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process.js
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process.js
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/***********************************************************************
A JavaScript tokenizer / parser / beautifier / compressor.
This version is suitable for Node.js. With minimal changes (the
exports stuff) it should work on any JS platform.
This file implements some AST processors. They work on data built
by parse-js.
Exported functions:
- ast_mangle(ast, options) -- mangles the variable/function names
in the AST. Returns an AST.
- ast_squeeze(ast) -- employs various optimizations to make the
final generated code even smaller. Returns an AST.
- gen_code(ast, options) -- generates JS code from the AST. Pass
true (or an object, see the code for some options) as second
argument to get "pretty" (indented) code.
-------------------------------- (C) ---------------------------------
Author: Mihai Bazon
http://mihai.bazon.net/blog
Distributed under the BSD license:
Copyright 2010 (c) Mihai Bazon <[email protected]>
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
* Redistributions of source code must retain the above
copyright notice, this list of conditions and the following
disclaimer.
* Redistributions in binary form must reproduce the above
copyright notice, this list of conditions and the following
disclaimer in the documentation and/or other materials
provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER “AS IS” AND ANY
EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
SUCH DAMAGE.
***********************************************************************/
var jsp = require("./parse-js"),
slice = jsp.slice,
member = jsp.member,
PRECEDENCE = jsp.PRECEDENCE,
OPERATORS = jsp.OPERATORS;
function NodeWithLine(str, line) {
this.str = str;
this.line = line;
}
NodeWithLine.prototype = new String();
NodeWithLine.prototype.toString = function() { return this.str; }
NodeWithLine.prototype.valueOf = function() { return this.str; }
NodeWithLine.prototype.lineComment = function() { return " //@line " + this.line; }
// XXX ugly hack
String.prototype.lineComment = function() { return ""; }
/* -----[ helper for AST traversal ]----- */
function ast_walker() {
function _vardefs(defs) {
return [ this[0], MAP(defs, function(def){
var a = [ def[0] ];
if (def.length > 1)
a[1] = walk(def[1]);
return a;
}) ];
};
function _block(statements) {
var out = [ this[0] ];
if (statements != null)
out.push(MAP(statements, walk));
return out;
};
var walkers = {
"string": function(str) {
return [ this[0], str ];
},
"num": function(num) {
return [ this[0], num ];
},
"name": function(name) {
return [ this[0], name ];
},
"toplevel": function(statements) {
return [ this[0], MAP(statements, walk) ];
},
"block": _block,
"splice": _block,
"var": _vardefs,
"const": _vardefs,
"try": function(t, c, f) {
return [
this[0],
MAP(t, walk),
c != null ? [ c[0], MAP(c[1], walk) ] : null,
f != null ? MAP(f, walk) : null
];
},
"throw": function(expr) {
return [ this[0], walk(expr) ];
},
"new": function(ctor, args) {
return [ this[0], walk(ctor), MAP(args, walk) ];
},
"switch": function(expr, body) {
return [ this[0], walk(expr), MAP(body, function(branch){
return [ branch[0] ? walk(branch[0]) : null,
MAP(branch[1], walk) ];
}) ];
},
"break": function(label) {
return [ this[0], label ];
},
"continue": function(label) {
return [ this[0], label ];
},
"conditional": function(cond, t, e) {
return [ this[0], walk(cond), walk(t), walk(e) ];
},
"assign": function(op, lvalue, rvalue) {
return [ this[0], op, walk(lvalue), walk(rvalue) ];
},
"dot": function(expr) {
return [ this[0], walk(expr) ].concat(slice(arguments, 1));
},
"call": function(expr, args) {
return [ this[0], walk(expr), MAP(args, walk) ];
},
"function": function(name, args, body) {
return [ this[0], name, args.slice(), MAP(body, walk) ];
},
"defun": function(name, args, body) {
return [ this[0], name, args.slice(), MAP(body, walk) ];
