Flesh out VHDL parser engine.

Add enough rules to parse a simple VHDL program:
  Parse library and use clauses,
  Parse entity declarations, and
  Parse architecture bodies.

Add some parser infrastructure:
  Handle syntax errors with useful error messages,
  Include file name and line numbers in parse errors,
  Add some parser debug aids.

vhdlpp/lexor.lex

@@ -25,6 +25,7 @@
 
 # include  "parse_api.h"
 # include  "lexor_keyword.h"
+# include  "parse.h"
 
 extern int lexor_keyword_code (const char*str, unsigned len);
 
@@ -35,7 +36,7 @@ extern int lexor_keyword_code (const char*str, unsigned len);
  * the name as it exists in the list (and delete the passed string.)
  * If the name is new, it will be added to the list.
  */
-YYLTYPE yylloc;
+extern YYLTYPE yylloc;
 
 static int comment_enter;
 
@@ -71,3 +72,22 @@ W [ \t\b\f\r]+
       int rc = lexor_keyword_code(yytext, yyleng);
       return rc;
   }
+
+  /* Compound symbols */
+"<=" { return LEQ; }
+">=" { return GEQ; }
+":=" { return VASSIGN; }
+
+. { return yytext[0]; }
+
+%%
+
+extern void yyparse_set_filepath(const char*path);
+
+void reset_lexor(FILE*fd, const char*path)
+{
+      yylloc.first_line = 1;
+      yyrestart(fd);
+
+      yyparse_set_filepath(path);
+}

vhdlpp/lexor_keyword.gperf

@@ -17,7 +17,19 @@ struct lexor_keyword { const char*name; int mask; int tokenType; };
 %%
 abs,		GN_KEYWORD_2008,	K_abs
 access,		GN_KEYWORD_2008,	K_access
+all,		GN_KEYWORD_2008,	K_all
+and,		GN_KEYWORD_2008,	K_and
 architecture,	GN_KEYWORD_2008,	K_architecture
+begin,		GN_KEYWORD_2008,	K_begin
+end,		GN_KEYWORD_2008,	K_end
+entity,		GN_KEYWORD_2008,	K_entity
+in,		GN_KEYWORD_2008,	K_in
+is,		GN_KEYWORD_2008,	K_is
+library,	GN_KEYWORD_2008,	K_library
+of,		GN_KEYWORD_2008,	K_of
+out,		GN_KEYWORD_2008,	K_out
+port,		GN_KEYWORD_2008,	K_port
+use,		GN_KEYWORD_2008,	K_use
 %%
 
 int lexor_keyword_mask = GN_KEYWORD_2008;

vhdlpp/main.cc

@@ -38,17 +38,33 @@ const char NOTICE[] =
 "  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.\n"
 ;
 
-# include <stdio.h>
+# include  "parse_api.h"
-# include  <stdlib.h>
+# include  <cstdio>
+# include  <cstdlib>
+# include  <cstring>
 #if defined(HAVE_GETOPT_H)
 # include  <getopt.h>
 #endif
 
+static void process_debug_token(const char*word)
+{
+      if (strcmp(word, "yydebug") == 0) {
+	    yydebug = 1;
+      } else if (strcmp(word, "no-yydebug") == 0) {
+	    yydebug = 0;
+      }
+}
+
 int main(int argc, char*argv[])
 {
       int opt;
+      int rc;
 
-      while ( (opt=getopt(argc, argv, "vV")) != EOF) switch (opt) {
+      while ( (opt=getopt(argc, argv, "D:vV")) != EOF) switch (opt) {
+
+	  case 'D':
+	    process_debug_token(optarg);
+	    break;
 
 	  case 'v':
 	    fprintf(stderr, "Icarus Verilog VHDL Parse version "
@@ -66,5 +82,25 @@ int main(int argc, char*argv[])
 
       }
 
+      for (int idx = optind ; idx < argc ; idx += 1) {
+	    parse_errors = 0;
+	    FILE*fd = fopen(argv[idx], "r");
+	    if (fd == 0) {
+		  perror(argv[idx]);
+		  return 1;
+	    }
+
+	    reset_lexor(fd, argv[idx]);
+	    rc = yyparse();
+	    fprintf(stderr, "yyparse() returns %d, parse_errors=%d\n", rc, parse_errors);
+
+	    if (parse_errors > 0) {
+		  fprintf(stderr, "%d errors parsing %s\n", parse_errors, argv[idx]);
+		  return 2;
+	    }
+
+	    fclose(fd);
+      }
+
       return 0;
 }

vhdlpp/parse.y

@@ -21,9 +21,12 @@
 
 # include "vhdlpp_config.h"
 # include "parse_api.h"
+# include  <cstdarg>
 
 static void yyerror(const char*msg);
 
+static void errormsg(const YYLTYPE&loc, const char*msg, ...);
+int parse_errors = 0;
 %}
 
   /* The keywords are all tokens. */
@@ -53,12 +56,192 @@ static void yyerror(const char*msg);
 %token K_xnor K_xor
  /* Identifiers that are not keywords are identifiers. */
 %token IDENTIFIER
+ /* compound symbols */
+%token LEQ GEQ VASSIGN
+
 %%
 
