pure-lang-svn Mailing List for Pure (Page 24)

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Revision: 291
          http://pure-lang.svn.sourceforge.net/pure-lang/?rev=291&view=rev
Author:   agraef
Date:     2008-06-23 16:38:50 -0700 (Mon, 23 Jun 2008)

Log Message:
-----------
Start refactoring the runtime library in order to provide a sensible public API to external modules which need access to Pure expression data.

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

Modified: pure/trunk/runtime.cc
===================================================================

--- pure/trunk/runtime.cc	2008-06-23 13:07:26 UTC (rev 290)
+++ pure/trunk/runtime.cc	2008-06-23 23:38:50 UTC (rev 291)
@@ -298,51 +298,17 @@
   return pure_const(interpreter::g_interp->symtab.segfault_sym().f);
 }
 
-extern "C"
-pure_expr *pure_clos(bool local, bool thunked, int32_t tag, uint32_t n,
-		     void *f, void *e, uint32_t m, /* m x pure_expr* */ ...)
-{
-  // Parameterless closures are always thunked, otherwise they would already
-  // have been executed.
-  if (n==0) thunked = true;
-  pure_expr *x = new_expr();
-  x->tag = tag;
-  x->data.clos = new pure_closure;
-  x->data.clos->local = local;
-  x->data.clos->thunked = thunked;
-  x->data.clos->n = n;
-  x->data.clos->m = m;
-  x->data.clos->fp = f;
-  x->data.clos->ep = e;
-  if (e) ((Env*)e)->refc++;
-  if (m == 0)
-    x->data.clos->env = 0;
-  else {
-    x->data.clos->env = new pure_expr*[m];
-    va_list ap;
-    va_start(ap, m);
-    for (size_t i = 0; i < m; i++) {
-      x->data.clos->env[i] = va_arg(ap, pure_expr*);
-      assert(x->data.clos->env[i]->refc > 0);
-    }
-    va_end(ap);
-  }
-  MEMDEBUG_NEW(x)
-  return x;
-}
+/* PUBLIC API. **************************************************************/
 
-extern "C"
-pure_expr *pure_const(int32_t tag)
-{
-  // XXXFIXME: We should cache these on a per interpreter basis, so that only
-  // a single expression node exists for each symbol.
-  pure_expr *x = new_expr();
-  x->tag = tag;
-  x->data.clos = 0;
-  MEMDEBUG_NEW(x)
-  return x;
-}
+// XXXTODO
 
+int32_t pure_sym(const char *s);
+int32_t pure_getsym(const char *s);
+const char *pure_sym_pname(int32_t sym);
+int8_t pure_sym_nprec(int32_t sym);
+
+pure_expr *pure_symbol(int32_t sym);
+
 extern "C"
 pure_expr *pure_int(int32_t i)
 {
@@ -369,7 +335,7 @@
   }
 }
 
-static void make_bigint(mpz_t z, int32_t size, limb_t *limbs)
+static void make_bigint(mpz_t z, int32_t size, const limb_t *limbs)
 {
   // FIXME: For efficiency, we poke directly into the mpz struct here, this
   // might need to be reviewed for future GMP revisions.
@@ -385,7 +351,7 @@
 }
 
 extern "C"
-pure_expr *pure_bigint(int32_t size, limb_t *limbs)
+pure_expr *pure_bigint(int32_t size, const limb_t *limbs)
 {
   pure_expr *x = new_expr();
   x->tag = EXPR::BIGINT;
@@ -395,7 +361,7 @@
 }
 
 extern "C"
-pure_expr *pure_mpz(mpz_t z)
+pure_expr *pure_mpz(const mpz_t z)
 {
   pure_expr *x = new_expr();
   x->tag = EXPR::BIGINT;
@@ -466,9 +432,113 @@
   return x;
 }
 
