cc.y

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

%{
#include "cc.h"
%}
%union	{
	Node*	node;
	Sym*	sym;
	Type*	type;
	struct
	{
		Type*	t;
		char	c;
	} tycl;
	struct
	{
		Type*	t1;
		Type*	t2;
	} tyty;
	struct
	{
		char*	s;
		long	l;
	} sval;
	long	lval;
	double	dval;
	vlong	vval;
}
%type	<sym>	ltag
%type	<lval>	gctname gcname cname gname tname
%type	<lval>	gctnlist gcnlist zgnlist
%type	<type>	tlist sbody complex
%type	<tycl>	types
%type	<node>	zarglist arglist zcexpr
%type	<node>	name block stmnt cexpr expr xuexpr pexpr
%type	<node>	zelist elist adecl slist uexpr string lstring
%type	<node>	xdecor xdecor2 labels label ulstmnt
%type	<node>	adlist edecor tag qual qlist
%type	<node>	abdecor abdecor1 abdecor2 abdecor3
%type	<node>	zexpr lexpr init ilist forexpr

%left	';'
%left	','
%right	'=' LPE LME LMLE LDVE LMDE LRSHE LLSHE LANDE LXORE LORE
%right	'?' ':'
%left	LOROR
%left	LANDAND
%left	'|'
%left	'^'
%left	'&'
%left	LEQ LNE
%left	'<' '>' LLE LGE
%left	LLSH LRSH
%left	'+' '-'
%left	'*' '/' '%'
%right	LMM LPP LMG '.' '[' '('

%token	<sym>	LNAME LTYPE
%token	<dval>	LFCONST LDCONST
%token	<vval>	LCONST LLCONST LUCONST LULCONST LVLCONST LUVLCONST
%token	<sval>	LSTRING LLSTRING
%token		LAUTO LBREAK LCASE LCHAR LCONTINUE LDEFAULT LDO
%token		LDOUBLE LELSE LEXTERN LFLOAT LFOR LGOTO
%token	LIF LINT LLONG LREGISTER LRETURN LSHORT LSIZEOF LUSED
%token	LSTATIC LSTRUCT LSWITCH LTYPEDEF LTYPESTR LUNION LUNSIGNED
%token	LWHILE LVOID LENUM LSIGNED LCONSTNT LVOLATILE LSET LSIGNOF
%token	LRESTRICT LINLINE
%%
prog:
|	prog xdecl

/*
 * external declarator
 */
xdecl:
	zctlist ';'
	{
		dodecl(xdecl, lastclass, lasttype, Z);
	}
|	zctlist xdlist ';'
|	zctlist xdecor
	{
		lastdcl = T;
		firstarg = S;
		dodecl(xdecl, lastclass, lasttype, $2);
		if(lastdcl == T || lastdcl->etype != TFUNC) {
			diag($2, "not a function");
			lastdcl = types[TFUNC];
		}
		thisfn = lastdcl;
		markdcl();
		firstdcl = dclstack;
		argmark($2, 0);
	}
	pdecl
	{
		argmark($2, 1);
	}
	block
	{
		Node *n;

		n = revertdcl();
		if(n)
			$6 = new(OLIST, n, $6);
		if(!debug['a'] && !debug['Z'])
			codgen($6, $2);
	}

xdlist:
	xdecor
	{
		dodecl(xdecl, lastclass, lasttype, $1);
	}
|	xdecor
	{
		$1 = dodecl(xdecl, lastclass, lasttype, $1);
	}
	'=' init
	{
		doinit($1->sym, $1->type, 0L, $4);
	}
|	xdlist ',' xdlist

xdecor:
	xdecor2
|	'*' zgnlist xdecor
	{
		$$ = new(OIND, $3, Z);
		$$->garb = simpleg($2);
	}

xdecor2:
	tag
|	'(' xdecor ')'
	{
		$$ = $2;
	}
|	xdecor2 '(' zarglist ')'
	{
		$$ = new(OFUNC, $1, $3);
	}
|	xdecor2 '[' zexpr ']'
	{
		$$ = new(OARRAY, $1, $3);
	}

