<s>
Ragel	B-Application
is	O
a	O
finite-state	B-Architecture
machine	I-Architecture
compiler	B-Language
and	O
a	O
parser	B-Language
generator	I-Language
.	O
</s>
<s>
Initially	O
Ragel	B-Application
supported	O
output	O
for	O
C	B-Language
,	O
C++	B-Language
and	O
Assembly	B-Language
source	O
code	O
,	O
and	O
was	O
expanded	O
to	O
support	O
several	O
other	O
languages	O
including	O
Objective	B-Language
C	I-Language
,	O
D	B-Application
,	O
Go	B-Application
,	O
Ruby	B-Language
,	O
and	O
Java	B-Language
.	O
</s>
<s>
It	O
supports	O
the	O
generation	O
of	O
table	B-Application
or	O
control	O
flow	O
driven	O
state	B-Architecture
machines	I-Architecture
from	O
regular	B-Language
expressions	I-Language
and/or	O
state	B-Application
charts	I-Application
and	O
can	O
also	O
build	O
lexical	B-Application
analysers	I-Application
via	O
the	O
longest-match	O
method	O
.	O
</s>
<s>
Ragel	B-Application
specifically	O
targets	O
text	O
parsing	O
and	O
input	O
validation	O
.	O
</s>
<s>
Ragel	B-Application
supports	O
the	O
generation	O
of	O
table	B-Application
or	O
control	O
flow	O
driven	O
state	B-Architecture
machines	I-Architecture
from	O
regular	B-Language
expressions	I-Language
and/or	O
state	B-Application
charts	I-Application
and	O
can	O
also	O
build	O
lexical	B-Application
analysers	I-Application
via	O
the	O
longest-match	O
method	O
.	O
</s>
<s>
A	O
unique	O
feature	O
of	O
Ragel	B-Application
is	O
that	O
user	O
actions	O
can	O
be	O
associated	O
with	O
arbitrary	O
state	B-Architecture
machine	I-Architecture
transitions	O
using	O
operators	O
that	O
are	O
integrated	O
into	O
the	O
regular	B-Language
expressions	I-Language
.	O
</s>
<s>
Ragel	B-Application
also	O
supports	O
visualization	O
of	O
the	O
generated	O
machine	O
via	O
graphviz	B-Language
.	O
</s>
<s>
The	O
above	O
graph	O
represents	O
a	O
state-machine	B-Architecture
that	O
takes	O
user	O
input	O
as	O
a	O
series	O
of	O
bytes	O
representing	O
ASCII	B-Protocol
characters	I-Protocol
and	O
control	O
codes	O
.	O
</s>
<s>
48	O
..	O
57	O
is	O
equivalent	O
to	O
the	O
regular	B-Language
expression	I-Language
 [ 0-9 ] 	O
(	O
i.e.	O
</s>
<s>
Ragel	B-Application
's	O
input	O
is	O
a	O
regular	B-Language
expression	I-Language
only	O
in	O
the	O
sense	O
that	O
it	O
describes	O
a	O
regular	B-General_Concept
language	I-General_Concept
;	O
it	O
is	O
usually	O
not	O
written	O
in	O
a	O
concise	O
regular	B-Language
expression	I-Language
,	O
but	O
written	O
out	O
into	O
multiple	O
parts	O
like	O
in	O
Extended	O
Backus	O
–	O
Naur	O
form	O
.	O
</s>
<s>
For	O
example	O
,	O
instead	O
of	O
supporting	O
POSIX	O
character	O
classes	O
in	O
regex	B-Language
syntax	O
,	O
Ragel	B-Application
implements	O
them	O
as	O
built-in	O
production	O
rules	O
.	O
</s>
<s>
As	O
with	O
usual	O
parser	B-Language
generators	I-Language
,	O
Ragel	B-Application
allows	O
for	O
handling	O
code	O
for	O
productions	O
to	O
be	O
written	O
with	O
the	O
syntax	O
.	O
</s>
