<?php
/**
* JavaScript Minifier
*
* This class is meant to safely minify javascript code, while leaving syntactically correct
* programs intact. Other libraries, such as JSMin require a certain coding style to work
* correctly. OTOH, libraries like jsminplus, that do parse the code correctly are rather
* slow, because they construct a complete parse tree before outputting the code minified.
* So this class is meant to allow arbitrary (but syntactically correct) input, while being
* fast enough to be used for on-the-fly minifying.
*
* Author: Paul Copperman <paul.copperman@gmail.com>
* License: choose any of Apache, MIT, GPL, LGPL
*/
class JavaScriptMinifier {
/* Class constants */
/* Parsing states.
* The state machine is only necessary to decide whether to parse a slash as division
* operator or as regexp literal.
* States are named after the next expected item. We only distinguish states when the
* distinction is relevant for our purpose.
*/
const STATEMENT = 0;
const CONDITION = 1;
const PROPERTY_ASSIGNMENT = 2;
const EXPRESSION = 3;
const EXPRESSION_NO_NL = 4; // only relevant for semicolon insertion
const EXPRESSION_OP = 5;
const EXPRESSION_FUNC = 6;
const EXPRESSION_TERNARY = 7; // used to determine the role of a colon
const EXPRESSION_TERNARY_OP = 8;
const EXPRESSION_TERNARY_FUNC = 9;
const PAREN_EXPRESSION = 10; // expression which is not on the top level
const PAREN_EXPRESSION_OP = 11;
const PAREN_EXPRESSION_FUNC = 12;
const PROPERTY_EXPRESSION = 13; // expression which is within an object literal
const PROPERTY_EXPRESSION_OP = 14;
const PROPERTY_EXPRESSION_FUNC = 15;
/* Token types */
const TYPE_UN_OP = 1; // unary operators
const TYPE_INCR_OP = 2; // ++ and --
const TYPE_BIN_OP = 3; // binary operators
const TYPE_ADD_OP = 4; // + and - which can be either unary or binary ops
const TYPE_HOOK = 5; // ?
const TYPE_COLON = 6; // :
const TYPE_COMMA = 7; // ,
const TYPE_SEMICOLON = 8; // ;
const TYPE_BRACE_OPEN = 9; // {
const TYPE_BRACE_CLOSE = 10; // }
const TYPE_PAREN_OPEN = 11; // ( and [
const TYPE_PAREN_CLOSE = 12; // ) and ]
const TYPE_RETURN = 13; // keywords: break, continue, return, throw
const TYPE_IF = 14; // keywords: catch, for, with, switch, while, if
const TYPE_DO = 15; // keywords: case, var, finally, else, do, try
const TYPE_FUNC = 16; // keywords: function
const TYPE_LITERAL = 17; // all literals, identifiers and unrecognised tokens
// Sanity limit to avoid excessive memory usage
const STACK_LIMIT = 1000;
/* Static functions */
/**
* Returns minified JavaScript code.
*
* NOTE: $maxLineLength isn't a strict maximum. Longer lines will be produced when
* literals (e.g. quoted strings) longer than $maxLineLength are encountered
* or when required to guard against semicolon insertion.
*
* @param $s String JavaScript code to minify
* @param $statementsOnOwnLine Bool Whether to put each statement on its own line
* @param $maxLineLength Int Maximum length of a single line, or -1 for no maximum.
