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19.2 An Overview of the Reentrant API

The API for reentrant scanners is different than for non-reentrant scanners. Here is a quick overview of the API:

• %option reentrant must be specified.
• All functions take one additional argument: yyscanner
• In C/C++, all global variables are replaced by their macro equivalents. (We tell you this because it may be important to you during debugging.) This is a historical-compatibilty hack; other back ends probably will not emulate it.
• In the default C/C++ yylex_init and yylex_destroy must be called before and after yylex, respectively. Other back ends may or may not require this.
• Accessor methods (get/set functions) provide access to common flex variables.
• User-specific data can be stored in yyextra.