<s>
Semmle	B-Language
Inc	O
is	O
a	O
code-analysis	O
platform	O
;	O
Semmle	B-Language
was	O
acquired	O
by	O
GitHub	B-Application
(	O
itself	O
owned	O
by	O
Microsoft	O
)	O
on	O
18	O
September	O
2019	O
for	O
an	O
undisclosed	O
amount	O
.	O
</s>
<s>
Semmle	B-Language
's	O
LGTM	O
technology	O
automates	O
code	O
review	O
,	O
tracks	O
developer	O
contributions	O
,	O
and	O
flags	O
software	O
security	O
issues	O
.	O
</s>
<s>
The	O
LGTM	O
platform	O
leverages	O
the	O
CodeQL	B-Language
query	O
engine	O
(	O
formerly	O
QL	B-Language
)	O
to	O
perform	O
semantic	O
analysis	O
on	O
software	O
code	O
bases	O
.	O
</s>
<s>
GitHub	B-Application
aims	O
to	O
integrate	O
Semmle	B-Language
technology	O
to	O
provide	O
continuous	O
vulnerability	O
detection	O
services	O
.	O
</s>
<s>
In	O
November	O
2019	O
,	O
use	O
of	O
CodeQL	B-Language
was	O
made	O
free	O
for	O
research	O
and	O
open	O
source	O
.	O
</s>
<s>
CodeQL	B-Language
either	O
shares	O
a	O
direct	O
pedigree	O
with	O
.QL	B-Language
(	O
dot-que-ell	O
)	O
,	O
which	O
derives	O
from	O
the	O
Datalog	B-Language
family	O
tree	O
,	O
or	O
is	O
an	O
evolution	O
of	O
similar	O
technology	O
.	O
</s>
<s>
SemmleCode	B-Language
is	O
an	O
object-oriented	B-Language
query	B-Language
language	I-Language
for	O
deductive	O
databases	O
developed	O
by	O
Semmle	B-Language
.	O
</s>
<s>
Semmle	B-Language
's	O
customers	O
included	O
Credit	O
Suisse	O
,	O
NASA	O
,	O
and	O
Dell	O
.	O
</s>
<s>
SemmleCode	B-Language
builds	O
on	O
academic	O
research	O
on	O
querying	O
the	O
source	O
of	O
software	O
programs	O
.	O
</s>
<s>
The	O
first	O
such	O
system	O
was	O
Linton	O
's	O
Omega	O
system	O
,	O
where	O
queries	O
were	O
phrased	O
in	O
QUEL	B-Language
.	O
</s>
<s>
QUEL	B-Language
did	O
not	O
allow	O
for	O
recursion	O
in	O
queries	O
,	O
making	O
it	O
difficult	O
to	O
inspect	O
hierarchical	O
program	O
structures	O
such	O
as	O
the	O
call	B-Application
graph	I-Application
.	O
</s>
<s>
The	O
next	O
significant	O
development	O
was	O
therefore	O
the	O
use	O
of	O
logic	B-Language
programming	I-Language
,	O
which	O
does	O
allow	O
such	O
recursive	O
queries	O
,	O
in	O
the	O
XL	O
C++	O
Browser	O
.	O
</s>
<s>
The	O
disadvantage	O
of	O
using	O
a	O
full	O
logic	B-Language
programming	I-Language
language	I-Language
is	O
however	O
that	O
it	O
is	O
very	O
difficult	O
to	O
attain	O
acceptable	O
efficiency	O
.	O
</s>
<s>
The	O
CodeQuest	O
system	O
,	O
developed	O
at	O
the	O
University	O
of	O
Oxford	O
,	O
was	O
the	O
first	O
to	O
exploit	O
the	O
observation	O
that	O
Datalog	B-Language
,	O
a	O
very	O
restrictive	O
version	O
of	O
logic	B-Language
programming	I-Language
,	O
is	O
in	O
the	O
sweet	O
spot	O
between	O
expressive	O
power	O
and	O
efficiency	O
.	O
</s>
<s>
The	O
QL	B-Language
query	B-Language
language	I-Language
is	O
an	O
object-oriented	B-Language
version	O
of	O
Datalog	B-Language
.	O
</s>
<s>
In	O
particular	O
it	O
became	O
the	O
cornerstone	O
of	O
systems	O
for	O
application	O
intelligence	O
(	O
data	B-Application
mining	I-Application
on	O
the	O
source	O
of	O
software	O
systems	O
)	O
and	O
software	O
renovation	O
.	O
</s>
<s>
SemmleCode	B-Language
differs	O
from	O
these	O
systems	O
in	O
its	O
use	O
of	O
an	O
object-oriented	B-Language
query	B-Language
language	I-Language
,	O
which	O
allows	O
programmers	O
to	O
easily	O
formulate	O
new	O
queries	O
that	O
are	O
particular	O
to	O
their	O
own	O
project	O
.	O
</s>
<s>
A	O
full	O
account	O
of	O
the	O
academic	O
and	O
industrial	O
developments	O
leading	O
up	O
to	O
the	O
creation	O
of	O
SemmleCode	B-Language
can	O
be	O
found	O
in	O
a	O
paper	O
by	O
Hajiyev	O
et	O
al	O
.	O
</s>
<s>
To	O
illustrate	O
the	O
use	O
of	O
QL	B-Language
,	O
consider	O
the	O
well-known	O
rule	O
in	O
object-oriented	B-Language
programming	I-Language
that	O
public	O
fields	O
should	O
be	O
declared	O
final	O
.	O
</s>
<s>
In	O
QL	B-Language
,	O
that	O
requirement	O
is	O
expressed	O
as	O
follows	O
:	O
</s>
<s>
SemmleCode	B-Language
provides	O
a	O
user	B-Application
interface	I-Application
via	O
the	O
Eclipse	B-Application
IDE	I-Application
to	O
query	O
Java	O
code	O
(	O
both	O
source	O
code	O
and	O
bytecode	O
)	O
as	O
well	O
as	O
XML	O
files	O
,	O
and	O
to	O
edit	O
QL	B-Language
queries	O
.	O
</s>
<s>
This	O
is	O
however	O
but	O
one	O
application	O
of	O
the	O
technology	O
that	O
underlies	O
it	O
:	O
QL	B-Language
can	O
be	O
used	O
to	O
query	O
any	O
other	O
type	O
of	O
complex	O
data	O
.	O
</s>
<s>
As	O
part	O
of	O
the	O
fold	O
into	O
the	O
Microsoft/GitHub	O
corporate	O
house	O
,	O
the	O
original	O
Eclipse-based	O
workflow	O
has	O
been	O
supplanted	O
with	O
a	O
workflow	O
based	O
around	O
Microsoft	O
's	O
Visual	B-Language
Studio	I-Language
Code	I-Language
.	O
</s>
