\section{Q-register Manipulation} \label{Q-register Manipulation} TECO provides data storage registers, called Q-registers, each of which may be used to store an integral numeric value and, simultaneously, an ASCII character string. Q-registers are described in section Q-registers; this section describes the commands used to load values into and retrieve values from Q-registers. An important kind of character string which may be stored in the text portion of a Q-register is a TECO command string. Such a command is known as a macro, and is available for execution via the {\tt Mq} command, described in Table \ref{Macro Invocation Commands} below. (See also section \ref{Immediate ESCAPE-Sequence Commands}, for a keypad method of macro invocation, and section \ref{Immediate Action Commands}, for the {\tt *q} command, which saves the last-typed command for possible editing or re-execution.) TECO-10 allows additional Q-registers other than those described in section Q-registers. Consult Appendix I for further details. Table \ref{Q-register Loading Commands} lists the commands which permit characters to be loaded into the Q-registers. \begin{table}[h] \caption{\bf{Q-register Loading Commands}} \label{Q-register Loading Commands} \end{table} \nopagebreak \begin{list}{}{\labelsep 20pt} \item[COMMAND] FUNCTION \nopagebreak \item[{\tt nUq}] Put {\tt n} in the numeric storage area of Q-register q. \item[{\tt m,nUq}] Equivalent to the {\tt nUqm} command. That is, this command puts the number {\tt n} into the numeric storage area of Q-register q and then returns the number {\tt m} as a value. The command {\tt UAUB} is useful at the beginning of a macro to save the two arguments specified on the macro call. (See the {\tt m,nMq} command below.) \item[{\tt n\%q}] Add {\tt n} to the contents of the number storage area of Q-register q. The updated contents of Q-register q are also returned as a value to be passed to the next command. If your intent is only to update the Q-register, good programming practice suggests following the {\tt n\%q} command with a {\tt } or \caret {\tt [} to prevent the returned value from unintentionally affecting the following command. \item[{\tt n\%q\escape}] Same as {\tt n\%q} but discards the value returned. \item {\tt \%q} Equivalent to {\tt 1\%q}. \item [\caret {\tt Uqstring} \escape] This command inserts character string {\tt string} into the text storage area of Q-register q. When entering a command string from the terminal, you must specify \caret {\tt U} using the caret/ {\tt U} format, since the {\tt} character is the line erase immediate action command. \ifnotintecoeight \item [{\tt :}\caret {\tt Uqstring}\escape] This command appends character string {\tt string} to the text storage area of Q-register {\tt q}. {\em [Not in TECO-8]} \fi \ifnotintecoeight \item [{\tt n} \caret {\tt Uq}\escape] This form of the \caret {\tt Uq}\escape command inserts the single character whose ASCII code is {\tt n} into the text storage area of Q-register {\tt q}. (n is taken modulo 256 in TECO-11, modulo 128 in other TECOs.) {\em [Not in TECO-8]} \fi \ifnotintecoeight \item [{\tt n:} \caret {\tt Uq}\escape] This form of the {\tt :}\caret {\tt Uq}\escape command appends the single character whose ASCII code is {\tt n} to the text storage area of Q-register {\tt q}. ({\tt n} is taken modulo 256 in TECO-11, modulo 128 in other TECOs.) {\em [Not in TECO-8]} \fi \item [{\tt @}\caret {\tt Uq/string/}] \item [{\tt @:} \caret {\tt Uq/string/}] \item [{\tt n@}\caret {\tt Uq//}] \item [{\tt n@:}\caret {\tt Uq//}] Equivalent, respectively, to the \caret {\tt Uqstring}\escape, {\tt :}\caret {\tt Uqstring}\escape, {\tt n}\caret {\tt Uq}\escape, and {\tt n:}\caret {\tt Uq}\escape commands, except that alternate delimiters are used and no {\tt } characters are necessary. \item [{\tt nXq}] Clear Q-register q and move {\tt n} lines into it, where {\tt n} is a signed integer. If {\tt n} is positive, the {\tt n} lines following the current pointer position are copied into the text storage area of Q-register q. If {\tt n} is negative, the {\tt n} lines preceding the pointer are copied. If {\tt n} is zero, the contents of the buffer from the beginning of the line on which the pointer is located up to the pointer is copied. The pointer is not moved. The text is not deleted. \item [{\tt Xq}] Equivalent to {\tt 1Xq}. \item [{\tt -Xq}] Equivalent to {\tt -1Xq}. \item [{\tt m,nXq}] Copy the contents of the buffer from the {\tt m}+1th character through and including the {\tt n}th character into the text storage area of Q-register q. {\tt m} and {\tt n} must be positive, and {\tt m} should be less than {\tt n}. \item [{\tt .,.+nXq}] Copy the {\tt n} characters immediately following the buffer pointer into the text storage area of Q-register q. {\tt N} should be greater than zero. \item [{\tt .-n,.Xq}] Copy the {\tt n} characters immediately preceeding the buffer pointer into the text storage area of Q-register q. {\tt N} should be greater than zero. \ifnotintecoeight \item [{\tt n:Xq}] Append {\tt n} lines to Q-register q, where {\tt n} is a signed integer with the same functions as {\tt n} in the {\tt nXq} command above. The pointer is not moved. {\em [Not in TECO-8]} \fi The colon construct for appending to a Q-register can be used with all forms of the {\tt X} command. \ifnotintecoeight \item [{\tt ]q}] Pop from the Q-register push-down list into Q-register q. Any previous contents of Q-register q are destroyed. Both the numeric and text parts of the Q-register are loaded by this command. The Q-register push-down list is a last-in first-out (LIFO) storage area. (See section \ref{Q-register Push-down List} for a description of the push-down list.) This command does not use or affect numeric values. Numeric values are passed through this command