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Auto merge of #22163 - bleibig:grammar-updates, r=sanxiyn
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Updates to the bison grammar:

* Fixes to range syntax - allow `expr[..]`, and fix precedence to allow `for _ in i.. { }`
* Allow "extern crate" in stmts
* Add qualified path expressions (`<TYPE as TRAIT_REF>::item`)
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@bors
bors committed Feb 11, 2015
2 parents 5936278 + 3bca5f2 commit 0047f8b
Showing 1 changed file with 48 additions and 83 deletions.
131 changes: 48 additions & 83 deletions src/grammar/parser-lalr.y
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Expand Up @@ -177,6 +177,8 @@ extern char *yytext;

%precedence '{' '[' '(' '.'

%precedence RANGE

%start crate

%%
Expand Down Expand Up @@ -258,11 +260,7 @@ mod_item

// items that can appear outside of a fn block
item
: item_static
| item_const
| item_type
| block_item
| view_item
: stmt_item
| item_macro
;

Expand All @@ -272,8 +270,7 @@ stmt_item
| item_const
| item_type
| block_item
| use_item
| extern_fn_item
| view_item
;

item_static
Expand All @@ -295,7 +292,6 @@ view_item
: use_item
| extern_fn_item
| EXTERN CRATE ident ';' { $$ = mk_node("ViewItemExternCrate", 1, $3); }
| EXTERN CRATE ident '=' str ';' { $$ = mk_node("ViewItemExternCrate", 2, $3, $5); }
| EXTERN CRATE str AS ident ';' { $$ = mk_node("ViewItemExternCrate", 2, $3, $5); }
;

Expand Down Expand Up @@ -1193,12 +1189,10 @@ maybe_stmts
//
// In non-stmts contexts, expr can relax this trichotomy.
//
// There are also two other expr subtypes: first, nonparen_expr
// disallows exprs surrounded by parens (including tuple expressions),
// this is necessary for BOX (place) expressions, so a parens expr
// following the BOX is always parsed as the place. There is also
// expr_norange used in index_expr, which disallows '..' in
// expressions as that has special meaning inside of brackets.
// There is also one other expr subtype: nonparen_expr disallows exprs
// surrounded by parens (including tuple expressions), this is
// necessary for BOX (place) expressions, so a parens expr following
// the BOX is always parsed as the place.

stmts
: stmt { $$ = mk_node("stmts", 1, $1); }
Expand Down Expand Up @@ -1265,7 +1259,7 @@ nonblock_expr
| path_expr '{' struct_expr_fields '}' { $$ = mk_node("ExprStruct", 2, $1, $3); }
| nonblock_expr '.' path_generic_args_with_colons { $$ = mk_node("ExprField", 2, $1, $3); }
| nonblock_expr '.' LIT_INTEGER { $$ = mk_node("ExprTupleIndex", 1, $1); }
| nonblock_expr '[' index_expr ']' { $$ = mk_node("ExprIndex", 2, $1, $3); }
| nonblock_expr '[' maybe_expr ']' { $$ = mk_node("ExprIndex", 2, $1, $3); }
| nonblock_expr '(' maybe_exprs ')' { $$ = mk_node("ExprCall", 2, $1, $3); }
| '[' vec_expr ']' { $$ = mk_node("ExprVec", 1, $2); }
| '(' maybe_exprs ')' { $$ = mk_node("ExprParen", 1, $2); }
Expand Down Expand Up @@ -1307,9 +1301,11 @@ nonblock_expr
| nonblock_expr DOTDOT { $$ = mk_node("ExprRange", 2, $1, mk_none()); }
| nonblock_expr DOTDOT expr { $$ = mk_node("ExprRange", 2, $1, $3); }
| DOTDOT expr { $$ = mk_node("ExprRange", 2, mk_none(), $2); }
| DOTDOT { $$ = mk_node("ExprRange", 2, mk_none(), mk_none()); }
| nonblock_expr AS ty { $$ = mk_node("ExprCast", 2, $1, $3); }
| BOX nonparen_expr { $$ = mk_node("ExprBox", 1, $2); }
| %prec BOXPLACE BOX '(' maybe_expr ')' nonblock_expr { $$ = mk_node("ExprBox", 2, $3, $5); }
| expr_qualified_path
| nonblock_prefix_expr
;

