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enhance collapse_vars (#3621)
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@alexlamsl
alexlamsl committed Dec 2, 2019
1 parent bef856a commit 500e31e
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Showing 2 changed files with 88 additions and 22 deletions.
93 changes: 71 additions & 22 deletions lib/compress.js
View file
Expand Up @@ -1124,7 +1124,7 @@ merge(Compressor.prototype, {
hit_index++;
if (hit_index < hit_stack.length) return handle_custom_scan_order(node);
hit = true;
stop_after = find_stop(node, 0);
stop_after = (value_def ? find_stop_value : find_stop)(node, 0);
if (stop_after === node) abort = true;
return node;
}
Expand Down Expand Up @@ -1540,46 +1540,95 @@ merge(Compressor.prototype, {

function find_stop(node, level) {
var parent = scanner.parent(level);
if (parent instanceof AST_Array) return value_def ? find_stop(parent, level + 1) : node;
if (parent instanceof AST_Array) return node;
if (parent instanceof AST_Assign) return node;
if (parent instanceof AST_Binary) return node;
if (parent instanceof AST_Call) return node;
if (parent instanceof AST_Case) return node;
if (parent instanceof AST_Conditional) return node;
if (parent instanceof AST_Definitions) return find_stop_unused(parent, level + 1);
if (parent instanceof AST_Exit) return node;
if (parent instanceof AST_If) return node;
if (parent instanceof AST_IterationStatement) return node;
if (parent instanceof AST_ObjectKeyVal) return node;
if (parent instanceof AST_PropAccess) return node;
if (parent instanceof AST_Sequence) {
return (parent.tail_node() === node ? find_stop : find_stop_unused)(parent, level + 1);
}
if (parent instanceof AST_SimpleStatement) return find_stop_unused(parent, level + 1);
if (parent instanceof AST_Switch) return node;
if (parent instanceof AST_Unary) return node;
if (parent instanceof AST_VarDef) return node;
return null;
}

function find_stop_value(node, level) {
var parent = scanner.parent(level);
if (parent instanceof AST_Array) return find_stop_value(parent, level + 1);
if (parent instanceof AST_Assign) {
if (!value_def) return node;
if (lhs.equivalent_to(parent.left)) return node;
if (get_rvalue(candidate).equivalent_to(parent.left)) return node;
return find_stop(parent, level + 1);
if (parent.left instanceof AST_SymbolRef) {
var name = parent.left.name;
if (lhs.name == name) return node;
if (value_def.name == name) return node;
}
return find_stop_value(parent, level + 1);
}
if (parent instanceof AST_Binary) {
if (!value_def) return node;
if (lazy_op[parent.operator] && parent.left !== node) {
var grandparent = scanner.parent(level + 1);
if (!(grandparent instanceof AST_Binary)) return node;
if (grandparent.operator != parent.operator) return node;
}
return find_stop(parent, level + 1);
return find_stop_value(parent, level + 1);
}
if (parent instanceof AST_Call) return parent;
if (parent instanceof AST_Case) {
if (parent.expression !== node) return node;
return find_stop_value(parent, level + 1);
}
if (parent instanceof AST_Call) return value_def ? parent : node;
if (parent instanceof AST_Case) return node;
if (parent instanceof AST_Conditional) {
if (!value_def || parent.condition !== node) return node;
return find_stop(parent, level + 1);
if (parent.condition !== node) return node;
return find_stop_value(parent, level + 1);
}
if (parent instanceof AST_Definitions) return find_stop_unused(parent, level + 1);
if (parent instanceof AST_Exit) return node;
if (parent instanceof AST_If) return node;
if (parent instanceof AST_IterationStatement) return node;
if (parent instanceof AST_ObjectKeyVal) {
return value_def ? find_stop(scanner.parent(level + 1), level + 2) : node;
if (parent instanceof AST_Do) return node;
if (parent instanceof AST_Exit) return find_stop_unused(parent, level + 1);
if (parent instanceof AST_For) {
if (parent.init !== node && parent.condition !== node) return node;
return find_stop_value(parent, level + 1);
}
if (parent instanceof AST_PropAccess) return node;
if (parent instanceof AST_ForIn) {
if (parent.init !== node) return node;
return find_stop_value(parent, level + 1);
}
if (parent instanceof AST_If) {
if (parent.condition !== node) return node;
return find_stop_value(parent, level + 1);
}
if (parent instanceof AST_ObjectKeyVal) return find_stop_value(scanner.parent(level + 1), level + 2);
if (parent instanceof AST_PropAccess) return find_stop_value(parent, level + 1);
if (parent instanceof AST_Sequence) {
return (parent.tail_node() === node ? find_stop : find_stop_unused)(parent, level + 1);
return (parent.tail_node() === node ? find_stop_value : find_stop_unused)(parent, level + 1);
}
if (parent instanceof AST_SimpleStatement) return find_stop_unused(parent, level + 1);
if (parent instanceof AST_Switch) return node;
if (parent instanceof AST_Switch) {
if (parent.expression !== node) return node;
return find_stop_value(parent, level + 1);
}
if (parent instanceof AST_Unary) {
if (parent.operator == "delete") return node;
return value_def ? find_stop(parent, level + 1) : node;
return find_stop_value(parent, level + 1);
}
if (parent instanceof AST_VarDef) {
var name = parent.name.name;
if (lhs.name == name) return node;
if (value_def.name == name) return node;
return find_stop_value(parent, level + 1);
}
if (parent instanceof AST_While) {
if (parent.condition !== node) return node;
return find_stop_value(parent, level + 1);
}
if (parent instanceof AST_VarDef) return node;
return null;
}

Expand Down
17 changes: 17 additions & 0 deletions test/compress/collapse_vars.js
View file
Expand Up @@ -2578,6 +2578,23 @@ chained_3: {
expect_stdout: "2"
}

chained_4: {
options = {
collapse_vars: true,
}
input: {
var a = "foo", b = 42;
var b = void (b = a);
console.log(a, b);
}
expect: {
var a = "foo", b = 42;
var b = void (b = a);
console.log(a, b);
}
expect_stdout: "foo undefined"
}

boolean_binary_1: {
options = {
collapse_vars: true,
Expand Down

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