SQL::Abstract::Tree - Represent SQL as an AST
Index
Code Index:
NAME
SQL::Abstract::Tree - Represent SQL as an AST
SYNOPSIS
my $sqla_tree = SQL::Abstract::Tree->new({ profile => 'console' });
print $sqla_tree->format('SELECT * FROM foo WHERE foo.a > 2');
# SELECT *
# FROM foo
# WHERE foo.a > 2
METHODS
new
my $sqla_tree = SQL::Abstract::Tree->new({ profile => 'console' });
$args = {
profile => 'console', # predefined profile to use (default: 'none')
fill_in_placeholders => 1, # true for placeholder population
placeholder_surround => # The strings that will be wrapped around
[GREEN, RESET], # populated placeholders if the above is set
indent_string => ' ', # the string used when indenting
indent_amount => 2, # how many of above string to use for a single
# indent level
newline => "\n", # string for newline
colormap => {
select => [RED, RESET], # a pair of strings defining what to surround
# the keyword with for colorization
# ...
},
indentmap => {
select => 0, # A zero means that the keyword will start on
# a new line
from => 1, # Any other positive integer means that after
on => 2, # said newline it will get that many indents
# ...
},
}
Returns a new SQL::Abstract::Tree object. All arguments are optional.
profiles
There are four predefined profiles, none, console, console_monochrome,
and html. Typically a user will probably just use console or
console_monochrome, but if something about a profile bothers you, merely
use the profile and override the parts that you don't like.
$sqlat->format('SELECT * FROM bar WHERE x = ?', [1])
Takes $sql and \@bindargs.
Returns a formatting string based on the string passed in
parse
$sqlat->parse('SELECT * FROM bar WHERE x = ?')
Returns a "tree" representing passed in SQL. Please do not depend on the
structure of the returned tree. It may be stable at some point, but not yet.
unparse
$sqlat->parse($tree_structure, \@bindargs)
Transform "tree" into SQL, applying various transforms on the way.
$sqlat->format_keyword('SELECT')
Currently this just takes a keyword and puts the colormap stuff around it.
Later on it may do more and allow for coderef based transforms.
pad_keyword
my ($before, $after) = @{$sqlat->pad_keyword('SELECT')};
Returns whitespace to be inserted around a keyword.
fill_in_placeholder
my $value = $sqlat->fill_in_placeholder(\@bindargs)
Removes last arg from passed arrayref and returns it, surrounded with
the values in placeholder_surround, and then surrounded with single quotes.
indent
Returns as many indent strings as indent amounts times the first argument.
ACCESSORS
colormap
fill_in_placeholders
indent_amount
indent_string
indentmap
newline
placeholder_surround
package SQL::Abstract::Tree;
use strict;
use warnings;
no warnings 'qw';
use Carp;
use Hash::Merge qw//;
use base 'Class::Accessor::Grouped';
__PACKAGE__->mk_group_accessors( simple => $_ ) for qw(
newline indent_string indent_amount colormap indentmap fill_in_placeholders
placeholder_surround
);
my $merger = Hash::Merge->new;
$merger->specify_behavior({
SCALAR => {
SCALAR => sub { $_[1] },
ARRAY => sub { [ $_[0], @{$_[1]} ] },
HASH => sub { $_[1] },
},
ARRAY => {
SCALAR => sub { $_[1] },
ARRAY => sub { $_[1] },
HASH => sub { $_[1] },
},
HASH => {
SCALAR => sub { $_[1] },
ARRAY => sub { [ values %{$_[0]}, @{$_[1]} ] },
HASH => sub { Hash::Merge::_merge_hashes( $_[0], $_[1] ) },
},
}, 'SQLA::Tree Behavior' );
my $op_look_ahead = '(?: (?= [\s\)\(\;] ) | \z)';
my $op_look_behind = '(?: (?<= [\,\s\)\(] ) | \A )';
my $quote_left = qr/[\`\'\"\[]/;
my $quote_right = qr/[\`\'\"\]]/;
my $placeholder_re = qr/(?: \? | \$\d+ )/x;
# These SQL keywords always signal end of the current expression (except inside
# of a parenthesized subexpression).
# Format: A list of strings that will be compiled to extended syntax ie.
# /.../x) regexes, without capturing parentheses. They will be automatically
# anchored to op boundaries (excluding quotes) to match the whole token.
my @expression_start_keywords = (
'SELECT',
'UPDATE',
'INSERT \s+ INTO',
'DELETE \s+ FROM',
'FROM',
'SET',
'(?:
(?:
(?: (?: LEFT | RIGHT | FULL ) \s+ )?
