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// The layout of the compressor follows the code generator (see
// output.js). Basically each node will have a "squeeze" method
// that will apply all known compression rules for that node, and
// return a new node (or the original node if there was no
// compression). We can't quite use the TreeWalker for this
// because it's too simplistic.
// The Compressor object is for storing the options and for
// maintaining various internal state that might be useful for
// squeezing nodes.
function Compressor(options) {
options = defaults(options, {
sequences : true,
dead_code : true,
keep_comps : true,
drop_debugger : true,
unsafe : true
});
var stack = [];
return {
option : function(key) { return options[key] },
push_node : function(node) { stack.push(node) },
pop_node : function() { return stack.pop() },
stack : function() { return stack },
parent : function(n) {
return stack[stack.length - 2 - (n || 0)];
}
};
};
(function(){
AST_Node.DEFMETHOD("squeeze", function(){
return this;
});
function SQUEEZE(nodetype, squeeze) {
nodetype.DEFMETHOD("squeeze", function(compressor){
compressor.push_node(this);
var new_node = squeeze(this, compressor);
compressor.pop_node();
return new_node || this;
});
};
function do_list(array, compressor) {
return MAP(array, function(node){
if (node instanceof Array) {
sys.debug(node.map(function(node){
return node.TYPE;
}).join("\n"));
}
return node.squeeze(compressor);
});
};
SQUEEZE(AST_Debugger, function(self, compressor){
if (compressor.option("drop_debugger"))
return new AST_EmptyStatement(self);
});
SQUEEZE(AST_LabeledStatement, function(self, compressor){
self = self.clone();
self.statement = self.statement.squeeze(compressor);
return self.label.references.length == 0 ? self.statement : self;
});
SQUEEZE(AST_Statement, function(self, compressor){
self = self.clone();
self.body = self.body.squeeze(compressor);
return self;
});
SQUEEZE(AST_BlockStatement, function(self, compressor){
self = self.clone();
self.body = do_list(self.body, compressor);
return self;
});
SQUEEZE(AST_EmptyStatement, function(self, compressor){
if (compressor.parent() instanceof AST_BlockStatement)
return MAP.skip;
});
SQUEEZE(AST_DWLoop, function(self, compressor){
self = self.clone();
self.condition = self.condition.squeeze(compressor);
self.body = self.body.squeeze(compressor);
return self;
});
SQUEEZE(AST_For, function(self, compressor){
self = self.clone();
if (self.init) self.init = self.init.squeeze(compressor);
if (self.condition) self.condition = self.condition.squeeze(compressor);
if (self.step) self.step = self.step.squeeze(compressor);
self.body = self.body.squeeze(compressor);
return self;
});
SQUEEZE(AST_ForIn, function(self, compressor){
self = self.clone();
self.init = self.init.squeeze(compressor);
self.object = self.object.squeeze(compressor);
self.body = self.body.squeeze(compressor);
return self;
});
SQUEEZE(AST_With, function(self, compressor){
self = self.clone();
self.expression = self.expression.squeeze(compressor);
self.body = self.body.squeeze(compressor);
});
SQUEEZE(AST_Exit, function(self, compressor){
self = self.clone();
if (self.value) self.value = self.value.squeeze(compressor);
return self;
});
SQUEEZE(AST_LoopControl, function(self, compressor){
self = self.clone();
if (self.label) self.label = self.label.squeeze(compressor);
return self;
});
SQUEEZE(AST_If, function(self, compressor){
self = self.clone();
self.condition = self.condition.squeeze(compressor);
self.consequent = self.consequent.squeeze(compressor);
if (self.alternative)
self.alternative = self.alternative.squeeze(compressor);
return self;
});
SQUEEZE(AST_Switch, function(self, compressor){
self = self.clone();
self.expression = self.expression.squeeze(compressor);
self.body = self.body.squeeze(compressor);
return self;
});
SQUEEZE(AST_Case, function(self, compressor){
self = self.clone();
self.expression = self.expression.squeeze(compressor);
self.body = do_list(self.body, compressor);
return self;
});
SQUEEZE(AST_Try, function(self, compressor){
self = self.clone();
self.btry = self.btry.squeeze(compressor);
if (self.bcatch) self.bcatch = self.bcatch.squeeze(compressor);
if (self.bfinally) self.bfinally = self.bfinally.squeeze(compressor);
return self;
});
SQUEEZE(AST_Definitions, function(self, compressor){
self = self.clone();
self.definitions = do_list(self.definitions, compressor);
return self;
});
SQUEEZE(AST_VarDef, function(self, compressor){
self = self.clone();
if (self.value) self.value = self.value.squeeze(compressor);
return self;
});
SQUEEZE(AST_Lambda, function(self, compressor){
self = self.clone();
if (self.name) self.name = self.name.squeeze(compressor);
self.argnames = do_list(self.argnames, compressor);
self.body = self.body.squeeze(compressor);
return self;
});
SQUEEZE(AST_Call, function(self, compressor){
self = self.clone();
self.expression = self.expression.squeeze(compressor);
self.args = do_list(self.args, compressor);
return self;
});
SQUEEZE(AST_Seq, function(self, compressor){
self = self.clone();
self.first = self.first.squeeze(compressor);
self.second = self.second.squeeze(compressor);
return self;
});
SQUEEZE(AST_Dot, function(self, compressor){
self = self.clone();
self.expression = self.expression.squeeze(compressor);
return self;
});
SQUEEZE(AST_Sub, function(self, compressor){
self = self.clone();
self.expression = self.expression.squeeze(compressor);
self.property = self.property.squeeze(compressor);
return self;
});
SQUEEZE(AST_Unary, function(self, compressor){
self = self.clone();
self.expression = self.expression.squeeze(compressor);
return self;
});
SQUEEZE(AST_Binary, function(self, compressor){
self = self.clone();
self.left = self.left.squeeze(compressor);
self.right = self.right.squeeze(compressor);
return self;
});
SQUEEZE(AST_Conditional, function(self, compressor){
self = self.clone();
self.condition = self.condition.squeeze(compressor);
self.consequent = self.consequent.squeeze(compressor);
self.alternative = self.alternative.squeeze(compressor);
return self;
});
SQUEEZE(AST_Array, function(self, compressor){
self = self.clone();
self.elements = do_list(self.elements, compressor);
return self;
});
SQUEEZE(AST_Object, function(self, compressor){
self = self.clone();
self.properties = do_list(self.properties, compressor);
return self;
});
SQUEEZE(AST_ObjectProperty, function(self, compressor){
self = self.clone();
self.value = self.value.squeeze(compressor);
return self;
});
})();
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