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

|	expr '&' expr
	{
		$$ = new(OAND, $1, $3);
	}
|	expr '^' expr
	{
		$$ = new(OXOR, $1, $3);
	}
|	expr '|' expr
	{
		$$ = new(OOR, $1, $3);
	}
|	expr LANDAND expr
	{
		$$ = new(OANDAND, $1, $3);
	}
|	expr LOROR expr
	{
		$$ = new(OOROR, $1, $3);
	}
|	expr '?' cexpr ':' expr
	{
		$$ = new(OCOND, $1, new(OLIST, $3, $5));
	}
|	expr '=' expr
	{
		$$ = new(OAS, $1, $3);
	}
|	expr LPE expr
	{
		$$ = new(OASADD, $1, $3);
	}
|	expr LME expr
	{
		$$ = new(OASSUB, $1, $3);
	}
|	expr LMLE expr
	{
		$$ = new(OASMUL, $1, $3);
	}
|	expr LDVE expr
	{
		$$ = new(OASDIV, $1, $3);
	}
|	expr LMDE expr
	{
		$$ = new(OASMOD, $1, $3);
	}
|	expr LLSHE expr
	{
		$$ = new(OASASHL, $1, $3);
	}
|	expr LRSHE expr
	{
		$$ = new(OASASHR, $1, $3);
	}
|	expr LANDE expr
	{
		$$ = new(OASAND, $1, $3);
	}
|	expr LXORE expr
	{
		$$ = new(OASXOR, $1, $3);
	}
|	expr LORE expr
	{
		$$ = new(OASOR, $1, $3);
	}

xuexpr:
	uexpr
|	'(' tlist abdecor ')' xuexpr
	{
		$$ = new(OCAST, $5, Z);
		dodecl(NODECL, CXXX, $2, $3);
		$$->type = lastdcl;
		$$->xcast = 1;
	}
|	'(' tlist abdecor ')' '{' ilist '}'	/* extension */
	{
		$$ = new(OSTRUCT, $6, Z);
		dodecl(NODECL, CXXX, $2, $3);
		$$->type = lastdcl;
	}

uexpr:
	pexpr
|	'*' xuexpr
	{
		$$ = new(OIND, $2, Z);
	}
|	'&' xuexpr
	{
		$$ = new(OADDR, $2, Z);
	}
|	'+' xuexpr
	{
		$$ = new(OPOS, $2, Z);
	}
|	'-' xuexpr
	{
		$$ = new(ONEG, $2, Z);
	}
|	'!' xuexpr
	{
		$$ = new(ONOT, $2, Z);
	}
|	'~' xuexpr
	{
		$$ = new(OCOM, $2, Z);
	}
|	LPP xuexpr
	{
		$$ = new(OPREINC, $2, Z);
	}
|	LMM xuexpr
	{
		$$ = new(OPREDEC, $2, Z);
	}
|	LSIZEOF uexpr
	{
		$$ = new(OSIZE, $2, Z);
	}
|	LSIGNOF uexpr
	{
		$$ = new(OSIGN, $2, Z);
	}

pexpr:
	'(' cexpr ')'
	{
		$$ = $2;
	}
|	LSIZEOF '(' tlist abdecor ')'
	{
		$$ = new(OSIZE, Z, Z);
		dodecl(NODECL, CXXX, $3, $4);
		$$->type = lastdcl;
	}
|	LSIGNOF '(' tlist abdecor ')'
	{
		$$ = new(OSIGN, Z, Z);
		dodecl(NODECL, CXXX, $3, $4);
		$$->type = lastdcl;
	}
|	pexpr '(' zelist ')'
	{
		$$ = new(OFUNC, $1, Z);
		if($1->op == ONAME)
		if($1->type == T)
			dodecl(xdecl, CXXX, types[TINT], $$);
		$$->right = invert($3);
	}
|	pexpr '[' cexpr ']'
	{
		$$ = new(OIND, new(OADD, $1, $3), Z);
	}
|	pexpr LMG ltag
	{
		$$ = new(ODOT, new(OIND, $1, Z), Z);
		$$->sym = $3;
	}
|	pexpr '.' ltag
	{
		$$ = new(ODOT, $1, Z);
		$$->sym = $3;
	}
|	pexpr LPP
	{
		$$ = new(OPOSTINC, $1, Z);
	}
|	pexpr LMM
	{
		$$ = new(OPOSTDEC, $1, Z);
	}
|	name
|	LCONST
	{
		$$ = new(OCONST, Z, Z);
		$$->type = types[TINT];
		$$->vconst = $1;
		$$->cstring = strdup(symb);
	}
|	LLCONST
	{
		$$ = new(OCONST, Z, Z);
		$$->type = types[TLONG];
		$$->vconst = $1;
		$$->cstring = strdup(symb);
	}
|	LUCONST
	{
		$$ = new(OCONST, Z, Z);
		$$->type = types[TUINT];
		$$->vconst = $1;
		$$->cstring = strdup(symb);
	}
|	LULCONST
	{
		$$ = new(OCONST, Z, Z);
		$$->type = types[TULONG];
		$$->vconst = $1;
		$$->cstring = strdup(symb);
	}
|	LDCONST
	{
		$$ = new(OCONST, Z, Z);
		$$->type = types[TDOUBLE];
		$$->fconst = $1;
		$$->cstring = strdup(symb);
	}
|	LFCONST
	{
		$$ = new(OCONST, Z, Z);
		$$->type = types[TFLOAT];
		$$->fconst = $1;
		$$->cstring = strdup(symb);
	}
|	LVLCONST
	{
		$$ = new(OCONST, Z, Z);
		$$->type = types[TVLONG];
		$$->vconst = $1;
		$$->cstring = strdup(symb);
	}
|	LUVLCONST
	{
		$$ = new(OCONST, Z, Z);
		$$->type = types[TUVLONG];
		$$->vconst = $1;
		$$->cstring = strdup(symb);
	}
|	string
|	lstring

