reader: Factor out new reader-find and reader-read procedures.

2 files changed, 26 insertions, 5 deletions

diff --git a/doc/haunt.texi b/doc/haunt.texi
index da05b9a..a612f35 100644
--- a/doc/haunt.texi
+++ b/doc/haunt.texi
@@ -639,6 +639,16 @@ Return @code{#t} if @var{file-name} is a file supported by
 @var{reader}.
 @end deffn
 
+@deffn {Procedure} reader-find? readers file-name
+Return the first reader in @var{readers} that can parse
+@var{file-name}, or @code{#f} if there is no such reader.
+@end deffn
+
+@deffn {Procedure} reader-read reader file-name
+Parse @var{file-name} using @var{reader} and return two values: an
+alist of metadata and an SXML tree.
+@end deffn
+
 @deffn {Procedure} read-post @var{reader} @var{file-name} [@var{default-metadata}]
 Read a post object from @var{file-name} using @var{reader}, merging
 its metadata with @var{default-metadata}, or the empty list if not
diff --git a/haunt/reader.scm b/haunt/reader.scm
index cc9ed67..5f575d8 100644
--- a/haunt/reader.scm
+++ b/haunt/reader.scm
@@ -50,6 +50,8 @@
             reader-matcher
             reader-proc
             reader-match?
+            reader-find
+            reader-read
             read-post
             read-posts
 
@@ -67,10 +69,20 @@
   "Return #t if FILE-NAME is a file supported by READER."
   ((reader-matcher reader) file-name))
 
+(define (reader-find readers file-name)
+  "Return the first reader in READERS that can parse FILE-NAME, or #f if
+there is no such reader."
+  (find (cut reader-match? <> file-name) readers))
+
+(define (reader-read reader file-name)
+  "Parse FILE-NAME using READER and return two values: an alist of
+metadata and an SXML tree."
+  ((reader-proc reader) file-name))
+
 (define* (read-post reader file-name #:optional (default-metadata '()))
   "Read a post object from FILE-NAME using READER, merging its
 metadata with DEFAULT-METADATA."
-  (let-values (((metadata sxml) ((reader-proc reader) file-name)))
+  (let-values (((metadata sxml) (reader-read reader file-name)))
     (make-post file-name
                (append metadata default-metadata)
                sxml)))
@@ -83,10 +95,9 @@ post."
 
   (define (leaf file-name stat memo)
     (if (keep? file-name)
-        (let ((reader (find (cut reader-match? <> file-name) readers)))
-          (if reader
-              (cons (read-post reader file-name default-metadata) memo)
-              (error "no reader available for post: " file-name)))
+        (match (reader-find readers file-name)
+          (reader (cons (read-post reader file-name default-metadata) memo))
+          (#f (error "no reader available for post: " file-name)))
         memo))
 
   (define (noop file-name stat result)