},
"if": function(conditional, t, e) {
return [ this[0], walk(conditional), walk(t), walk(e) ];
},
"for": function(init, cond, step, block) {
return [ this[0], walk(init), walk(cond), walk(step), walk(block) ];
},
"for-in": function(vvar, key, hash, block) {
return [ this[0], walk(vvar), walk(key), walk(hash), walk(block) ];
},
"while": function(cond, block) {
return [ this[0], walk(cond), walk(block) ];
},
"do": function(cond, block) {
return [ this[0], walk(cond), walk(block) ];
},
"return": function(expr) {
return [ this[0], walk(expr) ];
},
"binary": function(op, left, right) {
return [ this[0], op, walk(left), walk(right) ];
},
"unary-prefix": function(op, expr) {
return [ this[0], op, walk(expr) ];
},
"unary-postfix": function(op, expr) {
return [ this[0], op, walk(expr) ];
},
"sub": function(expr, subscript) {
return [ this[0], walk(expr), walk(subscript) ];
},
"object": function(props) {
return [ this[0], MAP(props, function(p){
return p.length == 2
? [ p[0], walk(p[1]) ]
: [ p[0], walk(p[1]), p[2] ]; // get/set-ter
}) ];
},
"regexp": function(rx, mods) {
return [ this[0], rx, mods ];
},
"array": function(elements) {
return [ this[0], MAP(elements, walk) ];
},
"stat": function(stat) {
return [ this[0], walk(stat) ];
},
"seq": function() {
return [ this[0] ].concat(MAP(slice(arguments), walk));
},
"label": function(name, block) {
return [ this[0], name, walk(block) ];
},
"with": function(expr, block) {
return [ this[0], walk(expr), walk(block) ];
},
"atom": function(name) {
return [ this[0], name ];
}
};
var user = {};
var stack = [];
function walk(ast) {
if (ast == null)
return null;
try {
stack.push(ast);
var type = ast[0];
var gen = user[type];
if (gen) {
var ret = gen.apply(ast, ast.slice(1));
if (ret != null)
return ret;
}
gen = walkers[type];
return gen.apply(ast, ast.slice(1));
} finally {
stack.pop();
}
};
function with_walkers(walkers, cont){
var save = {}, i;
for (i in walkers) if (HOP(walkers, i)) {
save[i] = user[i];
user[i] = walkers[i];
}
var ret = cont();
for (i in save) if (HOP(save, i)) {
if (!save[i]) delete user[i];
else user[i] = save[i];
}
return ret;
};
return {
walk: walk,
with_walkers: with_walkers,
parent: function() {
return stack[stack.length - 2]; // last one is current node
},
stack: function() {
return stack;
}
};
};
/* -----[ Scope and mangling ]----- */
function Scope(parent) {
this.names = {}; // names defined in this scope
this.mangled = {}; // mangled names (orig.name => mangled)
this.rev_mangled = {}; // reverse lookup (mangled => orig.name)
this.cname = -1; // current mangled name
this.refs = {}; // names referenced from this scope
this.uses_with = false; // will become TRUE if with() is detected in this or any subscopes
this.uses_eval = false; // will become TRUE if eval() is detected in this or any subscopes
this.parent = parent; // parent scope
this.children = []; // sub-scopes
if (parent) {
this.level = parent.level + 1;
parent.children.push(this);
} else {
this.level = 0;
}
};
var base54 = (function(){
var DIGITS = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ$_";
return function(num) {
var ret = "";
do {
ret = DIGITS.charAt(num % 54) + ret;
num = Math.floor(num / 54);
} while (num > 0);
return ret;
};
})();
Scope.prototype = {
has: function(name) {
for (var s = this; s; s = s.parent)
if (HOP(s.names, name))
return s;
},
has_mangled: function(mname) {
for (var s = this; s; s = s.parent)
if (HOP(s.rev_mangled, mname))
return s;
},
toJSON: function() {
return {
names: this.names,
uses_eval: this.uses_eval,
uses_with: this.uses_with
};
},
next_mangled: function() {
// we must be careful that the new mangled name:
//
// 1. doesn't shadow a mangled name from a parent
// scope, unless we don't reference the original
// name from this scope OR from any sub-scopes!
// This will get slow.
//
// 2. doesn't shadow an original name from a parent
// scope, in the event that the name is not mangled
// in the parent scope and we reference that name
// here OR IN ANY SUBSCOPES!
