Redo constant expression detection to happen

after parsing.

 Parse more operators and expressions.

PExpr.cc

@@ -17,10 +17,11 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #if !defined(WINNT)
-#ident "$Id: PExpr.cc,v 1.2 1998/11/11 00:01:51 steve Exp $"
+#ident "$Id: PExpr.cc,v 1.3 1999/05/16 05:08:42 steve Exp $"
 #endif
 
 # include  "PExpr.h"
+# include  "Module.h"
 # include  <typeinfo>
 
 PExpr::~PExpr()
@@ -32,6 +33,21 @@ bool PExpr::is_the_same(const PExpr*that) const
       return typeid(this) == typeid(that);
 }
 
+bool PExpr::is_constant(Module*) const
+{
+      return false;
+}
+
+/*
+ * An identifier can be in a constant expresion if (and only if) it is
+ * a parameter.
+ */
+bool PEIdent::is_constant(Module*mod) const
+{
+      map<string,PExpr*>::const_iterator cur = mod->parameters.find(text_);
+      return cur != mod->parameters.end();
+}
+
 bool PENumber::is_the_same(const PExpr*that) const
 {
       const PENumber*obj = dynamic_cast<const PENumber*>(that);
@@ -41,8 +57,24 @@ bool PENumber::is_the_same(const PExpr*that) const
       return *value_ == *obj->value_;
 }
 
+bool PENumber::is_constant(Module*) const
+{
+      return true;
+}
+
+bool PEString::is_constant(Module*) const
+{
+      return true;
+}
+
 /*
  * $Log: PExpr.cc,v $
+ * Revision 1.3  1999/05/16 05:08:42  steve
+ *  Redo constant expression detection to happen
+ *  after parsing.
+ *
+ *  Parse more operators and expressions.
+ *
  * Revision 1.2  1998/11/11 00:01:51  steve
  *  Check net ranges in declarations.
  *

PExpr.h

@@ -19,7 +19,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #if !defined(WINNT)
-#ident "$Id: PExpr.h,v 1.8 1999/05/10 00:16:57 steve Exp $"
+#ident "$Id: PExpr.h,v 1.9 1999/05/16 05:08:42 steve Exp $"
 #endif
 
 # include  <string>
@@ -28,6 +28,7 @@
 # include  "LineInfo.h"
 
 class Design;
+class Module;
 class NetNet;
 class NetExpr;
 
@@ -57,6 +58,12 @@ class PExpr : public LineInfo {
 	// this expression. This method is used for comparing
 	// expressions that must be structurally "identical".
       virtual bool is_the_same(const PExpr*that) const;
+
+	// Return true if this expression is a valid constant
+	// expression. the Module pointer is needed to find parameter
+	// identifiers and any other module specific interpretations
+	// of expresions.
+      virtual bool is_constant(Module*) const;
 };
 
 ostream& operator << (ostream&, const PExpr&);
@@ -99,6 +106,7 @@ class PEIdent : public PExpr {
       virtual void dump(ostream&) const;
       virtual NetNet* elaborate_net(Design*des, const string&path) const;
       virtual NetExpr*elaborate_expr(Design*des, const string&path) const;
+      virtual bool is_constant(Module*) const;
       verinum* eval_const(const Design*des, const string&path) const;
 
 	// XXXX
@@ -132,6 +140,7 @@ class PENumber : public PExpr {
       virtual verinum* eval_const(const Design*des, const string&path) const;
 
       virtual bool is_the_same(const PExpr*that) const;
+      virtual bool is_constant(Module*) const;
 
     private:
       verinum*const value_;
@@ -147,6 +156,8 @@ class PEString : public PExpr {
       virtual void dump(ostream&) const;
       virtual NetExpr*elaborate_expr(Design*des, const string&path) const;
 
+      virtual bool is_constant(Module*) const;
+
     private:
       const string text_;
 };
@@ -185,6 +196,12 @@ class PEBinary : public PExpr {
 
