Method getUrlMacroAllowlist_

src/service/variable-source.js:325–342

* For email documents, all URL macros are disallowed by default. * @return {Array |undefined} The allowlist of substitutable AMP variables * @private

()

   * @private
   */
  getUrlMacroAllowlist_() {
    if (this.variableAllowlist_) {
      return this.variableAllowlist_;
    }

    // Disallow all URL macros for AMP4Email format documents.
    if (this.ampdoc.isSingleDoc()) {
      const doc = /** @type {!Document} */ (this.ampdoc.getRootNode());
      if (isAmp4Email(doc)) {
        /**
         * The allowlist of variables allowed for variable substitution.
         * @private {?Array<string>}
         */
        this.variableAllowlist_ = [''];
        return this.variableAllowlist_;
      }
    }
  }
}