Docs

1 files changed, 81 insertions, 0 deletions

diff --git a/node_modules/sucrase/dist/esm/util/isIdentifier.js b/node_modules/sucrase/dist/esm/util/isIdentifier.js
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+++ b/node_modules/sucrase/dist/esm/util/isIdentifier.js
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+import {IS_IDENTIFIER_CHAR, IS_IDENTIFIER_START} from "../parser/util/identifier";
+
+// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Lexical_grammar
+// Hard-code a list of reserved words rather than trying to use keywords or contextual keywords
+// from the parser, since currently there are various exceptions, like `package` being reserved
+// but unused and various contextual keywords being reserved. Note that we assume that all code
+// compiled by Sucrase is in a module, so strict mode words and await are all considered reserved
+// here.
+const RESERVED_WORDS = new Set([
+  // Reserved keywords as of ECMAScript 2015
+  "break",
+  "case",
+  "catch",
+  "class",
+  "const",
+  "continue",
+  "debugger",
+  "default",
+  "delete",
+  "do",
+  "else",
+  "export",
+  "extends",
+  "finally",
+  "for",
+  "function",
+  "if",
+  "import",
+  "in",
+  "instanceof",
+  "new",
+  "return",
+  "super",
+  "switch",
+  "this",
+  "throw",
+  "try",
+  "typeof",
+  "var",
+  "void",
+  "while",
+  "with",
+  "yield",
+  // Future reserved keywords
+  "enum",
+  "implements",
+  "interface",
+  "let",
+  "package",
+  "private",
+  "protected",
+  "public",
+  "static",
+  "await",
+  // Literals that cannot be used as identifiers
+  "false",
+  "null",
+  "true",
+]);
+
+/**
+ * Determine if the given name is a legal variable name.
+ *
+ * This is needed when transforming TypeScript enums; if an enum key is a valid
+ * variable name, it might be referenced later in the enum, so we need to
+ * declare a variable.
+ */
+export default function isIdentifier(name) {
+  if (name.length === 0) {
+    return false;
+  }
+  if (!IS_IDENTIFIER_START[name.charCodeAt(0)]) {
+    return false;
+  }
+  for (let i = 1; i < name.length; i++) {
+    if (!IS_IDENTIFIER_CHAR[name.charCodeAt(i)]) {
+      return false;
+    }
+  }
+  return !RESERVED_WORDS.has(name);
+}