 /*
  * $Log: PExpr.h,v $
+ * Revision 1.9  1999/05/16 05:08:42  steve
+ *  Redo constant expression detection to happen
+ *  after parsing.
+ *
+ *  Parse more operators and expressions.
+ *
  * Revision 1.8  1999/05/10 00:16:57  steve
  *  Parse and elaborate the concatenate operator
  *  in structural contexts, Replace vector<PExpr*>

elaborate.cc

@@ -17,7 +17,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #if !defined(WINNT)
-#ident "$Id: elaborate.cc,v 1.25 1999/05/10 00:16:58 steve Exp $"
+#ident "$Id: elaborate.cc,v 1.26 1999/05/16 05:08:42 steve Exp $"
 #endif
 
 /*
@@ -724,7 +724,9 @@ NetExpr* PEBinary::elaborate_expr(Design*des, const string&path) const
 NetExpr* PENumber::elaborate_expr(Design*des, const string&path) const
 {
       assert(value_);
-      return new NetEConst(*value_);
+      NetEConst*tmp = new NetEConst(*value_);
+      tmp->set_line(*this);
+      return tmp;
 }
 
 NetExpr* PEString::elaborate_expr(Design*des, const string&path) const
@@ -789,7 +791,7 @@ NetExpr*PEIdent::elaborate_expr(Design*des, const string&path) const
 NetExpr* PExpr::elaborate_expr(Design*des, const string&path) const
 {
       cerr << "Cannot elaborate expression: " << *this << endl;
-      return new NetEConst(verinum());
+      return 0;
 }
 
 NetExpr* PEUnary::elaborate_expr(Design*des, const string&path) const
@@ -1148,6 +1150,12 @@ Design* elaborate(const map<string,Module*>&modules,
 
 /*
  * $Log: elaborate.cc,v $
+ * Revision 1.26  1999/05/16 05:08:42  steve
+ *  Redo constant expression detection to happen
+ *  after parsing.
+ *
+ *  Parse more operators and expressions.
+ *
  * Revision 1.25  1999/05/10 00:16:58  steve
  *  Parse and elaborate the concatenate operator
  *  in structural contexts, Replace vector<PExpr*>

lexor.lex

@@ -19,7 +19,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #if !defined(WINNT)
-#ident "$Id: lexor.lex,v 1.14 1999/05/13 04:02:09 steve Exp $"
+#ident "$Id: lexor.lex,v 1.15 1999/05/16 05:08:42 steve Exp $"
 #endif
 
       //# define YYSTYPE lexval
@@ -68,6 +68,8 @@ static verinum*make_unsized_hex(const char*txt);
 <CCOMMENT>\n   { yylloc.first_line += 1; yymore(); }
 <CCOMMENT>"*/" { BEGIN(0); }
 
+"<<" { return K_LS; }
+">>" { return K_RS; }
 "<=" { return K_LE; }
 ">=" { return K_GE; }
 "==" { return K_EQ; }
@@ -77,7 +79,7 @@ static verinum*make_unsized_hex(const char*txt);
 "||" { return K_LOR; }
 "&&" { return K_LAND; }
 
-[}{;:\[\],()#=.@&!<|^~+*/-] { return yytext[0]; }
+[}{;:\[\],()#=.@&!?<>%|^~+*/-] { return yytext[0]; }
 
 \"            { BEGIN(CSTRING); }
 <CSTRING>\\\" { yymore(); }

netlist.cc

@@ -17,7 +17,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #if !defined(WINNT)
-#ident "$Id: netlist.cc,v 1.25 1999/05/13 04:02:09 steve Exp $"
+#ident "$Id: netlist.cc,v 1.26 1999/05/16 05:08:42 steve Exp $"
 #endif
 
 # include  <cassert>
@@ -507,6 +507,11 @@ NetEConst::~NetEConst()
 
 void NetEConst::set_width(unsigned w)
 {
+      if (w > value_.len()) {
+	    cerr << get_line() << ": Cannot expand " << *this
+		 << " to " << w << " bits." << endl;
+	    assert(0);
+      }
       assert(w <= value_.len());
       value_ = verinum(value_, w);
       expr_width(w);
@@ -1054,6 +1059,12 @@ NetNet* Design::find_signal(bool (*func)(const NetNet*))
 
