diff options
| -rw-r--r-- | eval.h | 2 | ||||
| -rw-r--r-- | match.c | 3 | ||||
| -rw-r--r-- | match.h | 2 | ||||
| -rw-r--r-- | parser.y | 16 | ||||
| -rw-r--r-- | txr.1 | 54 |
5 files changed, 66 insertions, 11 deletions
@@ -25,7 +25,7 @@ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ -extern val dwim_s, lambda_s, vector_lit_s, vec_list_s, list_s; +extern val dwim_s, lambda_s, progn_s, vector_lit_s, vec_list_s, list_s; extern val hash_lit_s, hash_construct_s, struct_lit_s, qref_s, uref_s; extern val eval_error_s, if_s, call_s; extern val eq_s, eql_s, equal_s; @@ -58,7 +58,7 @@ int opt_arraydims = 1; val decline_k, next_spec_k, repeat_spec_k; val mingap_k, maxgap_k, gap_k, mintimes_k, maxtimes_k, times_k; val lines_k, chars_k; -val text_s, choose_s, gather_s, do_s, mod_s, modlast_s; +val text_s, choose_s, gather_s, do_s, mdo_s, mod_s, modlast_s; val line_s, data_s, fuzz_s, load_s; val include_s, close_s, require_s; val longest_k, shortest_k, greedy_k; @@ -4684,6 +4684,7 @@ static void syms_init(void) choose_s = intern(lit("choose"), user_package); gather_s = intern(lit("gather"), user_package); do_s = intern(lit("do"), user_package); + mdo_s = intern(lit("mdo"), user_package); load_s = intern(lit("load"), user_package); include_s = intern(lit("include"), user_package); close_s = intern(lit("close"), user_package); @@ -25,7 +25,7 @@ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ -extern val text_s, choose_s, gather_s, do_s, require_s; +extern val text_s, choose_s, gather_s, do_s, mdo_s, require_s; extern val close_s, load_s, include_s, mod_s, modlast_s, line_s; extern val counter_k, vars_k, env_k, var_k, into_k, named_k; val match_expand_keyword_args(val elem); @@ -67,7 +67,7 @@ static val unquotes_occur(val quoted_form, int level); static val rlrec(parser_t *, val form, val line); static wchar_t char_from_name(const wchar_t *name); static val make_expr(parser_t *, val sym, val rest, val lineno); -static val check_for_include(val spec_rev); +static val check_parse_time_action(val spec_rev); static void misplaced_consing_dot_check(scanner_t *scanner, val term_atom_cons); #if YYBISON @@ -212,8 +212,8 @@ byacc_fool : n_expr { internal_error("notreached"); } | { internal_error("notreached"); } ; -clauses_rev : clause { $$ = check_for_include(cons($1, nil)); } - | clauses_rev clause { $$ = check_for_include(cons($2, $1)); } +clauses_rev : clause { $$ = check_parse_time_action(cons($1, nil)); } + | clauses_rev clause { $$ = check_parse_time_action(cons($2, $1)); } ; clauses_opt : clauses_rev { $$ = nreverse($1); } @@ -1661,15 +1661,21 @@ static val make_expr(parser_t *parser, val sym, val rest, val lineno) return ret; } -static val check_for_include(val spec_rev) +static val check_parse_time_action(val spec_rev) { val line = first(spec_rev); if (consp(line)) { val elem = first(line); if (consp(elem)) { - if (car(elem) == include_s) + val sym = car(elem); + if (sym == include_s) { return nappend2(nreverse(include(line)), rest(spec_rev)); + } + if (sym == mdo_s) { + eval_intrinsic(cons(progn_s, cdr(elem)), nil); + return nil; + } } } return spec_rev; @@ -3263,9 +3263,19 @@ These directives allow \*(TX programs to be modularized. They bring in code from a file, in two different ways. .coIP @(do) -The do directive is used to evaluate \*(TL expressions, discarding their +The +.code do +directive is used to evaluate \*(TL expressions, discarding their result values. See the TXR LISP section far below. +.coIP @(mdo) +The +.code mdo +(macro +.codn do ) +directive evaluates \*(TL expressions immediately, during the parsing +of the \*(TX syntax in which it occurs. + .PP .SS* Subexpression Evaluation @@ -6508,10 +6518,12 @@ The syntax of is: .cblk -.mets @(do << lisp-expression ) +.mets @(do << lisp-expression *) .cble -The do directive evaluates a \*(TL expression. (See TXR LISP far +The +.code do +directive evaluates zero or more \*(TL expressions. (See TXR LISP far below.) The value of the expression is ignored, and matching continues continues with the directives which follow the .code do @@ -6532,6 +6544,42 @@ Example: @(do (set [h a] b)) .cble +.dir mdo + +The syntax of +.code @(mdo) +is: + +.cblk +.mets @(mdo << lisp-expression *) +.cble + +Like the +.code do +directive, +.code mdo +(macro-time +.codn do ) +evaluates zero or more \*(TL expressions. Unlike +.codn do , +.code mdo +performs this evaluation immediately upon being parsed. +Then it disappears from the syntax. + +The effect of +.code "@(mdo e0 e1 e2 ...)" +is exactly like +.code "@(do (macro-time e0 e1 e2 ...))" +except that +.code do +doesn't disappear from the syntax. + +Another difference is that +.code do +can be used as a horizontal or vertical directive, whereas +.code mdo +is only vertical. + .SS* Blocks .NP* Overview |