+// XXXTODO
+
+pure_expr *pure_app(pure_expr *fun, pure_expr *arg);
+
+pure_expr *pure_listl(size_t size, ...);
+pure_expr *pure_listv(size_t size, pure_expr **elems);
+pure_expr *pure_tuplel(size_t size, ...);
+pure_expr *pure_tuplev(size_t size, pure_expr **elems);
+
+bool pure_is_symbol(const pure_expr *x, int32_t *sym);
+bool pure_is_int(const pure_expr *x, int32_t *i);
+bool pure_is_long(const pure_expr *x, int64_t *l);
+bool pure_is_bigint(const pure_expr *x, int32_t *size, limb_t **limbs);
+bool pure_is_mpz(const pure_expr *x, mpz_t *z);
+bool pure_is_double(const pure_expr *x, double *d);
+bool pure_is_pointer(const pure_expr *x, void **p);
+
+bool pure_is_string(const pure_expr *x, const char **sym);
+bool pure_is_string_dup(const pure_expr *x, char **sym);
+bool pure_is_cstring_dup(const pure_expr *x, char **sym);
+
+bool pure_is_app(const pure_expr *x, pure_expr **fun, pure_expr **arg);
+
+bool pure_is_listv(const pure_expr *x, size_t *size, pure_expr ***elems);
+bool pure_is_tuplev(const pure_expr *x, size_t *size, pure_expr ***elems);
+
 extern "C"
-int32_t pure_cmp_bigint(pure_expr *x, int32_t size, limb_t *limbs)
+pure_expr *pure_new(pure_expr *x)
 {
+  return pure_new_internal(x);
+}
+
+extern "C"
+void pure_free(pure_expr *x)
+{
+  pure_free_internal(x);
+}
+
+extern "C"
+void pure_freenew(pure_expr *x)
+{
+  if (x->refc == 0)
+    pure_free_internal(pure_new_internal(x));
+}
+
+extern "C"
+void pure_ref(pure_expr *x)
+{
+  x->refc++;
+}
+
+extern "C"
+void pure_unref(pure_expr *x)
+{
+  pure_unref_internal(x);
+}
+
+/* END OF PUBLIC API. *******************************************************/
+
+extern "C"
+pure_expr *pure_const(int32_t tag)
+{
+  // XXXFIXME: We should cache these on a per interpreter basis, so that only
+  // a single expression node exists for each symbol.
+  pure_expr *x = new_expr();
+  x->tag = tag;
+  x->data.clos = 0;
+  MEMDEBUG_NEW(x)
+  return x;
+}
+
+extern "C"
+pure_expr *pure_clos(bool local, bool thunked, int32_t tag, uint32_t n,
+		     void *f, void *e, uint32_t m, /* m x pure_expr* */ ...)
+{
+  // Parameterless closures are always thunked, otherwise they would already
+  // have been executed.
+  if (n==0) thunked = true;
+  pure_expr *x = new_expr();
+  x->tag = tag;
+  x->data.clos = new pure_closure;
+  x->data.clos->local = local;
+  x->data.clos->thunked = thunked;
+  x->data.clos->n = n;
+  x->data.clos->m = m;
+  x->data.clos->fp = f;
+  x->data.clos->ep = e;
+  if (e) ((Env*)e)->refc++;
+  if (m == 0)
+    x->data.clos->env = 0;
+  else {
+    x->data.clos->env = new pure_expr*[m];
+    va_list ap;
+    va_start(ap, m);
+    for (size_t i = 0; i < m; i++) {
+      x->data.clos->env[i] = va_arg(ap, pure_expr*);
+      assert(x->data.clos->env[i]->refc > 0);
+    }
+    va_end(ap);
+  }
+  MEMDEBUG_NEW(x)
+  return x;
+}
+
+extern "C"
+int32_t pure_cmp_bigint(pure_expr *x, int32_t size, const limb_t *limbs)
+{
   assert(x && x->tag == EXPR::BIGINT);
   mpz_t z;
   make_bigint(z, size, limbs);
@@ -812,37 +882,6 @@
 }
 
 extern "C"
-pure_expr *pure_new(pure_expr *x)
-{
-  return pure_new_internal(x);
-}
-
-extern "C"
-void pure_free(pure_expr *x)
-{
-  pure_free_internal(x);
-}
-
-extern "C"
-void pure_freenew(pure_expr *x)
-{
-  if (x->refc == 0)
-    pure_free_internal(pure_new_internal(x));
-}
-
-extern "C"
-void pure_ref(pure_expr *x)
-{
-  x->refc++;
-}
-
-extern "C"
-void pure_unref(pure_expr *x)
-{
-  pure_unref_internal(x);
-}
-
-extern "C"
 void pure_new_args(uint32_t n, ...)
 {
   va_list ap;
@@ -1067,6 +1106,8 @@
   if (bail_out) exit(0);
 }
 
