+/* parse.y */
+
+/*
+ * Adapted from rc grammar, v10 manuals, volume 2.
+ */
+
+%{
+#include "rc.h"
+#ifndef lint
+#define lint /* hush up gcc -Wall, leave out the dumb sccsid's. */
+#endif
+static Node *star, *nolist;
+Node *parsetree; /* not using yylval because bison declares it as an auto */
+%}
+
+%token ANDAND BACKBACK BANG CASE COUNT DUP ELSE END FLAT FN FOR IF IN
+%token OROR PIPE REDIR SREDIR SUB SUBSHELL SWITCH TWIDDLE WHILE WORD HUH
+
+%left WHILE ')' ELSE
+%left ANDAND OROR '\n'
+%left BANG SUBSHELL
+%left PIPE
+%right '$'
+%left SUB
+/*
+*/
+
+%union {
+ struct Node *node;
+ struct Redir redir;
+ struct Pipe pipe;
+ struct Dup dup;
+ struct Word word;
+ char *keyword;
+}
+
+%type <redir> REDIR SREDIR
+%type <pipe> PIPE
+%type <dup> DUP
+%type <word> WORD
+%type <keyword> keyword
+%type <node> assign body brace case cbody cmd cmdsa cmdsan comword epilog
+ first line nlwords paren redir sword simple iftail word words
+
+%start rc
+
+%%
+
+rc : line end { parsetree = $1; YYACCEPT; }
+ | error end { yyerrok; parsetree = NULL; YYABORT; }
+
+/* an rc line may end in end-of-file as well as newline, e.g., rc -c 'ls' */
+end : END /* EOF */ { if (!heredoc(1)) YYABORT; } /* flag error if there is a heredoc in the queue */
+ | '\n' { if (!heredoc(0)) YYABORT; } /* get heredoc on \n */
+
+/* a cmdsa is a command followed by ampersand or newline (used in "line" and "body") */
+cmdsa : cmd ';'
+ | cmd '&' { $$ = ($1 != NULL ? mk(nNowait,$1) : $1); }
+
+/* a line is a single command, or a command terminated by ; or & followed by a line (recursive) */
+line : cmd
+ | cmdsa line { $$ = ($1 != NULL ? mk(nBody,$1,$2) : $2); }
+
+/* a body is like a line, only commands may also be terminated by newline */
+body : cmd
+ | cmdsan body { $$ = ($1 == NULL ? $2 : $2 == NULL ? $1 : mk(nBody,$1,$2)); }
+
+cmdsan : cmdsa
+ | cmd '\n' { $$ = $1; if (!heredoc(0)) YYABORT; } /* get h.d. on \n */
+
+brace : '{' body '}' { $$ = $2; }
+
+paren : '(' body ')' { $$ = $2; }
+
+assign : first '=' word { $$ = mk(nAssign,$1,$3); }
+
+epilog : { $$ = NULL; }
+ | redir epilog { $$ = mk(nEpilog,$1,$2); }
+
+/* a redirection is a dup (e.g., >[1=2]) or a file redirection. (e.g., > /dev/null) */
+redir : DUP { $$ = mk(nDup,$1.type,$1.left,$1.right); }
+ | REDIR word { $$ = mk(nRedir,$1.type,$1.fd,$2);
+ if ($1.type == rHeredoc && !qdoc($2, $$)) YYABORT; /* queue heredocs up */
+ }
+ | SREDIR word { $$ = mk(nRedir,$1.type,$1.fd,$2);
+ if ($1.type == rHeredoc && !qdoc($2, $$)) YYABORT; /* queue heredocs up */
+ }
+
+case : CASE words ';' { $$ = mk(nCase, $2); }
+ | CASE words '\n' { $$ = mk(nCase, $2); }
+
+cbody : cmd { $$ = mk(nCbody, $1, NULL); }
+ | case cbody { $$ = mk(nCbody, $1, $2); }
