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Bison grammar: refactor index expressions to use ordinary expressions as indexes, remove index_expr and expr_norange
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‎src/grammar/parser-lalr.y‎

Lines changed: 12 additions & 74 deletions
Original file line numberDiff line numberDiff line change
@@ -1193,12 +1193,10 @@ maybe_stmts
11931193
//
11941194
// In non-stmts contexts, expr can relax this trichotomy.
11951195
//
1196-
// There are also two other expr subtypes: first, nonparen_expr
1197-
// disallows exprs surrounded by parens (including tuple expressions),
1198-
// this is necessary for BOX (place) expressions, so a parens expr
1199-
// following the BOX is always parsed as the place. There is also
1200-
// expr_norange used in index_expr, which disallows '..' in
1201-
// expressions as that has special meaning inside of brackets.
1196+
// There is also one other expr subtype: nonparen_expr disallows exprs
1197+
// surrounded by parens (including tuple expressions), this is
1198+
// necessary for BOX (place) expressions, so a parens expr following
1199+
// the BOX is always parsed as the place.
12021200

12031201
stmts
12041202
: stmt { $$ = mk_node("stmts", 1, $1); }
@@ -1265,7 +1263,7 @@ nonblock_expr
12651263
| path_expr '{' struct_expr_fields '}' { $$ = mk_node("ExprStruct", 2, $1, $3); }
12661264
| nonblock_expr '.' path_generic_args_with_colons { $$ = mk_node("ExprField", 2, $1, $3); }
12671265
| nonblock_expr '.' LIT_INTEGER { $$ = mk_node("ExprTupleIndex", 1, $1); }
1268-
| nonblock_expr '[' index_expr ']' { $$ = mk_node("ExprIndex", 2, $1, $3); }
1266+
| nonblock_expr '[' maybe_expr ']' { $$ = mk_node("ExprIndex", 2, $1, $3); }
12691267
| nonblock_expr '(' maybe_exprs ')' { $$ = mk_node("ExprCall", 2, $1, $3); }
12701268
| '[' vec_expr ']' { $$ = mk_node("ExprVec", 1, $2); }
12711269
| '(' maybe_exprs ')' { $$ = mk_node("ExprParen", 1, $2); }
@@ -1307,6 +1305,7 @@ nonblock_expr
13071305
| nonblock_expr DOTDOT { $$ = mk_node("ExprRange", 2, $1, mk_none()); }
13081306
| nonblock_expr DOTDOT expr { $$ = mk_node("ExprRange", 2, $1, $3); }
13091307
| DOTDOT expr { $$ = mk_node("ExprRange", 2, mk_none(), $2); }
1308+
| DOTDOT { $$ = mk_node("ExprRange", 2, mk_none(), mk_none()); }
13101309
| nonblock_expr AS ty { $$ = mk_node("ExprCast", 2, $1, $3); }
13111310
| BOX nonparen_expr { $$ = mk_node("ExprBox", 1, $2); }
13121311
| %prec BOXPLACE BOX '(' maybe_expr ')' nonblock_expr { $$ = mk_node("ExprBox", 2, $3, $5); }
@@ -1322,7 +1321,7 @@ expr
13221321
| path_expr '{' struct_expr_fields '}' { $$ = mk_node("ExprStruct", 2, $1, $3); }
13231322
| expr '.' path_generic_args_with_colons { $$ = mk_node("ExprField", 2, $1, $3); }
13241323
| expr '.' LIT_INTEGER { $$ = mk_node("ExprTupleIndex", 1, $1); }
