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implement optional semicolons with help from the lexer,

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instead of having to double the type and statement grammars.

R=ken
OCL=29987
CL=29998
This commit is contained in:
Russ Cox 2009-06-06 19:27:48 -07:00
parent e9e388412c
commit 8abcdee175
3 changed files with 204 additions and 309 deletions
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5
src/cmd/gc/go.h
View File

@ -622,6 +622,7 @@ void importfile(Val*);
void cannedimports(char*, char*);
void unimportfile();
int32 yylex(void);
void yyoptsemi(int);
void typeinit(void);
void lexinit(void);
char* lexname(int);
@ -1017,6 +1018,10 @@ EXTERN Prog* breakpc;
EXTERN Prog* pc;
EXTERN Prog* firstpc;
EXTERN int yylast;
EXTERN int yynext;
EXTERN int yysemi;
void allocparams(void);
void cgen_as(Node *nl, Node *nr);
void cgen_callmeth(Node *n, int proc);

464
src/cmd/gc/go.y
View File

@ -20,10 +20,9 @@
* 3. semicolons can be omitted before and after the closing ) or }
* on a list of statements or declarations.
*
* Thus the grammar must distinguish productions that
* can omit the semicolon terminator and those that can't.
* Names like Astmt, Avardcl, etc. can drop the semicolon.
* Names like Bstmt, Bvardcl, etc. can't.
* This is accomplished by calling yyoptsemi() to mark the places
* where semicolons are optional. That tells the lexer that if a
* semicolon isn't the next token, it should insert one for us.
*/
%{
@ -49,16 +48,16 @@
%token LANDAND LANDNOT LBODY LCOMM LDEC LEQ LGE LGT
%token LIGNORE LINC LLE LLSH LLT LNE LOROR LRSH
%token LSEMIBRACE
%type <lint> lbrace
%type <sym> sym packname
%type <val> oliteral
%type <node> Acommon_dcl Aelse_stmt Afnres Astmt Astmt_list_r
%type <node> Avardcl Bcommon_dcl Belse_stmt Bfnres Bstmt
%type <node> Bstmt_list_r Bvardcl arg_type arg_type_list
%type <node> stmt
%type <node> arg_type arg_type_list
%type <node> arg_type_list_r braced_keyexpr_list case caseblock
%type <node> caseblock_list_r common_dcl complex_stmt
%type <node> caseblock_list_r common_dcl
%type <node> compound_stmt dotname embed expr expr_list
%type <node> expr_list_r expr_or_type expr_or_type_list
%type <node> expr_or_type_list_r fnbody fndcl fnliteral fnres
@ -69,16 +68,15 @@
%type <node> new_name oarg_type_list ocaseblock_list oexpr
%type <node> oexpr_list oexpr_or_type_list onew_name
%type <node> osimple_stmt ostmt_list oxdcl_list pexpr
%type <node> pseudocall range_stmt select_stmt semi_stmt
%type <node> pseudocall range_stmt select_stmt
%type <node> simple_stmt stmt_list_r structdcl structdcl_list_r
%type <node> switch_body switch_stmt uexpr vardcl vardcl_list_r
%type <node> xdcl xdcl_list_r xfndcl
%type <type> Achantype Afntype Anon_chan_type Anon_fn_type
%type <type> Aothertype Atype Bchantype Bfntype Bnon_chan_type
%type <type> Bnon_fn_type Bothertype Btype convtype dotdotdot
%type <type> fnlitdcl fntype indcl interfacetype nametype
%type <type> convtype dotdotdot
