/*
* Transforms obj["foo"] into obj.foo whenever possible, saving 3 bytes.
*/
public void optimizeObjectMemberAccess() {
String tv;
int i, length;
JavaScriptToken token;
for (i = 0, length = tokens.size(); i < length; i++) {
if (tokens.get(i).getType() == Token.LB
&& i > 0
&& i < length - 2
&& tokens.get(i - 1).getType() == Token.NAME
&& tokens.get(i + 1).getType() == Token.STRING
&& tokens.get(i + 2).getType() == Token.RB) {
token = tokens.get(i + 1);
tv = token.getValue();
tv = tv.substring(1, tv.length() - 1);
if (isValidIdentifier(tv)) {
tokens.set(i, new JavaScriptToken(Token.DOT, "."));
tokens.set(i + 1, new JavaScriptToken(Token.NAME, tv));
tokens.remove(i + 2);
i = i + 2;
length = length - 1;
}
}
}
}
private String getDebugString(int max) {
assert max > 0;
StringBuffer result = new StringBuffer();
int start = Math.max(offset - max, 0);
int end = Math.min(offset + max, tokens.size());
for (int i = start; i < end; i++) {
JavaScriptToken token = tokens.get(i);
if (i == offset - 1) {
result.append(" ---> ");
}
result.append(token.getValue());
if (i == offset - 1) {
result.append(" <--- ");
}
}
return result.toString();
}
/*
* Transforms 'foo': ... into foo: ... whenever possible, saving 2 bytes.
*/
public void optimizeObjLitMemberDecl() {
String tv;
int i, length;
JavaScriptToken token;
for (i = 0, length = tokens.size(); i < length; i++) {
if (tokens.get(i).getType() == Token.OBJECTLIT
&& i > 0
&& tokens.get(i - 1).getType() == Token.STRING) {
token = tokens.get(i - 1);
tv = token.getValue();
tv = tv.substring(1, tv.length() - 1);
if (isValidIdentifier(tv)) {
tokens.set(i - 1, new JavaScriptToken(Token.NAME, tv));
}
}
}
}
private void parseCatch() {
String symbol;
JavaScriptToken token;
ScriptOrFnScope currentScope;
JavaScriptIdentifier identifier;
token = getToken(-1);
assert token.getType() == Token.CATCH;
token = consumeToken();
assert token.getType() == Token.LP;
token = consumeToken();
assert token.getType() == Token.NAME;
symbol = token.getValue();
currentScope = getCurrentScope();
if (mode == BUILDING_SYMBOL_TREE) {
// We must declare the exception identifier in the containing
// function
// scope to avoid errors related to the obfuscation process. No need
// to
// display a warning if the symbol was already declared here...
currentScope.declareIdentifier(symbol, false);
} else {
identifier = getIdentifier(symbol, currentScope);
identifier.incrementRefcount();
}
token = consumeToken();
assert token.getType() == Token.RP;
}
private void parseScope(ScriptOrFnScope scope) {
String symbol;
JavaScriptToken token;
JavaScriptIdentifier identifier;
int length = tokens.size();
enterScope(scope); // 进入范围(将scope压入栈scopes中)
while (offset < length) { // 在此函数调用前已设置为0
token = consumeToken(); // 消费tokens,offset自增
switch (token.getType()) {
case Token.VAR: // 注意后面没有break;
if (mode == BUILDING_SYMBOL_TREE) {
scope.incrementVarCount(); // 当前范围内的var数量加1
}
/* FALLSTHROUGH(falls through) 失败 */
case Token.CONST:
// The var keyword is followed by at least one symbol name.
// If several symbols follow, they are comma(逗号) separated.