1325-
| expr '[' index_expr ']' { $$ = mk_node("ExprIndex", 2, $1, $3); }
1324+
| expr '[' maybe_expr ']' { $$ = mk_node("ExprIndex", 2, $1, $3); }
13261325
| expr '(' maybe_exprs ')' { $$ = mk_node("ExprCall", 2, $1, $3); }
13271326
| '(' maybe_exprs ')' { $$ = mk_node("ExprParen", 1, $2); }
13281327
| '[' vec_expr ']' { $$ = mk_node("ExprVec", 1, $2); }
@@ -1364,6 +1363,7 @@ expr
13641363
| expr DOTDOT { $$ = mk_node("ExprRange", 2, $1, mk_none()); }
13651364
| expr DOTDOT expr { $$ = mk_node("ExprRange", 2, $1, $3); }
13661365
| DOTDOT expr { $$ = mk_node("ExprRange", 2, mk_none(), $2); }
1366+
| DOTDOT { $$ = mk_node("ExprRange", 2, mk_none(), mk_none()); }
13671367
| expr AS ty { $$ = mk_node("ExprCast", 2, $1, $3); }
13681368
| BOX nonparen_expr { $$ = mk_node("ExprBox", 1, $2); }
13691369
| %prec BOXPLACE BOX '(' maybe_expr ')' expr { $$ = mk_node("ExprBox", 2, $3, $5); }
@@ -1381,7 +1381,7 @@ nonparen_expr
13811381
| path_expr '{' struct_expr_fields '}' { $$ = mk_node("ExprStruct", 2, $1, $3); }
13821382
| nonparen_expr '.' path_generic_args_with_colons { $$ = mk_node("ExprField", 2, $1, $3); }
13831383
| nonparen_expr '.' LIT_INTEGER { $$ = mk_node("ExprTupleIndex", 1, $1); }
1384-
| nonparen_expr '[' index_expr ']' { $$ = mk_node("ExprIndex", 2, $1, $3); }
1384+
| nonparen_expr '[' maybe_expr ']' { $$ = mk_node("ExprIndex", 2, $1, $3); }
13851385
| nonparen_expr '(' maybe_exprs ')' { $$ = mk_node("ExprCall", 2, $1, $3); }
13861386
| '[' vec_expr ']' { $$ = mk_node("ExprVec", 1, $2); }
13871387
| CONTINUE { $$ = mk_node("ExprAgain", 0); }
@@ -1422,6 +1422,7 @@ nonparen_expr
14221422
| nonparen_expr DOTDOT { $$ = mk_node("ExprRange", 2, $1, mk_none()); }
14231423
| nonparen_expr DOTDOT nonparen_expr { $$ = mk_node("ExprRange", 2, $1, $3); }
14241424
| DOTDOT nonparen_expr { $$ = mk_node("ExprRange", 2, mk_none(), $2); }
1425+
| DOTDOT { $$ = mk_node("ExprRange", 2, mk_none(), mk_none()); }
14251426
| nonparen_expr AS ty { $$ = mk_node("ExprCast", 2, $1, $3); }
14261427
| BOX nonparen_expr { $$ = mk_node("ExprBox", 1, $2); }
14271428
| %prec BOXPLACE BOX '(' maybe_expr ')' expr { $$ = mk_node("ExprBox", 1, $3, $5); }
@@ -1430,62 +1431,6 @@ nonparen_expr
14301431
| nonblock_prefix_expr
14311432
;
14321433

1433-
expr_norange
1434-
: lit { $$ = mk_node("ExprLit", 1, $1); }
1435-
| %prec IDENT
1436-
path_expr { $$ = mk_node("ExprPath", 1, $1); }
1437-
| SELF { $$ = mk_node("ExprPath", 1, mk_node("ident", 1, mk_atom("self"))); }
1438-
| macro_expr { $$ = mk_node("ExprMac", 1, $1); }
1439-
| path_expr '{' struct_expr_fields '}' { $$ = mk_node("ExprStruct", 2, $1, $3); }
1440-
| expr_norange '.' path_generic_args_with_colons { $$ = mk_node("ExprField", 2, $1, $3); }
1441-
| expr_norange '.' LIT_INTEGER { $$ = mk_node("ExprTupleIndex", 1, $1); }
1442-