+ | cmdsan cbody { $$ = mk(nCbody, $1, $2); }
+
+iftail : cmd %prec ELSE
+ | brace ELSE optnl cmd { $$ = mk(nElse,$1,$4); }
+
+cmd : /* empty */ %prec WHILE { $$ = NULL; }
+ | simple
+ | brace epilog { $$ = mk(nBrace,$1,$2); }
+ | IF paren optnl iftail { $$ = mk(nIf,$2,$4); }
+ | FOR '(' word IN words ')' optnl cmd { $$ = mk(nForin,$3,$5,$8); }
+ | FOR '(' word ')' optnl cmd { $$ = mk(nForin,$3,star,$6); }
+ | WHILE paren optnl cmd { $$ = mk(nWhile,$2,$4); }
+ | SWITCH '(' word ')' optnl '{' cbody '}' { $$ = mk(nSwitch,$3,$7); }
+ | TWIDDLE optcaret word words { $$ = mk(nMatch,$3,$4); }
+ | cmd ANDAND optnl cmd { $$ = mk(nAndalso,$1,$4); }
+ | cmd OROR optnl cmd { $$ = mk(nOrelse,$1,$4); }
+ | cmd PIPE optnl cmd { $$ = mk(nPipe,$2.left,$2.right,$1,$4); }
+ | redir cmd %prec BANG { $$ = ($2 != NULL ? mk(nPre,$1,$2) : $1); }
+ | assign cmd %prec BANG { $$ = ($2 != NULL ? mk(nPre,$1,$2) : $1); }
+ | BANG optcaret cmd { $$ = mk(nBang,$3); }
+ | SUBSHELL optcaret cmd { $$ = mk(nSubshell,$3); }
+ | FN words brace { $$ = mk(nNewfn,$2,$3); }
+ | FN words { $$ = mk(nRmfn,$2); }
+
+optcaret : /* empty */
+ | '^'
+
+simple : first
+ | simple word { $$ = ($2 != NULL ? mk(nArgs,$1,$2) : $1); }
+ | simple redir { $$ = mk(nArgs,$1,$2); }
+
+first : comword
+ | first '^' sword { $$ = mk(nConcat,$1,$3); }
+
+sword : comword
+ | keyword { $$ = mk(nWord,$1, NULL); }
+
+word : sword
+ | word '^' sword { $$ = mk(nConcat,$1,$3); }
+
+comword : '$' sword { $$ = mk(nVar,$2); }
+ | '$' sword SUB words ')' { $$ = mk(nVarsub,$2,$4); }
+ | COUNT sword { $$ = mk(nCount,$2); }
+ | FLAT sword { $$ = mk(nFlat, $2); }
+ | '`' sword { $$ = mk(nBackq,nolist,$2); }
+ | '`' brace { $$ = mk(nBackq,nolist,$2); }
+ | BACKBACK word brace { $$ = mk(nBackq,$2,$3); }
+ | BACKBACK word sword { $$ = mk(nBackq,$2,$3); }
+ | '(' nlwords ')' { $$ = $2; }
+ | REDIR brace { $$ = mk(nNmpipe,$1.type,$1.fd,$2); }
+ | WORD { $$ = ($1.w[0] == '\'') ? mk(nQword, $1.w+1, NULL) : mk(nWord,$1.w, $1.m); }
+
+keyword : FOR { $$ = "for"; }
+ | IN { $$ = "in"; }
+ | WHILE { $$ = "while"; }
+ | IF { $$ = "if"; }
+ | SWITCH { $$ = "switch"; }
+ | FN { $$ = "fn"; }
+ | ELSE { $$ = "else"; }
+ | CASE { $$ = "case"; }
+ | TWIDDLE { $$ = "~"; }
+ | BANG { $$ = "!"; }
+ | SUBSHELL { $$ = "@"; }
+
+words : { $$ = NULL; }
+ | words word { $$ = ($1 != NULL ? ($2 != NULL ? mk(nLappend,$1,$2) : $1) : $2); }
+
+nlwords : { $$ = NULL; }
+ | nlwords '\n'
+ | nlwords word { $$ = ($1 != NULL ? ($2 != NULL ? mk(nLappend,$1,$2) : $1) : $2); }
+
+optnl : /* empty */
+ | optnl '\n'
+
+%%
+
+void initparse() {
+ star = treecpy(mk(nVar,mk(nWord,"*",NULL)), ealloc);
+ nolist = treecpy(mk(nVar,mk(nWord,"ifs",NULL)), ealloc);
+}
+
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