Tcl_ParseCommand - function in Tcl's public C API for parsing a Tcl command from a string.
Official docs
http://www.purl.org/tcl/home/man/tcl8.4/TclLib/ParseCmd.htm
int
Tcl_ParseCommand(
Tcl_Interp *interp,
const char *string,
int numBytes,
int nested,
Tcl_Parse *parsePtr)