Support max length and depth for object printing.

* hash.c (hash_print_op): Implement max length.

* lib.c (lazy_str_put, out_lazy_str): Take struct strm_base *
parameter and implement max length.
(out_quasi_str_sym): Don't use obj_print_impl for symbol's
name string; just put_string. The use of obj_print_impl causes
symbols appearing as variables in quasiliterals to be
truncated when max length is imposed.
(out_quasi_str): Implement max length.
(obj_print_impl): Implement max length and depth. Note that
there is now always a non-null ctx pointer.
(obj_print): Always set up context pointer for obj_print_impl.
Context now has pointer to low-level stream structure, where
we can access max_length and max_depth. It also carries the
recursion depth.

* lib.h (lazy_str_put): Declaration updated.

* stream.c (strm_base_init): Add initializers for max_length
and max_depth.
(put_string): Pass stream structure to lazy_str_put.
(set_max_length, set_max_depth): New functions.
(stream_init): set-max-length and set-max-depth intrinsics
registered.

* stream.h (struct strm_ctx): New members depth and strm.
(struct strm_base): New members max_length and max_depth.
(set_max_length, set_max_depth): Declared.

* txr.1: Documented.

1 files changed, 8 insertions, 0 deletions

diff --git a/hash.c b/hash.c
index 2bf527b9..1aaaa375 100644
--- a/hash.c
+++ b/hash.c
@@ -494,12 +494,20 @@ static void hash_print_op(val hash, val out, val pretty, struct strm_ctx *ctx)
   put_string(lit(")"), out);
   {
     val iter = hash_begin(hash), cell;
+    cnum max_len = ctx->strm->max_length;
+    cnum max_count = max_len;
+
     while ((cell = hash_next(iter))) {
       val key = us_car(cell);
       val value = us_cdr(cell);
       if (width_check(out, chr(' ')))
         force_br = 1;
 
+      if (max_len && --max_count < 0) {
+        put_string(lit("..."), out);
+        break;
+      }
+
       put_string(lit("("), out);
       obj_print_impl(key, out, pretty, ctx);