From 353793082f9566a8c546b339386e437e689d6478 Mon Sep 17 00:00:00 2001
From: Jim Blandy <jimb@red-bean.com>
Date: Thu, 24 Apr 1997 09:24:03 +0000
Subject: [PATCH] =?UTF-8?q?Functions=20for=20finding=20variable=20bindings?=
 =?UTF-8?q?,=20grace=20=C3=A0=20Tim=20Pierce.=20*=20gh=5Fdata.c=20(gh=5Flo?=
 =?UTF-8?q?okup,=20gh=5Fmodule=5Flookup):=20New=20functions.=20*=20gh.h=20?=
 =?UTF-8?q?(gh=5Flookup,=20gh=5Fmodule=5Flookup):=20New=20prototypes.?=
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---
 libguile/gh.h      |  3 +++
 libguile/gh_data.c | 29 +++++++++++++++++++++++++++++
 2 files changed, 32 insertions(+)

diff --git a/libguile/gh.h b/libguile/gh.h
index 890b48883..94d575e52 100644
--- a/libguile/gh.h
+++ b/libguile/gh.h
@@ -148,6 +148,9 @@ SCM gh_vset(SCM vec, SCM pos, SCM val);
 SCM gh_vref(SCM vec, SCM pos);
 unsigned long gh_vector_length(SCM v);
 
+SCM gh_lookup (char *sname);
+SCM gh_module_lookup (SCM vector, char *sname);
+
 SCM gh_cons(SCM x, SCM y);
 #define gh_list scm_listify
 unsigned long gh_list_length(SCM l);
diff --git a/libguile/gh_data.c b/libguile/gh_data.c
index 3e1250c5e..b70228d8f 100644
--- a/libguile/gh_data.c
+++ b/libguile/gh_data.c
@@ -286,3 +286,32 @@ gh_vector_length (SCM v)
 {
   return gh_scm2ulong (scm_vector_length (v));
 }
+
+/* Data lookups between C and Scheme
+
+   Look up a symbol with a given name, and return the object to which
+   it is bound.  gh_lookup examines the Guile top level, and
+   gh_module_lookup checks the module namespace specified by the
+   `vec' argument.
+
+   The return value is the Scheme object to which SNAME is bound, or
+   SCM_UNDEFINED if SNAME is not bound in the given context. [FIXME:
+   should this be SCM_UNSPECIFIED?  Can a symbol ever legitimately be
+   bound to SCM_UNDEFINED or SCM_UNSPECIFIED?  What is the difference?
+   -twp] */
+
+SCM
+gh_lookup (char *sname)
+{
+  return gh_module_lookup (SCM_BOOL_F, sname);
+}
+
+SCM
+gh_module_lookup (SCM vec, char *sname)
+{
+  SCM sym = gh_symbol2scm (sname);
+  if ((scm_symbol_bound_p (vec, sym)) == SCM_BOOL_T)
+    return scm_symbol_binding (vec, sym);
+  else
+    return SCM_UNDEFINED;
+}