Expand All @@ -1322,7 +1318,7 @@ expr
| path_expr '{' struct_expr_fields '}' { $$ = mk_node("ExprStruct", 2, $1, $3); }
| expr '.' path_generic_args_with_colons { $$ = mk_node("ExprField", 2, $1, $3); }
| expr '.' LIT_INTEGER { $$ = mk_node("ExprTupleIndex", 1, $1); }
| expr '[' index_expr ']' { $$ = mk_node("ExprIndex", 2, $1, $3); }
| expr '[' maybe_expr ']' { $$ = mk_node("ExprIndex", 2, $1, $3); }
| expr '(' maybe_exprs ')' { $$ = mk_node("ExprCall", 2, $1, $3); }
| '(' maybe_exprs ')' { $$ = mk_node("ExprParen", 1, $2); }
| '[' vec_expr ']' { $$ = mk_node("ExprVec", 1, $2); }
Expand Down Expand Up @@ -1364,9 +1360,11 @@ expr
| expr DOTDOT { $$ = mk_node("ExprRange", 2, $1, mk_none()); }
| expr DOTDOT expr { $$ = mk_node("ExprRange", 2, $1, $3); }
| DOTDOT expr { $$ = mk_node("ExprRange", 2, mk_none(), $2); }
| DOTDOT { $$ = mk_node("ExprRange", 2, mk_none(), mk_none()); }
| expr AS ty { $$ = mk_node("ExprCast", 2, $1, $3); }
| BOX nonparen_expr { $$ = mk_node("ExprBox", 1, $2); }
| %prec BOXPLACE BOX '(' maybe_expr ')' expr { $$ = mk_node("ExprBox", 2, $3, $5); }
| expr_qualified_path
| block_expr
| block
| nonblock_prefix_expr
Expand All @@ -1381,7 +1379,7 @@ nonparen_expr
| path_expr '{' struct_expr_fields '}' { $$ = mk_node("ExprStruct", 2, $1, $3); }
| nonparen_expr '.' path_generic_args_with_colons { $$ = mk_node("ExprField", 2, $1, $3); }
| nonparen_expr '.' LIT_INTEGER { $$ = mk_node("ExprTupleIndex", 1, $1); }
| nonparen_expr '[' index_expr ']' { $$ = mk_node("ExprIndex", 2, $1, $3); }
| nonparen_expr '[' maybe_expr ']' { $$ = mk_node("ExprIndex", 2, $1, $3); }
| nonparen_expr '(' maybe_exprs ')' { $$ = mk_node("ExprCall", 2, $1, $3); }
| '[' vec_expr ']' { $$ = mk_node("ExprVec", 1, $2); }
| CONTINUE { $$ = mk_node("ExprAgain", 0); }
Expand Down Expand Up @@ -1422,65 +1420,11 @@ nonparen_expr
| nonparen_expr DOTDOT { $$ = mk_node("ExprRange", 2, $1, mk_none()); }
| nonparen_expr DOTDOT nonparen_expr { $$ = mk_node("ExprRange", 2, $1, $3); }
| DOTDOT nonparen_expr { $$ = mk_node("ExprRange", 2, mk_none(), $2); }
| DOTDOT { $$ = mk_node("ExprRange", 2, mk_none(), mk_none()); }
| nonparen_expr AS ty { $$ = mk_node("ExprCast", 2, $1, $3); }
| BOX nonparen_expr { $$ = mk_node("ExprBox", 1, $2); }
| %prec BOXPLACE BOX '(' maybe_expr ')' expr { $$ = mk_node("ExprBox", 1, $3, $5); }
| block_expr
| block
| nonblock_prefix_expr
;