* @return String Minified code
*/
public static function minify( $s, $statementsOnOwnLine = false, $maxLineLength = 1000 ) {
// First we declare a few tables that contain our parsing rules
// $opChars : characters, which can be combined without whitespace in between them
$opChars = array(
'!' => true,
'"' => true,
'%' => true,
'&' => true,
"'" => true,
'(' => true,
')' => true,
'*' => true,
'+' => true,
',' => true,
'-' => true,
'.' => true,
'/' => true,
':' => true,
';' => true,
'<' => true,
'=' => true,
'>' => true,
'?' => true,
'[' => true,
']' => true,
'^' => true,
'{' => true,
'|' => true,
'}' => true,
'~' => true
);
// $tokenTypes : maps keywords and operators to their corresponding token type
$tokenTypes = array(
'!' => self::TYPE_UN_OP,
'~' => self::TYPE_UN_OP,
'delete' => self::TYPE_UN_OP,
'new' => self::TYPE_UN_OP,
'typeof' => self::TYPE_UN_OP,
'void' => self::TYPE_UN_OP,
'++' => self::TYPE_INCR_OP,
'--' => self::TYPE_INCR_OP,
'!=' => self::TYPE_BIN_OP,
'!==' => self::TYPE_BIN_OP,
'%' => self::TYPE_BIN_OP,
'%=' => self::TYPE_BIN_OP,
'&' => self::TYPE_BIN_OP,
'&&' => self::TYPE_BIN_OP,
'&=' => self::TYPE_BIN_OP,
'*' => self::TYPE_BIN_OP,
'*=' => self::TYPE_BIN_OP,
'+=' => self::TYPE_BIN_OP,
'-=' => self::TYPE_BIN_OP,
'.' => self::TYPE_BIN_OP,
'/' => self::TYPE_BIN_OP,
'/=' => self::TYPE_BIN_OP,
'<' => self::TYPE_BIN_OP,
'<<' => self::TYPE_BIN_OP,
'<<=' => self::TYPE_BIN_OP,
'<=' => self::TYPE_BIN_OP,
'=' => self::TYPE_BIN_OP,
'==' => self::TYPE_BIN_OP,
'===' => self::TYPE_BIN_OP,
'>' => self::TYPE_BIN_OP,
'>=' => self::TYPE_BIN_OP,
'>>' => self::TYPE_BIN_OP,
'>>=' => self::TYPE_BIN_OP,
'>>>' => self::TYPE_BIN_OP,
'>>>=' => self::TYPE_BIN_OP,
'^' => self::TYPE_BIN_OP,
'^=' => self::TYPE_BIN_OP,
'|' => self::TYPE_BIN_OP,
'|=' => self::TYPE_BIN_OP,
'||' => self::TYPE_BIN_OP,
'in' => self::TYPE_BIN_OP,
'instanceof' => self::TYPE_BIN_OP,
'+' => self::TYPE_ADD_OP,
'-' => self::TYPE_ADD_OP,
'?' => self::TYPE_HOOK,
':' => self::TYPE_COLON,
',' => self::TYPE_COMMA,
';' => self::TYPE_SEMICOLON,
'{' => self::TYPE_BRACE_OPEN,
'}' => self::TYPE_BRACE_CLOSE,
'(' => self::TYPE_PAREN_OPEN,
'[' => self::TYPE_PAREN_OPEN,
')' => self::TYPE_PAREN_CLOSE,
']' => self::TYPE_PAREN_CLOSE,
'break' => self::TYPE_RETURN,
'continue' => self::TYPE_RETURN,
'return' => self::TYPE_RETURN,
'throw' => self::TYPE_RETURN,
'catch' => self::TYPE_IF,
'for' => self::TYPE_IF,
'if' => self::TYPE_IF,
'switch' => self::TYPE_IF,
'while' => self::TYPE_IF,
'with' => self::TYPE_IF,
'case' => self::TYPE_DO,
'do' => self::TYPE_DO,
'else' => self::TYPE_DO,
'finally' => self::TYPE_DO,
'try' => self::TYPE_DO,
'var' => self::TYPE_DO,
'function' => self::TYPE_FUNC
);
// $goto : This is the main table for our state machine. For every state/token pair
// the following state is defined. When no rule exists for a given pair,
// the state is left unchanged.