for (; ; ) {
token = consumeToken();
assert token.getType() == Token.NAME;
// 判断关键字var、const后的变量是否已经定义，未定义则定义，已定义则输出警告
if (mode == BUILDING_SYMBOL_TREE) {
symbol = token.getValue();
if (scope.getIdentifier(symbol) == null) {
scope.declareIdentifier(symbol, true); // 声明标识符
} else {
warn("变量" + symbol + "已经在相同的作用域中声明", true);
}
}
token = getToken(0); // offset不自增,token.getValue()的值一般为'='或';'
assert token.getType() == Token.SEMI
|| token.getType() == Token.ASSIGN
|| token.getType() == Token.COMMA
|| token.getType() == Token.IN;
if (token.getType() == Token.IN) {
break;
} else {
parseExpression(); // 解释表达式（例如解释var a = 'u';或var a;）
token = getToken(-1); // 得到的是';'
if (token.getType() == Token.SEMI) { // 变量声明完成
break;
}
}
}
break;
case Token.FUNCTION:
parseFunctionDeclaration();
break;
case Token.LC:
braceNesting++;
break;
case Token.RC:
braceNesting--;
assert braceNesting >= scope.getBraceNesting();
if (braceNesting == scope.getBraceNesting()) { // 说明要离开当前作用域了
leaveCurrentScope(); // 离开当前作用域
return;
}
break;
case Token.WITH:
if (mode == BUILDING_SYMBOL_TREE) {
// Inside a 'with' block, it is impossible to figure out
// statically whether a symbol is a local variable or an
// object member. As a consequence, the only thing we can
// do is turn the obfuscation off for the highest scope
// containing the 'with' block.
protectScopeFromObfuscation(scope);
warn("不推荐使用with关键字。" + (munge ? " 使用with会降低压缩水平" : ""), true);
}
break;
case Token.CATCH:
parseCatch();
break;
case Token.CONDCOMMENT:
if (mode == BUILDING_SYMBOL_TREE) {
protectScopeFromObfuscation(scope);
warn("不推荐使用JScript条件注释。" + (munge ? "使用JScript条件解释会降低压缩水平。" : ""), true);
}
break;
case Token.NAME:
symbol = token.getValue();
if (mode == BUILDING_SYMBOL_TREE) {
if (symbol.equals("eval")) {
protectScopeFromObfuscation(scope);
warn("不推荐使用'eval'关键字。" + (munge ? "使用'eval'会降低压缩水平！" : ""), true);
}
} else if (mode == CHECKING_SYMBOL_TREE) {
if ((offset < 2 || getToken(-2).getType() != Token.DOT)
&& getToken(0).getType() != Token.OBJECTLIT) {
identifier = getIdentifier(symbol, scope);
if (identifier == null) {
if (symbol.length() <= 3 && !builtin.contains(symbol)) {
// Here, we found an undeclared and
// un-namespaced symbol that is
// 3 characters or less in length. Declare it in
// the global scope.
// We don't need to declare longer symbols since
// they won't cause
// any conflict with other munged symbols.
globalScope.declareIdentifier(symbol, false);
// warn("Found an undeclared symbol: " + symbol,
// true);
}
} else {
identifier.incrementRefcount();
}
}
}
break;
}
}
}
private void parseExpression() {
// Parse the expression until we encounter a comma or a semi-colon
// in the same brace nesting, bracket nesting（方括号嵌套） and paren nesting.
// Parse functions if any...
String symbol;
JavaScriptToken token;
ScriptOrFnScope currentScope;
JavaScriptIdentifier identifier;
int expressionBraceNesting = braceNesting; // 花括号嵌套
int bracketNesting = 0; // 方括号嵌套
int parensNesting = 0; //
int length = tokens.size();
while (offset < length) {
token = consumeToken();
currentScope = getCurrentScope(); // return scopes.peek();
switch (token.getType()) {
case Token.SEMI:
case Token.COMMA:
if (braceNesting == expressionBraceNesting && bracketNesting == 0 && parensNesting == 0) {
return;
}
break;
case Token.FUNCTION:
parseFunctionDeclaration();
break;
case Token.LC:
braceNesting++;
break;
case Token.RC:
braceNesting--;
assert braceNesting >= expressionBraceNesting;
break;
case Token.LB:
bracketNesting++;
break;
case Token.RB:
bracketNesting--;
break;
case Token.LP:
parensNesting++;
break;
case Token.RP:
parensNesting--;
break;
case Token.CONDCOMMENT:
if (mode == BUILDING_SYMBOL_TREE) {
protectScopeFromObfuscation(currentScope);
warn("不推荐使用JScript条件注释。" + (munge ? "使用JScript条件注释会降低压缩水平！" : ""), true);
}
break;
case Token.NAME:
symbol = token.getValue();
if (mode == BUILDING_SYMBOL_TREE) {
if (symbol.equals("eval")) {
protectScopeFromObfuscation(currentScope);
warn("不推荐使用'eval'关键字。" + (munge ? "使用'eval'会降低压缩水平！" : ""), true);
}
} else if (mode == CHECKING_SYMBOL_TREE) {
if ((offset < 2
|| (getToken(-2).getType() != Token.DOT
&& getToken(-2).getType() != Token.GET
&& getToken(-2).getType() != Token.SET))
&& getToken(0).getType() != Token.OBJECTLIT) {
identifier = getIdentifier(symbol, currentScope);
if (identifier == null) {
if (symbol.length() <= 3 && !builtin.contains(symbol)) {
// Here, we found an undeclared and
// un-namespaced symbol that is
// 3 characters or less in length. Declare it in
// the global scope.