//
// 3. doesn't shadow a name that is referenced but not
// defined (possibly global defined elsewhere).
for (;;) {
var m = base54(++this.cname), prior;
// case 1.
prior = this.has_mangled(m);
if (prior && this.refs[prior.rev_mangled[m]] === prior)
continue;
// case 2.
prior = this.has(m);
if (prior && prior !== this && this.refs[m] === prior && !prior.has_mangled(m))
continue;
// case 3.
if (HOP(this.refs, m) && this.refs[m] == null)
continue;
// I got "do" once. :-/
if (!is_identifier(m))
continue;
return m;
}
},
set_mangle: function(name, m) {
this.rev_mangled[m] = name;
return this.mangled[name] = m;
},
get_mangled: function(name, newMangle) {
if (this.uses_eval || this.uses_with) return name; // no mangle if eval or with is in use
var s = this.has(name);
if (!s) return name; // not in visible scope, no mangle
if (HOP(s.mangled, name)) return s.mangled[name]; // already mangled in this scope
if (!newMangle) return name; // not found and no mangling requested
return s.set_mangle(name, s.next_mangled());
},
references: function(name) {
return name && !this.parent || this.uses_with || this.uses_eval || this.refs[name];
},
define: function(name, type) {
if (name != null) {
if (type == "var" || !HOP(this.names, name))
this.names[name] = type || "var";
return name;
}
}
};
function ast_add_scope(ast) {
var current_scope = null;
var w = ast_walker(), walk = w.walk;
var having_eval = [];
function with_new_scope(cont) {
current_scope = new Scope(current_scope);
var ret = current_scope.body = cont();
ret.scope = current_scope;
current_scope = current_scope.parent;
return ret;
};
function define(name, type) {
return current_scope.define(name, type);
};
function reference(name) {
current_scope.refs[name] = true;
};
function _lambda(name, args, body) {
var is_defun = this[0] == "defun";
return [ this[0], is_defun ? define(name, "defun") : name, args, with_new_scope(function(){
if (!is_defun) define(name, "lambda");
MAP(args, function(name){ define(name, "arg") });
return MAP(body, walk);
})];
};
function _vardefs(type) {
return function(defs) {
MAP(defs, function(d){
define(d[0], type);
if (d[1]) reference(d[0]);
});
};
};
return with_new_scope(function(){
// process AST
var ret = w.with_walkers({
"function": _lambda,
"defun": _lambda,
"label": function(name, stat) { define(name, "label") },
"break": function(label) { if (label) reference(label) },
"continue": function(label) { if (label) reference(label) },
"with": function(expr, block) {
for (var s = current_scope; s; s = s.parent)
s.uses_with = true;
},
"var": _vardefs("var"),
"const": _vardefs("const"),
"try": function(t, c, f) {
if (c != null) return [
this[0],
MAP(t, walk),
[ define(c[0], "catch"), MAP(c[1], walk) ],
f != null ? MAP(f, walk) : null
];
},
"name": function(name) {
if (name == "eval")
having_eval.push(current_scope);
reference(name);
}
}, function(){
return walk(ast);
});
// the reason why we need an additional pass here is
// that names can be used prior to their definition.
// scopes where eval was detected and their parents
// are marked with uses_eval, unless they define the
// "eval" name.
MAP(having_eval, function(scope){
if (!scope.has("eval")) while (scope) {
scope.uses_eval = true;
scope = scope.parent;
}
});
// for referenced names it might be useful to know
// their origin scope. current_scope here is the
// toplevel one.
function fixrefs(scope, i) {
// do children first; order shouldn't matter
for (i = scope.children.length; --i >= 0;)
fixrefs(scope.children[i]);
for (i in scope.refs) if (HOP(scope.refs, i)) {
// find origin scope and propagate the reference to origin
for (var origin = scope.has(i), s = scope; s; s = s.parent) {
s.refs[i] = origin;
if (s === origin) break;
}
}
};
fixrefs(current_scope);
return ret;
});
};
/* -----[ mangle names ]----- */
function ast_mangle(ast, options) {
var w = ast_walker(), walk = w.walk, scope;
options = options || {};
function get_mangled(name, newMangle) {
if (!options.toplevel && !scope.parent) return name; // don't mangle toplevel
if (options.except && member(name, options.except))
return name;
return scope.get_mangled(name, newMangle);
};
function get_define(name) {
if (options.defines) {
// we always lookup a defined symbol for the current scope FIRST, so declared
// vars trump a DEFINE symbol, but if no such var is found, then match a DEFINE value
if (!scope.has(name)) {
if (HOP(options.defines, name)) {
return options.defines[name];
}
}
return null;
}
};
function _lambda(name, args, body) {
var is_defun = this[0] == "defun", extra;
if (name) {
if (is_defun) name = get_mangled(name);
else {
extra = {};
if (!(scope.uses_eval || scope.uses_with))
name = extra[name] = scope.next_mangled();
else
extra[name] = name;
}
}
body = with_scope(body.scope, function(){
args = MAP(args, function(name){ return get_mangled(name) });
return MAP(body, walk);
}, extra);
return [ this[0], name, args, body ];
};
function with_scope(s, cont, extra) {
var _scope = scope;
scope = s;
if (extra) for (var i in extra) if (HOP(extra, i)) {
s.set_mangle(i, extra[i]);
}
for (var i in s.names) if (HOP(s.names, i)) {
get_mangled(i, true);
}
var ret = cont();
ret.scope = s;
scope = _scope;
return ret;
};
function _vardefs(defs) {
return [ this[0], MAP(defs, function(d){
return [ get_mangled(d[0]), walk(d[1]) ];
}) ];
};
return w.with_walkers({
"function": _lambda,
"defun": function() {
// move function declarations to the top when
// they are not in some block.
