finish `current-metas` (closes #166)

pollen/private/ts.rktd

@@ -1 +1 @@
-1516660322
+1518738938

pollen/render.rkt

@@ -77,7 +77,7 @@
                                    has/is-markup-source?
                                    has/is-scribble-source?
                                    has/is-markdown-source?))])
-       (pred so-path))
+             (pred so-path))
      (define-values (source-path output-path) (->source+output-paths so-path))
      (render-to-file-if-needed source-path #f output-path)]
     [(pagetree-source? so-path) (render-pagenodes so-path)])
@@ -151,7 +151,7 @@
   (define render-proc (for/first ([test (in-list tests)]
                                   [render-proc (in-list render-procs)]
                                   #:when (test source-path))
-                        render-proc))
+                                 render-proc))
   (unless render-proc
     (raise-argument-error 'render (format "valid rendering function for ~a" source-path) render-proc))
   
@@ -235,17 +235,18 @@
                     pollen/pagetree
                     pollen/core)
            DIRECTORY-REQUIRE-FILES
-           (parameterize ([current-pagetree (make-project-pagetree CPR)])
-             (define DOC-ID (cached-doc SOURCE-PATH-STRING))
-             (define META-ID (cached-metas SOURCE-PATH-STRING))
+           (define DOC-ID (cached-doc SOURCE-PATH-STRING))
+           (define META-ID (cached-metas SOURCE-PATH-STRING))
+           (parameterize ([current-pagetree (make-project-pagetree CPR)]
+                          [current-metas META-ID])
              (local-require pollen/template pollen/top)
              (define here (path->pagenode (or (select-from-metas 'HERE-PATH-KEY META-ID) 'unknown)))
              (if (bytes? DOC-ID) ; if main export is binary, just pass it through
                  DOC-ID
                  (include-template #:command-char COMMAND-CHAR (file TEMPLATE-PATH))))))))
-  ;; set current-directory because include-template wants to work relative to source location
-  (time (parameterize ([current-directory (->complete-path (dirname source-path))]) 
-          (render-through-eval expr-to-eval))))
+;; set current-directory because include-template wants to work relative to source location
+(time (parameterize ([current-directory (->complete-path (dirname source-path))]) 
+        (render-through-eval expr-to-eval))))
 
 
 (define (templated-source? path)
@@ -258,7 +259,7 @@
   (define (file-exists-or-has-source? p) ; p could be #f
     (and p (for/first ([proc (in-list (list values ->preproc-source-path ->null-source-path))]
                        #:when (file-exists? (proc p)))
-             p)))
+                      p)))
   
   (define (get-template)
     (define output-path (or maybe-output-path (->output-path source-path)))

pollen/scribblings/core.scrbl

@@ -146,3 +146,11 @@ Note that if @racket[_meta-source] is a relative path or pagenode, it is treated
 (select-from-metas 'nonexistent-key metas)
 ]
 
+@section{Parameters}
+
+@defparam[current-metas hash (or/c #f hash?) #:value #f]{Holds the @racket[metas] of the current Pollen source. In tag functions, rather than pass @racket[metas] as an argument, you can refer to @racket[(current-metas)] within the body of the function. Likewise, if your tag function calls other tag functions, they can all invoke @racket[(current-metas)] instead of passing the value around.
+
+@racket[(current-metas)] will also work in templates, holding the @racket[metas] of the source currently being rendered into the template. 
+
+Note that the default value is @racket[#f]. This indicates that no metas value is available. It is up to you to code your tag functions to do something sensible if this circumstance arises.}
+