$goto = array(
self::STATEMENT => array(
self::TYPE_UN_OP => self::EXPRESSION,
self::TYPE_INCR_OP => self::EXPRESSION,
self::TYPE_ADD_OP => self::EXPRESSION,
self::TYPE_PAREN_OPEN => self::PAREN_EXPRESSION,
self::TYPE_RETURN => self::EXPRESSION_NO_NL,
self::TYPE_IF => self::CONDITION,
self::TYPE_FUNC => self::CONDITION,
self::TYPE_LITERAL => self::EXPRESSION_OP
),
self::CONDITION => array(
self::TYPE_PAREN_OPEN => self::PAREN_EXPRESSION
),
self::PROPERTY_ASSIGNMENT => array(
self::TYPE_COLON => self::PROPERTY_EXPRESSION,
self::TYPE_BRACE_OPEN => self::STATEMENT
),
self::EXPRESSION => array(
self::TYPE_SEMICOLON => self::STATEMENT,
self::TYPE_BRACE_OPEN => self::PROPERTY_ASSIGNMENT,
self::TYPE_PAREN_OPEN => self::PAREN_EXPRESSION,
self::TYPE_FUNC => self::EXPRESSION_FUNC,
self::TYPE_LITERAL => self::EXPRESSION_OP
),
self::EXPRESSION_NO_NL => array(
self::TYPE_SEMICOLON => self::STATEMENT,
self::TYPE_BRACE_OPEN => self::PROPERTY_ASSIGNMENT,
self::TYPE_PAREN_OPEN => self::PAREN_EXPRESSION,
self::TYPE_FUNC => self::EXPRESSION_FUNC,
self::TYPE_LITERAL => self::EXPRESSION_OP
),
self::EXPRESSION_OP => array(
self::TYPE_BIN_OP => self::EXPRESSION,
self::TYPE_ADD_OP => self::EXPRESSION,
self::TYPE_HOOK => self::EXPRESSION_TERNARY,
self::TYPE_COLON => self::STATEMENT,
self::TYPE_COMMA => self::EXPRESSION,
self::TYPE_SEMICOLON => self::STATEMENT,
self::TYPE_PAREN_OPEN => self::PAREN_EXPRESSION
),
self::EXPRESSION_FUNC => array(
self::TYPE_BRACE_OPEN => self::STATEMENT
),
self::EXPRESSION_TERNARY => array(
self::TYPE_BRACE_OPEN => self::PROPERTY_ASSIGNMENT,
self::TYPE_PAREN_OPEN => self::PAREN_EXPRESSION,
self::TYPE_FUNC => self::EXPRESSION_TERNARY_FUNC,
self::TYPE_LITERAL => self::EXPRESSION_TERNARY_OP
),
self::EXPRESSION_TERNARY_OP => array(
self::TYPE_BIN_OP => self::EXPRESSION_TERNARY,
self::TYPE_ADD_OP => self::EXPRESSION_TERNARY,
self::TYPE_HOOK => self::EXPRESSION_TERNARY,
self::TYPE_COMMA => self::EXPRESSION_TERNARY,
self::TYPE_PAREN_OPEN => self::PAREN_EXPRESSION
),
self::EXPRESSION_TERNARY_FUNC => array(
self::TYPE_BRACE_OPEN => self::STATEMENT
),
self::PAREN_EXPRESSION => array(
self::TYPE_BRACE_OPEN => self::PROPERTY_ASSIGNMENT,
self::TYPE_PAREN_OPEN => self::PAREN_EXPRESSION,
self::TYPE_FUNC => self::PAREN_EXPRESSION_FUNC,
self::TYPE_LITERAL => self::PAREN_EXPRESSION_OP
),
self::PAREN_EXPRESSION_OP => array(
self::TYPE_BIN_OP => self::PAREN_EXPRESSION,
self::TYPE_ADD_OP => self::PAREN_EXPRESSION,
self::TYPE_HOOK => self::PAREN_EXPRESSION,
self::TYPE_COLON => self::PAREN_EXPRESSION,
self::TYPE_COMMA => self::PAREN_EXPRESSION,
self::TYPE_SEMICOLON => self::PAREN_EXPRESSION,
self::TYPE_PAREN_OPEN => self::PAREN_EXPRESSION
),
self::PAREN_EXPRESSION_FUNC => array(
self::TYPE_BRACE_OPEN => self::STATEMENT
),
self::PROPERTY_EXPRESSION => array(
self::TYPE_BRACE_OPEN => self::PROPERTY_ASSIGNMENT,
self::TYPE_PAREN_OPEN => self::PAREN_EXPRESSION,
self::TYPE_FUNC => self::PROPERTY_EXPRESSION_FUNC,
self::TYPE_LITERAL => self::PROPERTY_EXPRESSION_OP
),
self::PROPERTY_EXPRESSION_OP => array(
self::TYPE_BIN_OP => self::PROPERTY_EXPRESSION,
self::TYPE_ADD_OP => self::PROPERTY_EXPRESSION,
self::TYPE_HOOK => self::PROPERTY_EXPRESSION,
self::TYPE_COMMA => self::PROPERTY_ASSIGNMENT,
self::TYPE_PAREN_OPEN => self::PAREN_EXPRESSION
),
self::PROPERTY_EXPRESSION_FUNC => array(
self::TYPE_BRACE_OPEN => self::STATEMENT
)
);
// $push : This table contains the rules for when to push a state onto the stack.
