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process code with implicit return statement (#1522)

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Bookmarklet for instance implicitedly assumes a "completion value" without using `return`.
The `expression` option now supports such use cases.
Optimisations on IIFEs also enhanced.

fixes #354
fixes #543
fixes #625
fixes #628
fixes #640
closes #1293
This commit is contained in:
Alex Lam S.L
2017-03-03 18:13:07 +08:00
committed by GitHub
parent 18059cc94f
commit 07accd2fbb
8 changed files with 485 additions and 32 deletions
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3
README.md
View File

@@ -426,6 +426,9 @@ to set `true`; it's effectively a shortcut for `foo=true`).
such as `console.info` and/or retain side effects from function arguments
after dropping the function call then use `pure_funcs` instead.
- `expression` -- default `false`. Pass `true` to preserve completion values
from terminal statements without `return`, e.g. in bookmarklets.
- `keep_fargs` -- default `true`. Prevents the
compressor from discarding unused function arguments. You need this
for code which relies on `Function.length`.

90
lib/compress.js
View File

@@ -80,6 +80,7 @@ function Compressor(options, false_by_default) {
screw_ie8 : true,
drop_console : false,
angular : false,
expression : false,
warnings : true,
global_defs : {},
passes : 1,
@@ -116,12 +117,18 @@ Compressor.prototype = new TreeTransformer;
merge(Compressor.prototype, {
option: function(key) { return this.options[key] },
compress: function(node) {
if (this.option("expression")) {
node = node.process_expression(true);
}
var passes = +this.options.passes || 1;
for (var pass = 0; pass < passes && pass < 3; ++pass) {
if (pass > 0 || this.option("reduce_vars"))
node.reset_opt_flags(this, true);
node = node.transform(this);
}
if (this.option("expression")) {
node = node.process_expression(false);
}
return node;
},
warn: function(text, props) {
@@ -178,6 +185,42 @@ merge(Compressor.prototype, {
return this.print_to_string() == node.print_to_string();
});
AST_Node.DEFMETHOD("process_expression", function(insert) {
var self = this;
var tt = new TreeTransformer(function(node) {
if (insert && node instanceof AST_SimpleStatement) {
return make_node(AST_Return, node, {
value: node.body
});
}
if (!insert && node instanceof AST_Return) {
return make_node(AST_SimpleStatement, node, {
body: node.value || make_node(AST_Undefined, node)
});
}
if (node instanceof AST_Lambda && node !== self) {
return node;
}
if (node instanceof AST_Block) {
var index = node.body.length - 1;
if (index >= 0) {
node.body[index] = node.body[index].transform(tt);
}
}
if (node instanceof AST_If) {
node.body = node.body.transform(tt);
if (node.alternative) {
node.alternative = node.alternative.transform(tt);
}
}
if (node instanceof AST_With) {
node.body = node.body.transform(tt);
}
return node;
});
return self.transform(tt);
});
AST_Node.DEFMETHOD("reset_opt_flags", function(compressor, rescan){
var reduce_vars = rescan && compressor.option("reduce_vars");
var safe_ids = [];
@@ -2030,7 +2073,14 @@ merge(Compressor.prototype, {
def(AST_Constant, return_null);
def(AST_This, return_null);
def(AST_Call, function(compressor, first_in_statement){
if (!this.has_pure_annotation(compressor) && compressor.pure_funcs(this)) return this;
if (!this.has_pure_annotation(compressor) && compressor.pure_funcs(this)) {
if (this.expression instanceof AST_Function) {
var node = this.clone();
node.expression = node.expression.process_expression(false);
return node;
}
return this;
}
if (this.pure) {
compressor.warn("Dropping __PURE__ call [{file}:{line},{col}]", this.start);
this.pure.value = this.pure.value.replace(/[@#]__PURE__/g, ' ');
@@ -2522,12 +2572,13 @@ merge(Compressor.prototype, {
});
OPT(AST_Call, function(self, compressor){
var exp = self.expression;
if (compressor.option("unused")
&& self.expression instanceof AST_Function
&& !self.expression.uses_arguments
&& !self.expression.uses_eval
&& self.args.length > self.expression.argnames.length) {
var end = self.expression.argnames.length;
&& exp instanceof AST_Function
&& !exp.uses_arguments
&& !exp.uses_eval
&& self.args.length > exp.argnames.length) {
var end = exp.argnames.length;
for (var i = end, len = self.args.length; i < len; i++) {
var node = self.args[i].drop_side_effect_free(compressor);
if (node) {
@@ -2537,7 +2588,6 @@ merge(Compressor.prototype, {
self.args.length = end;
}
if (compressor.option("unsafe")) {
var exp = self.expression;
if (exp instanceof AST_SymbolRef && exp.undeclared()) {
switch (exp.name) {
case "Array":
@@ -2711,16 +2761,22 @@ merge(Compressor.prototype, {
return best_of(self, node);
}
}
if (compressor.option("side_effects")) {
if (self.expression instanceof AST_Function
&& self.args.length == 0
&& !AST_Block.prototype.has_side_effects.call(self.expression, compressor)) {
return make_node(AST_Undefined, self).transform(compressor);
if (exp instanceof AST_Function) {
if (exp.body[0] instanceof AST_Return
&& exp.body[0].value.is_constant()) {
var args = self.args.concat(exp.body[0].value);
return AST_Seq.from_array(args).transform(compressor);
}
if (compressor.option("side_effects")) {
if (!AST_Block.prototype.has_side_effects.call(exp, compressor)) {
var args = self.args.concat(make_node(AST_Undefined, self));
return AST_Seq.from_array(args).transform(compressor);
}
}
}
if (compressor.option("drop_console")) {
if (self.expression instanceof AST_PropAccess) {
var name = self.expression.expression;
if (exp instanceof AST_PropAccess) {
var name = exp.expression;
while (name.expression) {
name = name.expression;
}
@@ -2731,12 +2787,6 @@ merge(Compressor.prototype, {
}
}
}
if (self.args.length == 0
&& self.expression instanceof AST_Function
&& self.expression.body[0] instanceof AST_Return
&& self.expression.body[0].value.is_constant()) {
return self.expression.body[0].value;
}
if (compressor.option("negate_iife")
&& compressor.parent() instanceof AST_SimpleStatement
&& is_iife_call(self)) {

