1 files changed, 75 insertions, 0 deletions
diff --git a/node_modules/acorn/src/scope.js b/node_modules/acorn/src/scope.js
new file mode 100644
index 000000000..2ec044899
--- /dev/null
+++ b/node_modules/acorn/src/scope.js
@@ -0,0 +1,75 @@
+import {Parser} from "./state"
+import {has} from "./util"
+
+const pp = Parser.prototype
+
+// Object.assign polyfill
+const assign = Object.assign || function(target, ...sources) {
+  for (let i = 0; i < sources.length; i++) {
+    const source = sources[i]
+    for (const key in source) {
+      if (has(source, key)) {
+        target[key] = source[key]
+      }
+    }
+  }
+  return target
+}
+
+// The functions in this module keep track of declared variables in the current scope in order to detect duplicate variable names.
+
+pp.enterFunctionScope = function() {
+  // var: a hash of var-declared names in the current lexical scope
+  // lexical: a hash of lexically-declared names in the current lexical scope
+  // childVar: a hash of var-declared names in all child lexical scopes of the current lexical scope (within the current function scope)
+  // parentLexical: a hash of lexically-declared names in all parent lexical scopes of the current lexical scope (within the current function scope)
+  this.scopeStack.push({var: {}, lexical: {}, childVar: {}, parentLexical: {}})
+}
+
+pp.exitFunctionScope = function() {
+  this.scopeStack.pop()
+}
+
+pp.enterLexicalScope = function() {
+  const parentScope = this.scopeStack[this.scopeStack.length - 1]
+  const childScope = {var: {}, lexical: {}, childVar: {}, parentLexical: {}}
+
+  this.scopeStack.push(childScope)
+  assign(childScope.parentLexical, parentScope.lexical, parentScope.parentLexical)
+}
+
+pp.exitLexicalScope = function() {
+  const childScope = this.scopeStack.pop()
+  const parentScope = this.scopeStack[this.scopeStack.length - 1]
+
+  assign(parentScope.childVar, childScope.var, childScope.childVar)
+}
+
+/**
+ * A name can be declared with `var` if there are no variables with the same name declared with `let`/`const`
+ * in the current lexical scope or any of the parent lexical scopes in this function.
+ */
+pp.canDeclareVarName = function(name) {
+  const currentScope = this.scopeStack[this.scopeStack.length - 1]
+
+  return !has(currentScope.lexical, name) && !has(currentScope.parentLexical, name)
+}
+
+/**
+ * A name can be declared with `let`/`const` if there are no variables with the same name declared with `let`/`const`
+ * in the current scope, and there are no variables with the same name declared with `var` in the current scope or in
+ * any child lexical scopes in this function.
+ */
+pp.canDeclareLexicalName = function(name) {
+  const currentScope = this.scopeStack[this.scopeStack.length - 1]
+
+  return !has(currentScope.lexical, name) && !has(currentScope.var, name) && !has(currentScope.childVar, name)
+}
+
+pp.declareVarName = function(name) {
+  this.scopeStack[this.scopeStack.length - 1].var[name] = true
+}
+
+pp.declareLexicalName = function(name) {
+  this.scopeStack[this.scopeStack.length - 1].lexical[name] = true
+}