scm: implement field / fields procedures

Add procedures field & fields to get information about mu's database
fields, similar to "mu info fields".

Add docs & tests as well.

scm/mu-scm-test.scm

@@ -110,7 +110,7 @@
 
     ;; language
     (test-equal (language msg)
-      (if (assoc-ref (configuration) 'language-enabled?) 'en nil))
+      (if (assoc-ref (configuration) 'language-enabled?) 'en #f))
 
     ;; cc, bc, labels
     (test-equal '() (cc msg))
@@ -197,6 +197,13 @@
   (test-equal "2025-06-16 15:43:12" (time->string 1750077792 #:utc? #f))
   (test-equal "12:43:12" (time->string 1750077792 #:utc? #t #:format "%T"))
 
+  (let* ((subject (field 'subject)))
+    (test-assert subject)
+    (test-equal (assoc-ref subject 'name) "subject")
+    (test-equal (assoc-ref subject 'shortcut) #\s)
+    (test-equal (assoc-ref subject 'search-type) 'phrase)
+    (test-assert (assoc-ref subject 'value?)))
+
   ;; (define old-prefs %preferences)
   ;; (define %preferences '((utc? . #t) (short-date  . "%T %F")))
   ;; (test-equal "12:43:12 2025-06-16" (time->string 1750077792))

scm/mu-scm.cc

@@ -101,6 +101,39 @@ init_configuration()
 	scm_c_define("%configuration", scm_reverse_x(conf, SCM_EOL));
 }
 
+static void
+init_fields_info()
+{
+	SCM fields_scm{SCM_EOL};
+
+	const auto search_type = [&](const Field& field)->SCM {
+		if (field.is_boolean_term())
+			return make_symbol("boolean");
+		else if (field.is_phrasable_term())
+			return make_symbol("phrase");
+		else if (field.is_contact())
+			return make_symbol("contact");
+		else if (field.is_range())
+			return make_symbol("range");
+		else
+			return SCM_BOOL_F;
+	};
+
+	field_for_each([&](const auto& field) {
+		SCM field_scm = alist_add(SCM_EOL,
+					  make_symbol("field"), make_symbol(field.name),
+					  make_symbol("name"),   field.name,
+					  make_symbol("shortcut"),
+					  field.shortcut ? to_scm(field.shortcut) : SCM_BOOL_F,
+					  make_symbol("value?"), field.is_value(),
+					  make_symbol("search-type"), search_type(field));
+		fields_scm = scm_cons(scm_reverse_x(field_scm, SCM_EOL), fields_scm);
+	});
+
+	scm_c_define("%fields", scm_reverse_x(fields_scm, SCM_EOL));
+}
+
+
 static void
 init_misc()
 {
@@ -217,6 +250,8 @@ init_module_mu(void* data)
 
 	init_options(conf.opts);
 	init_configuration();
+	init_fields_info();
+
 	init_misc();
 	init_subrs();
 

scm/mu-scm.hh

@@ -271,6 +271,8 @@ namespace Mu::Scm {
 		}
 		else if constexpr (std::is_same_v<Type, bool>)
 			return scm_from_bool(val);
+		else if constexpr (std::is_same_v<Type, char>)
+			return SCM_MAKE_CHAR(static_cast<unsigned char>(val));
 		else if constexpr (std::is_same_v<Type, size_t>)
 			return scm_from_size_t(val);
 		else if constexpr (std::is_same_v<Type, int>)

scm/mu-scm.scm

@@ -20,6 +20,7 @@
   :use-module (oop goops)
   :use-module (system foreign)
   :use-module (rnrs bytevectors)
+  :use-module (srfi srfi-1) ;; lists
   :use-module (ice-9 optargs)
   :use-module (ice-9 format)
   :use-module (ice-9 binary-ports)
@@ -102,6 +103,8 @@
 	    ;; misc
             options
             configuration
+            fields
+            field
 
             %options  ;; deprecated, use (options)
 
@@ -635,9 +638,21 @@ init'. Uses the default-store."
 (set-documentation! '%configuration
 		    "Alist with the mu system configuration parameters.")
 (define (configuration)
-  "Alist with the mu system configuration parameters.."
+  "Alist with the mu system configuration parameters."
   %configuration)
 