// The pushed state is the state to return to when the corresponding
// closing token is found
$push = array(
self::STATEMENT => array(
self::TYPE_BRACE_OPEN => self::STATEMENT,
self::TYPE_PAREN_OPEN => self::EXPRESSION_OP
),
self::CONDITION => array(
self::TYPE_PAREN_OPEN => self::STATEMENT
),
self::PROPERTY_ASSIGNMENT => array(
self::TYPE_BRACE_OPEN => self::PROPERTY_ASSIGNMENT
),
self::EXPRESSION => array(
self::TYPE_BRACE_OPEN => self::EXPRESSION_OP,
self::TYPE_PAREN_OPEN => self::EXPRESSION_OP
),
self::EXPRESSION_NO_NL => array(
self::TYPE_BRACE_OPEN => self::EXPRESSION_OP,
self::TYPE_PAREN_OPEN => self::EXPRESSION_OP
),
self::EXPRESSION_OP => array(
self::TYPE_HOOK => self::EXPRESSION,
self::TYPE_PAREN_OPEN => self::EXPRESSION_OP
),
self::EXPRESSION_FUNC => array(
self::TYPE_BRACE_OPEN => self::EXPRESSION_OP
),
self::EXPRESSION_TERNARY => array(
self::TYPE_BRACE_OPEN => self::EXPRESSION_TERNARY_OP,
self::TYPE_PAREN_OPEN => self::EXPRESSION_TERNARY_OP
),
self::EXPRESSION_TERNARY_OP => array(
self::TYPE_HOOK => self::EXPRESSION_TERNARY,
self::TYPE_PAREN_OPEN => self::EXPRESSION_TERNARY_OP
),
self::EXPRESSION_TERNARY_FUNC => array(
self::TYPE_BRACE_OPEN => self::EXPRESSION_TERNARY_OP
),
self::PAREN_EXPRESSION => array(
self::TYPE_BRACE_OPEN => self::PAREN_EXPRESSION_OP,
self::TYPE_PAREN_OPEN => self::PAREN_EXPRESSION_OP
),
self::PAREN_EXPRESSION_OP => array(
self::TYPE_PAREN_OPEN => self::PAREN_EXPRESSION_OP
),
self::PAREN_EXPRESSION_FUNC => array(
self::TYPE_BRACE_OPEN => self::PAREN_EXPRESSION_OP
),
self::PROPERTY_EXPRESSION => array(
self::TYPE_BRACE_OPEN => self::PROPERTY_EXPRESSION_OP,
self::TYPE_PAREN_OPEN => self::PROPERTY_EXPRESSION_OP
),
self::PROPERTY_EXPRESSION_OP => array(
self::TYPE_PAREN_OPEN => self::PROPERTY_EXPRESSION_OP
),
self::PROPERTY_EXPRESSION_FUNC => array(
self::TYPE_BRACE_OPEN => self::PROPERTY_EXPRESSION_OP
)
);
// $pop : Rules for when to pop a state from the stack
$pop = array(
self::STATEMENT => array( self::TYPE_BRACE_CLOSE => true ),
self::PROPERTY_ASSIGNMENT => array( self::TYPE_BRACE_CLOSE => true ),
self::EXPRESSION => array( self::TYPE_BRACE_CLOSE => true ),
self::EXPRESSION_NO_NL => array( self::TYPE_BRACE_CLOSE => true ),
self::EXPRESSION_OP => array( self::TYPE_BRACE_CLOSE => true ),
self::EXPRESSION_TERNARY_OP => array( self::TYPE_COLON => true ),
self::PAREN_EXPRESSION => array( self::TYPE_PAREN_CLOSE => true ),
self::PAREN_EXPRESSION_OP => array( self::TYPE_PAREN_CLOSE => true ),
self::PROPERTY_EXPRESSION => array( self::TYPE_BRACE_CLOSE => true ),
self::PROPERTY_EXPRESSION_OP => array( self::TYPE_BRACE_CLOSE => true )
);
// $semicolon : Rules for when a semicolon insertion is appropriate
$semicolon = array(
self::EXPRESSION_NO_NL => array(
self::TYPE_UN_OP => true,
self::TYPE_INCR_OP => true,
self::TYPE_ADD_OP => true,
self::TYPE_BRACE_OPEN => true,
self::TYPE_PAREN_OPEN => true,
self::TYPE_RETURN => true,
self::TYPE_IF => true,
self::TYPE_DO => true,
self::TYPE_FUNC => true,
self::TYPE_LITERAL => true
),
self::EXPRESSION_OP => array(
self::TYPE_UN_OP => true,
self::TYPE_INCR_OP => true,
self::TYPE_BRACE_OPEN => true,
self::TYPE_RETURN => true,
self::TYPE_IF => true,
self::TYPE_DO => true,
self::TYPE_FUNC => true,
self::TYPE_LITERAL => true
)
);
// Rules for when newlines should be inserted if
// $statementsOnOwnLine is enabled.
