From 20f82b0a8b47cdcdead0939a2c8fd2d459774fc7 Mon Sep 17 00:00:00 2001
From: John MacFarlane <jgm@berkeley.edu>
Date: Sat, 1 Oct 2022 12:34:27 -0700
Subject: Makefile target to get module dependeny subgraphs.

E.g. what depends on Text.Pandoc.Parsing?

    make modules.pdf ROOTNODE=T.P.Parsing

This is helpful for figuring out what we can split out as separate
packages.
---
 Makefile            |  5 ++++-
 tools/cliptree.gvpr | 17 +++++++++++++++++
 2 files changed, 21 insertions(+), 1 deletion(-)
 create mode 100644 tools/cliptree.gvpr

diff --git a/Makefile b/Makefile
index ab37439d6..9388c5d6f 100644
--- a/Makefile
+++ b/Makefile
@@ -8,6 +8,7 @@ COMMIT=$(shell git rev-parse --short HEAD)
 TIMESTAMP=$(shell date "+%Y%m%d_%H%M")
 LATESTBENCH=$(word 1,$(shell ls -t bench_*.csv 2>/dev/null))
 BASELINE?=$(LATESTBENCH)
+ROOTNODE?=T.P
 ifeq ($(BASELINE),)
 BASELINECMD=
 else
@@ -174,8 +175,10 @@ modules.dot: $(SOURCEFILES)
 		| sed -e 's/Text\.Pandoc\([^ ]*\)/"T\.P\1"/g' >> $@
 	@echo "}" >> $@
 
+# To get the module dependencies of T.P.Parsing:
+# make modules.pdf ROOTNODE=T.P.Parsing
 modules.pdf: modules.dot
-	cat $< | dot -Tpdf > $@
+	gvpr -f tools/cliptree.gvpr -a '"$(ROOTNODE)"' $< | dot -Tpdf > $@
 
 clean: ## clean up
 	cabal clean
diff --git a/tools/cliptree.gvpr b/tools/cliptree.gvpr
new file mode 100644
index 000000000..428cdfee5
--- /dev/null
+++ b/tools/cliptree.gvpr
@@ -0,0 +1,17 @@
+/* Construct subgraph reachable from node ARGV[0] by forward edges */
+BEG_G {
+  node_t r = node($,ARGV[0]);
+
+  $tvroot = r;
+  $tvtype = TV_fwd;
+  //print ("//  Staring node: ", r.name);
+}
+N{
+  print ("// subgraph node: ", $.name);
+  $tvroot=NULL;
+  subnode($T,$);
+}
+E{
+  print ("// subgraph edge: ", $.name);
+  subedge($T,$);
+}
-- 
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