* Some utility functions for working with ATerms.

1 files changed, 55 insertions, 0 deletions

diff --git a/src/libnix/aterm.hh b/src/libnix/aterm.hh
new file mode 100644
index 0000000000..1e4ee80eea
--- /dev/null
+++ b/src/libnix/aterm.hh
@@ -0,0 +1,55 @@
+#ifndef __ATERM_H
+#define __ATERM_H
+
+extern "C" {
+#include <aterm2.h>
+}
+
+#include "util.hh"
+
+
+/* Print an ATerm. */
+string atPrint(ATerm t);
+
+/* Write an ATerm to an output stream. */
+ostream & operator << (ostream & stream, ATerm e);
+
+/* Type-safe matching. */
+
+struct ATMatcher 
+{
+    ATerm t;
+    int pos;
+    const static int failPos = -2;
+    const static int funPos = -1;
+
+    ATMatcher() : t(0), pos(failPos)
+    {
+    }
+
+    operator bool() const
+    {
+        return pos != failPos;
+    }
+};
+
+/* Initiate matching of a term. */
+ATMatcher & atMatch(ATMatcher & pos, ATerm t);
+
+/* Get the next argument of an application. */
+ATMatcher & operator >> (ATMatcher & pos, ATerm & out);
+
+/* Get the name of the function symbol of an applicatin, or the next
+   argument of an application as a string. */
+ATMatcher & operator >> (ATMatcher & pos, string & out);
+
+/* Like the previous, but check that the string is equal to the given
+   string. */
+ATMatcher & operator >> (ATMatcher & pos, const string & s);
+
+/* Get the next argument of an application, and verify that it is a
+   list. */
+ATMatcher & operator >> (ATMatcher & pos, ATermList & out);
+
+
+#endif /* !__ATERM_H */