[pure-lang-svn] SF.net SVN: pure-lang: [40] pure/trunk

[<ag...@us...>]

Revision: 40
          http://pure-lang.svn.sourceforge.net/pure-lang/?rev=40&view=rev
Author:   agraef
Date:     2008-05-03 15:02:26 -0700 (Sat, 03 May 2008)

Log Message:
-----------
Add operations to check for and deconstruct function applications.

Modified Paths:
--------------
    pure/trunk/lib/primitives.pure
    pure/trunk/runtime.cc
    pure/trunk/runtime.h

Modified: pure/trunk/lib/primitives.pure
===================================================================
--- pure/trunk/lib/primitives.pure	2008-05-03 21:06:12 UTC (rev 39)
+++ pure/trunk/lib/primitives.pure	2008-05-03 22:02:26 UTC (rev 40)
@@ -38,8 +38,11 @@
 stringp x	= case x of _::string  = 1; _ = 0 end;
 pointerp x	= case x of _::pointer = 1; _ = 0 end;
 
-/* Predicates to check for proper lists and tuples. */
+/* Predicates to check for function applications and proper lists and
+   tuples. */
 
+extern bool applp(expr*);
+
 listp []	= 1;
 listp (x:xs)	= listp xs;
 listp _		= 0 otherwise;
@@ -48,6 +51,10 @@
 tuplep (x,xs)	= 1;
 tuplep _	= 0 otherwise;
 
+/* Operations to return the function and the argument in an application. */
+
+extern expr* fun(expr*), expr* arg(expr*);
+
 /* Conversions between the different numeric and pointer types. */
 
 extern expr* pure_intval(expr*), expr* pure_dblval(expr*),

Modified: pure/trunk/runtime.cc
===================================================================
--- pure/trunk/runtime.cc	2008-05-03 21:06:12 UTC (rev 39)
+++ pure/trunk/runtime.cc	2008-05-03 22:02:26 UTC (rev 40)
@@ -1095,6 +1095,30 @@
 }
 
 extern "C"
+bool applp(const pure_expr *x)
+{
+  return (x->tag == EXPR::APP);
+}
+
+extern "C"
+pure_expr *fun(const pure_expr *x)
+{
+  if (x->tag == EXPR::APP)
+    return x->data.x[0];
+  else
+    return 0;
+}
+
+extern "C"
+pure_expr *arg(const pure_expr *x)
+{
+  if (x->tag == EXPR::APP)
+    return x->data.x[1];
+  else
+    return 0;
+}
+
+extern "C"
 int32_t pointer_get_byte(void *ptr)
 {
   uint8_t *p = (uint8_t*)ptr;

Modified: pure/trunk/runtime.h
===================================================================
--- pure/trunk/runtime.h	2008-05-03 21:06:12 UTC (rev 39)
+++ pure/trunk/runtime.h	2008-05-03 22:02:26 UTC (rev 40)
@@ -256,6 +256,16 @@
 
 bool same(const pure_expr *x, const pure_expr *y);
 
+/* Check whether an object is a function application, and return the function
+   and the argument of an application. Note that these operations can't be
+   defined in Pure because of the "head is function" rule which means that in
+   a pattern of the form f x, f is always a literal function symbol and not a
+   variable. */
+
+bool applp(const pure_expr *x);
+pure_expr *fun(const pure_expr *x);
+pure_expr *arg(const pure_expr *x);
+
 /* Direct memory accesses. */
 
 int32_t pointer_get_byte(void *ptr);


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