make contributor syntax uniform

Related to #5

TODO: refactor duplicated code in tree-parser.rkt

dia/attribution2.rkt

@@ -7,7 +7,7 @@
 Format:
   #lang abe/attribution2 exported-attributions-id
 
-  - Appraisal tree [N%]
+  - [contributors] Appraisal tree [N%]
   ...
 
 Meaning:
@@ -19,14 +19,9 @@ with bracketed percentags [N%] at the end of the line.
 - Validate attributions.
 - Export (provide) the exported-attributions-id bound to the attributions.
 
-To identify attributions, the first sequence of non-space characters after a
-bullet is used. For capital, this means that descriptive bullets without a
-project name should be given a faux project name.
-
-Additionally, a sequence of non-space characters followed by the text " and "
-and another sequence of non-space characters is considered an attributive "pair"
-and is attributed as a single unit, to account for teamwork. Groups of sizes
-larger than 2 are not yet supported.
+To identify attributions, contributors are listed, comma-separated, in
+[square-brackets] at the beginning of a bullet. This holds for labor, too, to
+name the project but permit additional description.
 
 |#
 
@@ -61,7 +56,7 @@ larger than 2 are not yet supported.
               (format "expected identifier\n  read: ~s" name)
               (current-continuation-marks)
               (list (srcloc src (syntax-line name) (syntax-column name) (syntax-position name) (syntax-span name))))))
-    (define tree (read-attribution-tree in))
+    (define tree (read-attribution-tree2 in))
     (strip-context #`(#,name <= #,tree)))
   (define (reader in)
     (syntax->datum (syntax-reader #f in))))

dia/tree-parser.rkt

@@ -1,6 +1,7 @@
 #lang racket
 
 (provide read-attribution-tree
+         read-attribution-tree2
          read-idea-attribution-tree
          read-idea-antecedents-tree)
 
@@ -25,6 +26,12 @@ corresponding kind of tree.
       (make-indent-based-tree (flow (regexp-replace* #px"[[:blank:]]" _ " ")))
       (tree-map label->attribution leaf->attribution)))
 
+(define-flow (read-attribution-tree2 ip)
+  (~> port->lines
+      (filter non-empty-string? _)
+      (make-indent-based-tree (flow (regexp-replace* #px"[[:blank:]]" _ " ")))
+      (tree-map label->attribution leaf->attribution2)))
+
 (define-flow (read-idea-attribution-tree ip)
   (~> port->lines
       (filter non-empty-string? _)
@@ -116,6 +123,19 @@ on format.
      (cons (if name2 (list name1 name2) name1)
            attribution)]))
 
+(define (leaf->attribution2 x)
+  (match x
+    ;; uniform contribution syntax (https://github.com/drym-org/dia/issues/5):
+    ;;     * [comma-separated contributors] contribution [allocation%]
+    ;; Arbitrary spaces are permitted between start of line and start of
+    ;; bulleted item.
+    [(regexp #px"^\\s*\\* \\[([^]]+)\\].*\\[([[:digit:].]+)%\\]"
+             (list _ contributors (app string->number attribution)))
+     (cons (~> (contributors)
+               (string-split ", ")
+               (if (~> cdr null?) car _))
+           attribution)]))
+
 (define (label->attribution x)
   (match x
     [(regexp #px"^\\s*\\* (.*) \\[([[:digit:].]+)%\\]"