+/* LIBRARY API. *************************************************************/
+
 extern "C"
 pure_expr *pure_byte_string(const char *s)
 {

Modified: pure/trunk/runtime.h
===================================================================
--- pure/trunk/runtime.h	2008-06-23 13:07:26 UTC (rev 290)
+++ pure/trunk/runtime.h	2008-06-23 23:38:50 UTC (rev 291)
@@ -15,6 +15,9 @@
 /* Our "limb" type. Used to pass bigint constants to the runtime. */
 typedef mp_limb_t limb_t;
 
+/* The following data structures should be considered opaque by
+   applications. */
+
 /* Closure data. This is a bit on the heavy side, so expressions which need
    it (i.e., functions) refer to this extra data via an allocated pointer. */
 
@@ -57,35 +60,178 @@
   pure_expr x[MEMSIZE];		// expression data
 } pure_mem;
 
-/* Expression constructors. */
+/* PUBLIC API. **************************************************************/
 
-pure_expr *pure_clos(bool local, bool thunked, int32_t tag, uint32_t n,
-		     void *f, void *e, uint32_t m, /* m x pure_expr* */ ...);
-pure_expr *pure_const(int32_t tag);
+/* The following routines are meant to be used by external C modules and other
+   applications which need direct access to Pure expression data. */
+
+/* Symbol table access. pure_sym returns the integer code of a (function or
+   variable) symbol given by its print name; if the symbol doesn't exist yet,
+   it is created (as an ordinary function or variable symbol). pure_getsym is
+   like pure_sym, but returns 0 if the symbol doesn't exist.
+
+   Given the (positive) symbol number, pure_sym_pname returns its print name
+   and pure_sym_nprec its "normalized" precedence. The latter is a small
+   integer value defined as nprec = 10*prec+fix, where prec is the precedence
+   level of the symbol and fix its fixity. For operators, the combined value
+   ranges from 0 (weakest infix operator on level 0) to 94 (strongest postfix
+   operator on level 9). Applications have nprec=95, ordinary function and
+   variable symbols nprec=100. */
+
+int32_t pure_sym(const char *s);
+int32_t pure_getsym(const char *s);
+const char *pure_sym_pname(int32_t sym);
+int8_t pure_sym_nprec(int32_t sym);
+
+/* Expression constructors. Atomic objects are constructed with the following
+   routines:
+
+   - pure_symbol: Takes the integer code of a symbol and returns that symbol
+     as a Pure value. If the symbol is a global variable or parameterless
+     function then it is evaluated, giving the value of the variable or the
+     return value of the function as the result.
+
+   - pure_int: Constructs a Pure machine int from a 32 bit integer value.
+
+   - pure_long: Constructs a Pure bigint from a 64 bit integer value.
+
+   - pure_bigint: Constructs a Pure bigint from a vector of limbs. The size
+     argument may be negative to denote a negative number, its absolute value
+     is the number of elements in the limbs vector (the vector is owned by the
+     caller and won't be be freed).
+
+   - pure_mpz: Constructs a Pure bigint from a (copy of a) GMP mpz_t.
+
+   - pure_double: Constructs a Pure floating point number from a double value.
+
+   - pure_pointer: Constructs a Pure pointer from a C pointer (void*). */
+
+pure_expr *pure_symbol(int32_t sym);
 pure_expr *pure_int(int32_t i);
 pure_expr *pure_long(int64_t l);
-pure_expr *pure_bigint(int32_t size, limb_t *limbs);
-pure_expr *pure_mpz(mpz_t z);
+pure_expr *pure_bigint(int32_t size, const limb_t *limbs);
+pure_expr *pure_mpz(const mpz_t z);
 pure_expr *pure_double(double d);
 pure_expr *pure_pointer(void *p);
 