var ast = _lambda.apply(this, arguments);
switch (w.parent()[0]) {
case "toplevel":
case "function":
case "defun":
return MAP.at_top(ast);
}
return ast;
},
"label": function(label, stat) { return [ this[0], get_mangled(label), walk(stat) ] },
"break": function(label) { if (label) return [ this[0], get_mangled(label) ] },
"continue": function(label) { if (label) return [ this[0], get_mangled(label) ] },
"var": _vardefs,
"const": _vardefs,
"name": function(name) {
return get_define(name) || [ this[0], get_mangled(name) ];
},
"try": function(t, c, f) {
return [ this[0],
MAP(t, walk),
c != null ? [ get_mangled(c[0]), MAP(c[1], walk) ] : null,
f != null ? MAP(f, walk) : null ];
},
"toplevel": function(body) {
var self = this;
return with_scope(self.scope, function(){
return [ self[0], MAP(body, walk) ];
});
}
}, function() {
return walk(ast_add_scope(ast));
});
};
/* -----[
- compress foo["bar"] into foo.bar,
- remove block brackets {} where possible
- join consecutive var declarations
- various optimizations for IFs:
- if (cond) foo(); else bar(); ==> cond?foo():bar();
- if (cond) foo(); ==> cond&&foo();
- if (foo) return bar(); else return baz(); ==> return foo?bar():baz(); // also for throw
- if (foo) return bar(); else something(); ==> {if(foo)return bar();something()}
]----- */
var warn = function(){};
function best_of(ast1, ast2) {
return gen_code(ast1).length > gen_code(ast2[0] == "stat" ? ast2[1] : ast2).length ? ast2 : ast1;
};
function last_stat(b) {
if (b[0] == "block" && b[1] && b[1].length > 0)
return b[1][b[1].length - 1];
return b;
}
function aborts(t) {
if (t) switch (last_stat(t)[0]) {
case "return":
case "break":
case "continue":
case "throw":
return true;
}
};
function boolean_expr(expr) {
return ( (expr[0] == "unary-prefix"
&& member(expr[1], [ "!", "delete" ])) ||
(expr[0] == "binary"
&& member(expr[1], [ "in", "instanceof", "==", "!=", "===", "!==", "<", "<=", ">=", ">" ])) ||
(expr[0] == "binary"
&& member(expr[1], [ "&&", "||" ])
&& boolean_expr(expr[2])
&& boolean_expr(expr[3])) ||
(expr[0] == "conditional"
&& boolean_expr(expr[2])
&& boolean_expr(expr[3])) ||
(expr[0] == "assign"
&& expr[1] === true
&& boolean_expr(expr[3])) ||
(expr[0] == "seq"
&& boolean_expr(expr[expr.length - 1]))
);
};
function make_conditional(c, t, e) {
var make_real_conditional = function() {
if (c[0] == "unary-prefix" && c[1] == "!") {
return e ? [ "conditional", c[2], e, t ] : [ "binary", "||", c[2], t ];
} else {
return e ? [ "conditional", c, t, e ] : [ "binary", "&&", c, t ];
}
};
// shortcut the conditional if the expression has a constant value
return when_constant(c, function(ast, val){
warn_unreachable(val ? e : t);
return (val ? t : e);
}, make_real_conditional);
};
function empty(b) {
return !b || (b[0] == "block" && (!b[1] || b[1].length == 0));
};
function is_string(node) {
return (node[0] == "string" ||
node[0] == "unary-prefix" && node[1] == "typeof" ||
node[0] == "binary" && node[1] == "+" &&
(is_string(node[2]) || is_string(node[3])));
};
var when_constant = (function(){
var $NOT_CONSTANT = {};
// this can only evaluate constant expressions. If it finds anything
// not constant, it throws $NOT_CONSTANT.
