languageEl              package:methods              R Documentation

_E_l_e_m_e_n_t_s _o_f _L_a_n_g_u_a_g_e _O_b_j_e_c_t_s

_D_e_s_c_r_i_p_t_i_o_n:

     Internal routines to support some operations on language objects.

_U_s_a_g_e:

     languageEl(object, which)

     isGrammarSymbol(symbol)

_S_u_m_m_a_r_y _o_f _F_u_n_c_t_i_o_n_s:


     '_l_a_n_g_u_a_g_e_E_l': extract an element of a language object,
          consistently for different kinds of objects.

          The 1st., etc. elements of a function are the corresponding
          formal arguments, with the default expression if any as
          value.

          The first element of a call is the name or the function
          object being called.  

          The 2nd, 3rd, etc. elements are the 1st, 2nd, etc. arguments
          expressions.  Note that the form of the extracted name is
          different for R and S-Plus.  When the name (the first
          element) of a call is replaced, the languageEl replacement
          function coerces a character string to the internal form for
          each system.

          The 1st, 2nd, 3rd elements of an 'if' expression are the
          test, first, and second branch.

          The 1st element of a 'for' object is the name (symbol) being
          used in the loop, the second is the expression for the range
          of the loop, the third is the body of the loop.

          The first element of a 'while' object is the loop test, and
          the second the body of the loop.


     '_i_s_G_r_a_m_m_a_r_S_y_m_b_o_l': Checks whether the symbol is part of the
          grammar. Don't use this function directly.