 /*
  * $Log: netlist.cc,v $
+ * Revision 1.26  1999/05/16 05:08:42  steve
+ *  Redo constant expression detection to happen
+ *  after parsing.
+ *
+ *  Parse more operators and expressions.
+ *
  * Revision 1.25  1999/05/13 04:02:09  steve
  *  More precise handling of verinum bit lengths.
  *

netlist.h

@@ -19,7 +19,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #if !defined(WINNT)
-#ident "$Id: netlist.h,v 1.30 1999/05/12 04:03:19 steve Exp $"
+#ident "$Id: netlist.h,v 1.31 1999/05/16 05:08:42 steve Exp $"
 #endif
 
 /*
@@ -327,7 +327,7 @@ class NetMemory  {
  * being referenced, so can handle garbage collection. Also, this
  * trick can be used to replace subexpressions.
  */
-class NetExpr {
+class NetExpr  : public LineInfo {
     public:
       explicit NetExpr(unsigned w =0) : width_(w), reflist_(0)  { }
       virtual ~NetExpr() =0;
@@ -881,15 +881,22 @@ class NetProcTop  : public LineInfo {
  *
  *   ^  -- Bit-wise exclusive OR
  *   +  -- Arithmetic add
- *   -  -- Arighmetic minus
+ *   -  -- Arithmetic minus
+ *   *  -- Arithmetic multiply
+ *   /  -- Arithmetic divide
+ *   %  -- Arithmetic modulus
  *   &  -- Bit-wise AND
  *   |  -- Bit-wise OR
  *   e  -- Logical equality (==)
  *   E  -- Case equality (===)
+ *   L  -- Less or equal
+ *   G  -- Greater or equal
  *   n  -- Logical inequality (!=)
  *   N  -- Case inequality (!==)
  *   a  -- Logical AND (&&)
  *   o  -- Logical OR (||)
+ *   l  -- Left shift (<<)
+ *   r  -- Right shift (>>)
  */
 class NetEBinary  : public NetExpr {
 
@@ -1178,6 +1185,12 @@ extern ostream& operator << (ostream&, NetNet::Type);
 
 /*
  * $Log: netlist.h,v $
+ * Revision 1.31  1999/05/16 05:08:42  steve
+ *  Redo constant expression detection to happen
+ *  after parsing.
+ *
+ *  Parse more operators and expressions.
+ *
  * Revision 1.30  1999/05/12 04:03:19  steve
  *  emit NetAssignMem objects in vvm target.
  *

parse.y

@@ -19,7 +19,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #if !defined(WINNT)
-#ident "$Id: parse.y,v 1.25 1999/05/10 00:16:58 steve Exp $"
+#ident "$Id: parse.y,v 1.26 1999/05/16 05:08:42 steve Exp $"
 #endif
 
 # include  "parse_misc.h"
@@ -61,7 +61,7 @@ extern void lex_end_table();
 
 %token <text>   IDENTIFIER PORTNAME SYSTEM_IDENTIFIER STRING
 %token <number> NUMBER
-%token K_LE K_GE K_EQ K_NE K_CEQ K_CNE
+%token K_LE K_GE K_EQ K_NE K_CEQ K_CNE K_LS K_RS
 %token K_LOR K_LAND
 %token K_always K_and K_assign K_begin K_buf K_bufif0 K_bufif1 K_case
 %token K_casex K_casez K_cmos K_deassign K_default K_defparam K_disable
@@ -101,7 +101,7 @@ extern void lex_end_table();
 %type <gate>  gate_instance
 %type <gates> gate_instance_list
 
-%type <expr>  bitsel delay delay_opt expression expr_primary const_expression
+%type <expr>  delay delay_opt expression expr_primary
 %type <expr>  lavalue lpvalue
 %type <exprs> expression_list
 
@@ -122,7 +122,9 @@ extern void lex_end_table();
 %left '&'
 %left K_EQ K_NE K_CEQ K_CNE
 %left K_GE K_LE '<' '>'
+%left K_LS K_RS
 %left '+' '-'
+%left '*' '/' '%'
 %left UNARY_PREC
 