function evaluate(expr) {
switch (expr[0]) {
case "string":
case "num":
return expr[1];
case "name":
case "atom":
switch (expr[1]) {
case "true": return true;
case "false": return false;
}
break;
case "unary-prefix":
switch (expr[1]) {
case "!": return !evaluate(expr[2]);
case "typeof": return typeof evaluate(expr[2]);
case "~": return ~evaluate(expr[2]);
case "-": return -evaluate(expr[2]);
case "+": return +evaluate(expr[2]);
}
break;
case "binary":
var left = expr[2], right = expr[3];
switch (expr[1]) {
case "&&" : return evaluate(left) && evaluate(right);
case "||" : return evaluate(left) || evaluate(right);
case "|" : return evaluate(left) | evaluate(right);
case "&" : return evaluate(left) & evaluate(right);
case "^" : return evaluate(left) ^ evaluate(right);
case "+" : return evaluate(left) + evaluate(right);
case "*" : return evaluate(left) * evaluate(right);
case "/" : return evaluate(left) / evaluate(right);
case "-" : return evaluate(left) - evaluate(right);
case "<<" : return evaluate(left) << evaluate(right);
case ">>" : return evaluate(left) >> evaluate(right);
case ">>>" : return evaluate(left) >>> evaluate(right);
case "==" : return evaluate(left) == evaluate(right);
case "===" : return evaluate(left) === evaluate(right);
case "!=" : return evaluate(left) != evaluate(right);
case "!==" : return evaluate(left) !== evaluate(right);
case "<" : return evaluate(left) < evaluate(right);
case "<=" : return evaluate(left) <= evaluate(right);
case ">" : return evaluate(left) > evaluate(right);
case ">=" : return evaluate(left) >= evaluate(right);
case "in" : return evaluate(left) in evaluate(right);
case "instanceof" : return evaluate(left) instanceof evaluate(right);
}
}
throw $NOT_CONSTANT;
};
return function(expr, yes, no) {
try {
var val = evaluate(expr), ast;
switch (typeof val) {
case "string": ast = [ "string", val ]; break;
case "number": ast = [ "num", val ]; break;
case "boolean": ast = [ "name", String(val) ]; break;
default: throw new Error("Can't handle constant of type: " + (typeof val));
}
return yes.call(expr, ast, val);
} catch(ex) {
if (ex === $NOT_CONSTANT) {
if (expr[0] == "binary"
&& (expr[1] == "===" || expr[1] == "!==")
&& ((is_string(expr[2]) && is_string(expr[3]))
|| (boolean_expr(expr[2]) && boolean_expr(expr[3])))) {
expr[1] = expr[1].substr(0, 2);
}
else if (no && expr[0] == "binary"
&& (expr[1] == "||" || expr[1] == "&&")) {
// the whole expression is not constant but the lval may be...
try {
var lval = evaluate(expr[2]);
expr = ((expr[1] == "&&" && (lval ? expr[3] : lval)) ||
(expr[1] == "||" && (lval ? lval : expr[3])) ||
expr);
} catch(ex2) {
// IGNORE... lval is not constant
}
}
return no ? no.call(expr, expr) : null;
}
else throw ex;
}
};
})();
function warn_unreachable(ast) {
if (!empty(ast))
warn("Dropping unreachable code: " + gen_code(ast, true));
};
function prepare_ifs(ast) {
var w = ast_walker(), walk = w.walk;
// In this first pass, we rewrite ifs which abort with no else with an
// if-else. For example:
//
// if (x) {
// blah();
// return y;
// }
// foobar();
//
// is rewritten into:
//
// if (x) {
// blah();
// return y;
// } else {
// foobar();
// }
function redo_if(statements) {
statements = MAP(statements, walk);
for (var i = 0; i < statements.length; ++i) {
var fi = statements[i];
if (fi[0] != "if") continue;
if (fi[3] && walk(fi[3])) continue;
var t = walk(fi[2]);
if (!aborts(t)) continue;
var conditional = walk(fi[1]);
var e_body = statements.slice(i + 1);
var e = e_body.length == 1 ? e_body[0] : [ "block", e_body ];
var ret = statements.slice(0, i).concat([ [
fi[0], // "if"
conditional, // conditional
t, // then
e // else
] ]);
return redo_if(ret);
}
return statements;
};
function redo_if_lambda(name, args, body) {
body = redo_if(body);
return [ this[0], name, args, body ];
};
function redo_if_block(statements) {
