_one', -join =>
+      [ 't2', 'on', { 'table_one.x' => 't2.x' } ],
+  ] }
+
+  # aqt
+  { -join => {
+      from =>
+        {
+          -as => [ { -ident => [ 't1' ] }, { -ident => [ 'table_one' ] } ]
+        },
+      on => { -op => [
+          '=', { -ident => [ 'table_one', 'x' ] },
+          { -ident => [ 't2', 'x' ] },
+      ] },
+      to => { -ident => [ 't2' ] },
+      type => undef,
+  } }
+
+  # query
+  t1 AS table_one JOIN t2 ON table_one.x = t2.x
+  []
+
+Or with using:
+
+  # expr
+  { -from_list =>
+      [ 't1', -as => 'table_one', -join => [ 't2', 'using', [ 'x' ] ] ]
+  }
+
+  # aqt
+  { -join => {
+      from =>
+        {
+          -as => [ { -ident => [ 't1' ] }, { -ident => [ 'table_one' ] } ]
+        },
+      to => { -ident => [ 't2' ] },
+      type => undef,
+      using =>
+        { -op => [ 'or', { -op => [ 'or', { -ident => [ 'x' ] } ] } ] },
+  } }
+
+  # query
+  t1 AS table_one JOIN t2 USING ( x )
+  []
+
+With oddities:
+
+  # expr
+  { -from_list => [
+      'x', -join =>
+      [ [ 'y', -join => [ 'z', 'type', 'left' ] ], 'type', 'left' ],
+  ] }
+
+  # aqt
+  { -join => {
+      from => { -ident => [ 'x' ] },
+      to => { -join => {
+          from => { -ident => [ 'y' ] },
+          to => { -ident => [ 'z' ] },
+          type => 'left',
+      } },
+      type => 'left',
+  } }
+
+  # query
+  x LEFT JOIN ( y LEFT JOIN z )
+  []
+
 =cut