Add unflatten functionality

cgraph/cgraph.go

@@ -108,6 +108,11 @@ func ParseBytes(bytes []byte) (*Graph, error) {
 	return toGraph(graph), nil
 }
 
+func UnflattenGraph(graph *Graph, maxMinlen int, chainLimit int, doFans bool) *Graph {
+	ccall.Transform(graph.Agraph, maxMinlen, chainLimit, doFans)
+	return graph
+}
+
 func ParseFile(path string) (*Graph, error) {
 	file, err := ioutil.ReadFile(path)
 	if err != nil {

graphviz.go

@@ -54,6 +54,10 @@ func ParseBytes(bytes []byte) (*cgraph.Graph, error) {
 	return graph, nil
 }
 
+func UnflattenGraph(graph *cgraph.Graph, maxMinlen int, chainLimit int, doFans bool) *cgraph.Graph {
+	return cgraph.UnflattenGraph(graph, maxMinlen, chainLimit, doFans)
+}
+
 func New() *Graphviz {
 	return &Graphviz{
 		ctx:    gvc.New(),

internal/ccall/unflatten.c

@@ -0,0 +1 @@
+#include "unflatten/unflatten.c"

internal/ccall/unflatten.go

@@ -0,0 +1,17 @@
+package ccall
+
+/*
+#cgo CFLAGS: -Iunflatten
+#include "unflatten.h"
+*/
+import "C"
+
+func Transform(g *Agraph, maxMinlen int, chainLimit int, doFans bool) {
+	var doFansValue int
+	if doFans {
+		doFansValue = 1
+	} else {
+		doFansValue = 0
+	}
+	C.transform(g.c, C.int(maxMinlen), C.int(chainLimit), C.int(doFansValue))
+}

internal/ccall/unflatten/unflatten.c

@@ -0,0 +1,132 @@
+/*************************************************************************
+ * Copyright (c) 2011 AT&T Intellectual Property 
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors: Details at https://graphviz.org
+ *************************************************************************/
+
+
+/*
+ * Written by Stephen North
+ * Updated by Emden Gansner
+ * https://gitlab.com/graphviz/graphviz/-/blob/main/cmd/tools/unflatten.c
+ */
+#include "config.h"
+
+#include    <stdbool.h>
+#include    <stdio.h>
+#include    <stdlib.h>
+#include    <string.h>
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>
+#endif
+#include    <cgraph/cgraph.h>
+#include    <ingraphs/ingraphs.h>
+#include    <unflatten/unflatten.h>
+
+#include <getopt.h>
+
+int myindegree(Agnode_t *n)
+{
+	return agdegree(n->root, n, TRUE, FALSE);
+}
+
+/* need outdegree without selfarcs */
+int myoutdegree(Agnode_t *n)
+{
+	Agedge_t 	*e;
+	int rv = 0;
+
+	for (e = agfstout(n->root, n); e; e = agnxtout(n->root, e)) {
+		if (agtail(e) != aghead(e)) rv++;
+	}
+	return rv;
+}
+
+bool isleaf(Agnode_t * n)
+{
+    return myindegree(n) + myoutdegree(n) == 1;
+}
+
+bool ischainnode(Agnode_t * n)
+{
+    return myindegree(n) == 1 && myoutdegree(n) == 1;
+}
+
+void adjustlen(Agedge_t * e, Agsym_t * sym, int newlen)
+{
+    char buf[12];
+
+    snprintf(buf, sizeof(buf), "%d", newlen);
+    agxset(e, sym, buf);
+}
+
+Agsym_t *bindedgeattr(Agraph_t * g, char *str)
+{
+    return agattr(g, AGEDGE, str, "");
+}
+
+void transform(Agraph_t * g, int maxMinlen, int chainLimit, int doFans)
+{
+	bool Do_fans = doFans == 1;
+	int chainSize = 0;
+	Agnode_t *chainNode = NULL;
+	Agnode_t *n;
+	Agedge_t *e;
+	char *str;
+	Agsym_t *m_ix, *s_ix;
+	int cnt, d;
+
+	m_ix = bindedgeattr(g, "minlen");
+	s_ix = bindedgeattr(g, "style");
+
+	for (n = agfstnode(g); n; n = agnxtnode(g, n)) {
+		d = myindegree(n) + myoutdegree(n);
+		if (d == 0) {
+	    if (chainLimit < 1)	{
+				continue;
+			}
+	    if (chainNode) {
+				e = agedge(g, chainNode, n, "", TRUE);
+				agxset(e, s_ix, "invis");
+				chainSize++;
+				if (chainSize < chainLimit) {
+						chainNode = n;
+				} else {
+						chainNode = NULL;
+						chainSize = 0;
+				}
+	    } else {
+				chainNode = n;
+			}
+		} else if (d > 1) {
+			if (maxMinlen < 1) {
+				continue;
+			}
+			cnt = 0;
+			for (e = agfstin(g, n); e; e = agnxtin(g, e)) {
+				if (isleaf(agtail(e))) {
+					str = agxget(e, m_ix);
+					if (str[0] == 0) {
+						adjustlen(e, m_ix, cnt % maxMinlen + 1);
+						cnt++;
+					}
+				}
+			}
+
+			cnt = 0;
+			for (e = agfstout(g, n); e; e = agnxtout(g, e)) {
+				if (isleaf(e->node) || (Do_fans && ischainnode(e->node))) {
+					str = agxget(e, m_ix);
+					if (str[0] == 0) {
+						adjustlen(e, m_ix, cnt % maxMinlen + 1);
+					}
+					cnt++;
+				}
+			}
+		}
+	}
+}

internal/ccall/unflatten/unflatten.h

@@ -0,0 +1,3 @@
+#include <cgraph.h>
+
+void transform(Agraph_t * g, int maxMinlen, int chainLimit, int doFans);