// $newlineBefore is checked before switching state,
// $newlineAfter is checked after
$newlineBefore = array(
self::STATEMENT => array(
self::TYPE_BRACE_CLOSE => true,
),
);
$newlineAfter = array(
self::STATEMENT => array(
self::TYPE_BRACE_OPEN => true,
self::TYPE_PAREN_CLOSE => true,
self::TYPE_SEMICOLON => true,
),
);
// $divStates : Contains all states that can be followed by a division operator
$divStates = array(
self::EXPRESSION_OP => true,
self::EXPRESSION_TERNARY_OP => true,
self::PAREN_EXPRESSION_OP => true,
self::PROPERTY_EXPRESSION_OP => true
);
// Here's where the minifying takes place: Loop through the input, looking for tokens
// and output them to $out, taking actions to the above defined rules when appropriate.
$out = '';
$pos = 0;
$length = strlen( $s );
$lineLength = 0;
$newlineFound = true;
$state = self::STATEMENT;
$stack = array();
$last = ';'; // Pretend that we have seen a semicolon yet
while( $pos < $length ) {
// First, skip over any whitespace and multiline comments, recording whether we
// found any newline character
$skip = strspn( $s, " \t\n\r\xb\xc", $pos );
if( !$skip ) {
$ch = $s[$pos];
if( $ch === '/' && substr( $s, $pos, 2 ) === '/*' ) {
// Multiline comment. Search for the end token or EOT.
$end = strpos( $s, '*/', $pos + 2 );
$skip = $end === false ? $length - $pos : $end - $pos + 2;
}
}
if( $skip ) {
// The semicolon insertion mechanism needs to know whether there was a newline
// between two tokens, so record it now.
if( !$newlineFound && strcspn( $s, "\r\n", $pos, $skip ) !== $skip ) {
$newlineFound = true;
}
$pos += $skip;
continue;
}
// Handle C++-style comments and html comments, which are treated as single line
// comments by the browser, regardless of whether the end tag is on the same line.
// Handle --> the same way, but only if it's at the beginning of the line
if( ( $ch === '/' && substr( $s, $pos, 2 ) === '//' )
|| ( $ch === '<' && substr( $s, $pos, 4 ) === '<!--' )
|| ( $ch === '-' && $newlineFound && substr( $s, $pos, 3 ) === '-->' )
) {
$pos += strcspn( $s, "\r\n", $pos );
continue;
}
// Find out which kind of token we're handling. $end will point past the end of it.