// We don't need to declare longer symbols since
// they won't cause
// any conflict with other munged symbols.
globalScope.declareIdentifier(symbol, false);
// I removed the warning since was only being
// done when
// for identifiers 3 chars or less, and was just
// causing
// noise for people who happen to rely on an
// externally
// declared variable that happen to be that
// short. We either
// should always warn or never warn -- the fact
// that we
// declare the short symbols in the global space
// doesn't
// change anything.
// warn("Found an undeclared symbol: " + symbol,
// true);
}
} else {
identifier.incrementRefcount();
}
}
}
break;
}
}
}
private void parseFunctionDeclaration() {
String symbol;
JavaScriptToken token;
ScriptOrFnScope currentScope, fnScope;
JavaScriptIdentifier identifier;
currentScope = getCurrentScope(); // 得到此函数声明所在的域
token = consumeToken();
// 如果是函数名（说明这种函数的声明方式是：function funName(){}）
// 否则是：var varName = function(){}
if (token.getType() == Token.NAME) {
if (mode == BUILDING_SYMBOL_TREE) {
// Get the name of the function and declare it in the current
// scope.
symbol = token.getValue(); // 得到的是函数名
if (currentScope.getIdentifier(symbol) != null) {
warn("函数" + symbol + "已经在相同的作用域中声明。", true);
}
currentScope.declareIdentifier(symbol, false); // 在本作用域中声明标识符
}
token = consumeToken(); // 得到左圆括号
}
assert token.getType() == Token.LP;
if (mode == BUILDING_SYMBOL_TREE) {
fnScope = new ScriptOrFnScope(braceNesting, currentScope); // 新建一个作用域，并把当前域传递过去最为父作用域
indexedScopes.put(new Integer(offset), fnScope); // 圆括号的下一个索引映射到函数作用域
} else {
fnScope = indexedScopes.get(new Integer(offset));
}
// Parse function arguments.解释函数参数
int argpos = 0;
while ((token = consumeToken()).getType() != Token.RP) {
assert token.getType() == Token.NAME || token.getType() == Token.COMMA;
if (token.getType() == Token.NAME && mode == BUILDING_SYMBOL_TREE) {
symbol = token.getValue();
identifier = fnScope.declareIdentifier(symbol, false);
if (symbol.equals("$super") && argpos == 0) {
// Exception for Prototype 1.6...
identifier.preventMunging();
}
argpos++;
}
}
token = consumeToken(); // 得到函数的左花括号
assert token.getType() == Token.LC;
braceNesting++;
token = getToken(0);
if (token.getType() == Token.STRING && getToken(1).getType() == Token.SEMI) {
// This is a hint. Hints are empty statements that look like
// "localvar1:nomunge, localvar2:nomunge"; They allow developers
// to prevent specific symbols from getting obfuscated (some heretic
// implementations, such as Prototype 1.6, require specific variable
// names, such as $super for example, in order to work
// appropriately.
