From 5a4d281d6701e9f27b67bf9def3842780410ab56 Mon Sep 17 00:00:00 2001
From: Kaz Kylheku <kaz@kylheku.com>
Date: Fri, 27 May 2016 20:47:15 -0700
Subject: Reduce work done by hashing.

Curtail traversal of objects and strings.

* hash.c (struct hash): hash_fun member takes int *
parameter now.
(HASH_STR_LIMIT, HASH_REC_LIMIT): New macros.
(hash_c_str): Hash only HASH_STR_LIMIT characters.
(equal_hash): Becomes extern function. Takes pointer-to-int
count argument, which is decremented. Function stops
recursing and returns zero when this hits zero.
(eql_hash): Also takes int * param, for compatibility
with function pointer in struct hash. This parameter
is not used, though.
(cobj_hash_op): Take pointer-to-count parameter,
but ignore it.
(hash_hash_op): Take pointer-to-count parameter,
decrement and check that it has not hit zero,
pass down to equal hash.
(hash_grow, gethash_c, gethash, gethash_f, gethash_n,
remhash): Initialize a counter to HASH_REC_LIMIT and
pass down to hashing function.
(hash_eql): Pass down a pointer to a dummy counter
to eql_hash.
(hash_equal): Initialize a counter to HASH_REC_LIMIT
and pass down to hash_equal.

* hash.h (equal_hash): Declared.

* lib.h (cobj_ops): hash member takes int * parameter.
(cobj_hash_op): Declaration updated with new param.

* struct.c (struct_inst_hash): Takes new int * parameter
for count. Calls equal_hash instead of hash_equal,
eliminating c_num calls; pointer to count is
passed to equal_hash.
---
 lib.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

(limited to 'lib.h')

diff --git a/lib.h b/lib.h
index 18f7f6d9..a004926b 100644
--- a/lib.h
+++ b/lib.h
@@ -226,7 +226,7 @@ struct cobj_ops {
   void (*print)(val self, val stream, val pretty);
   void (*destroy)(val self);
   void (*mark)(val self);
-  cnum (*hash)(val self);
+  cnum (*hash)(val self, int *count);
   val (*equalsub)(val self);
 };
 
@@ -245,7 +245,7 @@ void cobj_print_op(val, val, val);
 void cobj_destroy_stub_op(val);
 void cobj_destroy_free_op(val);
 void cobj_mark_op(val);
-cnum cobj_hash_op(val);
+cnum cobj_hash_op(val, int *);
 
 struct env {
   obj_common;
-- 
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