[PATCH] Add parse-path-with-ellipsis, and use it for GUILE_LOAD_PATH et al

[Mark H Weaver <mhw@netris.org>]

[-- Attachment #1: Type: text/plain, Size: 319 bytes --]

Hi Ludovic,

ludo@gnu.org (Ludovic Courtès) writes:
> I pretty much like Mark’s suggestion of using ‘...’ as a special marker,
> even though that’s a valid file name.

Here's a patch to implement the "..." special marker.
It would be good to have this in 2.0.7.

What do you think?

      Mark



[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #2: [PATCH] Add parse-path-with-ellipsis, and use it for GUILE_LOAD_PATH et al --]
[-- Type: text/x-diff, Size: 3958 bytes --]

From 4a78f4a638334a5bd8eb08308891b541bbde9b1e Mon Sep 17 00:00:00 2001
From: Mark H Weaver <mhw@netris.org>
Date: Wed, 28 Nov 2012 18:01:35 -0500
Subject: [PATCH] Add parse-path-with-ellipsis, and use it for GUILE_LOAD_PATH
 et al.

* libguile/load.c (scm_parse_path_with_ellipsis): New procedure.
  (scm_init_load_path): Use 'scm_parse_path_with_ellipsis' to
  handle GUILE_LOAD_PATH and GUILE_LOAD_COMPILED_PATH.

* libguile/load.h (scm_parse_path_with_ellipsis): Add prototype.

* doc/ref/api-evaluation.texi (Load Paths): Add docs.
---
 doc/ref/api-evaluation.texi |    9 +++++++++
 libguile/load.c             |   31 +++++++++++++++++++++++++++++--
 libguile/load.h             |    1 +
 3 files changed, 39 insertions(+), 2 deletions(-)

diff --git a/doc/ref/api-evaluation.texi b/doc/ref/api-evaluation.texi
index 37e41e1..6a442c7 100644
--- a/doc/ref/api-evaluation.texi
+++ b/doc/ref/api-evaluation.texi
@@ -943,6 +943,15 @@ a list and return the resulting list with @var{tail} appended. If
 @var{path} is @code{#f}, @var{tail} is returned.
 @end deffn
 
+@deffn {Scheme Procedure} parse-path-with-ellipsis path base
+@deffnx {C Function} scm_parse_path_with_ellipsis (path, base)
+Parse @var{path}, which is expected to be a colon-separated string, into
+a list and return the resulting list with @var{base} (a list) spliced in
+place of the @code{...} path component, if present, or else @var{base}
+is added to the end.  If @var{path} is @code{#f}, @var{base} is
+returned.
+@end deffn
+
 @deffn {Scheme Procedure} search-path path filename [extensions [require-exts?]]
 @deffnx {C Function} scm_search_path (path, filename, rest)
 Search @var{path} for a directory containing a file named
diff --git a/libguile/load.c b/libguile/load.c
index af2ca45..76bbd83 100644
--- a/libguile/load.c
+++ b/libguile/load.c
@@ -243,6 +243,33 @@ SCM_DEFINE (scm_parse_path, "parse-path", 1, 1, 0,
 }
 #undef FUNC_NAME
 
+SCM_DEFINE (scm_parse_path_with_ellipsis, "parse-path-with-ellipsis", 2, 0, 0,
+            (SCM path, SCM base),
+	    "Parse @var{path}, which is expected to be a colon-separated\n"
+	    "string, into a list and return the resulting list with\n"
+	    "@var{base} (a list) spliced in place of the @code{...} path\n"
+            "component, if present, or else @var{base} is added to the end.\n"
+            "If @var{path} is @code{#f}, @var{base} is returned.")
+#define FUNC_NAME s_scm_parse_path_with_ellipsis
+{
+  SCM ellipsis = scm_from_latin1_string ("...");
+  SCM lst = scm_parse_path (path, SCM_EOL);
+  SCM walk = lst;
+  SCM *prev = &lst;
+
+  while (!scm_is_null (walk) &&
+         scm_is_false (scm_equal_p (scm_car (walk), ellipsis)))
+    {
+      prev = SCM_CDRLOC (walk);
+      walk = *prev;
+    }
+  *prev = scm_is_null (walk)
+    ? base
+    : scm_append (scm_list_2 (base, scm_cdr (walk)));
+  return lst;
+}
+#undef FUNC_NAME
+
 
 /* Initialize the global variable %load-path, given the value of the
    SCM_SITE_DIR and SCM_LIBRARY_DIR preprocessor symbols and the
@@ -316,11 +343,11 @@ scm_init_load_path ()
 
   env = getenv ("GUILE_LOAD_PATH");
   if (env)
-    path = scm_parse_path (scm_from_locale_string (env), path);
+    path = scm_parse_path_with_ellipsis (scm_from_locale_string (env), path);
 
   env = getenv ("GUILE_LOAD_COMPILED_PATH");
   if (env)
-    cpath = scm_parse_path (scm_from_locale_string (env), cpath);
+    cpath = scm_parse_path_with_ellipsis (scm_from_locale_string (env), cpath);
 
   *scm_loc_load_path = path;
   *scm_loc_load_compiled_path = cpath;
diff --git a/libguile/load.h b/libguile/load.h
index 0bddac2..698bbaf 100644
--- a/libguile/load.h
+++ b/libguile/load.h
@@ -27,6 +27,7 @@
 
 \f
 SCM_API SCM scm_parse_path (SCM path, SCM tail);
+SCM_API SCM scm_parse_path_with_ellipsis (SCM path, SCM base);
 SCM_API SCM scm_primitive_load (SCM filename);
 SCM_API SCM scm_c_primitive_load (const char *filename);
 SCM_API SCM scm_sys_package_data_dir (void);
-- 
1.7.10.4