// Note: right now, only "nomunge" is supported in the right hand
// side
// of a hint. However, in the future, the right hand side(右边) may
// contain
// other values.
consumeToken();
String hints = token.getValue();
// Remove the leading and trailing quotes...
hints = hints.substring(1, hints.length() - 1).trim();
StringTokenizer st1 = new StringTokenizer(hints, ","); // Tokenizer分词器,以','为分词界限
while (st1.hasMoreTokens()) {
String hint = st1.nextToken();
int idx = hint.indexOf(':');
if (idx <= 0 || idx >= hint.length() - 1) {
if (mode == BUILDING_SYMBOL_TREE) {
// No need to report the error twice, hence the test...
warn("提示语句有语法错误：" + hint, true);
}
break;
}
String variableName = hint.substring(0, idx).trim();
String variableType = hint.substring(idx + 1).trim();
if (mode == BUILDING_SYMBOL_TREE) {
fnScope.addHint(variableName, variableType);
} else if (mode == CHECKING_SYMBOL_TREE) {
identifier = fnScope.getIdentifier(variableName);
if (identifier != null) {
if (variableType.equals("nomunge")) {
identifier.preventMunging();
} else {
warn("不支持的提示指令： " + hint, true);
}
} else {
warn("提示指令指向未知的标识符: " + hint, true);
}
}
}
}
parseScope(fnScope); // 解释函数域
}
// 此函数是将表达式优化,形式参数中的tokens是诸如'+','-','*'等单字符的操作符（当然也是关键字）和NAME，REGEXP，STRING等类型
public void processStringLiterals(boolean merge) {
String tv;
int i, length = tokens.size();
JavaScriptToken token, prevToken, nextToken;
if (merge) { // 如果优化
// Concatenate string literals(连接字符串常量) that are being appended
// wherever
// it is safe to do so. Note that we take care of the case:
// "a" + "b".toUpperCase()
for (i = 0; i < length; i++) {
token = tokens.get(i);
switch (token.getType()) {
case Token.ADD:
if (i > 0 && i < length) {
prevToken = tokens.get(i - 1);
nextToken = tokens.get(i + 1);
if (prevToken.getType() == Token.STRING
&& nextToken.getType() == Token.STRING
&& (i == length - 1 || tokens.get(i + 2).getType() != Token.DOT)) {
tokens.set(
i - 1,
new JavaScriptToken(
Token.STRING, prevToken.getValue() + nextToken.getValue())); // 设置对应索引处的值
tokens.remove(i + 1); // 移除之前的值
tokens.remove(i); // 移除之前的值
i = i - 1;
length = length - 2;
break;
}
}
}
}
}
// Second
// pass...Token中保存的STRING类型形如abc，经以下处理后变为"abc"，a'b'c-->"a'b'c",a"b"c-->'a"b"c'
for (i = 0; i < length; i++) {
token = tokens.get(i);
if (token.getType() == Token.STRING) {
tv = token.getValue();
// Finally, add the quoting characters（引号字符） and escape the
// string（滤过字符串）. We use
// the quoting character that minimizes the amount of escaping
// to save
// a few additional bytes.
char quotechar;
int singleQuoteCount = countChar(tv, '\''); // 计算单引号数量
int doubleQuoteCount = countChar(tv, '"'); // 计算双引号数量
if (doubleQuoteCount <= singleQuoteCount) {
quotechar = '"';
} else {
quotechar = '\'';
}
tv = quotechar + escapeString(tv, quotechar) + quotechar;
// String concatenation transforms the old script scheme:
// '<scr'+'ipt ...><'+'/script>'
// into the following:
// '<script ...></script>'
// which breaks if this code is embedded inside an HTML
// document.