%type <type> fnlitdcl fntype indcl interfacetype
%type <type> new_type structtype type typedclname
%type <type> chantype non_chan_type othertype non_fn_type
%type <sym> hidden_importsym hidden_pkg_importsym
@ -285,55 +283,21 @@ xdcl:
}
common_dcl:
Acommon_dcl
| Bcommon_dcl
Acommon_dcl:
LVAR Avardcl
LVAR vardcl
{
$$ = $2;
if(yylast == LSEMIBRACE)
yyoptsemi(0);
}
| LVAR '(' vardcl_list_r osemi ')'
{
$$ = rev($3);
yyoptsemi(0);
}
| LVAR '(' ')'
{
$$ = N;
}
| LCONST '(' constdcl osemi ')'
{
iota = 0;
lastconst = N;
$$ = N;
}
| LCONST '(' constdcl ';' constdcl_list_r osemi ')'
{
iota = 0;
lastconst = N;
$$ = N;
}
| LCONST '(' ')'
{
$$ = N;
}
| LTYPE Atypedcl
{
$$ = N;
}
| LTYPE '(' typedcl_list_r osemi ')'
{
$$ = N;
}
| LTYPE '(' ')'
{
$$ = N;
}
Bcommon_dcl:
LVAR Bvardcl
{
$$ = $2;
yyoptsemi(0);
}
| LCONST constdcl
{
@ -341,17 +305,49 @@ Bcommon_dcl:
iota = 0;
lastconst = N;
}
| LTYPE Btypedcl
| LCONST '(' constdcl osemi ')'
{
iota = 0;
lastconst = N;
$$ = N;
yyoptsemi(0);
}
| LCONST '(' constdcl ';' constdcl_list_r osemi ')'
{
iota = 0;
lastconst = N;
$$ = N;
yyoptsemi(0);
}
| LCONST '(' ')'
{
$$ = N;
yyoptsemi(0);
}
| LTYPE typedcl
{
$$ = N;
if(yylast == LSEMIBRACE)
yyoptsemi(0);
}
| LTYPE '(' typedcl_list_r osemi ')'
{
$$ = N;
yyoptsemi(0);
}
| LTYPE '(' ')'
{
$$ = N;
yyoptsemi(0);
}
varoptsemi:
{
yyoptsemi('=');
}
vardcl:
Avardcl
| Bvardcl
Avardcl:
name_list Atype
name_list type varoptsemi
{
dodclvar($$, $2);
@ -362,25 +358,12 @@ Avardcl:
addtotop($$);
}
}
Bvardcl:
name_list Btype
{
dodclvar($$, $2);
if(funcdepth == 0) {
$$ = N;
} else {
$$ = nod(OAS, $$, N);
addtotop($$);
}
}
| name_list type '=' expr_list
| name_list type varoptsemi '=' expr_list
{
if(addtop != N)
fatal("new_name_list_r type '=' expr_list");
$$ = variter($1, $2, $4);
$$ = variter($1, $2, $5);
addtotop($$);
}
| name_list '=' expr_list
@ -421,18 +404,7 @@ typedclname:
}
typedcl:
Atypedcl
| Btypedcl
Atypedcl:
typedclname Atype
{
updatetype($1, $2);
resumecheckwidth();
}
Btypedcl:
typedclname Btype
typedclname type
{
updatetype($1, $2);
resumecheckwidth();
@ -448,18 +420,6 @@ Btypedcl:
resumecheckwidth();
}
Aelse_stmt:
complex_stmt
| compound_stmt
Belse_stmt:
simple_stmt
| semi_stmt
| ';'
{
$$ = N;
}
simple_stmt:
expr
{
@ -498,22 +458,6 @@ simple_stmt:
$$->etype = OSUB;
}
complex_stmt:
for_stmt
| switch_stmt
| select_stmt
| if_stmt
{
popdcl();
$$ = $1;
}
| if_stmt LELSE Aelse_stmt
{
popdcl();
$$ = $1;
$$->nelse = $3;
}
case:
LCASE expr_list ':'
{
@ -576,43 +520,6 @@ case:
$$ = nod(OXCASE, N, N);
}
semi_stmt:
LFALL
{
// will be converted to OFALL
$$ = nod(OXFALL, N, N);
}
| LBREAK onew_name
{
$$ = nod(OBREAK, $2, N);
}
| LCONTINUE onew_name
{
$$ = nod(OCONTINUE, $2, N);
}
| LGO pseudocall
{
$$ = nod(OPROC, $2, N);
}
| LDEFER pseudocall
{
$$ = nod(ODEFER, $2, N);
}
| LGOTO new_name
{
$$ = nod(OGOTO, $2, N);
}
| LRETURN oexpr_list
{
$$ = nod(ORETURN, $2, N);
}
| if_stmt LELSE Belse_stmt
{
popdcl();
$$ = $1;
$$->nelse = $3;
}
compound_stmt:
'{'
{