+%fields ;; defined in c++
+(set-documentation! '%fields
+		    "Alist with information about mu database fields.")
+(define (fields)
+  "Alist with information about mu database fields."
+  %fields)
+
+(define (field field-id)
+  "Get the information alist for FIELD-ID.
+If FIELD does not exist, return #f."
+  (find (lambda(item) (eq? (assoc-ref item 'field) field-id)) (fields)))
+
 (define %preferences
   '( (short-date  . "%F %T")
      (utc?        . #f)))

scm/mu-scm.texi

@@ -968,14 +968,58 @@ Other options may be added.
 @deffn {Scheme Procedure} configuration
 @end deffn
 
-An association-list (alist) of the @t{mu} system configuration. This might look
-something like:
+An association-list (alist) of the @t{mu} system configuration, similar to what
+you get with the @code{mu info} command. This might look something like:
 @lisp
 (configuration)
-((mu-version . "1.14.3") (xapian-version . "1.4.30") (glib-version . "2.88.2")
+=> ((mu-version . "1.14.3") (xapian-version . "1.4.30") (glib-version . "2.88.2")
  (gmime-version . "3.2.15") (scm-enabled? . #t) (language-enabled? . #t))
 @end lisp
 
+
+@deffn {Scheme Procedure} fields
+@end deffn
+
+An association-list (alist) with information about @t{mu}'s database fields,
+similar to what you get with the @command{mu info fields} command. This looks something like:
+
+@lisp
+(fields)
+=> (((field . bcc) (name . "bcc") (shortcut . #\h) (value? . #t) (search-type . phrase))
+((field . body) (name . "body") (shortcut . #\b) (value? . #f) (search-type . phrase))
+((field . cc) (name . "cc") (shortcut . #\c) (value? . #t) (search-type . phrase))
+((field . changed) (name . "changed") (shortcut . #\k) (value? . #t) (search-type . range))
+((field . date) (name . "date") (shortcut . #\d) (value? . #t) (search-type . range))
+((field . embed) (name . "embed") (shortcut . #\e) (value? . #f) (search-type . phrase))
+((field . file) (name . "file") (shortcut . #\j) (value? . #f) (search-type . boolean))
+((field . flags) (name . "flags") (shortcut . #\g) (value? . #t) (search-type . boolean))
+((field . from) (name . "from") (shortcut . #\f) (value? . #t) (search-type . phrase))
+((field . language) (name . "language") (shortcut . #\a) (value? . #t) (search-type . boolean))
+((field . maildir) (name . "maildir") (shortcut . #\m) (value? . #t) (search-type . boolean))
+((field . list) (name . "list") (shortcut . #\v) (value? . #t) (search-type . boolean))
+((field . message-id) (name . "message-id") (shortcut . #\i) (value? . #t) (search-type . boolean))
+((field . mime) (name . "mime") (shortcut . #\y) (value? . #f) (search-type . boolean))
+((field . path) (name . "path") (shortcut . #\l) (value? . #t) (search-type . boolean))
+((field . priority) (name . "priority") (shortcut . #\p) (value? . #t) (search-type . boolean))
+((field . references) (name . "references") (shortcut . #\r) (value? . #t) (search-type . boolean))
+((field . size) (name . "size") (shortcut . #\z) (value? . #t) (search-type . range))
+((field . subject) (name . "subject") (shortcut . #\s) (value? . #t) (search-type . phrase))
+((field . tags) (name . "tags") (shortcut . #\x) (value? . #t) (search-type . boolean))
+((field . thread) (name . "thread") (shortcut . #\w) (value? . #t) (search-type . boolean))
+((field . to) (name . "to") (shortcut . #\t) (value? . #t) (search-type . phrase))
+((field . labels) (name . "labels") (shortcut . #\q) (value? . #t) (search-type . boolean)))
+@end lisp
+
+@deffn {Scheme Procedure} field
+@end deffn
+
+Gets information about one specific fields (from @code{fields}). E.g.
+
+@lisp
+(field 'subject)
+=> ((field . subject) (name . "subject") (shortcut . #\s) (value? . #t) (search-type . phrase))
+@end lisp
+
 @c @defvar %preferences
 @c @end defvar