// Since this is not the right way to do this, let's fix the
// code by
// transforming all "</script" into "<\/script"
if (tv.indexOf("</script") >= 0) {
tv = tv.replaceAll("<\\/script", "<\\\\/script");
}
tokens.set(i, new JavaScriptToken(Token.STRING, tv));
}
}
}
public StringBuffer printSymbolTree(int linebreakpos, boolean preserveAllSemiColons)
throws IOException {
offset = 0;
braceNesting = 0;
scopes.clear();
String symbol;
JavaScriptToken token;
// begin
if (tokens.size() == 0) {
StringBuffer result = new StringBuffer();
return result;
}
// end
JavaScriptToken lastToken = getToken(0);
ScriptOrFnScope currentScope;
JavaScriptIdentifier identifier;
int length = tokens.size(); // 文本的长度
StringBuffer result = new StringBuffer();
int linestartpos = 0;
enterScope(globalScope); // 将globalScope压入栈scopes中
while (offset < length) {
token = consumeToken();
symbol = token.getValue();
currentScope = getCurrentScope();
switch (token.getType()) {
case Token.GET:
case Token.SET:
lastToken = token; // 注意没有break;
case Token.NAME:
if (offset >= 2 && getToken(-2).getType() == Token.DOT
|| getToken(0).getType() == Token.OBJECTLIT) {
result.append(symbol);
} else {
identifier = getIdentifier(symbol, currentScope);
if (identifier != null) {
if (identifier.getMungedValue() != null) {
result.append(identifier.getMungedValue());
} else {
result.append(symbol);
}
if (currentScope != globalScope // 全局域中的变量可能被HTML文档使用，不需要发出警告
&& identifier.getRefcount() == 0) {
warn("标识符" + symbol + "已经声明但未使用 ", true);
}
} else {
result.append(symbol);
}
}
break;
case Token.REGEXP:
case Token.STRING:
result.append(symbol);
break;
case Token.NUMBER:
if (getToken(0).getType() == Token.DOT) {
// calling methods on int requires a leading dot so JS
// doesn't
// treat the method as the decimal component of a float
result.append('(');
result.append(symbol);
result.append(')');
} else {
result.append(symbol);
}
break;
case Token.ADD:
case Token.SUB:
result.append(literals.get(new Integer(token.getType())));
if (offset < length) {
token = getToken(0);
if (token.getType() == Token.INC
|| token.getType() == Token.DEC
|| token.getType() == Token.ADD
|| token.getType() == Token.DEC) {
// Handle the case x +/- ++/-- y
// We must keep a white space here. Otherwise, x +++ y
// would be
// interpreted as x ++ + y by the compiler, which is a
// bug (due
// to the implicit(隐式的) assignment being done on the
// wrong variable)
result.append(' ');
} else if (token.getType() == Token.POS && getToken(-1).getType() == Token.ADD
|| token.getType() == Token.NEG && getToken(-1).getType() == Token.SUB) {
// Handle the case x + + y and x - - y
result.append(' ');
}
}
break;
case Token.FUNCTION:
if (lastToken.getType() != Token.GET && lastToken.getType() != Token.SET) {
result.append("function");
}
lastToken = token;
token = consumeToken();
if (token.getType() == Token.NAME) {
result.append(' ');
symbol = token.getValue();
identifier = getIdentifier(symbol, currentScope);
assert identifier != null;
if (identifier.getMungedValue() != null) {
result.append(identifier.getMungedValue());
} else {
result.append(symbol);
}
if (currentScope != globalScope && identifier.getRefcount() == 0) {
warn("标识符" + symbol + "已经声明但未使用", true);
}
token = consumeToken();
}
assert token.getType() == Token.LP;
result.append('(');
currentScope = indexedScopes.get(new Integer(offset)); // 根据左圆括号的下一个索引映射得到函数作用域
enterScope(currentScope);
while ((token = consumeToken()).getType() != Token.RP) {
assert token.getType() == Token.NAME || token.getType() == Token.COMMA;
if (token.getType() == Token.NAME) {
symbol = token.getValue();
identifier = getIdentifier(symbol, currentScope);
assert identifier != null;
if (identifier.getMungedValue() != null) {
result.append(identifier.getMungedValue());
} else {
result.append(symbol);
}
} else if (token.getType() == Token.COMMA) {
result.append(',');
}
}
result.append(')');
token = consumeToken(); // 得到左花括号
assert token.getType() == Token.LC;
result.append("{"); // nomodify
braceNesting++;
token = getToken(0);
if (token.getType() == Token.STRING && getToken(1).getType() == Token.SEMI) {
// This is a hint. Skip it!
consumeToken();
consumeToken();
}
break;
case Token.RETURN:
case Token.TYPEOF:
result.append(literals.get(new Integer(token.getType())));
// No space needed after 'return' and 'typeof' when followed
// by '(', '[', '{', a string or a regexp.
if (offset < length) {
token = getToken(0);
if (token.getType() != Token.LP
&& token.getType() != Token.LB
&& token.getType() != Token.LC
&& token.getType() != Token.STRING
&& token.getType() != Token.REGEXP
&& token.getType() != Token.SEMI) {
result.append(' ');
}
}
break;
case Token.CASE:
case Token.THROW:
result.append(literals.get(new Integer(token.getType())));
// White-space needed after 'case' and 'throw' when not followed
// by a string.