expr_norange
: lit { $$ = mk_node("ExprLit", 1, $1); }
| %prec IDENT
path_expr { $$ = mk_node("ExprPath", 1, $1); }
| SELF { $$ = mk_node("ExprPath", 1, mk_node("ident", 1, mk_atom("self"))); }
| macro_expr { $$ = mk_node("ExprMac", 1, $1); }
| path_expr '{' struct_expr_fields '}' { $$ = mk_node("ExprStruct", 2, $1, $3); }
| expr_norange '.' path_generic_args_with_colons { $$ = mk_node("ExprField", 2, $1, $3); }
| expr_norange '.' LIT_INTEGER { $$ = mk_node("ExprTupleIndex", 1, $1); }
| expr_norange '[' index_expr ']' { $$ = mk_node("ExprIndex", 2, $1, $3); }
| expr_norange '(' maybe_exprs ')' { $$ = mk_node("ExprCall", 2, $1, $3); }
| '(' maybe_exprs ')' { $$ = mk_node("ExprParen", 1, $2); }
| '[' vec_expr ']' { $$ = mk_node("ExprVec", 1, $2); }
| CONTINUE { $$ = mk_node("ExprAgain", 0); }
| CONTINUE ident { $$ = mk_node("ExprAgain", 1, $2); }
| RETURN { $$ = mk_node("ExprRet", 0); }
| RETURN expr { $$ = mk_node("ExprRet", 1, $2); }
| BREAK { $$ = mk_node("ExprBreak", 0); }
| BREAK ident { $$ = mk_node("ExprBreak", 1, $2); }
| expr_norange '=' expr_norange { $$ = mk_node("ExprAssign", 2, $1, $3); }
| expr_norange SHLEQ expr_norange { $$ = mk_node("ExprAssignShl", 2, $1, $3); }
| expr_norange SHREQ expr_norange { $$ = mk_node("ExprAssignShr", 2, $1, $3); }
| expr_norange MINUSEQ expr_norange { $$ = mk_node("ExprAssignSub", 2, $1, $3); }
| expr_norange ANDEQ expr_norange { $$ = mk_node("ExprAssignBitAnd", 2, $1, $3); }
| expr_norange OREQ expr_norange { $$ = mk_node("ExprAssignBitOr", 2, $1, $3); }
| expr_norange PLUSEQ expr_norange { $$ = mk_node("ExprAssignAdd", 2, $1, $3); }
| expr_norange STAREQ expr_norange { $$ = mk_node("ExprAssignMul", 2, $1, $3); }
| expr_norange SLASHEQ expr_norange { $$ = mk_node("ExprAssignDiv", 2, $1, $3); }
| expr_norange CARETEQ expr_norange { $$ = mk_node("ExprAssignBitXor", 2, $1, $3); }
| expr_norange PERCENTEQ expr_norange { $$ = mk_node("ExprAssignRem", 2, $1, $3); }
| expr_norange OROR expr_norange { $$ = mk_node("ExprBinary", 3, mk_atom("BiOr"), $1, $3); }
| expr_norange ANDAND expr_norange { $$ = mk_node("ExprBinary", 3, mk_atom("BiAnd"), $1, $3); }
| expr_norange EQEQ expr_norange { $$ = mk_node("ExprBinary", 3, mk_atom("BiEq"), $1, $3); }
| expr_norange NE expr_norange { $$ = mk_node("ExprBinary", 3, mk_atom("BiNe"), $1, $3); }
| expr_norange '<' expr_norange { $$ = mk_node("ExprBinary", 3, mk_atom("BiLt"), $1, $3); }
| expr_norange '>' expr_norange { $$ = mk_node("ExprBinary", 3, mk_atom("BiGt"), $1, $3); }
| expr_norange LE expr_norange { $$ = mk_node("ExprBinary", 3, mk_atom("BiLe"), $1, $3); }
| expr_norange GE expr_norange { $$ = mk_node("ExprBinary", 3, mk_atom("BiGe"), $1, $3); }
| expr_norange '|' expr_norange { $$ = mk_node("ExprBinary", 3, mk_atom("BiBitOr"), $1, $3); }
| expr_norange '^' expr_norange { $$ = mk_node("ExprBinary", 3, mk_atom("BiBitXor"), $1, $3); }
| expr_norange '&' expr_norange { $$ = mk_node("ExprBinary", 3, mk_atom("BiBitAnd"), $1, $3); }
| expr_norange SHL expr_norange { $$ = mk_node("ExprBinary", 3, mk_atom("BiShl"), $1, $3); }
| expr_norange SHR expr_norange { $$ = mk_node("ExprBinary", 3, mk_atom("BiShr"), $1, $3); }
| expr_norange '+' expr_norange { $$ = mk_node("ExprBinary", 3, mk_atom("BiAdd"), $1, $3); }
| expr_norange '-' expr_norange { $$ = mk_node("ExprBinary", 3, mk_atom("BiSub"), $1, $3); }
| expr_norange '*' expr_norange { $$ = mk_node("ExprBinary", 3, mk_atom("BiMul"), $1, $3); }
| expr_norange '/' expr_norange { $$ = mk_node("ExprBinary", 3, mk_atom("BiDiv"), $1, $3); }
| expr_norange '%' expr_norange { $$ = mk_node("ExprBinary", 3, mk_atom("BiRem"), $1, $3); }
| expr_norange AS ty { $$ = mk_node("Expr_NorangeCast", 2, $1, $3); }
| BOX nonparen_expr { $$ = mk_node("ExprBox", 1, $2); }
| %prec BOXPLACE BOX '(' maybe_expr ')' expr_norange { $$ = mk_node("ExprBox", 2, $3, $5); }
| expr_qualified_path
| block_expr
| block
| nonblock_prefix_expr
Expand All @@ -1494,7 +1438,7 @@ expr_nostruct
| macro_expr { $$ = mk_node("ExprMac", 1, $1); }
| expr_nostruct '.' path_generic_args_with_colons { $$ = mk_node("ExprField", 2, $1, $3); }
| expr_nostruct '.' LIT_INTEGER { $$ = mk_node("ExprTupleIndex", 1, $1); }
| expr_nostruct '[' index_expr ']' { $$ = mk_node("ExprIndex", 2, $1, $3); }
| expr_nostruct '[' maybe_expr ']' { $$ = mk_node("ExprIndex", 2, $1, $3); }
| expr_nostruct '(' maybe_exprs ')' { $$ = mk_node("ExprCall", 2, $1, $3); }
| '[' vec_expr ']' { $$ = mk_node("ExprVec", 1, $2); }
| '(' maybe_exprs ')' { $$ = mk_node("ExprParen", 1, $2); }
Expand Down Expand Up @@ -1533,12 +1477,14 @@ expr_nostruct
| expr_nostruct '*' expr_nostruct { $$ = mk_node("ExprBinary", 3, mk_atom("BiMul"), $1, $3); }
| expr_nostruct '/' expr_nostruct { $$ = mk_node("ExprBinary", 3, mk_atom("BiDiv"), $1, $3); }
| expr_nostruct '%' expr_nostruct { $$ = mk_node("ExprBinary", 3, mk_atom("BiRem"), $1, $3); }
| expr_nostruct DOTDOT { $$ = mk_node("ExprRange", 2, $1, mk_none()); }
| expr_nostruct DOTDOT %prec RANGE { $$ = mk_node("ExprRange", 2, $1, mk_none()); }
| expr_nostruct DOTDOT expr_nostruct { $$ = mk_node("ExprRange", 2, $1, $3); }
| DOTDOT expr_nostruct { $$ = mk_node("ExprRange", 2, mk_none(), $2); }
| DOTDOT { $$ = mk_node("ExprRange", 2, mk_none(), mk_none()); }
| expr_nostruct AS ty { $$ = mk_node("ExprCast", 2, $1, $3); }
| BOX nonparen_expr { $$ = mk_node("ExprBox", 1, $2); }
| %prec BOXPLACE BOX '(' maybe_expr ')' expr_nostruct { $$ = mk_node("ExprBox", 1, $3, $5); }
| expr_qualified_path
| block_expr
| block
| nonblock_prefix_expr_nostruct
Expand Down Expand Up @@ -1566,6 +1512,33 @@ nonblock_prefix_expr
| proc_expr
;