/*
 * automatic declarator
 */
adecl:
	ctlist ';'
	{
		$$ = dodecl(adecl, lastclass, lasttype, Z);
	}
|	ctlist adlist ';'
	{
		$$ = $2;
	}

adlist:
	xdecor
	{
		dodecl(adecl, lastclass, lasttype, $1);
		$$ = Z;
	}
|	xdecor
	{
		$1 = dodecl(adecl, lastclass, lasttype, $1);
	}
	'=' init
	{
		long w;

		w = $1->sym->type->width;
		$$ = doinit($1->sym, $1->type, 0L, $4);
		$$ = contig($1->sym, $$, w);
	}
|	adlist ',' adlist
	{
		$$ = $1;
		if($3 != Z) {
			$$ = $3;
			if($1 != Z)
				$$ = new(OLIST, $1, $3);
		}
	}

/*
 * parameter declarator
 */
pdecl:
|	pdecl ctlist pdlist ';'

pdlist:
	xdecor
	{
		dodecl(pdecl, lastclass, lasttype, $1);
	}
|	pdlist ',' pdlist

/*
 * structure element declarator
 */
edecl:
	tlist
	{
		lasttype = $1;
	}
	zedlist ';'
|	edecl tlist
	{
		lasttype = $2;
	}
	zedlist ';'

zedlist:					/* extension */
	{
		lastfield = 0;
		edecl(CXXX, lasttype, S);
	}
|	edlist

edlist:
	edecor
	{
		dodecl(edecl, CXXX, lasttype, $1);
	}
|	edlist ',' edlist

edecor:
	xdecor
	{
		lastbit = 0;
		firstbit = 1;
	}
|	tag ':' lexpr
	{
		$$ = new(OBIT, $1, $3);
	}
|	':' lexpr
	{
		$$ = new(OBIT, Z, $2);
	}

/*
 * abstract declarator
 */
abdecor:
	{
		$$ = (Z);
	}
|	abdecor1

abdecor1:
	'*' zgnlist
	{
		$$ = new(OIND, (Z), Z);
		$$->garb = simpleg($2);
	}
|	'*' zgnlist abdecor1
	{
		$$ = new(OIND, $3, Z);
		$$->garb = simpleg($2);
	}
|	abdecor2

abdecor2:
	abdecor3
|	abdecor2 '(' zarglist ')'
	{
		$$ = new(OFUNC, $1, $3);
	}
|	abdecor2 '[' zexpr ']'
	{
		$$ = new(OARRAY, $1, $3);
	}

abdecor3:
	'(' ')'
	{
		$$ = new(OFUNC, (Z), Z);
	}
|	'[' zexpr ']'
	{
		$$ = new(OARRAY, (Z), $2);
	}
|	'(' abdecor1 ')'
	{
		$$ = $2;
	}

init:
	expr
|	'{' ilist '}'
	{
		$$ = new(OINIT, invert($2), Z);
	}

qual:
	'[' lexpr ']'
	{
		$$ = new(OARRAY, $2, Z);
	}
|	'.' ltag
	{
		$$ = new(OELEM, Z, Z);
		$$->sym = $2;
	}
|	qual '='

qlist:
	init ','
|	qlist init ','
	{
		$$ = new(OLIST, $1, $2);
	}
|	qual
|	qlist qual
	{
		$$ = new(OLIST, $1, $2);
	}

ilist:
	qlist
|	init
|	qlist init
	{
		$$ = new(OLIST, $1, $2);
	}

zarglist:
	{
		$$ = Z;
	}
|	arglist
	{
		$$ = invert($1);
	}


arglist:
	name
|	tlist abdecor
	{
		$$ = new(OPROTO, $2, Z);
		$$->type = $1;
	}
|	tlist xdecor
	{
		$$ = new(OPROTO, $2, Z);
		$$->type = $1;
	}
|	'.' '.' '.'
	{
		$$ = new(ODOTDOT, Z, Z);
	}
|	arglist ',' arglist
	{
		$$ = new(OLIST, $1, $3);
	}

block:
	'{' slist '}'
	{
		$$ = invert($2);
	//	if($2 != Z)
	//		$$ = new(OLIST, $2, $$);
		if($$ == Z)
			$$ = new(OLIST, Z, Z);
	}

slist:
	{
		$$ = Z;
	}
|	slist adecl
	{
		$$ = new(OLIST, $1, $2);
	}
|	slist stmnt
	{
		$$ = new(OLIST, $1, $2);
	}

labels:
	label
|	labels label
	{
		$$ = new(OLIST, $1, $2);
	}

label:
	LCASE expr ':'
	{
		$$ = new(OCASE, $2, Z);
	}
|	LDEFAULT ':'
	{
		$$ = new(OCASE, Z, Z);
	}
|	LNAME ':'
	{
		$$ = new(OLABEL, dcllabel($1, 1), Z);
	}

