[bug#27907] [PATCH] graph: Provide access to the package record in the emit

[Roel Janssen <roel@gnu.org>]

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From 0243051f4a650f729e20645606d45d7138f2aa8c Mon Sep 17 00:00:00 2001
From: Roel Janssen <roel@gnu.org>
Date: Tue, 1 Aug 2017 16:30:02 +0200
Subject: [PATCH] graph:  Provide access to the package record in the emit
 functions.

* guix/graph.scm (export-graph): Pass the node to the emit functions, instead
  of the node's label.
---
 guix/graph.scm | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/guix/graph.scm b/guix/graph.scm
index d7fd5f3..0219787 100644
--- a/guix/graph.scm
+++ b/guix/graph.scm
@@ -22,6 +22,7 @@
   #:use-module (guix monads)
   #:use-module (guix records)
   #:use-module (guix sets)
+  #:use-module (guix packages)
   #:use-module (rnrs io ports)
   #:use-module (srfi srfi-1)
   #:use-module (srfi srfi-9)
@@ -170,9 +171,9 @@ typically returned by 'node-edges' or 'node-back-edges'."
           name))
 (define (emit-epilogue port)
   (display "\n}\n" port))
-(define (emit-node id label port)
+(define (emit-node id node port)
   (format port "  \"~a\" [label = \"~a\", shape = box, fontname = Helvetica];~%"
-          id label))
+          id (package-full-name node)))
 (define (emit-edge id1 id2 port)
   (format port "  \"~a\" -> \"~a\" [color = ~a];~%"
           id1 id2 (pop-color id1)))
@@ -213,11 +214,11 @@ var nodes = {},
   (format port "</script><script type=\"text/javascript\" src=\"~a\"></script></body></html>"
           (search-path %load-path "graph.js")))
 
-(define (emit-d3js-node id label port)
+(define (emit-d3js-node id node port)
   (format port "\
 nodes[\"~a\"] = {\"id\": \"~a\", \"label\": \"~a\", \"index\": nodeArray.length};
 nodeArray.push(nodes[\"~a\"]);~%"
-          id id label id))
+          id id (package-full-name node) id))
 
 (define (emit-d3js-edge id1 id2 port)
   (format port "links.push({\"source\": \"~a\", \"target\": \"~a\"});~%"
@@ -241,9 +242,9 @@ nodeArray.push(nodes[\"~a\"]);~%"
 (define (emit-cypher-epilogue port)
   (format port ""))
 
-(define (emit-cypher-node id label port)
+(define (emit-cypher-node id node port)
   (format port "MERGE (p:Package { id: ~s }) SET p.name = ~s;~%"
-          id label ))
+          id (package-name node)))
 
 (define (emit-cypher-edge id1 id2 port)
   (format port "MERGE (a:Package { id: ~s });~%" id1)
@@ -296,7 +297,7 @@ true, draw reverse arrows."
                                         (ids          (mapm %store-monad
                                                             node-identifier
                                                             dependencies)))
-                     (emit-node id (node-label head) port)
+                     (emit-node id head port)
                      (for-each (lambda (dependency dependency-id)
                                  (if reverse-edges?
                                      (emit-edge dependency-id id port)
-- 
2.7.4


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Dear Guix,

I would like to expand the Cypher back-end and in the long run add a
SPARQL graph back-end to GNU Guix.  For this, I will need to have access
to the package records inside the emit-* functions.

This patch makes this change by essentially changing the "label"
parameter of the emit-* functions passed as "(node-label head)" into a
"node" parameter, passed as "head".

The rest of the patch adapts the current emit-* functions to this
change.

I tested the Graphviz, D3js, and Cypher back-ends, and all seem to work
as before.

Is it OK to apply this change?

Kind regards,
Roel Janssen