1 files changed, 97 insertions, 0 deletions
diff --git a/deps/npm/node_modules/readable-stream/node_modules/unreachable-branch-transform/unreachableBranchTransformer.js b/deps/npm/node_modules/readable-stream/node_modules/unreachable-branch-transform/unreachableBranchTransformer.js
new file mode 100644
index 0000000000..7469897dad
--- /dev/null
+++ b/deps/npm/node_modules/readable-stream/node_modules/unreachable-branch-transform/unreachableBranchTransformer.js
@@ -0,0 +1,97 @@
+var Evaluator = require('esmangle-evaluator');
+
+var recast = require('recast');
+var types = recast.types;
+var b = types.builders;
+
+var VISITOR_METHODS = {
+  visitLogicalExpression: visitLogicalExp,
+  visitIfStatement: visitCondition,
+  visitConditionalExpression: visitCondition
+};
+
+module.exports = function(branch) {
+  recast.visit(branch, VISITOR_METHODS);
+  return branch;
+};
+
+
+/**
+ *  "||" and "&&"
+ */
+function visitLogicalExp(path) {
+  var leftEval = Evaluator.booleanCondition(path.node.left);
+
+  if (typeof leftEval !== 'boolean') {
+    // console.log('___ %s ___', path.node.operator);
+    this.traverse(path);
+    return;
+  }
+
+  var leftSideEffect = Evaluator.hasSideEffect(path.node.left);
+  if (leftSideEffect) {
+    this.traverse(path);
+    return;
+  }
+
+  if (leftEval === true && path.node.operator === '||') {
+    // console.log('true || ___');
+    path.replace(path.node.left);
+    recast.visit(path, VISITOR_METHODS);
+    return false;
+  }
+
+  if (leftEval === true && path.node.operator === '&&') {
+    // console.log('true && ___');
+    path.replace(path.node.right);
+    recast.visit(path, VISITOR_METHODS);
+    return false;
+  }
+
+  if (leftEval === false && path.node.operator === '&&') {
+    // console.log('false && ___');
+    path.replace(path.node.left);
+    recast.visit(path, VISITOR_METHODS);
+    return false;
+  }
+
+  if (leftEval === false && path.node.operator === '||') {
+    // console.log('false || ___');
+    path.replace(path.node.right);
+    recast.visit(path, VISITOR_METHODS);
+    return false;
+  }
+}
+
+/**
+ *  "if" and ternary "?"
+ */
+function visitCondition(path) {
+  var testEval = Evaluator.booleanCondition(path.node.test);
+
+  if (typeof testEval !== 'boolean') {
+    // console.log('if/? ___');
+    this.traverse(path);
+    return;
+  }
+
+  var testSideEffect = Evaluator.hasSideEffect(path.node.test);
+  if (testSideEffect) {
+    this.traverse(path);
+    return;
+  }
+
+  if (testEval === true) {
+    // console.log('if/? (true)');
+    path.replace(path.value.consequent);
+    recast.visit(path, VISITOR_METHODS);
+    return false;
+  }
+
+  if (testEval === false) {
+    // console.log('if/? (false)');
+    path.replace(path.value.alternate);
+    recast.visit(path, VISITOR_METHODS);
+    return false;
+  }
+}