return [ this[0], statements != null ? redo_if(statements) : null ];
};
return w.with_walkers({
"defun": redo_if_lambda,
"function": redo_if_lambda,
"block": redo_if_block,
"splice": redo_if_block,
"toplevel": function(statements) {
return [ this[0], redo_if(statements) ];
},
"try": function(t, c, f) {
return [
this[0],
redo_if(t),
c != null ? [ c[0], redo_if(c[1]) ] : null,
f != null ? redo_if(f) : null
];
}
}, function() {
return walk(ast);
});
};
function for_side_effects(ast, handler) {
var w = ast_walker(), walk = w.walk;
var $stop = {}, $restart = {};
function stop() { throw $stop };
function restart() { throw $restart };
function found(){ return handler.call(this, this, w, stop, restart) };
function unary(op) {
if (op == "++" || op == "--")
return found.apply(this, arguments);
};
return w.with_walkers({
"try": found,
"throw": found,
"return": found,
"new": found,
"switch": found,
"break": found,
"continue": found,
"assign": found,
"call": found,
"if": found,
"for": found,
"for-in": found,
"while": found,
"do": found,
"return": found,
"unary-prefix": unary,
"unary-postfix": unary,
"defun": found
}, function(){
while (true) try {
walk(ast);
break;
} catch(ex) {
if (ex === $stop) break;
if (ex === $restart) continue;
throw ex;
}
});
};
function ast_lift_variables(ast) {
var w = ast_walker(), walk = w.walk, scope;
function do_body(body, env) {
var _scope = scope;
scope = env;
body = MAP(body, walk);
var hash = {}, names = MAP(env.names, function(type, name){
if (type != "var") return MAP.skip;
if (!env.references(name)) return MAP.skip;
hash[name] = true;
return [ name ];
});
if (names.length > 0) {
// looking for assignments to any of these variables.
// we can save considerable space by moving the definitions
// in the var declaration.
for_side_effects([ "block", body ], function(ast, walker, stop, restart) {
if (ast[0] == "assign"
&& ast[1] === true
&& ast[2][0] == "name"
&& HOP(hash, ast[2][1])) {
// insert the definition into the var declaration
for (var i = names.length; --i >= 0;) {
if (names[i][0] == ast[2][1]) {
if (names[i][1]) // this name already defined, we must stop
stop();
names[i][1] = ast[3]; // definition
names.push(names.splice(i, 1)[0]);
break;
}
}
// remove this assignment from the AST.
var p = walker.parent();
if (p[0] == "seq") {
var a = p[2];
a.unshift(0, p.length);
p.splice.apply(p, a);
}
else if (p[0] == "stat") {
p.splice(0, p.length, "block"); // empty statement
}
else {
stop();
}
restart();
}
stop();
});
body.unshift([ "var", names ]);
}
scope = _scope;
return body;
};
function _vardefs(defs) {
var ret = null;
for (var i = defs.length; --i >= 0;) {
var d = defs[i];
if (!d[1]) continue;
d = [ "assign", true, [ "name", d[0] ], d[1] ];
if (ret == null) ret = d;
else ret = [ "seq", d, ret ];
}
if (ret == null) {
if (w.parent()[0] == "for-in")
return [ "name", defs[0][0] ];
return MAP.skip;
}
return [ "stat", ret ];
};
function _toplevel(body) {
return [ this[0], do_body(body, this.scope) ];
};
return w.with_walkers({
"function": function(name, args, body){
for (var i = args.length; --i >= 0 && !body.scope.references(args[i]);)
args.pop();
if (!body.scope.references(name)) name = null;
return [ this[0], name, args, do_body(body, body.scope) ];
},
"defun": function(name, args, body){
if (!scope.references(name)) return MAP.skip;
for (var i = args.length; --i >= 0 && !body.scope.references(args[i]);)
args.pop();
return [ this[0], name, args, do_body(body, body.scope) ];
},
"var": _vardefs,
"toplevel": _toplevel
}, function(){
return walk(ast_add_scope(ast));
});
};
function ast_squeeze(ast, options) {
options = defaults(options, {
make_seqs : true,
dead_code : true,
keep_comps : true,
no_warnings : false
});
var w = ast_walker(), walk = w.walk, scope;
function negate(c) {
var not_c = [ "unary-prefix", "!", c ];
switch (c[0]) {
case "unary-prefix":
return c[1] == "!" && boolean_expr(c[2]) ? c[2] : not_c;