From 0c4574cc31414a5204eabfad7eb0ac5095c0ace1 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= Date: Wed, 15 Nov 2017 13:12:11 +0100 Subject: erl_parse: Use a new pat_expr rule for pattern expressions In the grammar file for the Erlang language, patterns are parsed as expressions. erl_lint will then weed out expressions that are not legal patterns. The rule sharing causes problems if we were to introduce new syntax, for example a pattern followed by a ':'. There would be a shift/reduce conflict, and a pattern followed by a ':' would be parsed as a remote call. Introduce a new pat_expr rule to express exactly the subset of expressions that is allowed in pattern. Note: For the moment, we must allow full expressions in case clauses to keep 'merl' working. --- lib/stdlib/src/erl_parse.yrl | 74 +++++++++++++++++++++++++++++++++++++++----- 1 file changed, 67 insertions(+), 7 deletions(-) diff --git a/lib/stdlib/src/erl_parse.yrl b/lib/stdlib/src/erl_parse.yrl index 6e72d64acc..298d96834b 100644 --- a/lib/stdlib/src/erl_parse.yrl +++ b/lib/stdlib/src/erl_parse.yrl @@ -29,6 +29,10 @@ clause_args clause_guard clause_body expr expr_100 expr_150 expr_160 expr_200 expr_300 expr_400 expr_500 expr_600 expr_700 expr_800 expr_max +pat_expr pat_expr_200 pat_expr_300 pat_expr_400 pat_expr_500 +pat_expr_600 pat_expr_700 pat_expr_800 +pat_expr_max map_pat_expr record_pat_expr +pat_argument_list pat_exprs list tail list_comprehension lc_expr lc_exprs binary_comprehension @@ -66,7 +70,7 @@ char integer float atom string var 'spec' 'callback' % helper dot. -Expect 2. +Expect 0. Rootsymbol form. @@ -210,7 +214,7 @@ function_clause -> atom clause_args clause_guard clause_body : {clause,?anno('$1'),element(3, '$1'),'$2','$3','$4'}. -clause_args -> argument_list : element(1, '$1'). +clause_args -> pat_argument_list : element(1, '$1'). clause_guard -> 'when' guard : '$2'. clause_guard -> '$empty' : []. @@ -275,6 +279,53 @@ expr_max -> receive_expr : '$1'. expr_max -> fun_expr : '$1'. expr_max -> try_expr : '$1'. +pat_expr -> pat_expr_200 '=' pat_expr : {match,?anno('$2'),'$1','$3'}. +pat_expr -> pat_expr_200 : '$1'. + +pat_expr_200 -> pat_expr_300 comp_op pat_expr_300 : + ?mkop2('$1', '$2', '$3'). +pat_expr_200 -> pat_expr_300 : '$1'. + +pat_expr_300 -> pat_expr_400 list_op pat_expr_300 : + ?mkop2('$1', '$2', '$3'). +pat_expr_300 -> pat_expr_400 : '$1'. + +pat_expr_400 -> pat_expr_400 add_op pat_expr_500 : + ?mkop2('$1', '$2', '$3'). +pat_expr_400 -> pat_expr_500 : '$1'. + +pat_expr_500 -> pat_expr_500 mult_op pat_expr_600 : + ?mkop2('$1', '$2', '$3'). +pat_expr_500 -> pat_expr_600 : '$1'. + +pat_expr_600 -> prefix_op pat_expr_700 : + ?mkop1('$1', '$2'). +pat_expr_600 -> map_pat_expr : '$1'. +pat_expr_600 -> pat_expr_700 : '$1'. + +pat_expr_700 -> record_pat_expr : '$1'. +pat_expr_700 -> pat_expr_800 : '$1'. + +pat_expr_800 -> pat_expr_max : '$1'. + +pat_expr_max -> var : '$1'. +pat_expr_max -> atomic : '$1'. +pat_expr_max -> list : '$1'. +pat_expr_max -> binary : '$1'. +pat_expr_max -> tuple : '$1'. +pat_expr_max -> '(' pat_expr ')' : '$2'. + +map_pat_expr -> '#' map_tuple : + {map, ?anno('$1'),'$2'}. +map_pat_expr -> pat_expr_max '#' map_tuple : + {map, ?anno('$2'),'$1','$3'}. +map_pat_expr -> map_pat_expr '#' map_tuple : + {map, ?anno('$2'),'$1','$3'}. + +record_pat_expr -> '#' atom '.' atom : + {record_index,?anno('$1'),element(3, '$2'),'$4'}. +record_pat_expr -> '#' atom record_tuple : + {record,?anno('$1'),element(3, '$2'),'$3'}. list -> '[' ']' : {nil,?anno('$1')}. list -> '[' expr tail : {cons,?anno('$1'),'$2','$3'}. @@ -397,6 +448,10 @@ case_expr -> 'case' expr 'of' cr_clauses 'end' : cr_clauses -> cr_clause : ['$1']. cr_clauses -> cr_clause ';' cr_clauses : ['$1' | '$3']. +%% FIXME: merl in syntax_tools depends on patterns in a 'case' being +%% full expressions. Therefore, we can't use pat_expr here. There +%% should be a better way. + cr_clause -> expr clause_guard clause_body : {clause,?anno('$1'),['$1'],'$2','$3'}. @@ -424,11 +479,11 @@ integer_or_var -> var : '$1'. fun_clauses -> fun_clause : ['$1']. fun_clauses -> fun_clause ';' fun_clauses : ['$1' | '$3']. -fun_clause -> argument_list clause_guard clause_body : +fun_clause -> pat_argument_list clause_guard clause_body : {Args,Anno} = '$1', {clause,Anno,'fun',Args,'$2','$3'}. -fun_clause -> var argument_list clause_guard clause_body : +fun_clause -> var pat_argument_list clause_guard clause_body : {clause,element(2, '$1'),element(3, '$1'),element(1, '$2'),'$3','$4'}. try_expr -> 'try' exprs 'of' cr_clauses try_catch : @@ -446,13 +501,13 @@ try_catch -> 'after' exprs 'end' : try_clauses -> try_clause : ['$1']. try_clauses -> try_clause ';' try_clauses : ['$1' | '$3']. -try_clause -> expr clause_guard clause_body : +try_clause -> pat_expr clause_guard clause_body : A = ?anno('$1'), {clause,A,[{tuple,A,[{atom,A,throw},'$1',{var,A,'_'}]}],'$2','$3'}. -try_clause -> atom ':' expr clause_guard clause_body : +try_clause -> atom ':' pat_expr clause_guard clause_body : A = ?anno('$1'), {clause,A,[{tuple,A,['$1','$3',{var,A,'_'}]}],'$4','$5'}. -try_clause -> var ':' expr clause_guard clause_body : +try_clause -> var ':' pat_expr clause_guard clause_body : A = ?anno('$1'), {clause,A,[{tuple,A,['$1','$3',{var,A,'_'}]}],'$4','$5'}. @@ -460,10 +515,15 @@ try_clause -> var ':' expr clause_guard clause_body : argument_list -> '(' ')' : {[],?anno('$1')}. argument_list -> '(' exprs ')' : {'$2',?anno('$1')}. +pat_argument_list -> '(' ')' : {[],?anno('$1')}. +pat_argument_list -> '(' pat_exprs ')' : {'$2',?anno('$1')}. exprs -> expr : ['$1']. exprs -> expr ',' exprs : ['$1' | '$3']. +pat_exprs -> pat_expr : ['$1']. +pat_exprs -> pat_expr ',' pat_exprs : ['$1' | '$3']. + guard -> exprs : ['$1']. guard -> exprs ';' guard : ['$1'|'$3']. -- cgit v1.2.3