@ -624,6 +531,7 @@ compound_stmt:
if($$ == N)
$$ = nod(OEMPTY, N, N);
popdcl();
yyoptsemi(0);
}
switch_body:
@ -637,6 +545,7 @@ switch_body:
if($$ == N)
$$ = nod(OEMPTY, N, N);
popdcl();
yyoptsemi(0);
}
caseblock:
@ -708,6 +617,7 @@ for_body:
{
$$ = $1;
$$->nbody = list($$->nbody, $2);
yyoptsemi(0);
}
for_stmt:
@ -747,6 +657,7 @@ if_stmt:
$$ = $3;
$$->nbody = $4;
// no popdcl; maybe there's an LELSE
yyoptsemi(LELSE);
}
switch_stmt:
@ -1099,73 +1010,40 @@ convtype:
/*
* to avoid parsing conflicts, type is split into
* named types
* channel types
* function types
* parenthesized types
* any other type
*
* (and also into A/B as described above).
*
* the type system makes additional restrictions,
* but those are not implemented in the grammar.
*/
type:
Atype
| Btype
Atype:
Achantype
| Afntype
| Aothertype
Btype:
nametype
| Bchantype
| Bfntype
| Bothertype
| '(' type ')'
{
$$ = $2;
}
dotdotdot:
LDDD
{
$$ = typ(TDDD);
}
Anon_chan_type:
Afntype
| Aothertype
Bnon_chan_type:
nametype
| Bfntype
| Bothertype
| '(' Btype ')'
type:
chantype
| fntype
| othertype
| '(' type ')'
{
$$ = $2;
}
Anon_fn_type:
Achantype
| Aothertype
Bnon_fn_type:
nametype
| Bchantype
| Bothertype
nametype:
dotname
non_chan_type:
fntype
| othertype
| '(' type ')'
{
if($1->op == OTYPE)
if($1->type->etype == TANY)
if(strcmp(package, "PACKAGE") != 0)
yyerror("the any type is restricted");
$$ = oldtype($1->sym);
$$ = $2;
}
non_fn_type:
chantype
| othertype
dotname:
name %prec NotDot
| name '.' sym
@ -1180,70 +1058,44 @@ dotname:
$$ = adddot($$);
}
Aothertype:
'[' oexpr ']' Atype
othertype:
'[' oexpr ']' type
{
$$ = aindex($2, $4);
}
| LCOMM LCHAN Atype
| LCOMM LCHAN type
{
$$ = typ(TCHAN);
$$->type = $3;
$$->chan = Crecv;
}
| LCHAN LCOMM Anon_chan_type
| LCHAN LCOMM non_chan_type
{
$$ = typ(TCHAN);
$$->type = $3;
$$->chan = Csend;
}
| LMAP '[' type ']' Atype
| LMAP '[' type ']' type
{
$$ = maptype($3, $5);
}
| '*' Atype
| '*' type
{
$$ = ptrto($2);
}
| structtype
| interfacetype
Bothertype:
'[' oexpr ']' Btype
| dotname
{
$$ = aindex($2, $4);
}
| LCOMM LCHAN Btype
{
$$ = typ(TCHAN);
$$->type = $3;
$$->chan = Crecv;
}
| LCHAN LCOMM Bnon_chan_type
{
$$ = typ(TCHAN);
$$->type = $3;
$$->chan = Csend;
}
| LMAP '[' type ']' Btype
{
$$ = maptype($3, $5);
}
| '*' Btype
{
$$ = ptrto($2);
if($1->op == OTYPE)
if($1->type->etype == TANY)
if(strcmp(package, "PACKAGE") != 0)
yyerror("the any type is restricted");
$$ = oldtype($1->sym);
}
Achantype:
LCHAN Atype
{
$$ = typ(TCHAN);
$$->type = $2;
$$->chan = Cboth;
}
Bchantype:
LCHAN Btype
chantype:
LCHAN type
{
$$ = typ(TCHAN);
$$->type = $2;
@ -1254,10 +1106,15 @@ structtype:
LSTRUCT '{' structdcl_list_r osemi '}'
{
$$ = dostruct(rev($3), TSTRUCT);
// Distinguish closing brace in struct from
// other closing braces by explicitly marking it.
// Used above (yylast == LSEMIBRACE).
yylast = LSEMIBRACE;
}
| LSTRUCT '{' '}'
{
$$ = dostruct(N, TSTRUCT);
yylast = LSEMIBRACE;
}
interfacetype:
@ -1265,10 +1122,12 @@ interfacetype:
{
$$ = dostruct(rev($3), TINTER);
