[pure-lang-svn] SF.net SVN: pure-lang:[719] pure/trunk

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

Revision: 719
          http://pure-lang.svn.sourceforge.net/pure-lang/?rev=719&view=rev
Author:   agraef
Date:     2008-09-05 13:40:46 +0000 (Fri, 05 Sep 2008)

Log Message:
-----------
User can now override print representations of expressions at runtime via the __show__ function.

Modified Paths:
--------------
    pure/trunk/ChangeLog
    pure/trunk/printer.cc
    pure/trunk/symtable.cc
    pure/trunk/symtable.hh

Modified: pure/trunk/ChangeLog
===================================================================
--- pure/trunk/ChangeLog	2008-09-05 12:11:50 UTC (rev 718)
+++ pure/trunk/ChangeLog	2008-09-05 13:40:46 UTC (rev 719)
@@ -1,5 +1,9 @@
 2008-09-05  Albert Graef  <Dr....@t-...>
 
+	* printer.cc (operator << (ostream& os, const pure_expr *x)):
+	Experimental support for calling a user-defined __show__ function
+	to override print representations of expressions at runtime.
+
 	* configure.ac, runtime.cc (pure_sys_vars): Add configure checks
 	for POSIX/ISOC99 complex types. (Requires reconfigure.)
 

Modified: pure/trunk/printer.cc
===================================================================
--- pure/trunk/printer.cc	2008-09-05 12:11:50 UTC (rev 718)
+++ pure/trunk/printer.cc	2008-09-05 13:40:46 UTC (rev 719)
@@ -622,6 +622,28 @@
     return os << p.x;
 }
 
+static inline bool pstr(ostream& os, pure_expr *x)
+{
+  interpreter& interp = *interpreter::g_interp;
+  int32_t f = interp.symtab.__show__sym;
+  if (f > 0 && interp.globenv.find(f) != interp.globenv.end()) {
+    assert(x->refc > 0);
+    pure_expr *y = pure_app(pure_symbol(f), x);
+    assert(y);
+    if (y->tag == EXPR::STR) {
+      char *s = fromutf8(y->data.s);
+      pure_freenew(y);
+      if (s) {
+	os << s; free(s);
+	return true;
+      } else
+	return false;
+    } else
+      return false;
+  } else
+    return false;
+}
+
 ostream& operator << (ostream& os, const pure_expr *x)
 {
   char test;
@@ -631,6 +653,7 @@
     throw err("stack overflow in printer");
   char buf[64];
   assert(x);
+  if (pstr(os, (pure_expr*)x)) return os;
   //os << "{" << x->refc << "}";
   switch (x->tag) {
   case EXPR::INT:

Modified: pure/trunk/symtable.cc
===================================================================
--- pure/trunk/symtable.cc	2008-09-05 12:11:50 UTC (rev 718)
+++ pure/trunk/symtable.cc	2008-09-05 13:40:46 UTC (rev 719)
@@ -2,7 +2,7 @@
 #include "symtable.hh"
 #include <assert.h>
 
-symtable::symtable() : fno(0), rtab(1024)
+symtable::symtable() : fno(0), rtab(1024), __show__sym(0)
 {
   // enter any predefined symbols here, e.g.:
   //sym("-", 6, infixl);
@@ -72,6 +72,7 @@
     _sym = symbol(s, fno, modno);
     //cout << "new symbol " << _sym.f << ": " << _sym.s << endl;
     rtab[fno] = &_sym;
+    if (__show__sym == 0 && s == "__show__") __show__sym = fno;
   }
   return _sym;
 }
@@ -88,6 +89,7 @@
     _sym = symbol(s, fno, prec, fix, modno);
     //cout << "new symbol " << _sym.f << ": " << _sym.s << endl;
     rtab[fno] = &_sym;
+    if (__show__sym == 0 && s == "__show__") __show__sym = fno;
   }
   return _sym;
 }
@@ -125,6 +127,7 @@
     _sym = symbol(s, fno, prec, fix, modno);
     //cout << "new symbol " << _sym.f << ": " << _sym.s << endl;
     rtab[fno] = &_sym;
+    if (__show__sym == 0 && s == "__show__") __show__sym = fno;
   }
   return _sym;
 }

Modified: pure/trunk/symtable.hh
===================================================================
--- pure/trunk/symtable.hh	2008-09-05 12:11:50 UTC (rev 718)
+++ pure/trunk/symtable.hh	2008-09-05 13:40:46 UTC (rev 719)
@@ -63,6 +63,7 @@
   // get a symbol by its number
   symbol& sym(int32_t f);
   // retrieve various builtin symbols (create when necessary)
+  int32_t __show__sym; // This is cached here to improve performance.
   symbol& nil_sym();
   symbol& cons_sym();
   symbol& void_sym();


This was sent by the SourceForge.net collaborative development platform, the world's largest Open Source development site.