ref: a291bbdeddfd41a2f0907ecbd7b819f0eedffdaf
dir: /sys/src/cmd/rc/syn.y/
%term FOR IN WHILE IF NOT TWIDDLE BANG SUBSHELL SWITCH FN
%term WORD REDIR DUP PIPE SUB
%term SIMPLE ARGLIST WORDS BRACE PAREN PCMD PIPEFD /* not used in syntax */
/* operator priorities -- lowest first */
%left IF WHILE FOR SWITCH ')' NOT
%left ANDAND OROR
%left BANG SUBSHELL
%left PIPE
%left '^'
%right '$' COUNT '"'
%left SUB
%{
#include "rc.h"
#include "fns.h"
%}
%union{
struct tree *tree;
};
%type<tree> line paren brace body cmdsa cmdsan assign epilog redir
%type<tree> cmd simple first word comword keyword words
%type<tree> NOT FOR IN WHILE IF TWIDDLE BANG SUBSHELL SWITCH FN
%type<tree> WORD REDIR DUP PIPE
%%
rc: { return 1;}
| line '\n' {return !compile($1);}
line: cmd
| cmdsa line {$$=tree2(';', $1, $2);}
body: cmd
| cmdsan body {$$=tree2(';', $1, $2);}
cmdsa: cmd ';'
| cmd '&' {$$=tree1('&', $1);}
cmdsan: cmdsa
| cmd '\n'
brace: '{' body '}' {$$=tree1(BRACE, $2);}
paren: '(' body ')' {$$=tree1(PCMD, $2);}
assign: first '=' word {$$=tree2('=', $1, $3);}
epilog: {$$=0;}
| redir epilog {$$=mung2($1, $1->child[0], $2);}
redir: REDIR word {$$=mung1($1, $1->rtype==HERE?heredoc($2):$2);}
| DUP
cmd: {$$=0;}
| brace epilog {$$=epimung($1, $2);}
| IF paren {skipnl();} cmd
{$$=mung2($1, $2, $4);}
| IF NOT {skipnl();} cmd {$$=mung1($2, $4);}
| FOR '(' word IN words ')' {skipnl();} cmd
/*
* if ``words'' is nil, we need a tree element to distinguish between
* for(i in ) and for(i), the former being a loop over the empty set
* and the latter being the implicit argument loop. so if $5 is nil
* (the empty set), we represent it as "()". don't parenthesize non-nil
* functions, to avoid growing parentheses every time we reread the
* definition.
*/
{$$=mung3($1, $3, $5 ? $5 : tree1(PAREN, $5), $8);}
| FOR '(' word ')' {skipnl();} cmd
{$$=mung3($1, $3, (struct tree *)0, $6);}
| WHILE paren {skipnl();} cmd
{$$=mung2($1, $2, $4);}
| SWITCH word {skipnl();} brace
{$$=tree2(SWITCH, $2, $4);}
| simple {$$=simplemung($1);}
| TWIDDLE word words {$$=mung2($1, $2, $3);}
| cmd ANDAND cmd {$$=tree2(ANDAND, $1, $3);}
| cmd OROR cmd {$$=tree2(OROR, $1, $3);}
| cmd PIPE cmd {$$=mung2($2, $1, $3);}
| redir cmd %prec BANG {$$=mung2($1, $1->child[0], $2);}
| assign cmd %prec BANG {$$=mung3($1, $1->child[0], $1->child[1], $2);}
| BANG cmd {$$=mung1($1, $2);}
| SUBSHELL cmd {$$=mung1($1, $2);}
| FN words brace {$$=tree2(FN, $2, $3);}
| FN words {$$=tree1(FN, $2);}
simple: first
| simple word {$$=tree2(ARGLIST, $1, $2);}
| simple redir {$$=tree2(ARGLIST, $1, $2);}
first: comword
| first '^' word {$$=tree2('^', $1, $3);}
word: keyword {lastword=1; $1->type=WORD;}
| comword
| word '^' word {$$=tree2('^', $1, $3);}
comword: '$' word {$$=tree1('$', $2);}
| '$' word SUB words ')' {$$=tree2(SUB, $2, $4);}
| '"' word {$$=tree1('"', $2);}
| COUNT word {$$=tree1(COUNT, $2);}
| WORD
| '`' brace {$$=tree1('`', $2);}
| '(' words ')' {$$=tree1(PAREN, $2);}
| REDIR brace {$$=mung1($1, $2); $$->type=PIPEFD;}
keyword: FOR|IN|WHILE|IF|NOT|TWIDDLE|BANG|SUBSHELL|SWITCH|FN
words: {$$=(struct tree*)0;}
| words word {$$=tree2(WORDS, $1, $2);}