string:
	LSTRING
	{
		$$ = new(OSTRING, Z, Z);
		$$->type = typ(TARRAY, types[TCHAR]);
		$$->type->width = $1.l + 1;
		$$->cstring = $1.s;
		$$->sym = symstring;
		$$->etype = TARRAY;
		$$->class = CSTATIC;
	}
|	string LSTRING
	{
		char *s;
		int n;

		n = $1->type->width - 1;
		s = alloc(n+$2.l+MAXALIGN);

		memcpy(s, $1->cstring, n);
		memcpy(s+n, $2.s, $2.l);
		s[n+$2.l] = 0;

		$$ = $1;
		$$->type->width += $2.l;
		$$->cstring = s;
	}

lstring:
	LLSTRING
	{
		$$ = new(OLSTRING, Z, Z);
		$$->type = typ(TARRAY, types[TUSHORT]);
		$$->type->width = $1.l + sizeof(ushort);
		$$->rstring = (ushort*)$1.s;
		$$->sym = symstring;
		$$->etype = TARRAY;
		$$->class = CSTATIC;
	}
|	lstring LLSTRING
	{
		char *s;
		int n;

		n = $1->type->width - sizeof(ushort);
		s = alloc(n+$2.l+MAXALIGN);

		memcpy(s, $1->rstring, n);
		memcpy(s+n, $2.s, $2.l);
		*(ushort*)(s+n+$2.l) = 0;

		$$ = $1;
		$$->type->width += $2.l;
		$$->rstring = (ushort*)s;
	}

zelist:
	{
		$$ = Z;
	}
|	elist

elist:
	expr
|	elist ',' elist
	{
		$$ = new(OLIST, $1, $3);
	}

sbody:
	'{'
	{
		$<tyty>$.t1 = strf;
		$<tyty>$.t2 = strl;
		strf = T;
		strl = T;
		lastbit = 0;
		firstbit = 1;
	}
	edecl '}'
	{
		$$ = strf;
		strf = $<tyty>2.t1;
		strl = $<tyty>2.t2;
	}

zctlist:
	{
		lastclass = CXXX;
		lasttype = types[TINT];
	}
|	ctlist

types:
	complex
	{
		$$.t = $1;
		$$.c = CXXX;
	}
|	tname
	{
		$$.t = simplet($1);
		$$.c = CXXX;
	}
|	gcnlist
	{
		$$.t = simplet($1);
		$$.c = simplec($1);
		$$.t = garbt($$.t, $1);
	}
|	complex gctnlist
	{
		$$.t = $1;
		$$.c = simplec($2);
		$$.t = garbt($$.t, $2);
		if($2 & ~BCLASS & ~BGARB)
			diag(Z, "duplicate types given: %T and %Q", $1, $2);
	}
|	tname gctnlist
	{
		$$.t = simplet(typebitor($1, $2));
		$$.c = simplec($2);
		$$.t = garbt($$.t, $2);
	}
|	gcnlist complex zgnlist
	{
		$$.t = $2;
		$$.c = simplec($1);
		$$.t = garbt($$.t, $1|$3);
	}
|	gcnlist tname
	{
		$$.t = simplet($2);
		$$.c = simplec($1);
		$$.t = garbt($$.t, $1);
	}
|	gcnlist tname gctnlist
	{
		$$.t = simplet(typebitor($2, $3));
		$$.c = simplec($1|$3);
		$$.t = garbt($$.t, $1|$3);
	}

tlist:
	types
	{
		$$ = $1.t;
		if($1.c != CXXX)
			diag(Z, "illegal combination of class 4: %s", cnames[$1.c]);
	}

