Initial revision

diff --git a/nodetype.h b/nodetype.h
new file mode 100644 (file)
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--- /dev/null
+++ b/nodetype.h
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+/* nodetype.h -- macros that describe the semantics of nodes */
+
+#define car    u.n.left
+#define cdr    u.n.right
+
+/*
+ * Define token classes for consistency checks here.  The theory is
+ * that by separating this from the tree-traversal machinery below, we
+ * may be able to parametrize for different source languages someday.
+ */
+/* does the node represent an atom? */
+#define ATOMIC(n)      ((n) == IDENTIFIER || (n) == NUMBER || (n) == STRING)
+/* does the node reference a statement label? */
+#define SLABELREF(n)   ((n) == GO || (n) == OG)
+/* does the node reference a block label? */
+#define BLABELREF(n)   ((n) == PERFORM)
+/* does the node set a variable? */
+#define VARSET(n)      ((n) == LET || (n) == READ || (n) == ITERATE)
+/* does the (non-VARSET) node refer to its left operand as a variable? */ 
+#define LEFTREF(n)     ((n) != FOR && (n) != GO && (n) != OG && (n) != LABEL \
+                               && (n) != ALLOCATE && (n) != WATCH \
+                               && (n) != ITERATE && (n) != FROM \
+                               && (n) != PERFORM)
+/* does the (non-VARSET) node refer to its right operand? */
+#define RIGHTREF(n)    ((n) != PERFORM)
+
+/* nodetype.h ends here */