2
test/compress/drop-unused.js
View File

@@ -632,7 +632,7 @@ iife: {
}
expect: {
function f() {
~function() {}(b);
b;
}
}
}

8
test/compress/evaluate.js
View File

@@ -640,9 +640,7 @@ call_args: {
expect: {
const a = 1;
console.log(1);
+function(a) {
return 1;
}(1);
+(1, 1);
}
}
@@ -663,9 +661,7 @@ call_args_drop_param: {
expect: {
const a = 1;
console.log(1);
+function() {
return 1;
}(b);
+(b, 1);
}
}

8
test/compress/functions.js
View File

@@ -35,9 +35,9 @@ iifes_returning_constants_keep_fargs_true: {
console.log("okay");
console.log(123);
console.log(void 0);
console.log(function(x,y,z){return 2}(1,2,3));
console.log(function(x,y){return 6}(2,3));
console.log(function(x, y){return 6}(2,3,a(),b()));
console.log(2);
console.log(6);
console.log((a(), b(), 6));
}
}
@@ -71,6 +71,6 @@ iifes_returning_constants_keep_fargs_false: {
console.log(void 0);
console.log(2);
console.log(6);
console.log(function(){return 6}(a(),b()));
console.log((a(), b(), 6));
}
}

317
test/compress/issue-640.js Normal file
View File

@@ -0,0 +1,317 @@
cond_5: {
options = {
conditionals: true,
expression: true,
}
input: {
if (some_condition()) {
if (some_other_condition()) {
do_something();
} else {
alternate();
}
} else {
alternate();
}
if (some_condition()) {
if (some_other_condition()) {
do_something();
}
}
}
expect: {
some_condition() && some_other_condition() ? do_something() : alternate();
if (some_condition() && some_other_condition()) do_something();
}
}
dead_code_const_annotation_regex: {
options = {
booleans : true,
conditionals : true,
dead_code : true,
evaluate : true,
expression : true,
loops : true,
}
input: {
var unused;
// @constraint this shouldn't be a constant
var CONST_FOO_ANN = false;
if (CONST_FOO_ANN) {
console.log("reachable");
}
}
expect: {
var unused;
var CONST_FOO_ANN = !1;
if (CONST_FOO_ANN) console.log('reachable');
}
}
drop_console_2: {
options = {
drop_console: true,
expression: true,
}
input: {
console.log('foo');
console.log.apply(console, arguments);
}
expect: {
// with regular compression these will be stripped out as well
void 0;
void 0;
}
}
drop_value: {
options = {
expression: true,
side_effects: true,
}
input: {
(1, [2, foo()], 3, {a:1, b:bar()});
}
expect: {
foo(), {a:1, b:bar()};
}
}
wrongly_optimized: {
options = {
conditionals: true,
booleans: true,
evaluate: true,
expression: true,
}
input: {
function func() {
foo();
}
if (func() || true) {
bar();
}
}
expect: {
function func() {
foo();
}
// TODO: optimize to `func(), bar()`
if (func(), !0) bar();
}
}
negate_iife_1: {
options = {
expression: true,
negate_iife: true,
}
input: {
(function(){ stuff() })();
}
expect: {
(function(){ stuff() })();
}
}
negate_iife_3: {
options = {
conditionals: true,
expression: true,
negate_iife: true,
}
input: {
(function(){ return t })() ? console.log(true) : console.log(false);
}
expect: {
(function(){ return t })() ? console.log(true) : console.log(false);
}
}
negate_iife_3_off: {
options = {
conditionals: true,
expression: true,
negate_iife: false,
}
input: {
(function(){ return t })() ? console.log(true) : console.log(false);
}
expect: {
(function(){ return t })() ? console.log(true) : console.log(false);
}
}
negate_iife_4: {
options = {
conditionals: true,
expression: true,
negate_iife: true,
sequences: true,
}
input: {
(function(){ return t })() ? console.log(true) : console.log(false);
(function(){
console.log("something");
})();
}
expect: {
(function(){ return t })() ? console.log(true) : console.log(false), function(){
console.log("something");
}();
}
}
negate_iife_5: {
options = {
conditionals: true,
expression: true,
negate_iife: true,
sequences: true,
}
input: {
if ((function(){ return t })()) {
foo(true);
} else {
bar(false);
}
(function(){
console.log("something");
})();
}
expect: {
(function(){ return t })() ? foo(true) : bar(false), function(){