 %%
@@ -132,11 +134,6 @@ source_file
 	| source_file description
 	;
 
-bitsel
-	: '[' const_expression ']'
-		{ $$ = $2; }
-	;
-
 case_item
 	: expression ':' statement_opt
 		{ PCase::Item*tmp = new PCase::Item;
@@ -171,52 +168,6 @@ case_items
 		}
 	;
 
-  /* const_expressions are restricted expressions that have guaranteed
-     known values at compile time. I treat them differently at parse
-     time so that I can tack correctness checking onto the parse
-     process. */
-const_expression
-	: NUMBER
-		{ verinum*tmp = $1;
-		  if (tmp == 0) {
-			yyerror(@1, "XXXX internal error: const_expression.");
-			$$ = 0;
-		  } else {
-			PENumber*tmp = new PENumber($1);
-			tmp->set_file(@1.text);
-			tmp->set_lineno(@1.first_line);
-			$$ = tmp;
-		  }
-		}
-	| STRING
-		{ PEString*tmp = new PEString(*$1);
-		  tmp->set_file(@2.text);
-		  tmp->set_lineno(@2.first_line);
-		  delete $1;
-		  $$ = tmp;
-		}
-	| IDENTIFIER
-		{ if (!pform_is_parameter(*$1)) {
-		        yyerror(@1, "Identifier in constant expression"
-			        " must be a parameter name.");
-			delete $1;
-			$$ = 0;
-		  } else {
-			PEIdent*tmp = new PEIdent(*$1);
-			tmp->set_file(@1.text);
-			tmp->set_lineno(@1.first_line);
-			$$ = tmp;
-			delete $1;
-		  }
-		}
-	| const_expression '-' const_expression
-		{ PEBinary*tmp = new PEBinary('-', $1, $3);
-		  tmp->set_file(@2.text);
-		  tmp->set_lineno(@2.first_line);
-		  $$ = tmp;
-		}
-	;
-
 delay
 	: '#' NUMBER
 		{ verinum*tmp = $2;
@@ -332,6 +283,15 @@ expression
 	| expression '^' expression
 		{ $$ = new PEBinary('^', $1, $3);
 		}
+	| expression '*' expression
+		{ $$ = new PEBinary('*', $1, $3);
+		}
+	| expression '/' expression
+		{ $$ = new PEBinary('/', $1, $3);
+		}
+	| expression '%' expression
+		{ $$ = new PEBinary('%', $1, $3);
+		}
 	| expression '+' expression
 		{ $$ = new PEBinary('+', $1, $3);
 		}
@@ -350,12 +310,24 @@ expression
 	| expression '>' expression
 		{ $$ = new PEBinary('>', $1, $3);
 		}
+	| expression K_LS expression
+		{ $$ = new PEBinary('l', $1, $3);
+		}
+	| expression K_RS expression
+		{ $$ = new PEBinary('r', $1, $3);
+		}
 	| expression K_EQ expression
 		{ $$ = new PEBinary('e', $1, $3);
 		}
 	| expression K_CEQ expression
 		{ $$ = new PEBinary('E', $1, $3);
 		}
+	| expression K_LE expression
+		{ $$ = new PEBinary('L', $1, $3);
+		}
+	| expression K_GE expression
+		{ $$ = new PEBinary('G', $1, $3);
+		}
 	| expression K_NE expression
 		{ $$ = new PEBinary('n', $1, $3);
 		}
@@ -396,7 +368,10 @@ expr_primary
 		        yyerror(@1, "XXXX No number value in primary?");
 			$$ = 0;
 		  } else {
-			$$ = new PENumber($1);
+			PENumber*tmp = new PENumber($1);
+			tmp->set_file(@1.text);
+			tmp->set_lineno(@1.first_line);
+			$$ = tmp;
 		  }
 		}
 	| STRING
@@ -579,9 +554,16 @@ lavalue
 		  delete $1;
 		  $$ = tmp;
 		}
-	| IDENTIFIER bitsel
+	| IDENTIFIER '[' expression ']'
 		{ PEIdent*tmp = new PEIdent(*$1);
-		  tmp->msb_ = $2;
+		  PExpr*sel = $3;
+		  if (! pform_expression_is_constant(sel)) {
+			yyerror(@2, "Bit select in lvalue must "
+			        "contain a constant expression.");
+			delete sel;
+		  } else {
+			tmp->msb_ = sel;
+		  }
 		  tmp->set_file(@1.text);
 		  tmp->set_lineno(@1.first_line);
 		  delete $1;
@@ -623,6 +605,14 @@ lpvalue
 