(?: (?: CROSS | INNER | OUTER ) \s+ )?
)?
JOIN
)',
'ON',
'WHERE',
'(?: DEFAULT \s+ )? VALUES',
'EXISTS',
'GROUP \s+ BY',
'HAVING',
'ORDER \s+ BY',
'SKIP',
'FIRST',
'LIMIT',
'OFFSET',
'FOR',
'UNION',
'INTERSECT',
'EXCEPT',
'BEGIN \s+ WORK',
'COMMIT',
'ROLLBACK \s+ TO \s+ SAVEPOINT',
'ROLLBACK',
'SAVEPOINT',
'RELEASE \s+ SAVEPOINT',
'RETURNING',
'ROW_NUMBER \s* \( \s* \) \s+ OVER',
);
my $expr_start_re = join ("\n\t|\n", @expression_start_keywords );
$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
# _recurse_parse()
# 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
# ahead/behind (e.g. "x"="y" )
my @math_op_keywords = (qw/ < > != <> = <= >= /);
my $math_re = join ("\n\t|\n", map
{ "(?: (?<= [\\w\\s] | $quote_right ) | \\A )" . quotemeta ($_) . "(?: (?= [\\w\\s] | $quote_left ) | \\z )" }
@math_op_keywords
);
$math_re = qr/$math_re/x;
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",
$math_re,
$op_look_behind . 'IS (?:\s+ NOT)?' . "(?= \\s+ NULL \\b | $op_look_ahead )",
;
$binary_op_re = qr/$binary_op_re/x;
sub _binary_op_re { $binary_op_re }
my $all_known_re = join("\n\t|\n",
$expr_start_re,
$binary_op_re,
"$op_look_behind (?i: AND|OR|NOT|\\* ) $op_look_ahead",
(map { quotemeta $_ } qw/, ( )/),
$placeholder_re,
);
$all_known_re = qr/$all_known_re/x;
#this one *is* capturing for the split below
# splits on whitespace if all else fails
my $tokenizer_re = qr/ \s* ( $all_known_re ) \s* | \s+ /x;
# Parser states for _recurse_parse()
use constant PARSE_TOP_LEVEL => 0;
use constant PARSE_IN_EXPR => 1;
use constant PARSE_IN_PARENS => 2;
use constant PARSE_IN_FUNC => 3;
use constant PARSE_RHS => 4;
my $expr_term_re = qr/ ^ (?: $expr_start_re | \) ) $/x;
my $rhs_term_re = qr/ ^ (?: $expr_term_re | $binary_op_re | (?i: AND | OR | NOT | \, ) ) $/x;
my $func_start_re = qr/^ (?: \* | $placeholder_re | \( ) $/x;
my %indents = (
select => 0,
update => 0,
'insert into' => 0,
'delete from' => 0,
from => 1,
where => 0,
join => 1,
'left join' => 1,
on => 2,
having => 0,
'group by' => 0,
'order by' => 0,
set => 1,
into => 1,
values => 1,
limit => 1,
offset => 1,
skip => 1,
first => 1,
);
my %profiles = (
console => {
fill_in_placeholders => 1,
placeholder_surround => ['?/', ''],
indent_string => ' ',
indent_amount => 2,
newline => "\n",
colormap => {},
indentmap => \%indents,
eval { require Term::ANSIColor }
? do {
my $c = \&Term::ANSIColor::color;
my $red = [$c->('red') , $c->('reset')];
my $cyan = [$c->('cyan') , $c->('reset')];
my $green = [$c->('green') , $c->('reset')];
my $yellow = [$c->('yellow') , $c->('reset')];
my $blue = [$c->('blue') , $c->('reset')];
my $magenta = [$c->('magenta'), $c->('reset')];
my $b_o_w = [$c->('black on_white'), $c->('reset')];
(
placeholder_surround => [$c->('black on_magenta'), $c->('reset')],
colormap => {
'begin work' => $b_o_w,
commit => $b_o_w,
rollback => $b_o_w,
savepoint => $b_o_w,
'rollback to savepoint' => $b_o_w,
'release savepoint' => $b_o_w,
select => $red,
'insert into' => $red,
update => $red,
'delete from' => $red,
set => $cyan,
from => $cyan,
where => $green,
values => $yellow,
join => $magenta,
'left join' => $magenta,
on => $blue,
'group by' => $yellow,
having => $yellow,
'order by' => $yellow,
skip => $green,
first => $green,
limit => $green,
offset => $green,
}
);
} : (),
},
console_monochrome => {
fill_in_placeholders => 1,
placeholder_surround => ['?/', ''],
indent_string => ' ',
indent_amount => 2,
newline => "\n",
colormap => {},
indentmap => \%indents,
},
html => {
fill_in_placeholders => 1,
placeholder_surround => ['<span class="placeholder">', '</span>'],
