Java Reference
In-Depth Information
function
S
()
returns
Token
while
s
.
peek()=
blank
do call
s
.
advance()
if
s
.
EOF( )
then
ans
.
type
← $
else
if
s
.
peek()∈{0,1,...,9}
then
ans
←
canner
S
can
D
igits
()
else
ch
←
s
.
advance()
switch
(
ch
)
case
{
a
,
b
,...,
z
}−{
i
,
f
,
p
}
ans
.
type
← id
ans
.
val
←
ch
case
f
ans
.
type
← floatdcl
case
i
ans
.
type
← intdcl
case
p
ans
.
type
← print
case
=
ans
.
type
← assign
case
+
ans
.
type
← plus
case
-
ans
.
type
←minus
case
de f ault
call
L
exical
E
rror
()
return
(
ans
)
end
Figure 2.5: Scanner for the ac language. The variable
s
is an input
stream of characters.