-main : ;
+ /* The design_file is the root for the VHDL parse. */
+design_file : design_units ;
+
+architecture_body
+  : K_architecture IDENTIFIER
+    K_of IDENTIFIER
+    K_is
+    K_begin architecture_statement_part K_end K_architecture_opt ';'
+  | K_architecture IDENTIFIER
+    K_of IDENTIFIER
+    K_is
+    K_begin error K_end K_architecture_opt ';'
+      { errormsg(@1, "Syntax error in architecture statement.\n"); yyerrok; }
+  | K_architecture error ';'
+      { errormsg(@1, "Syntax error in architecture body.\n"); yyerrok; }
+  ;
+
+  /* The architecture_statement_part is a list of concurrent
+     statements. */
+architecture_statement_part
+  : architecture_statement_part concurrent_statement
+  | concurrent_statement
+  ;
+
+concurrent_signal_assignment_statement
+  : IDENTIFIER LEQ waveform ';'
+  ;
+
+concurrent_statement
+  : concurrent_signal_assignment_statement
+  ;
+
+context_clause : context_items | ;
+
+context_item
+  : library_clause
+  | use_clause
+  ;
+
+context_items
+  : context_items context_item
+  | context_item
+  ;
+
+
+design_unit
+  : context_clause library_unit
+  | error { errormsg(@1, "Invalid design_unit\n"); }
+  ;
+
+design_units
+  : design_units design_unit 
+  | design_unit
+  ;
+
+entity_declaration
+  : K_entity IDENTIFIER K_is entity_header K_end K_entity ';'
+  ;
+
+entity_header
+  : port_clause
+  ;
+
+expression
+  : expression_logical
+  ;
+
+expression_logical
+  : relation K_and relation
+  | relation K_or relation
+  ;
+
+factor : primary ;
+
+  /* The interface_element is also an interface_declaration */
+interface_element
+  : IDENTIFIER ':' mode IDENTIFIER
+  ;
+
+interface_list
+  : interface_list ';' interface_element
+  | interface_element
+  ;
+
+library_clause
+  : K_library logical_name_list ';'
+  | K_library error ';'
+     { errormsg(@1, "Syntax error in library clause.\n"); yyerrok; }
+  ;
+
+  /* Collapse the primary_unit and secondary_unit of the library_unit
+     into this single set of rules. */
+library_unit
+  : entity_declaration
+  | architecture_body
+  ;
+
+logical_name : IDENTIFIER ;
+
+logical_name_list
+  : logical_name_list ',' logical_name
+  | logical_name
+  ;
+
+mode : K_in | K_out ;
+
+port_clause : K_port '(' interface_list ')' ';' ;
+
+primary
+  : IDENTIFIER
+  ;
+
+relation : shift_expression ;
+
+selected_name
+  : IDENTIFIER '.' K_all
+  | IDENTIFIER '.' IDENTIFIER '.' K_all
+  ;
+
+selected_names
+  : selected_names ',' selected_name
+  | selected_name
+  ;
+
+shift_expression : simple_expression ;
+
+simple_expression : term ;
+
+term : factor ;
+
+use_clause
+  : K_use selected_names ';'
+  | K_use error ';'
+     { errormsg(@1, "Syntax error in use clause.\n"); yyerrok; }
+  ;
+
+waveform
+  : waveform_elements
+  | K_unaffected
+  ;
+
+waveform_elements
+  : waveform_elements ',' waveform_element
+  | waveform_element
+  ;
+
+waveform_element
+  : expression
+  | K_null
+  ;
+
+  /* Some keywords are optional in some contexts. In all such cases, a
+     similar rule is used, as described here. */
+K_architecture_opt : K_architecture | ;
 
 %%
 
 static void yyerror(const char*msg)
 {
+      fprintf(stderr, "%s\n", msg);
+      parse_errors += 1;
+}
+
+static const char*file_path = "";
+
+static void errormsg(const YYLTYPE&loc, const char*fmt, ...)
+{
+      va_list ap;
+      va_start(ap, fmt);
+
+      fprintf(stderr, "%s:%d: ", file_path, loc.first_line);
+      vfprintf(stderr, fmt, ap);
+      va_end(ap);
+      parse_errors += 1;
+}
+
+/*
+ * This is used only by the lexor, to set the file path used in error
+ * messages.
+ */
+void yyparse_set_filepath(const char*path)
+{
+      file_path = path;
 }

vhdlpp/parse_api.h

@@ -19,6 +19,8 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 
+# include  <cstdio>
+
 /*
  * The vlltype supports the passing of detailed source file location
  * information between the lexical analyzer and the parser. Defining
@@ -33,6 +35,26 @@ struct yyltype {
 };
 # define YYLTYPE struct yyltype
 
+/*
+ * The reset_lexor function takes the fd and makes it the input file
+ * for the lexor. The path argument is used in lexor/parser error messages.
+ */
+extern void reset_lexor(FILE*fd, const char*path);
+
 extern int yylex(void);
 
+extern int yyparse(void);
+
+/*
+ * Set this to a non-zero value to enable parser debug output.
+ */
+extern int yydebug;
+
+/*
+ * The parser counts the errors that is handed in the parse_errors
+ * variable. For a clean compile, this value should not change. (The
+ * caller sets its initial value.)
+ */
+extern int parse_errors;
+
 #endif