indent_string => ' ',
indent_amount => 2,
newline => "<br />\n",
colormap => {
select => ['<span class="select">' , '</span>'],
'insert into' => ['<span class="insert-into">' , '</span>'],
update => ['<span class="select">' , '</span>'],
'delete from' => ['<span class="delete-from">' , '</span>'],
set => ['<span class="set">', '</span>'],
from => ['<span class="from">' , '</span>'],
where => ['<span class="where">' , '</span>'],
values => ['<span class="values">', '</span>'],
join => ['<span class="join">' , '</span>'],
'left join' => ['<span class="left-join">','</span>'],
on => ['<span class="on">' , '</span>'],
'group by' => ['<span class="group-by">', '</span>'],
having => ['<span class="having">', '</span>'],
'order by' => ['<span class="order-by">', '</span>'],
skip => ['<span class="skip">', '</span>'],
first => ['<span class="first">', '</span>'],
limit => ['<span class="limit">', '</span>'],
offset => ['<span class="offset">', '</span>'],
'begin work' => ['<span class="begin-work">', '</span>'],
commit => ['<span class="commit">', '</span>'],
rollback => ['<span class="rollback">', '</span>'],
savepoint => ['<span class="savepoint">', '</span>'],
'rollback to savepoint' => ['<span class="rollback-to-savepoint">', '</span>'],
'release savepoint' => ['<span class="release-savepoint">', '</span>'],
},
indentmap => \%indents,
},
none => {
colormap => {},
indentmap => {},
},
);
sub new {
my $class = shift;
my $args = shift || {};
my $profile = delete $args->{profile} || 'none';
die "No such profile '$profile'!" unless exists $profiles{$profile};
my $data = $merger->merge( $profiles{$profile}, $args );
bless $data, $class
}
sub parse {
my ($self, $s) = @_;
# tokenize string, and remove all optional whitespace
my $tokens = [];
foreach my $token (split $tokenizer_re, $s) {
push @$tokens, $token if (
defined $token
and
length $token
and
$token =~ /\S/
);
}
$self->_recurse_parse($tokens, PARSE_TOP_LEVEL);
}
sub _recurse_parse {
my ($self, $tokens, $state) = @_;
my $left;
while (1) { # left-associative parsing
my $lookahead = $tokens->[0];
if ( not defined($lookahead)
or
($state == PARSE_IN_PARENS && $lookahead eq ')')
or
($state == PARSE_IN_EXPR && $lookahead =~ $expr_term_re )
or
($state == PARSE_RHS && $lookahead =~ $rhs_term_re )
or
($state == PARSE_IN_FUNC && $lookahead !~ $func_start_re) # if there are multiple values - the parenthesis will switch the $state
) {
return $left||();
}
my $token = shift @$tokens;
# nested expression in ()
if ($token eq '(' ) {
my $right = $self->_recurse_parse($tokens, PARSE_IN_PARENS);
$token = shift @$tokens or croak "missing closing ')' around block " . $self->unparse($right);
$token eq ')' or croak "unexpected token '$token' terminating block " . $self->unparse($right);
$left = $left ? [$left, [PAREN => [$right||()] ]]
: [PAREN => [$right||()] ];
}
# AND/OR and LIST (,)
elsif ($token =~ /^ (?: OR | AND | \, ) $/xi ) {
my $op = ($token eq ',') ? 'LIST' : uc $token;
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] ];
}
else {
$left = [$op => [ $left||(), $right||() ]];
}
}
# binary operator keywords
elsif ( $token =~ /^ $binary_op_re $ /x ) {
my $op = uc $token;
my $right = $self->_recurse_parse($tokens, PARSE_RHS);
# A between with a simple LITERAL for a 1st RHS argument needs a
# rerun of the search to (hopefully) find the proper AND construct
if ($op eq 'BETWEEN' and $right->[0] eq 'LITERAL') {
unshift @$tokens, $right->[1][0];
$right = $self->_recurse_parse($tokens, PARSE_IN_EXPR);
}
$left = [$op => [$left, $right] ];
}