$$ = sortinter($$);
yylast = LSEMIBRACE;
}
| LINTERFACE '{' '}'
{
$$ = dostruct(N, TINTER);
yylast = LSEMIBRACE;
}
keyval:
@ -1322,21 +1181,10 @@ fndcl:
$$->type = functype(N, $6, $8);
funchdr($$);
}
}
fntype:
Afntype
| Bfntype
Afntype:
LFUNC '(' oarg_type_list ')' Afnres
{
$$ = functype(N, $3, $5);
}
Bfntype:
LFUNC '(' oarg_type_list ')' Bfnres
LFUNC '(' oarg_type_list ')' fnres
{
$$ = functype(N, $3, $5);
}
@ -1361,29 +1209,18 @@ fnbody:
$$ = $2;
if($$ == N)
$$ = nod(ORETURN, N, N);
yyoptsemi(0);
}
| {
$$ = N;
}
fnres:
Afnres
| Bfnres
Afnres:
Anon_fn_type
{
$$ = nod(ODCLFIELD, N, N);
$$->type = $1;
$$ = cleanidlist($$);
}
Bfnres:
%prec NotParen
{
$$ = N;
}
| Bnon_fn_type
| non_fn_type
{
$$ = nod(ODCLFIELD, N, N);
$$->type = $1;
@ -1558,57 +1395,73 @@ arg_type_list:
}
/*
* statement that doesn't need semicolon terminator
* statement
*/
Astmt:
complex_stmt
| compound_stmt
| Acommon_dcl
| ';'
stmt:
{
$$ = N;
}
| error Astmt
{
$$ = N;
}
| labelname ':'
{
$$ = nod(OLABEL, $1, N);
}
| Bstmt ';'
/*
* statement that does
*/
Bstmt:
semi_stmt
| Bcommon_dcl
| simple_stmt
/*
* statement list that doesn't need semicolon terminator
*/
Astmt_list_r:
Astmt
| Astmt_list_r Astmt
| compound_stmt
| common_dcl
| for_stmt
| switch_stmt
| select_stmt
| if_stmt
{
$$ = list($1, $2);
popdcl();
$$ = $1;
}
/*
* statement list that needs semicolon terminator
*/
Bstmt_list_r:
Bstmt
| Astmt_list_r Bstmt
| if_stmt LELSE stmt
{
$$ = list($1, $2);
popdcl();
$$ = $1;
$$->nelse = $3;
}
| error
{
$$ = N;
}
| labelname ':' stmt
{
$$ = nod(OLIST, nod(OLABEL, $1, N), $3);
}
| LFALL
{
// will be converted to OFALL
$$ = nod(OXFALL, N, N);
}
| LBREAK onew_name
{
$$ = nod(OBREAK, $2, N);
}
| LCONTINUE onew_name
{
$$ = nod(OCONTINUE, $2, N);
}
| LGO pseudocall
{
$$ = nod(OPROC, $2, N);
}
| LDEFER pseudocall
{
$$ = nod(ODEFER, $2, N);
}
| LGOTO new_name
{
$$ = nod(OGOTO, $2, N);
}
| LRETURN oexpr_list
{
$$ = nod(ORETURN, $2, N);
}
stmt_list_r:
Astmt_list_r
| Bstmt_list_r
stmt
| stmt_list_r ';' stmt
{
$$ = list($1, $3);
}
name_list_r:
name
@ -1765,10 +1618,7 @@ osimple_stmt:
| simple_stmt
ostmt_list:
{
$$ = N;
}
| stmt_list_r
stmt_list_r
{
$$ = rev($1);
}

44
src/cmd/gc/lex.c
View File

@ -8,6 +8,8 @@
#include "y.tab.h"
#include <ar.h>
extern int yychar;
#define DBG if(!debug['x']);else print
enum
{
@ -366,8 +368,8 @@ isfrog(int c)
return 0;
}
int32
yylex(void)
static int32
_yylex(void)
{
int c, c1, clen;
vlong v;
@ -941,6 +943,44 @@ caseout:
return LLITERAL;
}
/*
* help the parser. if the next token is not c and not ';',
* insert a ';' before it.
*/
void
yyoptsemi(int c)
{
if(c == 0)
c = -1;
if(yychar <= 0)
yysemi = c;
}
int32
yylex(void)
{
// if we delayed a token, return that one.
if(yynext) {
yylast = yynext;
yynext = 0;
return yylast;
}
yylast = _yylex();
// if there's an optional semicolon needed,
// delay the token we just read.
if(yysemi) {
if(yylast != ';' && yylast != yysemi) {
yynext = yylast;
yylast = ';';
}
yysemi = 0;
}
return yylast;
}
int
getc(void)
{