if (offset < length && getToken(0).getType() != Token.STRING) {
result.append(' ');
}
break;
case Token.BREAK:
case Token.CONTINUE:
result.append(literals.get(new Integer(token.getType())));
if (offset < length && getToken(0).getType() != Token.SEMI) {
// If 'break' or 'continue' is not followed by a
// semi-colon（分号）, it must
// be followed by a label, hence(因此) the need for a white
// space.
result.append(' ');
}
break;
case Token.LC:
result.append("{"); // nomodify
braceNesting++;
break;
case Token.RC:
result.append('}');
braceNesting--;
assert braceNesting >= currentScope.getBraceNesting();
if (braceNesting == currentScope.getBraceNesting()) {
leaveCurrentScope();
}
break;
case Token.SEMI:
// No need to output a semi-colon if the next character is a
// right-curly...
if (preserveAllSemiColons || offset < length && getToken(0).getType() != Token.RC) {
result.append(';');
}
if (linebreakpos >= 0 && result.length() - linestartpos > linebreakpos) {
// Some source control tools don't like it when files
// containing lines longer
// than, say 8000 characters, are checked in. The linebreak
// option is used in
// that case to split long lines after a specific column.
result.append('\n');
linestartpos = result.length();
}
break;
case Token.COMMA:
// No need to output a comma if the next character is a
// right-curly or a right-square bracket
if (offset < length
&& getToken(0).getType() != Token.RC
&& getToken(0).getType() != Token.RB) {
result.append(',');
}
break;
case Token.CONDCOMMENT:
case Token.KEEPCOMMENT:
if (result.length() > 0 && result.charAt(result.length() - 1) != '\n') {
result.append("\n");
}
result.append("/*");
if (token.getType() == Token.KEEPCOMMENT) {
result.append("!");
}
result.append(symbol);
result.append("*/\n");
break;
// begin--这个分支用于实现压扁控制流
// 此分支将if(expression){...}else if(expression){...}else{...}转化为
// switch(expression){case true:原if块;break;case false:原else块;break;}
case Token.IF:
if (!EditOptionPanel.checkBoxFlatten.isSelected()) {
result.append(symbol);
break;
}
FlattenIF flattenIF = new FlattenIF(offset, length, tokens, currentScope);
String switchBlock = flattenIF.flattenIF();
result.append(switchBlock);
offset = flattenIF.offset;
break;
case Token.WHILE:
if (!EditOptionPanel.checkBoxOpacity.isSelected()) {
result.append(symbol);
break;
}
result.append(symbol);
OpacityPredicate opacityPredicateWhile =
new OpacityPredicate(offset, tokens, currentScope);
String whileBlock = opacityPredicateWhile.opacityPredicateWhile();
result.append(whileBlock);
offset = opacityPredicateWhile.offset;
break;
case Token.DO:
if (!EditOptionPanel.checkBoxOpacity.isSelected()) {
result.append(symbol);
break;
}
result.append(symbol);
OpacityPredicate opacityPredicateDoWhile =
new OpacityPredicate(offset, tokens, currentScope);
String doWhileBlock = opacityPredicateDoWhile.opacityPredicateDoWhile();
result.append(doWhileBlock);
offset = opacityPredicateDoWhile.offset;
break;
// end
default:
String literal = literals.get(new Integer(token.getType()));
if (literal != null) {
result.append(literal);
} else {
warn("此标志符不能被打印出来：" + symbol, true);
}
break;
}
}
// Append a semi-colon at the end, even if unnecessary semi-colons are
// supposed to be removed. This is especially useful when concatenating
// several minified files (the absence of an ending semi-colon at the
// end of one file may very likely cause a syntax error)
/*if (!preserveAllSemiColons && result.length() > 0
&& getToken(-1).getType() != Token.CONDCOMMENT
&& getToken(-1).getType() != Token.KEEPCOMMENT) {
if (result.charAt(result.length() - 1) == '\n') {
result.setCharAt(result.length() - 1, ';');
} else {
result.append(';');
}
}*/
// 暂时用不上，注释掉
return result;
}
