Generate "pure" parsers from yacc, and do not require having a yacc to build the shell

.circleci/config.yml

@@ -11,7 +11,7 @@ jobs:
           name: Install dependencies
           command: |
             sudo apt-get update
-            sudo apt-get install -qy make gcc libtool autoconf automake bison libreadline-dev
+            sudo apt-get install -qy make gcc libtool autoconf automake libreadline-dev
 
       - run:
           name: Autotools

.gitattributes

@@ -1 +1,4 @@
 test/tests/trip.es text diff
+y.tab.c -diff
+y.tab.h -diff
+token.h -diff

.gitignore

@@ -34,13 +34,13 @@ config.h
 
 # yacc
 
-y.*
+y.output
+y.tab.h
 
 # es
 
 initial.c
 sigmsgs.c
-token.h
 es
 esdump
 testrun

Makefile.in

@@ -34,10 +34,7 @@ mandir	= @mandir@
 bindir	= @bindir@
 srcdir  = @srcdir@
 testdir	= @srcdir@/test
-
 VPATH = $(srcdir)
-
-
 SHELL	= /bin/sh
 CC	= @CC@
 YACC	= @YACC@
@@ -52,7 +49,7 @@ LDFLAGS	= @LDFLAGS@ $(ADDLDFLAGS)
 LIBS	= @READLINE_LIBS@ @LIBS@ $(ADDLIBS)
 
 HFILES	= config.h es.h gc.h input.h prim.h print.h sigmsgs.h \
-	  stdenv.h syntax.h term.h var.h
+	  stdenv.h syntax.h term.h token.h var.h
 CFILES	= access.c closure.c conv.c dict.c eval.c except.c fd.c gc.c glob.c \
 	  glom.c input.c heredoc.c history.c list.c main.c match.c open.c opt.c \
 	  prim-ctl.c prim-etc.c prim-io.c prim-sys.c prim.c print.c proc.c \
@@ -64,7 +61,7 @@ OFILES	= access.o closure.o conv.o dict.o eval.o except.o fd.o gc.o glob.o \
 	  sigmsgs.o signal.o split.o status.o str.o syntax.o term.o token.o \
 	  tree.o util.o var.o vec.o version.o y.tab.o
 OTHER	= Makefile parse.y mksignal
-GEN	= esdump y.tab.c y.tab.h y.output token.h sigmsgs.c initial.c
+GEN	= esdump y.tab.h y.output sigmsgs.c initial.c
 
 SIGFILES = @SIGFILES@
 
@@ -104,14 +101,12 @@ testclean	:
 src	:
 	@echo $(OTHER) $(CFILES) $(HFILES)
 
-y.tab.h	: parse.y
-	$(YACC) -vd $(srcdir)/parse.y
-
-y.tab.c	: y.tab.h
-
-token.h : y.tab.h
+token.h	: parse.y
+	$(YACC) -vd -b y $(srcdir)/parse.y
 	-cmp -s y.tab.h token.h || cp y.tab.h token.h
 
+y.tab.c	: token.h
+
 initial.c : esdump $(srcdir)/initial.es
 	./esdump < $(srcdir)/initial.es > initial.c
 
@@ -134,9 +129,9 @@ fd.o : fd.c es.h config.h stdenv.h
 gc.o : gc.c es.h config.h stdenv.h gc.h
 glob.o : glob.c es.h config.h stdenv.h gc.h
 glom.o : glom.c es.h config.h stdenv.h gc.h
-input.o : input.c es.h config.h stdenv.h input.h
-heredoc.o : heredoc.c es.h config.h stdenv.h gc.h input.h syntax.h
-history.o : history.c es.h config.h stdenv.h gc.h input.h
+input.o : input.c es.h config.h stdenv.h input.h token.h
+heredoc.o : heredoc.c es.h config.h stdenv.h gc.h input.h syntax.h token.h
+history.o : history.c es.h config.h stdenv.h gc.h input.h token.h
 list.o : list.c es.h config.h stdenv.h gc.h
 main.o : main.c es.h config.h stdenv.h
 match.o : match.c es.h config.h stdenv.h

configure.ac

@@ -22,6 +22,8 @@ dnl Build configuration.
 
 AC_ARG_ENABLE(strict, AS_HELP_STRING([--enable-strict], [enable strict compiler flags for testing and debugging; not all compilers support these]), opt_strict_mode=$enableval, opt_strict_mode=no)
 
+AC_ARG_VAR(YACC, [yacc command. es requires bison, byacc, or something else that supports generating pure parsers.])
+
 if test $opt_strict_mode = yes; then
 	AC_SUBST([STRICT_CFLAGS], ["-ansi -pedantic -DGCDEBUG=1 -D_POSIX_C_SOURCE=200112L -DREF_ASSERTIONS=1"])
 fi
@@ -31,7 +33,12 @@ AC_PROG_CC
 AC_PROG_CPP
 AC_PROG_INSTALL
 AC_PROG_MKDIR_P
-AC_PROG_YACC
+
+dnl Custom yacc check, because we don't want POSIX yacc.
+dnl If we don't find either bison or byacc, just set it to yacc and see if it
+dnl works or barfs on the extension.
+
+AC_CHECK_PROGS(YACC, bison byacc, yacc)
 