 /* String constructors. There are four variations of these, depending on
    whether the original string is already in utf-8 (_string routines) or in
    the system encoding (_cstring), and whether the string should be copied
-   (_dup suffix) or whether Pure takes ownership of the string (no _dup
-   suffix). All these routines also handle the case that the given string is a
-   null pointer and will then return the appropriate Pure pointer expression
-   instead. */
+   (_dup suffix) or whether Pure takes ownership of the string. All four
+   routines handle the case that the given string is a null pointer and will
+   then return the appropriate Pure pointer expression instead. */
 
 pure_expr *pure_string_dup(const char *s);
 pure_expr *pure_cstring_dup(const char *s);
 pure_expr *pure_string(char *s);
 pure_expr *pure_cstring(char *s);
 
+/* Function applications. pure_app applies the given function to the given
+   argument. The result is evaluated if possible (i.e., if it is a saturated
+   function call). Otherwise, the result is a literal application and
+   references on function and argument are counted automatically. */
+
+pure_expr *pure_app(pure_expr *fun, pure_expr *arg);
+
+/* Convenience functions to construct Pure list and tuple values from a vector
+   or a varargs list of element expressions. (Internally these are actually
+   represented as function applications.) The vectors are owned by the caller
+   and won't be freed. References on the element expressions are counted
+   automatically. */
+
+pure_expr *pure_listl(size_t size, ...);
+pure_expr *pure_listv(size_t size, pure_expr **elems);
+pure_expr *pure_tuplel(size_t size, ...);
+pure_expr *pure_tuplev(size_t size, pure_expr **elems);
+
+/* Expression deconstructors for all the expression types above. These all
+   return a bool value indicating whether the given expression is of the
+   corresponding type and, if so, set the remaining parameter pointers to the
+   corresponding values. Parameter pointers may be NULL in which case they are
+   not set and only the result of the type check is returned.
+
+   NOTES: pure_is_symbol will return true not only for constant and unbound
+   variable symbols, but also for arbitrary closures including local and
+   anonymous functions. In the case of an anonymous closure, the returned
+   symbol will be 0. You can check whether an expression actually represents a
+   named or anonymous closure using the funp and lambdap predicates from the
+   library API (see below).
+
+   pure_is_long checks whether the result actually fits into a 64 bit integer.
+   pure_is_bigint mallocs the returned limb vector (if limbs!=NULL); the
+   caller is responsible for freeing it. */
+
+bool pure_is_symbol(const pure_expr *x, int32_t *sym);
+bool pure_is_int(const pure_expr *x, int32_t *i);
+bool pure_is_long(const pure_expr *x, int64_t *l);
+bool pure_is_bigint(const pure_expr *x, int32_t *size, limb_t **limbs);
+bool pure_is_mpz(const pure_expr *x, mpz_t *z);
+bool pure_is_double(const pure_expr *x, double *d);
+bool pure_is_pointer(const pure_expr *x, void **p);
+
+/* String results are copied with the _dup routines (it is then the caller's
+   responsibility to free them when appropriate). pure_is_cstring_dup also
+   converts the string to the system encoding. The string value returned by
+   pure_is_string points directly to the string data in the Pure expression
+   and must not be changed by the caller. */
+
+bool pure_is_string(const pure_expr *x, const char **sym);
+bool pure_is_string_dup(const pure_expr *x, char **sym);
+bool pure_is_cstring_dup(const pure_expr *x, char **sym);
+
+/* Deconstruct literal applications. */
+
+bool pure_is_app(const pure_expr *x, pure_expr **fun, pure_expr **arg);
+
+/* Convenience functions to deconstruct lists and tuples. Returned element
+   vectors are malloc'd and must be freed by the caller. Note that
+   pure_is_tuplev will always return true, since a singleton expression, which
+   is not either a pair or (), is considered a tuple of size 1. */
+
+bool pure_is_listv(const pure_expr *x, size_t *size, pure_expr ***elems);
+bool pure_is_tuplev(const pure_expr *x, size_t *size, pure_expr ***elems);
+
+/* Memory management. */
+
+/* Count a new reference to an expression. This should be called whenever you
+   want to store an expression somewhere, in order to prevent it from being
+   garbage-collected. */
+
+pure_expr *pure_new(pure_expr *x);
+
+/* Drop a reference to an expression. This will cause the expression to be
+   garbage-collected when it is no longer needed. */
+
+void pure_free(pure_expr *x);
+
+/* Count a reference and then immediately drop it. This is useful to collect
+   temporaries which are not referenced yet. */
+
+void pure_freenew(pure_expr *x);
+
+/* Increment and decrement the reference counter of an expression. This can be
+   used to temporarily protect an expression from being garbage-collected. It
+   doesn't actually change the status of the expression and does not collect
+   it. */
+
+void pure_ref(pure_expr *x);
+void pure_unref(pure_expr *x);
+
+/* END OF PUBLIC API. *******************************************************/
+
+/* Stuff below this line is for internal use by the Pure interpreter. Don't
+   call these directly, unless you know what you are doing. */
+
+/* Construct constant symbols and closures. */
+
+pure_expr *pure_const(int32_t tag);
+pure_expr *pure_clos(bool local, bool thunked, int32_t tag, uint32_t n,
+		     void *f, void *e, uint32_t m, /* m x pure_expr* */ ...);
+
 /* Compare a bigint or string expression against a constant value. This is
    used by the pattern matching code. */
 