$end = $pos + 1;
// Handle string literals
if( $ch === "'" || $ch === '"' ) {
// Search to the end of the string literal, skipping over backslash escapes
$search = $ch . '\\';
do{
$end += strcspn( $s, $search, $end ) + 2;
} while( $end - 2 < $length && $s[$end - 2] === '\\' );
$end--;
// We have to distinguish between regexp literals and division operators
// A division operator is only possible in certain states
} elseif( $ch === '/' && !isset( $divStates[$state] ) ) {
// Regexp literal, search to the end, skipping over backslash escapes and
// character classes
for( ; ; ) {
do{
$end += strcspn( $s, '/[\\', $end ) + 2;
} while( $end - 2 < $length && $s[$end - 2] === '\\' );
$end--;
if( $end - 1 >= $length || $s[$end - 1] === '/' ) {
break;
}
do{
$end += strcspn( $s, ']\\', $end ) + 2;
} while( $end - 2 < $length && $s[$end - 2] === '\\' );
$end--;
};
// Search past the regexp modifiers (gi)
while( $end < $length && ctype_alpha( $s[$end] ) ) {
$end++;
}
} elseif(
ctype_digit( $ch )
|| ( $ch === '.' && $pos + 1 < $length && ctype_digit( $s[$pos + 1] ) )
) {
// Numeric literal. Search for the end of it, but don't care about [+-]exponent
// at the end, as the results of "numeric [+-] numeric" and "numeric" are
// identical to our state machine.
$end += strspn( $s, '0123456789ABCDEFabcdefXx.', $end );
while( $s[$end - 1] === '.' ) {
// Special case: When a numeric ends with a dot, we have to check the
// literal for proper syntax
$decimal = strspn( $s, '0123456789', $pos, $end - $pos - 1 );
if( $decimal === $end - $pos - 1 ) {
break;
} else {
$end--;
}
}
} elseif( isset( $opChars[$ch] ) ) {
// Punctuation character. Search for the longest matching operator.
while(
$end < $length
&& isset( $tokenTypes[substr( $s, $pos, $end - $pos + 1 )] )
) {
$end++;
}
} else {
// Identifier or reserved word. Search for the end by excluding whitespace and
// punctuation.
$end += strcspn( $s, " \t\n.;,=<>+-{}()[]?:*/%'\"!&|^~\xb\xc\r", $end );
}
// Now get the token type from our type array
$token = substr( $s, $pos, $end - $pos ); // so $end - $pos == strlen( $token )
$type = isset( $tokenTypes[$token] ) ? $tokenTypes[$token] : self::TYPE_LITERAL;
if( $newlineFound && isset( $semicolon[$state][$type] ) ) {
// This token triggers the semicolon insertion mechanism of javascript. While we
// could add the ; token here ourselves, keeping the newline has a few advantages.
$out .= "\n";
$state = self::STATEMENT;
$lineLength = 0;
} elseif( $maxLineLength > 0 && $lineLength + $end - $pos > $maxLineLength &&
!isset( $semicolon[$state][$type] ) && $type !== self::TYPE_INCR_OP )
{
// This line would get too long if we added $token, so add a newline first.
// Only do this if it won't trigger semicolon insertion and if it won't
// put a postfix increment operator on its own line, which is illegal in js.
$out .= "\n";
$lineLength = 0;
// Check, whether we have to separate the token from the last one with whitespace
} elseif( !isset( $opChars[$last] ) && !isset( $opChars[$ch] ) ) {
$out .= ' ';
$lineLength++;
// Don't accidentally create ++, -- or // tokens
} elseif( $last === $ch && ( $ch === '+' || $ch === '-' || $ch === '/' ) ) {
$out .= ' ';
$lineLength++;
}
$out .= $token;
$lineLength += $end - $pos; // += strlen( $token )
$last = $s[$end - 1];
$pos = $end;
$newlineFound = false;
// Output a newline after the token if required
// This is checked before AND after switching state
$newlineAdded = false;
if ( $statementsOnOwnLine && !$newlineAdded && isset( $newlineBefore[$state][$type] ) ) {
$out .= "\n";
$lineLength = 0;
$newlineAdded = true;
}
// Now that we have output our token, transition into the new state.
if( isset( $push[$state][$type] ) && count( $stack ) < self::STACK_LIMIT ) {
$stack[] = $push[$state][$type];
}
if( $stack && isset( $pop[$state][$type] ) ) {
$state = array_pop( $stack );
} elseif( isset( $goto[$state][$type] ) ) {
$state = $goto[$state][$type];
}
// Check for newline insertion again
if ( $statementsOnOwnLine && !$newlineAdded && isset( $newlineAfter[$state][$type] ) ) {
$out .= "\n";
$lineLength = 0;
}
}
return $out;
}
}