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using
System;
using
System.IO;
/// <summary>
/// Represents a filter which removes comments and unnecessary whitespace from JavaScript files.
/// </summary>
public
class
JSMin
{
const
int
EOF = -1;
StringReader sr;
StringWriter sw;
int
theA;
int
theB;
int
theLookahead = EOF;
/// <summary>
/// Compresses the specified script source.
/// </summary>
/// <param name="source">The script source.</param>
/// <returns>The compressed script content.</returns>
public
string
Minify(
string
source)
{
using
(sr =
new
StringReader(source))
{
using
(sw =
new
StringWriter())
{
jsmin();
return
sw.ToString();
}
}
}
/* jsmin -- Copy the input to the output, deleting the characters which are
insignificant to JavaScript. Comments will be removed. Tabs will be
replaced with spaces. Carriage returns will be replaced with linefeeds.
Most spaces and linefeeds will be removed.
*/
void
jsmin()
{
theA =
'\n'
;
action( 3 );
while
( theA != EOF )
{
switch
( theA )
{
case
' '
:
{
if
( isAlphanum( theB ) )
{
action( 1 );
}
else
{
action( 2 );
}
break
;
}
case
'\n'
:
{
switch
( theB )
{
case
'{'
:
case
'['
:
case
'('
:
case
'+'
:
case
'-'
:
{
action( 1 );
break
;
}
case
' '
:
{
action( 3 );
break
;
}
default
:
{
if
( isAlphanum( theB ) )
{
action( 1 );
}
else
{
action( 2 );
}
break
;
}
}
break
;
}
default
:
{
switch
( theB )
{
case
' '
:
{
if
( isAlphanum( theA ) )
{
action( 1 );
break
;
}
action( 3 );
break
;
}
case
'\n'
:
{
switch
( theA )
{
case
'}'
:
case
']'
:
case
')'
:
case
'+'
:
case
'-'
:
case
'"'
:
case
'\''
:
{
action( 1 );
break
;
}
default
:
{
if
( isAlphanum( theA ) )
{
action( 1 );
}
else
{
action( 3 );
}
break
;
}
}
break
;
}
default
:
{
action( 1 );
break
;
}
}
break
;
}
}
}
}
/* action -- do something! What you do is determined by the argument:
1 Output A. Copy B to A. Get the next B.
2 Copy B to A. Get the next B. (Delete A).
3 Get the next B. (Delete B).
action treats a string as a single character. Wow!
action recognizes a regular expression if it is preceded by ( or , or =.
*/
void
action(
int
d )
{
if
( d <= 1 )
{
put( theA );
}
if
( d <= 2 )
{
theA = theB;
if
( theA ==
'\''
|| theA ==
'"'
)
{
for
( ; ; )
{
put( theA );
theA =
get
();
if
( theA == theB )
{
break
;
}
if
( theA <=
'\n'
)
{
throw
new
Exception(
string
.Format(
"Error: JSMIN unterminated string literal: {0}\n"
, theA ) );
}
if
( theA ==
'\\'
)
{
put( theA );
theA =
get
();
}
}
}
}
if
( d <= 3 )
{
theB = next();
if
( theB ==
'/'
&& (theA ==
'('
|| theA ==
','
|| theA ==
'='
||
theA ==
'['
|| theA ==
'!'
|| theA ==
':'
||
theA ==
'&'
|| theA ==
'|'
|| theA ==
'?'
||
theA ==
'{'
|| theA ==
'}'
|| theA ==
';'
||
theA ==
'\n'
) )
{
put( theA );
put( theB );
for
( ; ; )
{
theA =
get
();
if
( theA ==
'/'
)
{
break
;
}
else
if
( theA ==
'\\'
)
{
put( theA );
theA =
get
();
}
else
if
( theA <=
'\n'
)
{
throw
new
Exception(
string
.Format(
"Error: JSMIN unterminated Regular Expression literal : {0}.\n"
, theA ) );
}
put( theA );
}
theB = next();
}
}
}
/* next -- get the next character, excluding comments. peek() is used to see
if a '/' is followed by a '/' or '*'.
*/
int
next()
{
int
c =
get
();
if
( c ==
'/'
)
{
switch
( peek() )
{
case
'/'
:
{
for
( ; ; )
{
c =
get
();
if
( c <=
'\n'
)
{
return
c;
}
}
}
case
'*'
:
{
get
();
for
( ; ; )
{
switch
(
get
() )
{
case
'*'
:
{
if
( peek() ==
'/'
)
{
get
();
return
' '
;
}
break
;
}
case
EOF:
{
throw
new
Exception(
"Error: JSMIN Unterminated comment.\n"
);
}
}
}
}
default
:
{
return
c;
}
}
}
return
c;
}
/* peek -- get the next character without getting it.
*/
int
peek()
{
theLookahead =
get
();
return
theLookahead;
}
/* get -- return the next character from stdin. Watch out for lookahead. If
the character is a control character, translate it to a space or
linefeed.
*/
int
get
()
{
int
c = theLookahead;
theLookahead = EOF;
if
( c == EOF )
{
c = sr.Read();
}
if
( c >=
' '
|| c ==
'\n'
|| c == EOF )
{
return
c;
}
if
( c ==
'\r'
)
{
return
'\n'
;
}
return
' '
;
}
void
put(
int
c )
{
sw.Write( (
char
)c );
}
/* isAlphanum -- return true if the character is a letter, digit, underscore,
dollar sign, or non-ASCII character.
*/
bool
isAlphanum(
int
c )
{
return
((c >=
'a'
&& c <=
'z'
) || (c >=
'0'
&& c <=
'9'
) ||
(c >=
'A'
&& c <=
'Z'
) || c ==
'_'
|| c ==
'$'
|| c ==
'\\'
||
c > 126);
}
}
|
王德水