# expression terminator keywords (as they start a new expression)
elsif ( $token =~ / ^ $expr_start_re $ /x ) {
my $op = uc $token;
my $right = $self->_recurse_parse($tokens, PARSE_IN_EXPR);
$left = $left ? [ $left, [$op => [$right||()] ]]
: [ $op => [$right||()] ];
}
# NOT
elsif ( $token =~ /^ NOT $/ix ) {
my $op = uc $token;
my $right = $self->_recurse_parse ($tokens, PARSE_RHS);
$left = $left ? [ @$left, [$op => [$right] ]]
: [ $op => [$right] ];
}
elsif ( $token =~ $placeholder_re) {
$left = $left ? [ $left, [ PLACEHOLDER => [ $token ] ] ]
: [ PLACEHOLDER => [ $token ] ];
}
# we're now in "unknown token" land - start eating tokens until
# we see something familiar
else {
my $right;
# check if the current token is an unknown op-start
if (@$tokens and $tokens->[0] =~ $func_start_re) {
$right = [ $token => [ $self->_recurse_parse($tokens, PARSE_IN_FUNC) || () ] ];
}
else {
$right = [ LITERAL => [ $token ] ];
}
$left = $left ? [ $left, $right ]
: $right;
}
}
}
sub format_keyword {
my ($self, $keyword) = @_;
if (my $around = $self->colormap->{lc $keyword}) {
$keyword = "$around->[0]$keyword$around->[1]";
}
return $keyword
}
my %starters = (
select => 1,
update => 1,
'insert into' => 1,
'delete from' => 1,
);
sub pad_keyword {
my ($self, $keyword, $depth) = @_;
my $before = '';
if (defined $self->indentmap->{lc $keyword}) {
$before = $self->newline . $self->indent($depth + $self->indentmap->{lc $keyword});
}
$before = '' if $depth == 0 and defined $starters{lc $keyword};
return [$before, ''];
}
sub indent { ($_[0]->indent_string||'') x ( ( $_[0]->indent_amount || 0 ) * $_[1] ) }
sub _is_key {
my ($self, $tree) = @_;
$tree = $tree->[0] while ref $tree;
defined $tree && defined $self->indentmap->{lc $tree};
}
sub fill_in_placeholder {
my ($self, $bindargs) = @_;
if ($self->fill_in_placeholders) {
my $val = shift @{$bindargs} || '';
my $quoted = $val =~ s/^(['"])(.*)\1$/$2/;
my ($left, $right) = @{$self->placeholder_surround};
$val =~ s/\\/\\\\/g;
$val =~ s/'/\\'/g;
$val = qq('$val') if $quoted;
return qq($left$val$right)
}
return '?'
}
# FIXME - terrible name for a user facing API
sub unparse {
my ($self, $tree, $bindargs) = @_;
$self->_unparse($tree, [@{$bindargs||[]}], 0);
}
sub _unparse {
my ($self, $tree, $bindargs, $depth) = @_;
if (not $tree or not @$tree) {
return '';
}
$self->_parenthesis_unroll($tree);
my ($car, $cdr) = @{$tree}[0,1];
if (! defined $car or (! ref $car and ! defined $cdr) ) {
require Data::Dumper;
Carp::confess( sprintf ( "Internal error - malformed branch at depth $depth:\n%s",
Data::Dumper::Dumper($tree)
) );
}
if (ref $car) {
return join (' ', map $self->_unparse($_, $bindargs, $depth), @$tree);
}
elsif ($car eq 'LITERAL') {
return $cdr->[0];
}
elsif ($car eq 'PLACEHOLDER') {
return $self->fill_in_placeholder($bindargs);
}
elsif ($car eq 'PAREN') {
return sprintf ('( %s )',
join (' ', map { $self->_unparse($_, $bindargs, $depth + 2) } @{$cdr} )
.
($self->_is_key($cdr)
? ( $self->newline||'' ) . $self->indent($depth + 1)
: ''
)
);
}
elsif ($car eq 'AND' or $car eq 'OR' or $car =~ / ^ $binary_op_re $ /x ) {
return join (" $car ", map $self->_unparse($_, $bindargs, $depth), @{$cdr});
}
elsif ($car eq 'LIST' ) {
return join (', ', map $self->_unparse($_, $bindargs, $depth), @{$cdr});
}
else {
my ($l, $r) = @{$self->pad_keyword($car, $depth)};
return sprintf "$l%s%s%s$r",
$self->format_keyword($car),
( ref $cdr eq 'ARRAY' and ref $cdr->[0] eq 'ARRAY' and $cdr->[0][0] and $cdr->[0][0] eq 'PAREN' )
? '' # mysql--
: ' '
,
$self->_unparse($cdr, $bindargs, $depth),
;
}
}
# 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;