From: Ulya Trofimovich <skvadrik@gmail.com>
Date: Sat, 8 Apr 2017 10:35:14 +0000 (+0100)
Subject: 'save' commands also need topological sorting: they may depend on history.
X-Git-Tag: 1.0~39^2~69
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=9cfa0ca3c93545ffaef500834a2e2406b00b0e21;p=re2c

'save' commands also need topological sorting: they may depend on history.
---

diff --git a/re2c/src/dfa/find_state.cc b/re2c/src/dfa/find_state.cc
index 95a85423..9a36b217 100644
--- a/re2c/src/dfa/find_state.cc
+++ b/re2c/src/dfa/find_state.cc
@@ -292,7 +292,7 @@ tcmd_t *kernels_t::actions(tcmd_t *acts)
 	*pa = acts;
 
 	// see note [topological ordering of copy commands]
-	tcmd_t::topsort(&copy, indeg);
+	tcmd_t::topsort1(&copy, indeg);
 
 	return copy;
 }
diff --git a/re2c/src/dfa/tcmd.cc b/re2c/src/dfa/tcmd.cc
index 9fa77fd3..2ea2f4d8 100644
--- a/re2c/src/dfa/tcmd.cc
+++ b/re2c/src/dfa/tcmd.cc
@@ -134,6 +134,49 @@ tcmd_t **topsort_(tcmd_t **phead, uint32_t *indeg)
 	return py;
 }
 
+static tagver_t depend(const tcmd_t *x)
+{
+	const tagver_t r = x->rhs, h = x->pred;
+	return tcmd_t::iscopy(r) ? r : h;
+}
+
+void tcmd_t::topsort1(tcmd_t **phead, uint32_t *indeg)
+{
+	tcmd_t
+		*x0 = *phead, **px, *x,
+		*y0 = NULL, **py, **py1;
+
+	// initialize in-degree
+	for (x = x0; x; x = x->next) {
+		++indeg[depend(x)];
+	}
+
+	for (py = &y0;;) {
+		// reached end of list
+		if (!x0) break;
+
+		px = &x0;
+		py1 = py;
+		for (x = x0; x; x = x->next) {
+			if (indeg[x->lhs] == 0) {
+				--indeg[depend(x)];
+				*py = x;
+				py = &x->next;
+			} else {
+				*px = x;
+				px = &x->next;
+			}
+		}
+		*px = NULL;
+
+		// only cycles left
+		if (py == py1) break;
+	}
+	*py = x0;
+
+	*phead = y0;
+}
+
 tcpool_t::tcpool_t()
 	: alc()
 	, index()
diff --git a/re2c/src/dfa/tcmd.h b/re2c/src/dfa/tcmd.h
index 1dbd3f80..93aa6334 100644
--- a/re2c/src/dfa/tcmd.h
+++ b/re2c/src/dfa/tcmd.h
@@ -21,6 +21,7 @@ struct tcmd_t
 	static void swap(tcmd_t &x, tcmd_t &y);
 	static bool equal(const tcmd_t &x, const tcmd_t &y);
 	static void topsort(tcmd_t **phead, uint32_t *indeg);
+	static void topsort1(tcmd_t **phead, uint32_t *indeg);
 	static bool iscopy(tagver_t rhs);
 	static bool isset(const tcmd_t *cmd);
 	static bool isadd(const tcmd_t *cmd);