 		  $$ = tmp;
 		}
+	| identifier '[' expression ':' expression ']'
+		{ yyerror(@1, "Sorry, part selects"
+		          " not supported in lvalue.");
+		  $$ = 0;
+		  delete $1;
+		  delete $3;
+		  delete $5;
+		}
 	| '{' expression_list '}'
 		{ yyerror(@1, "Sorry, concatenation expressions"
 		          " not supported in lvalue.");
@@ -721,14 +711,25 @@ net_type
 	;
 
 parameter_assign
-	: IDENTIFIER '=' const_expression
+	: IDENTIFIER '=' expression
-		{ pform_set_parameter(*$1, $3);
+		{ PExpr*tmp = $3;
+		  if (!pform_expression_is_constant(tmp)) {
+			yyerror(@3, "parameter value must be constant.");
+			delete tmp;
+			tmp = 0;
+		  }
+		  pform_set_parameter(*$1, tmp);
 		  delete $1;
 		}
 	;
 
 parameter_assign_list
 	: parameter_assign
+	| range parameter_assign
+		{ yyerror(@1, "Ranges in parameter definition "
+		          "are not supported.");
+		  delete $1;
+		}
 	| parameter_assign_list ',' parameter_assign
 	;
 
@@ -738,12 +739,25 @@ port
 		  $$->port_type = NetNet::PIMPLICIT;
 		  delete $1;
 		}
-	| IDENTIFIER '[' const_expression ':' const_expression ']'
+	| IDENTIFIER '[' expression ':' expression ']'
-		{ $$ = new PWire(*$1, NetNet::IMPLICIT);
+		{ PWire*tmp = new PWire(*$1, NetNet::IMPLICIT);
-		  $$->port_type = NetNet::PIMPLICIT;
+		  tmp->port_type = NetNet::PIMPLICIT;
-		  $$->msb = $3;
+		  if (!pform_expression_is_constant($3)) {
-		  $$->lsb = $5;
+			yyerror(@3, "msb expression of port bit select "
+			        "must be constant.");
+			delete $3;
+		  } else {
+			tmp->msb = $3;
+		  }
+		  if (!pform_expression_is_constant($5)) {
+			yyerror(@3, "lsb expression of port bit select "
+			        "must be constant.");
+			delete $5;
+		  } else {
+			tmp->msb = $5;
+		  }
 		  delete $1;
+		  $$ = tmp;
 		}
 	| IDENTIFIER '[' error ']'
 		{ yyerror(@1, "invalid port bit select");
@@ -754,10 +768,14 @@ port
 	;
 
 port_name
-	: PORTNAME '(' IDENTIFIER ')'
+	: PORTNAME '(' expression ')'
 		{ delete $1;
 		  delete $3;
 		}
+	| PORTNAME '(' error ')'
+		{ yyerror(@3, "invalid port connection expression.");
+		  delete $1;
+		}
 	| PORTNAME '(' ')'
 		{ delete $1;
 		}
@@ -775,10 +793,20 @@ port_type
 	;
 