-int32_t pure_cmp_bigint(pure_expr *x, int32_t size, limb_t *limbs);
+int32_t pure_cmp_bigint(pure_expr *x, int32_t size, const limb_t *limbs);
 int32_t pure_cmp_string(pure_expr *x, const char *s);
 
 /* Get the string value of a string expression in the system encoding. Each
@@ -127,33 +273,10 @@
 /* Run a Pure function and catch exceptions. If everything goes normal,
    pure_invoke returns the return value of the executed function. Otherwise it
    returns 0 and sets e to the exception value, as given by pure_throw().
-   XXXFIXME: This only supports parameterless functions right now. */
+   FIXME: This only supports parameterless functions right now. */
 
 pure_expr *pure_invoke(void *f, pure_expr** e);
 
-/* Count a new reference to an expression. This should be called whenever you
-   want to store an expression somewhere, in order to prevent it from being
-   garbage-collected. */
-
-pure_expr *pure_new(pure_expr *x);
-
-/* Drop a reference to an expression. This will cause the expression to be
-   garbage-collected when it is no longer needed. */
-
-void pure_free(pure_expr *x);
-
-/* Count a reference and then immediately drop it. This is useful to collect
-   temporaries which are not referenced yet. */
-
-void pure_freenew(pure_expr *x);
-
-/* Increment and decrement the reference counter. This can be used to
-   temporarily protect an expression from being garbage-collected. It doesn't
-   actually change the status of the expression and does not collect it. */
-
-void pure_ref(pure_expr *x);
-void pure_unref(pure_expr *x);
-
 /* Manage arguments of a function call. pure_new_args counts references on a
    given collection of arguments in preparation for a function call, while
    pure_free_args collects the arguments of a function call. In both cases the
@@ -199,8 +322,12 @@
 
 void pure_debug(int32_t tag, const char *format, ...);
 
-/* Supplementary routines. These are used in the standard library. */
+/* LIBRARY API. *************************************************************/
 
+/* Add any stuff that is needed in the standard library here. Applications and
+   external C modules may call these, but be warned that these APIs are
+   subject to change without further notice. */
+
 /* Conversions between numeric and pointer types. The input argument must be
    an expression denoting an int, double, bigint or pointer value. The numeric
    value of a pointer is its address, cast to a suitably large integer type,
@@ -272,7 +399,8 @@
 
 /* Convert a Pure expression to a string and vice versa. Note that eval() will
    actually parse and execute any Pure source, so it can be used, e.g., to add
-   new rules to the executing program at runtime. */
+   new rules to the executing program at runtime. The result of eval() is the
+   last computed expression (NULL if none). */
 
 pure_expr *str(const pure_expr *x);
 pure_expr *eval(const char *s);


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