Adding a debugger. This is an experimental prototype.

* Makefile (OBJS): New object file debug.o.

* dep.mk: Updated.

* match.c (h_fun): Use debug_begin and debug_end macros
to set up a debug frame for backtracing.
(match_line, match_files): Call debug_check to give debugger a chance
to instrument call.
(v_fun): Use debug_begin and debug_end macros to set up a debug frame
for backtracing. Call debug_check to give debugger a chance to
instrument call.

* stream.c (struct strm_ops): New function pointer, flush.
(stdio_maybe_write_error): Wrong word in error message corrected.
(stdio_flush): New static function.
(stdio_ops, pipe_ops): New function entered into tables.
(flush_stream): New function.

* stream.h (flush_stream): Declared.

* txr.c (help): New options documented.
(main): call to debug_init added. New debug options parsed and
opt_debugger set accordingly.

* unwind.c (uw_push_debug, uw_current_frame): New function.

* unwind.h (uw_frtype): New enumeration member UW_DBG.
(struct uw_debug): New frame variant.
(union uw_frame): New member, db.
(uw_push_debug, uw_current_frame): Declared,

* debug.c: New file.

* debug.h: New file.

1 files changed, 106 insertions, 0 deletions

diff --git a/debug.c b/debug.c
new file mode 100644
index 00000000..f5c74188
--- /dev/null
+++ b/debug.c
@@ -0,0 +1,106 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <dirent.h>
+#include <setjmp.h>
+#include <stdarg.h>
+#include <wchar.h>
+#include "config.h"
+#include "lib.h"
+#include "debug.h"
+#include "gc.h"
+#include "unwind.h"
+#include "stream.h"
+#include "parser.h"
+
+int opt_debugger;
+static int step_mode;
+val breakpoints;
+val last_command;
+
+static void help(void)
+{
+}
+
+val debug(val form, val bindings, val data, val line, val chr)
+{
+  val lineno = source_loc(form);
+
+  if (!step_mode && !memqual(lineno, breakpoints)) {
+    return nil;
+  } else {
+    format(std_output, lit("stopped at line ~a\n"), lineno, nao);
+    format(std_output, lit("form: ~s\n"), form, nao);
+    format(std_output, lit("data (~s):\n~s\n"), line, data, nao);
+    if (chr)
+       format(std_output, lit("(character ~s)\n"), chr, nao);
+
+    for (;;) {
+      val input, command;
+
+      format(std_output, lit("txr> "), nao);
+      flush_stream(std_output);
+
+      input = split_str_set(get_line(std_input), lit("\t "));
+      command = or2(first(input), last_command);
+      last_command = command;
+
+      if (equal(command, lit("?")) || equal(command, lit("help"))) {
+        help();
+        continue;
+      } else if (equal(command, lit("c"))) {
+        step_mode = 0;
+        return nil;
+      } else if (equal(command, lit("n"))) {
+        step_mode = 1;
+        return nil;
+      } else if (equal(command, lit("v"))) {
+        format(std_output, lit("bindings: ~s\n"), bindings, nao);
+      } else if (equal(command, lit("f"))) {
+        format(std_output, lit("stopped at line ~a\n"), lineno, nao);
+        format(std_output, lit("form: ~s\n"), form, nao);
+      } else if (equal(command, lit("d"))) {
+        if (data) {
+          format(std_output, lit("data (~s):\n~s\n"), line, data, nao);
+          if (chr)
+             format(std_output, lit("(character ~s)\n"), chr, nao);
+        }
+      } else if (equal(command, lit("b")) || equal(command, lit("d"))) {
+        if (!rest(input)) {
+          format(std_output, lit("b needs argument\n"), nao);
+          continue;
+        } else {
+          long n = wcstol(c_str(second(input)), NULL, 10);
+          if (equal(command, lit("b")))
+            push(num(n), &breakpoints);
+        }
+      } else if (equal(command, lit("l"))) {
+        format(std_output, lit("breakpoints: ~s\n"), breakpoints, nao);
+      } else if (equal(command, lit("w"))) {
+        format(std_output, lit("backtrace:\n"), nao);
+        {
+          uw_frame_t *iter;
+
+          for (iter = uw_current_frame(); iter != 0; iter = iter->uw.up) {
+            if (iter->uw.type == UW_DBG) {
+              format(std_output, lit("(~s ~s)\n"), iter->db.func, iter->db.args, nao);
+            }
+          }
+        }
+      } else if (equal(command, lit("q"))) {
+        uw_throwf(query_error_s, lit("terminated via debugger"), nao);
+      } else {
+        format(std_output, lit("unrecognized command: ~a\n"), command, nao);
+      }
+    }
+
+    return nil;
+  }
+}
+
+void debug_init(void)
+{
+  step_mode = 1;
+  protect(&breakpoints, &last_command, (val *) 0);
+}