X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2FSQL%2FAbstract%2FTree.pm;h=d490a83b19204fa69c4f71cd35da8116fe2b76c1;hb=6c4d8eb8d2b9a5deb84400fd35f72c23818f442e;hp=9536ce9c92eedea91f2b40ef643e5565416a2091;hpb=257ecc8a4f33c53c658100982c39f27c736e4423;p=dbsrgits%2FSQL-Abstract.git

diff --git a/lib/SQL/Abstract/Tree.pm b/lib/SQL/Abstract/Tree.pm
index 9536ce9..d490a83 100644
--- a/lib/SQL/Abstract/Tree.pm
+++ b/lib/SQL/Abstract/Tree.pm
@@ -50,10 +50,10 @@ my $placeholder_re = qr/(?: \? | \$\d+ )/x;
 my @expression_start_keywords = (
   'SELECT',
   'UPDATE',
+  'SET',
   'INSERT \s+ INTO',
   'DELETE \s+ FROM',
   'FROM',
-  'SET',
   '(?:
     (?:
         (?: (?: LEFT | RIGHT | FULL ) \s+ )?
@@ -64,7 +64,7 @@ my @expression_start_keywords = (
   'ON',
   'WHERE',
   '(?: DEFAULT \s+ )? VALUES',
-  'EXISTS',
+  '(?: NOT \s+)? EXISTS',
   'GROUP \s+ BY',
   'HAVING',
   'ORDER \s+ BY',
@@ -95,6 +95,7 @@ $expr_start_re = qr/ $op_look_behind (?i: $expr_start_re ) $op_look_ahead /x;
 # * BETWEEN without paranthesis around the ANDed arguments (which
 #   makes it a non-binary op) is detected and accomodated in
 #   _recurse_parse()
+# * AS is not really an operator but is handled here as it's also LHS/RHS
 
 # this will be included in the $binary_op_re, the distinction is interesting during
 # testing as one is tighter than the other, plus mathops have different look
@@ -111,7 +112,7 @@ sub _math_op_re { $math_re }
 
 my $binary_op_re = '(?: NOT \s+)? (?:' . join ('|', qw/IN BETWEEN R?LIKE/) . ')';
 $binary_op_re = join "\n\t|\n",
-  "$op_look_behind (?i: $binary_op_re ) $op_look_ahead",
+  "$op_look_behind (?i: $binary_op_re | AS ) $op_look_ahead",
   $math_re,
   $op_look_behind . 'IS (?:\s+ NOT)?' . "(?= \\s+ NULL \\b | $op_look_ahead )",
 ;
@@ -309,6 +310,10 @@ sub parse {
   $self->_recurse_parse($tokens, PARSE_TOP_LEVEL);
 }
 
+{
+# this is temporary, lists can be parsed *without* recursing, but
+# it requires a massive rewrite of the AST generator
+no warnings qw/recursion/;
 sub _recurse_parse {
   my ($self, $tokens, $state) = @_;
 
@@ -344,14 +349,14 @@ sub _recurse_parse {
     elsif ($token =~ /^ (?: OR | AND | \, ) $/xi )  {
       my $op = ($token eq ',') ? 'LIST' : uc $token;
 
-      my $right = $self->_recurse_parse($tokens, PARSE_IN_EXPR);
+      my $right = $self->_recurse_parse($tokens, PARSE_IN_EXPR) || [];
 
       # Merge chunks if logic matches
-      if (ref $right and $op eq $right->[0]) {
-        $left = [ (shift @$right ), [$left||(), map { @$_ } @$right] ];
+      if (ref $right and @$right and $op eq $right->[0]) {
+        $left = [ (shift @$right ), [$left||[], map { @$_ } @$right] ];
       }
       else {
-        $left = [$op => [ $left||(), $right||() ]];
+        $left = [$op => [ $left||[], $right ]];
       }
     }
     # binary operator keywords
@@ -379,8 +384,8 @@ sub _recurse_parse {
     elsif ( $token =~ /^ NOT $/ix ) {
       my $op = uc $token;
       my $right = $self->_recurse_parse ($tokens, PARSE_RHS);
-      $left = $left ? [ @$left, [$op => [$right] ]]
-                    : [ $op => [$right] ];
+      $left = $left ? [ @$left, [$op => [$right||()] ]]
+                    : [ $op => [$right||()] ];
 
     }
     elsif ( $token =~ $placeholder_re) {
@@ -405,6 +410,7 @@ sub _recurse_parse {
     }
   }
 }
+}
 
 sub format_keyword {
   my ($self, $keyword) = @_;
@@ -471,6 +477,7 @@ sub _unparse {
     return '';
   }
 