expr_qualified_path
: '<' ty_sum AS trait_ref '>' MOD_SEP ident
{
$$ = mk_node("ExprQualifiedPath", 3, $2, $4, $7);
}
| '<' ty_sum AS trait_ref '>' MOD_SEP ident generic_args
{
$$ = mk_node("ExprQualifiedPath", 4, $2, $4, $7, $8);
}
| SHL ty_sum AS trait_ref '>' MOD_SEP ident AS trait_ref '>' MOD_SEP ident
{
$$ = mk_node("ExprQualifiedPath", 3, mk_node("ExprQualifiedPath", 3, $2, $4, $7), $9, $12);
}
| SHL ty_sum AS trait_ref '>' MOD_SEP ident generic_args AS trait_ref '>' MOD_SEP ident
{
$$ = mk_node("ExprQualifiedPath", 3, mk_node("ExprQualifiedPath", 4, $2, $4, $7, $8), $10, $13);
}
| SHL ty_sum AS trait_ref '>' MOD_SEP ident AS trait_ref '>' MOD_SEP ident generic_args
{
$$ = mk_node("ExprQualifiedPath", 4, mk_node("ExprQualifiedPath", 3, $2, $4, $7), $9, $12, $13);
}
| SHL ty_sum AS trait_ref '>' MOD_SEP ident generic_args AS trait_ref '>' MOD_SEP ident generic_args
{
$$ = mk_node("ExprQualifiedPath", 4, mk_node("ExprQualifiedPath", 4, $2, $4, $7, $8), $10, $13, $14);
}


lambda_expr
: %prec LAMBDA
OROR ret_ty expr { $$ = mk_node("ExprFnBlock", 3, mk_none(), $2, $3); }
Expand Down Expand Up @@ -1612,14 +1585,6 @@ vec_expr
| exprs ';' expr { $$ = mk_node("VecRepeat", 2, $1, $3); }
;

index_expr
: expr_norange { $$ = mk_node("Index", 1, $1); }
| expr_norange DOTDOT { $$ = mk_node("SliceToEnd", 1, $1); }
| DOTDOT expr_norange { $$ = mk_node("SliceFromBeginning", 1, $2); }
| expr_norange DOTDOT expr_norange { $$ = mk_node("Slice", 2, $1, $3); }
| %empty { $$ = mk_none(); }
;

struct_expr_fields
: field_inits
| field_inits ','
Expand Down

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