| expr_norange '[' index_expr ']' { $$ = mk_node("ExprIndex", 2, $1, $3); }
1443-
| expr_norange '(' maybe_exprs ')' { $$ = mk_node("ExprCall", 2, $1, $3); }
1444-
| '(' maybe_exprs ')' { $$ = mk_node("ExprParen", 1, $2); }
1445-
| '[' vec_expr ']' { $$ = mk_node("ExprVec", 1, $2); }
1446-
| CONTINUE { $$ = mk_node("ExprAgain", 0); }
1447-
| CONTINUE ident { $$ = mk_node("ExprAgain", 1, $2); }
1448-
| RETURN { $$ = mk_node("ExprRet", 0); }
1449-
| RETURN expr { $$ = mk_node("ExprRet", 1, $2); }
1450-
| BREAK { $$ = mk_node("ExprBreak", 0); }
1451-
| BREAK ident { $$ = mk_node("ExprBreak", 1, $2); }
1452-
| expr_norange '=' expr_norange { $$ = mk_node("ExprAssign", 2, $1, $3); }
1453-
| expr_norange SHLEQ expr_norange { $$ = mk_node("ExprAssignShl", 2, $1, $3); }
1454-
| expr_norange SHREQ expr_norange { $$ = mk_node("ExprAssignShr", 2, $1, $3); }
1455-
| expr_norange MINUSEQ expr_norange { $$ = mk_node("ExprAssignSub", 2, $1, $3); }
1456-
| expr_norange ANDEQ expr_norange { $$ = mk_node("ExprAssignBitAnd", 2, $1, $3); }
1457-
| expr_norange OREQ expr_norange { $$ = mk_node("ExprAssignBitOr", 2, $1, $3); }
1458-
| expr_norange PLUSEQ expr_norange { $$ = mk_node("ExprAssignAdd", 2, $1, $3); }
1459-
| expr_norange STAREQ expr_norange { $$ = mk_node("ExprAssignMul", 2, $1, $3); }
1460-
| expr_norange SLASHEQ expr_norange { $$ = mk_node("ExprAssignDiv", 2, $1, $3); }
1461-
| expr_norange CARETEQ expr_norange { $$ = mk_node("ExprAssignBitXor", 2, $1, $3); }
1462-
| expr_norange PERCENTEQ expr_norange { $$ = mk_node("ExprAssignRem", 2, $1, $3); }
1463-
| expr_norange OROR expr_norange { $$ = mk_node("ExprBinary", 3, mk_atom("BiOr"), $1, $3); }
1464-
| expr_norange ANDAND expr_norange { $$ = mk_node("ExprBinary", 3, mk_atom("BiAnd"), $1, $3); }
1465-
| expr_norange EQEQ expr_norange { $$ = mk_node("ExprBinary", 3, mk_atom("BiEq"), $1, $3); }
1466-
| expr_norange NE expr_norange { $$ = mk_node("ExprBinary", 3, mk_atom("BiNe"), $1, $3); }
1467-
| expr_norange '<' expr_norange { $$ = mk_node("ExprBinary", 3, mk_atom("BiLt"), $1, $3); }
1468-
| expr_norange '>' expr_norange { $$ = mk_node("ExprBinary", 3, mk_atom("BiGt"), $1, $3); }
1469-
| expr_norange LE expr_norange { $$ = mk_node("ExprBinary", 3, mk_atom("BiLe"), $1, $3); }
1470-
| expr_norange GE expr_norange { $$ = mk_node("ExprBinary", 3, mk_atom("BiGe"), $1, $3); }
1471-
| expr_norange '|' expr_norange { $$ = mk_node("ExprBinary", 3, mk_atom("BiBitOr"), $1, $3); }
1472-
| expr_norange '^' expr_norange { $$ = mk_node("ExprBinary", 3, mk_atom("BiBitXor"), $1, $3); }
1473-
| expr_norange '&' expr_norange { $$ = mk_node("ExprBinary", 3, mk_atom("BiBitAnd"), $1, $3); }
1474-
| expr_norange SHL expr_norange { $$ = mk_node("ExprBinary", 3, mk_atom("BiShl"), $1, $3); }
1475-