+  $self->_parenthesis_unroll($tree);
   my ($car, $cdr) = @{$tree}[0,1];
 
   if (! defined $car or (! ref $car and ! defined $cdr) ) {
@@ -519,6 +526,139 @@ sub _unparse {
   }
 }
 
+# All of these keywords allow their parameters to be specified with or without parenthesis without changing the semantics
+my @unrollable_ops = (
+  'ON',
+  'WHERE',
+  'GROUP \s+ BY',
+  'HAVING',
+  'ORDER \s+ BY',
+  'I?LIKE',
+);
+my $unrollable_ops_re = join ' | ', @unrollable_ops;
+$unrollable_ops_re = qr/$unrollable_ops_re/xi;
+
+sub _parenthesis_unroll {
+  my $self = shift;
+  my $ast = shift;
+
+  #return if $self->parenthesis_significant;
+  return unless (ref $ast and ref $ast->[1]);
+
+  my $changes;
+  do {
+    my @children;
+    $changes = 0;
+
+    for my $child (@{$ast->[1]}) {
+      # the current node in this loop is *always* a PAREN
+      if (! ref $child or ! @$child or $child->[0] ne 'PAREN') {
+        push @children, $child;
+        next;
+      }
+
+      # unroll nested parenthesis
+      while ( @{$child->[1]} && $child->[1][0][0] eq 'PAREN') {
+        $child = $child->[1][0];
+        $changes++;
+      }
+
+      # if the parenthesis are wrapped around an AND/OR matching the parent AND/OR - open the parenthesis up and merge the list
+      if (
+        ( $ast->[0] eq 'AND' or $ast->[0] eq 'OR')
+            and
+          $child->[1][0][0] eq $ast->[0]
+      ) {
+        push @children, @{$child->[1][0][1]};
+        $changes++;
+      }
+
+      # if the parent operator explcitly allows it nuke the parenthesis
+      elsif ( $ast->[0] =~ $unrollable_ops_re ) {
+        push @children, $child->[1][0];
+        $changes++;
+      }
+
+      # only *ONE* LITERAL or placeholder element
+      # as an AND/OR/NOT argument
+      elsif (
+        @{$child->[1]} == 1 && (
+          $child->[1][0][0] eq 'LITERAL'
+            or
+          $child->[1][0][0] eq 'PLACEHOLDER'
+        ) && (
+          $ast->[0] eq 'AND' or $ast->[0] eq 'OR' or $ast->[0] eq 'NOT'
+        )
+      ) {
+        push @children, $child->[1][0];
+        $changes++;
+      }
+
+      # only one element in the parenthesis which is a binary op
+      # and has exactly two grandchildren
+      # the only time when we can *not* unroll this is when both
+      # the parent and the child are mathops (in which case we'll
+      # break precedence) or when the child is BETWEEN (special
+      # case)
+      elsif (
+        @{$child->[1]} == 1
+          and
+        $child->[1][0][0] =~ SQL::Abstract::Tree::_binary_op_re()
+          and
+        $child->[1][0][0] ne 'BETWEEN'
+          and
+        @{$child->[1][0][1]} == 2
+          and
+        ! (
+          $child->[1][0][0] =~ SQL::Abstract::Tree::_math_op_re()
+            and
+          $ast->[0] =~ SQL::Abstract::Tree::_math_op_re()
+        )
+      ) {
+        push @children, $child->[1][0];
+        $changes++;
+      }
+
+      # a function binds tighter than a mathop - see if our ancestor is a
+      # mathop, and our content is:
+      # a single non-mathop child with a single PAREN grandchild which
+      # would indicate mathop ( nonmathop ( ... ) )
+      # or a single non-mathop with a single LITERAL ( nonmathop foo )
+      # or a single non-mathop with a single PLACEHOLDER ( nonmathop ? )
+      elsif (
+        @{$child->[1]} == 1
+          and
+        @{$child->[1][0][1]} == 1
+          and
+        $ast->[0] =~ SQL::Abstract::Tree::_math_op_re()
+          and
+        $child->[1][0][0] !~ SQL::Abstract::Tree::_math_op_re
+          and
+        (
+          $child->[1][0][1][0][0] eq 'PAREN'
+            or
+          $child->[1][0][1][0][0] eq 'LITERAL'
+            or
+          $child->[1][0][1][0][0] eq 'PLACEHOLDER'
+        )
+      ) {
+        push @children, $child->[1][0];
+        $changes++;
+      }
+
+
+      # otherwise no more mucking for this pass
+      else {
+        push @children, $child;
+      }
+    }
+
+    $ast->[1] = \@children;
+
+  } while ($changes);
+
+}
+
 sub format { my $self = shift; $self->unparse($self->parse($_[0]), $_[1]) }
 
 1;