console.log("something");
}();
}
}
negate_iife_5_off: {
options = {
conditionals: true,
expression: true,
negate_iife: false,
sequences: true,
};
input: {
if ((function(){ return t })()) {
foo(true);
} else {
bar(false);
}
(function(){
console.log("something");
})();
}
expect: {
(function(){ return t })() ? foo(true) : bar(false), function(){
console.log("something");
}();
}
}
issue_1254_negate_iife_true: {
options = {
expression: true,
negate_iife: true,
}
input: {
(function() {
return function() {
console.log('test')
};
})()();
}
expect_exact: '(function(){return function(){console.log("test")}})()();'
}
issue_1254_negate_iife_nested: {
options = {
expression: true,
negate_iife: true,
}
input: {
(function() {
return function() {
console.log('test')
};
})()()()()();
}
expect_exact: '(function(){return function(){console.log("test")}})()()()()();'
}
conditional: {
options = {
expression: true,
pure_funcs: [ "pure" ],
side_effects: true,
}
input: {
pure(1 | a() ? 2 & b() : 7 ^ c());
pure(1 | a() ? 2 & b() : 5);
pure(1 | a() ? 4 : 7 ^ c());
pure(1 | a() ? 4 : 5);
pure(3 ? 2 & b() : 7 ^ c());
pure(3 ? 2 & b() : 5);
pure(3 ? 4 : 7 ^ c());
pure(3 ? 4 : 5);
}
expect: {
1 | a() ? b() : c();
1 | a() && b();
1 | a() || c();
a();
3 ? b() : c();
3 && b();
3 || c();
pure(3 ? 4 : 5);
}
}
limit_1: {
options = {
expression: true,
sequences: 3,
}
input: {
a;
b;
c;
d;
e;
f;
g;
h;
i;
j;
k;
}
expect: {
// Turned into a single return statement
// so it can no longer be split into lines
a,b,c,d,e,f,g,h,i,j,k;
}
}
iife: {
options = {
expression: true,
sequences: true,
}
input: {
x = 42;
(function a() {})();
!function b() {}();
~function c() {}();
+function d() {}();
-function e() {}();
void function f() {}();
typeof function g() {}();
}
expect: {
x = 42, function a() {}(), function b() {}(), function c() {}(),
function d() {}(), function e() {}(), function f() {}(), typeof function g() {}();
}
}

87
test/compress/negate-iife.js
View File

@@ -32,6 +32,19 @@ negate_iife_2: {
}
}
negate_iife_2_side_effects: {
options = {
negate_iife: true,
side_effects: true,
}
input: {
(function(){ return {} })().x = 10; // should not transform this one
}
expect: {
(function(){ return {} })().x = 10;
}
}
negate_iife_3: {
options = {
negate_iife: true,
@@ -45,6 +58,34 @@ negate_iife_3: {
}
}
negate_iife_3_evaluate: {
options = {
conditionals: true,
evaluate: true,
negate_iife: true,
}
input: {
(function(){ return true })() ? console.log(true) : console.log(false);
}
expect: {
console.log(true);
}
}
negate_iife_3_side_effects: {
options = {
conditionals: true,
negate_iife: true,
side_effects: true,
}
input: {
(function(){ return t })() ? console.log(true) : console.log(false);
}
expect: {
!function(){ return t }() ? console.log(false) : console.log(true);
}
}
negate_iife_3_off: {
options = {
negate_iife: false,
@@ -58,6 +99,20 @@ negate_iife_3_off: {
}
}
negate_iife_3_off_evaluate: {
options = {
conditionals: true,
evaluate: true,
negate_iife: false,
}
input: {
(function(){ return true })() ? console.log(true) : console.log(false);
}
expect: {
console.log(true);
}
}
negate_iife_4: {
options = {
negate_iife: true,
@@ -320,3 +375,35 @@ issue_1288: {
}(0);
}
}
issue_1288_side_effects: {
options = {
conditionals: true,
negate_iife: true,
side_effects: true,
}
input: {
if (w) ;
else {
(function f() {})();
}
if (!x) {
(function() {
x = {};
})();
}
if (y)
(function() {})();
else
(function(z) {
return z;
})(0);
}
expect: {
w;
x || function() {
x = {};
}();
y;
}
}

2
test/compress/sequences.js
View File

@@ -248,6 +248,6 @@ iife: {
}
expect: {
x = 42, function a() {}(), function b() {}(), function c() {}(),
function d() {}(), function e() {}(), function f() {}(), function g() {}()
function d() {}(), function e() {}(), function f() {}(), function g() {}();
}
}