 range
-	: '[' const_expression ':' const_expression ']'
+	: '[' expression ':' expression ']'
 		{ svector<PExpr*>*tmp = new svector<PExpr*> (2);
-		  (*tmp)[0] = $2;
+		  if (!pform_expression_is_constant($2)) {
-		  (*tmp)[1] = $4;
+			yyerror(@2, "msb of range must be constant.");
+			delete $2;
+		  } else {
+			(*tmp)[0] = $2;
+		  }
+		  if (!pform_expression_is_constant($4)) {
+			yyerror(@4, "msb of range must be constant.");
+			delete $4;
+		  } else {
+			(*tmp)[1] = $4;
+		  }
 		  $$ = tmp;
 		}
 	;
@@ -798,8 +826,12 @@ register_variable
 		{ pform_makewire(*$1, NetNet::REG);
 		  $$ = $1;
 		}
-	| IDENTIFIER '[' const_expression ':' const_expression ']'
+	| IDENTIFIER '[' expression ':' expression ']'
 		{ pform_makewire(*$1, NetNet::REG);
+		  if (! pform_expression_is_constant($3))
+			yyerror(@3, "msb of register range must be constant.");
+		  if (! pform_expression_is_constant($5))
+			yyerror(@3, "lsb of register range must be constant.");
 		  pform_set_reg_idx(*$1, $3, $5);
 		  $$ = $1;
 		}

pform.cc

@@ -17,7 +17,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #if !defined(WINNT)
-#ident "$Id: pform.cc,v 1.17 1999/05/10 00:16:58 steve Exp $"
+#ident "$Id: pform.cc,v 1.18 1999/05/16 05:08:42 steve Exp $"
 #endif
 
 # include  "pform.h"
@@ -82,6 +82,11 @@ void pform_endmodule(const string&name)
       cur_module = 0;
 }
 
+bool pform_expression_is_constant(const PExpr*ex)
+{
+      return ex->is_constant(cur_module);
+}
+
 void pform_make_udp(string*name, list<string>*parms,
 		    list<PWire*>*decl, list<string>*table,
 		    Statement*init_expr)
@@ -421,13 +426,6 @@ void pform_set_parameter(const string&name, PExpr*expr)
       cur_module->parameters[name] = expr;
 }
 
-bool pform_is_parameter(const string&name)
-{
-      map<string,PExpr*>::const_iterator cur =
-	    cur_module->parameters.find(name);
-      return cur != cur_module->parameters.end();
-}
-
 void pform_set_port_type(list<string>*names, NetNet::PortType pt)
 {
       for (list<string>::const_iterator cur = names->begin()
@@ -518,6 +516,12 @@ int pform_parse(const char*path, map<string,Module*>&modules,
 
 /*
  * $Log: pform.cc,v $
+ * Revision 1.18  1999/05/16 05:08:42  steve
+ *  Redo constant expression detection to happen
+ *  after parsing.
+ *
+ *  Parse more operators and expressions.
+ *
  * Revision 1.17  1999/05/10 00:16:58  steve
  *  Parse and elaborate the concatenate operator
  *  in structural contexts, Replace vector<PExpr*>

pform.h

@@ -19,7 +19,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #if !defined(WINNT)
-#ident "$Id: pform.h,v 1.13 1999/05/10 00:16:58 steve Exp $"
+#ident "$Id: pform.h,v 1.14 1999/05/16 05:08:42 steve Exp $"
 #endif
 
 # include  "netlist.h"
@@ -107,13 +107,14 @@ extern void pform_set_attrib(const string&name, const string&key,
 extern void pform_set_type_attrib(const string&name, const string&key,
 				  const string&value);
 extern void pform_set_parameter(const string&name, PExpr*expr);
-extern bool pform_is_parameter(const string&name);
 extern PProcess*  pform_make_behavior(PProcess::Type, Statement*);
 extern Statement* pform_make_block(PBlock::BL_TYPE, list<Statement*>*);
 extern Statement* pform_make_calltask(string*t, svector<PExpr*>* =0);
 
 extern list<PWire*>* pform_make_udp_input_ports(list<string>*);
 
+extern bool pform_expression_is_constant(const PExpr*);
+
 /*
  * The makegate function creates a new gate (which need not have a
  * name) and connects it to the specified wires.
@@ -139,6 +140,12 @@ extern void pform_dump(ostream&out, Module*mod);
 
 /*
  * $Log: pform.h,v $
+ * Revision 1.14  1999/05/16 05:08:42  steve
+ *  Redo constant expression detection to happen
+ *  after parsing.
+ *
+ *  Parse more operators and expressions.
+ *
  * Revision 1.13  1999/05/10 00:16:58  steve
  *  Parse and elaborate the concatenate operator
  *  in structural contexts, Replace vector<PExpr*>