| expr_norange SHR expr_norange { $$ = mk_node("ExprBinary", 3, mk_atom("BiShr"), $1, $3); }
1476-
| expr_norange '+' expr_norange { $$ = mk_node("ExprBinary", 3, mk_atom("BiAdd"), $1, $3); }
1477-
| expr_norange '-' expr_norange { $$ = mk_node("ExprBinary", 3, mk_atom("BiSub"), $1, $3); }
1478-
| expr_norange '*' expr_norange { $$ = mk_node("ExprBinary", 3, mk_atom("BiMul"), $1, $3); }
1479-
| expr_norange '/' expr_norange { $$ = mk_node("ExprBinary", 3, mk_atom("BiDiv"), $1, $3); }
1480-
| expr_norange '%' expr_norange { $$ = mk_node("ExprBinary", 3, mk_atom("BiRem"), $1, $3); }
1481-
| expr_norange AS ty { $$ = mk_node("Expr_NorangeCast", 2, $1, $3); }
1482-
| BOX nonparen_expr { $$ = mk_node("ExprBox", 1, $2); }
1483-
| %prec BOXPLACE BOX '(' maybe_expr ')' expr_norange { $$ = mk_node("ExprBox", 2, $3, $5); }
1484-
| block_expr
1485-
| block
1486-
| nonblock_prefix_expr
1487-
;
1488-
14891434
expr_nostruct
14901435
: lit { $$ = mk_node("ExprLit", 1, $1); }
14911436
| %prec IDENT
@@ -1494,7 +1439,7 @@ expr_nostruct
14941439
| macro_expr { $$ = mk_node("ExprMac", 1, $1); }
14951440
| expr_nostruct '.' path_generic_args_with_colons { $$ = mk_node("ExprField", 2, $1, $3); }
14961441
| expr_nostruct '.' LIT_INTEGER { $$ = mk_node("ExprTupleIndex", 1, $1); }
1497-
| expr_nostruct '[' index_expr ']' { $$ = mk_node("ExprIndex", 2, $1, $3); }
1442+
| expr_nostruct '[' maybe_expr ']' { $$ = mk_node("ExprIndex", 2, $1, $3); }
14981443
| expr_nostruct '(' maybe_exprs ')' { $$ = mk_node("ExprCall", 2, $1, $3); }
14991444
| '[' vec_expr ']' { $$ = mk_node("ExprVec", 1, $2); }
15001445
| '(' maybe_exprs ')' { $$ = mk_node("ExprParen", 1, $2); }
@@ -1536,6 +1481,7 @@ expr_nostruct
15361481
| expr_nostruct DOTDOT { $$ = mk_node("ExprRange", 2, $1, mk_none()); }
15371482
| expr_nostruct DOTDOT expr_nostruct { $$ = mk_node("ExprRange", 2, $1, $3); }
15381483
| DOTDOT expr_nostruct { $$ = mk_node("ExprRange", 2, mk_none(), $2); }
1484+
| DOTDOT { $$ = mk_node("ExprRange", 2, mk_none(), mk_none()); }
15391485
| expr_nostruct AS ty { $$ = mk_node("ExprCast", 2, $1, $3); }
15401486
| BOX nonparen_expr { $$ = mk_node("ExprBox", 1, $2); }
15411487
| %prec BOXPLACE BOX '(' maybe_expr ')' expr_nostruct { $$ = mk_node("ExprBox", 1, $3, $5); }
@@ -1612,14 +1558,6 @@ vec_expr
16121558
| exprs ';' expr { $$ = mk_node("VecRepeat", 2, $1, $3); }
16131559
;
16141560

1615-
index_expr
1616-
: expr_norange { $$ = mk_node("Index", 1, $1); }
1617-
| expr_norange DOTDOT { $$ = mk_node("SliceToEnd", 1, $1); }
1618-
| DOTDOT expr_norange { $$ = mk_node("SliceFromBeginning", 1, $2); }
1619-
| expr_norange DOTDOT expr_norange { $$ = mk_node("Slice", 2, $1, $3); }
1620-
| %empty { $$ = mk_none(); }
1621-
;
1622-
16231561
struct_expr_fields
16241562
: field_inits
16251563
| field_inits ','

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