From 0ed240e1230d35f81523b09523e7dedfb09240f7 Mon Sep 17 00:00:00 2001
From: joe-conigliaro <joe-conigliaro@users.noreply.github.com>
Date: Mon, 22 Jul 2019 20:44:08 +1000
Subject: [PATCH] modules: cycle error improvements

---
 compiler/modules.v | 34 +++++++++++++++++++++++-----------
 1 file changed, 23 insertions(+), 11 deletions(-)

diff --git a/compiler/modules.v b/compiler/modules.v
index 8817ad4400..cc664ebd19 100644
--- a/compiler/modules.v
+++ b/compiler/modules.v
@@ -5,8 +5,10 @@
 module main
 
 struct ModDepGraphNode  {
+mut:
 	name string
 	deps []string
+	last_cycle string
 }
 
 struct ModDepGraph {
@@ -21,13 +23,13 @@ struct DepSet {
 	items []string
 }
 
-pub fn(mapset mut DepSet) add(item string) {
-	mapset.items << item
+pub fn(dset mut DepSet) add(item string) {
+	dset.items << item
 }
 
-pub fn(mapset &DepSet) diff(otherset DepSet) DepSet {
+pub fn(dset &DepSet) diff(otherset DepSet) DepSet {
 	mut diff := DepSet{}
-	for item in mapset.items {
+	for item in dset.items {
 		if !item in otherset.items {
 			diff.items << item
 		}
@@ -35,8 +37,8 @@ pub fn(mapset &DepSet) diff(otherset DepSet) DepSet {
 	return diff
 }
 
-pub fn(mapset &DepSet) size() int {
-	return mapset.items.len
+pub fn(dset &DepSet) size() int {
+	return dset.items.len
 }
 
 pub fn new_mod_dep_graph() *ModDepGraph {
@@ -88,13 +90,18 @@ pub fn(graph &ModDepGraph) resolve() *ModDepGraph {
 		if ready_set.size() == 0 {
 			mut g := new_mod_dep_graph()
 			g.acyclic = false
+			ndk := node_deps.keys()
 			for name, _ in node_deps {				
-				g.nodes << node_names[name]
+				mut node := node_names[name]
+				if name == ndk[node_deps.size-1] {
+					node.last_cycle = node_deps[name].items[node_deps[name].items.len-1]
+				}
+				g.nodes << node
 			}
 			return g
 		}
 
-		ready_set.items.len > 0 {
+		ready_set.size() > 0 {
 			mut new_set := map[string]DepSet{}
 			for name in ready_set.items {
 				// node_deps.remove(name)
@@ -133,9 +140,14 @@ pub fn(graph &ModDepGraph) last_node() {
 }
 
 pub fn(graph &ModDepGraph) display() {
-	for _, node in graph.nodes {
-		for _, dep in node.deps {
-			println(' * $node.name -> $dep')
+	for i:=0; i<graph.nodes.len; i++ {
+		node := graph.nodes[i]
+		for dep in node.deps {
+			mut out := ' * $node.name -> $dep'
+			if !graph.acyclic && i == graph.nodes.len-1 && dep == node.last_cycle {
+				out += ' <-- last cycle'
+			}
+			println(out)
 		}
 	}
 }