ctlist:
	types
	{
		lasttype = $1.t;
		lastclass = $1.c;
	}

complex:
	LSTRUCT ltag
	{
		dotag($2, TSTRUCT, 0);
		$$ = $2->suetag;
	}
|	LSTRUCT ltag
	{
		dotag($2, TSTRUCT, autobn);
	}
	sbody
	{
		$$ = $2->suetag;
		if($$->link != T)
			diag(Z, "redeclare tag: %s", $2->name);
		$$->link = $4;
		suallign($$);
	}
|	LSTRUCT sbody
	{
		taggen++;
		sprint(symb, "_%d_", taggen);
		$$ = dotag(lookup(), TSTRUCT, autobn);
		$$->link = $2;
		suallign($$);
	}
|	LUNION ltag
	{
		dotag($2, TUNION, 0);
		$$ = $2->suetag;
	}
|	LUNION ltag
	{
		dotag($2, TUNION, autobn);
	}
	sbody
	{
		$$ = $2->suetag;
		if($$->link != T)
			diag(Z, "redeclare tag: %s", $2->name);
		$$->link = $4;
		suallign($$);
	}
|	LUNION sbody
	{
		taggen++;
		sprint(symb, "_%d_", taggen);
		$$ = dotag(lookup(), TUNION, autobn);
		$$->link = $2;
		suallign($$);
	}
|	LENUM ltag
	{
		dotag($2, TENUM, 0);
		$$ = $2->suetag;
		if($$->link == T)
			$$->link = types[TINT];
		$$ = $$->link;
	}
|	LENUM ltag
	{
		dotag($2, TENUM, autobn);
	}
	'{'
	{
		en.tenum = T;
		en.cenum = T;
	}
	enum '}'
	{
		$$ = $2->suetag;
		if($$->link != T)
			diag(Z, "redeclare tag: %s", $2->name);
		if(en.tenum == T) {
			diag(Z, "enum type ambiguous: %s", $2->name);
			en.tenum = types[TINT];
		}
		$$->link = en.tenum;
		$$ = en.tenum;
	}
|	LENUM '{'
	{
		en.tenum = T;
		en.cenum = T;
	}
	enum '}'
	{
		$$ = en.tenum;
	}
|	LTYPE
	{
		$$ = tcopy($1->type);
	}

gctnlist:
	gctname
|	gctnlist gctname
	{
		$$ = typebitor($1, $2);
	}

zgnlist:
	{
		$$ = 0;
	}
|	zgnlist gname
	{
		$$ = typebitor($1, $2);
	}

gctname:
	tname
|	gname
|	cname

gcnlist:
	gcname
|	gcnlist gcname
	{
		$$ = typebitor($1, $2);
	}

gcname:
	gname
|	cname

enum:
	LNAME
	{
		doenum($1, Z);
	}
|	LNAME '=' expr
	{
		doenum($1, $3);
	}
|	enum ','
|	enum ',' enum

tname:	/* type words */
	LCHAR { $$ = BCHAR; }
|	LSHORT { $$ = BSHORT; }
|	LINT { $$ = BINT; }
|	LLONG { $$ = BLONG; }
|	LSIGNED { $$ = BSIGNED; }
|	LUNSIGNED { $$ = BUNSIGNED; }
|	LFLOAT { $$ = BFLOAT; }
|	LDOUBLE { $$ = BDOUBLE; }
|	LVOID { $$ = BVOID; }

cname:	/* class words */
	LAUTO { $$ = BAUTO; }
|	LSTATIC { $$ = BSTATIC; }
|	LEXTERN { $$ = BEXTERN; }
|	LTYPEDEF { $$ = BTYPEDEF; }
|	LTYPESTR { $$ = BTYPESTR; }
|	LREGISTER { $$ = BREGISTER; }
|	LINLINE { $$ = 0; }

gname:	/* garbage words */
	LCONSTNT { $$ = BCONSTNT; }
|	LVOLATILE { $$ = BVOLATILE; }
|	LRESTRICT { $$ = 0; }

name:
	LNAME
	{
		$$ = new(ONAME, Z, Z);
		if($1->class == CLOCAL)
			$1 = mkstatic($1);
		$$->sym = $1;
		$$->type = $1->type;
		$$->etype = TVOID;
		if($$->type != T)
			$$->etype = $$->type->etype;
		$$->xoffset = $1->offset;
		$$->class = $1->class;
		$1->aused = 1;
	}
tag:
	ltag
	{
		$$ = new(ONAME, Z, Z);
		$$->sym = $1;
		$$->type = $1->type;
		$$->etype = TVOID;
		if($$->type != T)
			$$->etype = $$->type->etype;
		$$->xoffset = $1->offset;
		$$->class = $1->class;
	}
ltag:
	LNAME
|	LTYPE
%%