<s>
In	O
computer	B-General_Concept
science	I-General_Concept
,	O
tail	B-Application
recursive	I-Application
parsers	I-Application
are	O
a	O
derivation	O
from	O
the	O
more	O
common	O
recursive	B-Application
descent	I-Application
parsers	I-Application
.	O
</s>
<s>
Tail	B-Application
recursive	I-Application
parsers	I-Application
are	O
commonly	O
used	O
to	O
parse	O
left	B-Application
recursive	I-Application
grammars	O
.	O
</s>
<s>
They	O
use	O
a	O
smaller	O
amount	O
of	O
stack	O
space	O
than	O
regular	O
recursive	B-Application
descent	I-Application
parsers	I-Application
.	O
</s>
<s>
Typical	O
recursive	B-Application
descent	I-Application
parsers	I-Application
make	O
parsing	O
left	B-Application
recursive	I-Application
grammars	O
impossible	O
(	O
because	O
of	O
an	O
infinite	O
loop	O
problem	O
)	O
.	O
</s>
<s>
Tail	B-Application
recursive	I-Application
parsers	I-Application
use	O
a	O
node	O
reparenting	O
technique	O
that	O
makes	O
this	O
allowable	O
.	O
</s>
<s>
A	O
simple	O
tail	B-Application
recursive	I-Application
parser	I-Application
can	O
be	O
written	O
much	O
like	O
a	O
recursive	B-Application
descent	I-Application
parser	I-Application
.	O
</s>
<s>
The	O
typical	O
algorithm	O
for	O
parsing	O
a	O
grammar	O
like	O
this	O
using	O
an	O
abstract	B-Data_Structure
syntax	I-Data_Structure
tree	I-Data_Structure
is	O
:	O
</s>
<s>
A	O
basic	O
example	O
of	O
this	O
kind	O
of	O
parser	O
in	O
C	B-Language
is	O
shown	O
here	O
.	O
</s>