stmnt:
	error ';'
	{
		$$ = Z;
	}
|	ulstmnt
|	labels ulstmnt
	{
		$$ = new(OLIST, $1, $2);
	}

forexpr:
	zcexpr
|	ctlist adlist
	{
		$$ = $2;
	}

ulstmnt:
	zcexpr ';'
|	{
		markdcl();
	}
	block
	{
		$$ = revertdcl();
		if($$)
			$$ = new(OLIST, $$, $2);
		else
			$$ = $2;
	}
|	LIF '(' cexpr ')' stmnt
	{
		$$ = new(OIF, $3, new(OLIST, $5, Z));
		if($5 == Z)
			warn($3, "empty if body");
	}
|	LIF '(' cexpr ')' stmnt LELSE stmnt
	{
		$$ = new(OIF, $3, new(OLIST, $5, $7));
		if($5 == Z)
			warn($3, "empty if body");
		if($7 == Z)
			warn($3, "empty else body");
	}
|	{ markdcl(); } LFOR '(' forexpr ';' zcexpr ';' zcexpr ')' stmnt
	{
		$$ = revertdcl();
		if($$){
			if($4)
				$4 = new(OLIST, $$, $4);
			else
				$4 = $$;
		}
		$$ = new(OFOR, new(OLIST, $6, new(OLIST, $4, $8)), $10);
	}
|	LWHILE '(' cexpr ')' stmnt
	{
		$$ = new(OWHILE, $3, $5);
	}
|	LDO stmnt LWHILE '(' cexpr ')' ';'
	{
		$$ = new(ODWHILE, $5, $2);
	}
|	LRETURN zcexpr ';'
	{
		$$ = new(ORETURN, $2, Z);
		$$->type = thisfn->link;
	}
|	LSWITCH '(' cexpr ')' stmnt
	{
		$$ = new(OCONST, Z, Z);
		$$->vconst = 0;
		$$->type = types[TINT];
		$3 = new(OSUB, $$, $3);

		$$ = new(OCONST, Z, Z);
		$$->vconst = 0;
		$$->type = types[TINT];
		$3 = new(OSUB, $$, $3);

		$$ = new(OSWITCH, $3, $5);
	}
|	LBREAK ';'
	{
		$$ = new(OBREAK, Z, Z);
	}
|	LCONTINUE ';'
	{
		$$ = new(OCONTINUE, Z, Z);
	}
|	LGOTO ltag ';'
	{
		$$ = new(OGOTO, dcllabel($2, 0), Z);
	}
|	LUSED '(' zelist ')' ';'
	{
		$$ = new(OUSED, $3, Z);
	}
|	LSET '(' zelist ')' ';'
	{
		$$ = new(OSET, $3, Z);
	}

zcexpr:
	{
		$$ = Z;
	}
|	cexpr

zexpr:
	{
		$$ = Z;
	}
|	lexpr

lexpr:
	expr
	{
		$$ = new(OCAST, $1, Z);
		$$->type = types[TLONG];
	}

cexpr:
	expr
|	cexpr ',' cexpr
	{
		$$ = new(OCOMMA, $1, $3);
	}

expr:
	xuexpr
|	expr '*' expr
	{
		$$ = new(OMUL, $1, $3);
	}
|	expr '/' expr
	{
		$$ = new(ODIV, $1, $3);
	}
|	expr '%' expr
	{
		$$ = new(OMOD, $1, $3);
	}
|	expr '+' expr
	{
		$$ = new(OADD, $1, $3);
	}
|	expr '-' expr
	{
		$$ = new(OSUB, $1, $3);
	}
|	expr LRSH expr
	{
		$$ = new(OASHR, $1, $3);
	}
|	expr LLSH expr
	{
		$$ = new(OASHL, $1, $3);
	}
|	expr '<' expr
	{
		$$ = new(OLT, $1, $3);
	}
|	expr '>' expr
	{
		$$ = new(OGT, $1, $3);
	}
|	expr LLE expr
	{
		$$ = new(OLE, $1, $3);
	}
|	expr LGE expr
	{
		$$ = new(OGE, $1, $3);
	}
|	expr LEQ expr
	{
		$$ = new(OEQ, $1, $3);
	}
|	expr LNE expr
	{
		$$ = new(ONE, $1, $3);
	}