Fix the reassembler to treat RNO as the precious special snowflake it is

[dbsrgits/SQL-Abstract.git] / lib / SQL / Abstract / Tree.pm

diff --git a/lib/SQL/Abstract/Tree.pm b/lib/SQL/Abstract/Tree.pm
index 8e743a6..97b90a6 100644 (file)
--- a/lib/SQL/Abstract/Tree.pm
+++ b/lib/SQL/Abstract/Tree.pm
@@ -68,6 +68,7 @@ my @expression_start_keywords = (
   'HAVING',
   'ORDER \s+ BY',
   'SKIP',
+  'FETCH',
   'FIRST',
   'LIMIT',
   'OFFSET',
@@ -82,7 +83,6 @@ my @expression_start_keywords = (
   'SAVEPOINT',
   'RELEASE \s+ SAVEPOINT',
   'RETURNING',
-  'ROW_NUMBER \s* \( \s* \) \s+ OVER',
 );
 
 my $expr_start_re = join ("\n\t|\n", @expression_start_keywords );
@@ -91,8 +91,8 @@ $expr_start_re = qr/ $op_look_behind (?i: $expr_start_re ) $op_look_ahead /x;
 # These are binary operator keywords always a single LHS and RHS
 # * AND/OR are handled separately as they are N-ary
 # * so is NOT as being unary
-# * BETWEEN without paranthesis around the ANDed arguments (which
-#   makes it a non-binary op) is detected and accomodated in
+# * BETWEEN without parentheses around the ANDed arguments (which
+#   makes it a non-binary op) is detected and accommodated in
 #   _recurse_parse()
 # * AS is not really an operator but is handled here as it's also LHS/RHS
 
@@ -114,7 +114,9 @@ $binary_op_re = join "\n\t|\n",
 ;
 $binary_op_re = qr/$binary_op_re/x;
 
-my $unary_op_re = '(?: NOT \s+ EXISTS | NOT )';
+my $rno_re = qr/ROW_NUMBER \s* \( \s* \) \s+ OVER/ix;
+
+my $unary_op_re = 'NOT \s+ EXISTS | NOT | ' . $rno_re;
 $unary_op_re = join "\n\t|\n",
   "$op_look_behind (?i: $unary_op_re ) $op_look_ahead",
 ;
@@ -136,7 +138,7 @@ my $tokenizer_re = join("\n\t|\n",
 
 # this one *is* capturing for the split below
 # splits on whitespace if all else fails
-# has to happen before the composiign qr's are anchored (below)
+# has to happen before the composing qr's are anchored (below)
 $tokenizer_re = qr/ \s* ( $tokenizer_re ) \s* | \s+ /x;
 
 # Parser states for _recurse_parse()
@@ -169,7 +171,8 @@ for (
   $_ = qr/ \A $_ \z /x;
 }
 
-
+# what can be bunched together under one MISC in an AST
+my $compressable_node_re = qr/^ \- (?: MISC | LITERAL | PLACEHOLDER ) $/x;
 
 my %indents = (
    select        => 0,
@@ -417,12 +420,16 @@ sub _recurse_parse {
         @right = $self->_recurse_parse($tokens, PARSE_IN_EXPR);
       }
 
-      @left = [$op => [ @left, @right ]];
+      push @left, [$op => [ (@left ? pop @left : ''), @right ]];
     }
 
     # unary op keywords
     elsif ( $token =~ $unary_op_re ) {
       my $op = uc $token;
+
+      # normalize RNO explicitly
+      $op = 'ROW_NUMBER() OVER' if $op =~ /^$rno_re$/;
+
       my @right = $self->_recurse_parse ($tokens, PARSE_RHS);
 
       push @left, [ $op => \@right ];
@@ -447,23 +454,50 @@ sub _recurse_parse {
     }
 
     # we're now in "unknown token" land - start eating tokens until
-    # we see something familiar
+    # we see something familiar, OR in the case of RHS (binop) stop
+    # after the first token
+    # Also stop processing when we could end up with an unknown func
     else {
       my @lits = [ -LITERAL => [$token] ];
 
-      while (@$tokens and $tokens->[0] !~ $all_std_keywords_re) {
-        push @lits, [ -LITERAL => [ shift @$tokens ] ];
-       }
+      unshift @lits, pop @left if @left == 1;
 
-      if (@left == 1) {
-        unshift @lits, pop @left;
-       }
+      unless ( $state == PARSE_RHS ) {
+        while (
+          @$tokens
+            and
+          $tokens->[0] !~ $all_std_keywords_re
+            and
+          ! ( @$tokens > 1 and $tokens->[1] eq '(' )
+        ) {
+          push @lits, [ -LITERAL => [ shift @$tokens ] ];
+        }
+      }
 
       @lits = [ -MISC => [ @lits ] ] if @lits > 1;
 
       push @left, @lits;
     }
 
+    # compress -LITERAL -MISC and -PLACEHOLDER pieces into a single
+    # -MISC container
+    if (@left > 1) {
+      my $i = 0;
+      while ($#left > $i) {
+        if ($left[$i][0] =~ $compressable_node_re and $left[$i+1][0] =~ $compressable_node_re) {
+          splice @left, $i, 2, [ -MISC => [
+            map { $_->[0] eq '-MISC' ? @{$_->[1]} : $_ } (@left[$i, $i+1])
+          ]];
+        }
+        else {
+          $i++;
+        }
+      }
+    }
+
+    return @left if $state == PARSE_RHS;
+
+    # deal with post-fix operators
     if (@$tokens) {
       # asc/desc
       if ($tokens->[0] =~ $asc_desc_re) {
@@ -630,13 +664,14 @@ sub _parenthesis_unroll {
       }
 
       # unroll nested parenthesis
-      while ( @{$child->[1]} == 1 and $child->[1][0][0] eq '-PAREN') {
+      while ( $ast->[0] ne 'IN' and @{$child->[1]} == 1 and $child->[1][0][0] eq '-PAREN') {
         $child = $child->[1][0];
         $changes++;
       }
 
-      # if the parent operator explcitly allows it nuke the parenthesis
-      if ( $ast->[0] =~ $unrollable_ops_re ) {
+      # if the parent operator explicitly allows it AND the child isn't a subselect
+      # nuke the parenthesis
+      if ($ast->[0] =~ $unrollable_ops_re and $child->[1][0][0] ne 'SELECT') {
         push @children, @{$child->[1]};
         $changes++;
       }
@@ -724,7 +759,10 @@ sub _parenthesis_unroll {
 
       # a construct of ... ( somefunc ( ... ) ) ... can safely lose the outer parens
       # except for the case of ( NOT ( ... ) ) which has already been handled earlier
+      # and except for the case of RNO, where the double are explicit syntax
       elsif (
+        $ast->[0] ne 'ROW_NUMBER() OVER'
+          and
         @{$child->[1]} == 1
           and
         @{$child->[1][0][1]} == 1