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enhance join_vars (#5162)

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This commit is contained in:
Alex Lam S.L
2021-11-02 11:33:24 +08:00
committed by GitHub
parent 6d94242318
commit 3acb5a329e
2 changed files with 130 additions and 19 deletions
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64
lib/compress.js
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@@ -3476,15 +3476,26 @@ merge(Compressor.prototype, {
var exprs = extract_exprs(body);
if (!exprs) return;
var trimmed = false;
for (var i = exprs.length - 1; --i >= 0;) {
for (var i = exprs.length; --i >= 0;) {
var expr = exprs[i];
if (!(expr instanceof AST_Assign)) continue;
if (expr.operator != "=") continue;
if (!(expr.left instanceof AST_SymbolRef)) continue;
var tail = exprs.slice(i + 1);
if (!can_trim(expr)) continue;
var tail;
if (expr.left instanceof AST_SymbolRef) {
tail = exprs.slice(i + 1);
} else if (expr.left instanceof AST_PropAccess && can_trim(expr.left.expression)) {
tail = exprs.slice(i + 1);
var flattened = expr.clone();
expr = expr.left.expression;
flattened.left = flattened.left.clone();
flattened.left.expression = expr.left.clone();
tail.unshift(flattened);
} else {
continue;
}
if (tail.length == 0) continue;
if (!trim_assigns(expr.left, expr.right, tail)) continue;
trimmed = true;
exprs = exprs.slice(0, i + 1).concat(tail);
exprs = exprs.slice(0, i).concat(expr, tail);
}
if (defn instanceof AST_Definitions) {
keep = keep || 0;
@@ -3498,6 +3509,10 @@ merge(Compressor.prototype, {
if (defn instanceof AST_Var && join_var_assign(defn.definitions, exprs, keep)) trimmed = true;
}
return trimmed && exprs;
function can_trim(node) {
return node instanceof AST_Assign && node.operator == "=";
}
}
function merge_assigns(prev, defn) {
@@ -3554,22 +3569,35 @@ merge(Compressor.prototype, {
}
function trim_assigns(name, value, exprs) {
var names = Object.create(null);
names[name.name] = true;
while (value instanceof AST_Assign && value.operator == "=") {
if (value.left instanceof AST_SymbolRef) names[value.left.name] = true;
value = value.right;
}
if (!(value instanceof AST_Object)) return;
var trimmed = false;
do {
var node = exprs[0];
if (!(node instanceof AST_Assign)) break;
if (node.operator != "=") break;
if (!(node.left instanceof AST_PropAccess)) break;
if (!try_join(exprs[0])) break;
exprs.shift();
trimmed = true;
} while (exprs.length);
return trimmed;
function try_join(node) {
if (!(node instanceof AST_Assign)) return;
if (node.operator != "=") return;
if (!(node.left instanceof AST_PropAccess)) return;
var sym = node.left.expression;
if (!(sym instanceof AST_SymbolRef)) break;
if (name.name != sym.name) break;
if (!node.right.is_constant_expression(scope)) break;
if (!(sym instanceof AST_SymbolRef)) return;
if (!names[sym.name]) return;
if (!node.right.is_constant_expression(scope)) return;
var prop = node.left.property;
if (prop instanceof AST_Node) {
if (try_join(prop)) prop = node.left.property = prop.right;
prop = prop.evaluate(compressor);
}
if (prop instanceof AST_Node) break;
if (prop instanceof AST_Node) return;
prop = "" + prop;
var diff = prop == "__proto__" || compressor.has_directive("use strict") ? function(node) {
var key = node.key;
@@ -3581,15 +3609,13 @@ merge(Compressor.prototype, {
}
return key !== "__proto__";
};
if (!all(value.properties, diff)) break;
if (!all(value.properties, diff)) return;
value.properties.push(make_node(AST_ObjectKeyVal, node, {
key: prop,
value: node.right
}));
exprs.shift();
trimmed = true;
} while (exprs.length);
return trimmed;
return true;
}
}
function join_consecutive_vars(statements) {