transparently. This allows macros to restore Q-registers and still return numeric values. {\em [Not in TECO-8]} \item [{\tt :]q}] Execute the {\tt ]q} command and return a numeric value. A -1 indicates that there was another item on the Q-register push-down list to be popped. A 0 indicates that the Q-register push-down list was empty, so Q-register q was not modified. {\em [Not in TECO-8]} \fi \item [{\tt *q}] Save last-typed command string. See section \ref{Immediate Action Commands}. \end{list} Table \ref{Q-register Retrieval Commands} lists the commands which permit data to be retrieved from the Q-registers. \begin{table}[h] \caption{\bf{Q-register Retrieval Commands}} \label{Q-register Retrieval Commands} \end{table} \nopagebreak \begin{list}{}{\labelsep 20pt} \item [COMMAND] FUNCTION \item [{\tt Qq}] Use the integer stored in the number storage area of Q-register q as the argument of the next command. \item [{\tt nQq}] Return the ASCII value of the {\em (n+1)}th character in Q-register q. The argument {\tt n} must be between 0 and the Q-register's size minus 1. If {\tt n} is out of range, a value of -1 is returned. Characters within a Q-register are numbered the same way that characters in the text buffer are numbered. The initial character is at character position 0, the next character is at character position 1, etc. Therefore, if Q-register A contains {\tt xyz} then {\tt 0QA} will return the ASCII code for {\tt x} and {\tt 1QA} will return the ASCII code for {\tt y}. \item [{\tt :Qq}] Use the number of characters stored in the text storage area of Q-register q as the argument of the next command. \item [{\tt Gq}] Copy the contents of the text storage area of Q-register q into the buffer at the current position of the buffer pointer, leaving the pointer positioned after the last character copied. \item [{\tt :Gq}] Print the contents of the text storage area of Q-register q on the terminal. Neither the text buffer nor the buffer pointer is changed by this command. \ifnotintecoeight \item [{\tt [q}] Copy the contents of the numeric and text storage areas of Q-register q into the Q-register push-down list. This command does not alter either the numeric or text storage areas of Q-register q. It does not use or affect numeric values. Numeric values are passed through this command transparently, allowing macros to save temporary Q-registers and still accept numeric values. (Note, however, macros written to use local Q-registers, available in TECO-11, may be able to avoid saving and restoring Q-registers via the the pushdown list.) The command sequence {\tt[A]B} replicates the text string and numeric value from Q-register {\tt A} into Q-register {\tt B}. {\em [Not in TECO-8]} \fi \end{list} Table \ref{Macro Invocation Commands} lists the commands which cause macros (strings stored in Q-registers) to be executed. Macro invocations can be nested recursively; the limit is set by the amount of pushdown storage TECO has available. In this table only, a distinction is made between a global Q-register name (indicated below by {\tt q}) and a local Q-register name (indicated below by {\tt .q}). Elsewhere in this manual, {\tt q} indicates either a global or local Q-register name. \begin{table}[h] \caption{\bf{Macro Invocation Commands}} \label{Macro Invocation Commands} \end{table} \nopagebreak \begin{list}{}{\labelsep 20pt} \item [COMMAND] FUNCTION \nopagebreak \item [{\tt Mq}] Execute the contents of the text storage area of global Q-register q as a command string. In TECO-11, a new set of local Q-registers is created before the macro is invoked. \item [{\tt nMq}] Execute the {\tt Mq} command as above, using {\tt n} as a numeric argument for the first command contained in global Q-register q. In TECO-11, a new set of local Q-registers is created. \item [{\tt m,nMq}] Execute the {\tt Mq} command as above, using {\tt m,n} as numeric arguments for the first command contained in global Q-register q. In TECO-11, a new set of local Q-registers is created. \item [{\tt :Mq}] Execute the contents of the text storage area of global Q-register q as a command string. In TECO-11, the current set of local Q-registers remains available to the invoked macro; no new set is created. \item [{\tt n:Mq}] Execute the {\tt :Mq} command as above, using {\tt n} as a numeric argument for the first command contained in global Q-register q. In TECO-11, no new set of local Q-registers is created. \item [{\tt m,n:Mq}] Execute the {\tt :Mq} command as above, using {\tt m,n} as numeric arguments for the first command contained in global Q-register q. In TECO-11, no new set of local Q-registers is created. \item [{\tt M.q}] Execute the contents of the text storage area of local Q-register .q as a command string. In TECO-11, no new set of local Q-registers is created. \item [{\tt nM.q}] Execute the {\tt M.q} command as above, using {\tt n} as a numeric argument for the first command contained in local Q-register .q. In TECO-11, no new set of local Q-registers is created. \item [{\tt m,nM.q}] Execute the {\tt M.q} command as above, using {\tt m,n} as numeric arguments for the first command contained in local Q-register .q. In TECO-11, no new set of local Q-registers is created. \item [{\tt :M.q}] Execute the contents of the text storage area of local Q-register .q as a command string. In TECO-11, no new set of local Q-registers is created. \item [{\tt n:M.q}] Execute the {\tt :M.q} command as above, using {\tt n} as a numeric argument for the first command contained in local Q-register .q. In TECO-11, no new set of local Q-registers is created. \item [{\tt m,n:M.q}] Execute the {\tt :M.q} command as above, using {\tt m,n} as numeric arguments for the first command contained in local Q-register .q. In TECO-11, no new set of local Q-registers is created. \end{list}