 dnl ----------------------------
 dnl CHECK FOR /dev/fd FILESYSTEM

input.h

@@ -2,6 +2,8 @@
 
 #define	MAXUNGET	2		/* maximum 2 character pushback */
 
+#include "token.h"	/* for YYSTYPE */
+
 typedef struct Input Input;
 struct Input {
 	int (*get)(Input *self);
@@ -34,7 +36,7 @@ extern void yyerror(const char *s);
 /* token.c */
 
 extern const char dnw[];
-extern int yylex(void);
+extern int yylex(YYSTYPE *y);
 extern void inityy(void);
 extern void print_prompt2(void);
 

parse.y

@@ -7,6 +7,8 @@
 #include "syntax.h"
 %}
 
+%define api.pure full
+
 %token <str>	WORD QWORD
 %token		LOCAL LET FOR CLOSURE FN
 %token <tree>	REDIR DUP

token.c

@@ -141,13 +141,12 @@ static Boolean getfds(int fd[2], int c, int default0, int default1) {
 	return TRUE;
 }
 
-extern int yylex(void) {
+extern int yylex(YYSTYPE *y) {
 	static Boolean dollar = FALSE;
 	int c;
 	size_t i;			/* The purpose of all these local assignments is to	*/
 	const char *meta;		/* allow optimizing compilers like gcc to load these	*/
 	char *buf = tokenbuf;		/* values into registers. On a sparc this is a		*/
-	YYSTYPE *y = &yylval;		/* win, in code size *and* execution time		*/
 
 	if (goterror) {
 		goterror = FALSE;

token.h

@@ -0,0 +1,110 @@
+/* A Bison parser, made by GNU Bison 3.8.2.  */
+
+/* Bison interface for Yacc-like parsers in C
+
+   Copyright (C) 1984, 1989-1990, 2000-2015, 2018-2021 Free Software Foundation,
+   Inc.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+/* As a special exception, you may create a larger work that contains
+   part or all of the Bison parser skeleton and distribute that work
+   under terms of your choice, so long as that work isn't itself a
+   parser generator using the skeleton or a modified version thereof
+   as a parser skeleton.  Alternatively, if you modify or redistribute
+   the parser skeleton itself, you may (at your option) remove this
+   special exception, which will cause the skeleton and the resulting
+   Bison output files to be licensed under the GNU General Public
+   License without this special exception.
+
+   This special exception was added by the Free Software Foundation in
+   version 2.2 of Bison.  */
+
+/* DO NOT RELY ON FEATURES THAT ARE NOT DOCUMENTED in the manual,
+   especially those whose name start with YY_ or yy_.  They are
+   private implementation details that can be changed or removed.  */
+
+#ifndef YY_YY_Y_TAB_H_INCLUDED
+# define YY_YY_Y_TAB_H_INCLUDED
+/* Debug traces.  */
+#ifndef YYDEBUG
+# define YYDEBUG 0
+#endif
+#if YYDEBUG
+extern int yydebug;
+#endif
+
+/* Token kinds.  */
+#ifndef YYTOKENTYPE
+# define YYTOKENTYPE
+  enum yytokentype
+  {
+    YYEMPTY = -2,
+    YYEOF = 0,                     /* "end of file"  */
+    YYerror = 256,                 /* error  */
+    YYUNDEF = 257,                 /* "invalid token"  */
+    WORD = 258,                    /* WORD  */
+    QWORD = 259,                   /* QWORD  */
+    LOCAL = 260,                   /* LOCAL  */
+    LET = 261,                     /* LET  */
+    FOR = 262,                     /* FOR  */
+    CLOSURE = 263,                 /* CLOSURE  */
+    FN = 264,                      /* FN  */
+    REDIR = 265,                   /* REDIR  */
+    DUP = 266,                     /* DUP  */
+    ANDAND = 267,                  /* ANDAND  */
+    BACKBACK = 268,                /* BACKBACK  */
+    BBFLAT = 269,                  /* BBFLAT  */
+    BFLAT = 270,                   /* BFLAT  */
+    EXTRACT = 271,                 /* EXTRACT  */
+    CALL = 272,                    /* CALL  */
+    COUNT = 273,                   /* COUNT  */
+    FLAT = 274,                    /* FLAT  */
+    OROR = 275,                    /* OROR  */
+    PRIM = 276,                    /* PRIM  */
+    SUB = 277,                     /* SUB  */
+    NL = 278,                      /* NL  */
+    ENDFILE = 279,                 /* ENDFILE  */
+    ERROR = 280,                   /* ERROR  */
+    MATCH = 281,                   /* MATCH  */
+    PIPE = 282                     /* PIPE  */
+  };
+  typedef enum yytokentype yytoken_kind_t;
+#endif
+
+/* Value type.  */
+#if ! defined YYSTYPE && ! defined YYSTYPE_IS_DECLARED
+union YYSTYPE
+{
+#line 27 "./parse.y"
+
+	Tree *tree;
+	char *str;
+	NodeKind kind;
+
+#line 97 "y.tab.h"
+
+};
+typedef union YYSTYPE YYSTYPE;
+# define YYSTYPE_IS_TRIVIAL 1
+# define YYSTYPE_IS_DECLARED 1
+#endif
+
+
+
+
+int yyparse (void);
+
+
+#endif /* !YY_YY_Y_TAB_H_INCLUDED  */