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authorBjörn Gustavsson <[email protected]>2016-03-01 06:23:36 +0100
committerBjörn Gustavsson <[email protected]>2016-03-01 13:59:22 +0100
commit205405f0bf1d2fa37d4c8170c11689a2937f5d9c (patch)
treea55b2a94a43ecf521db5c06a41be2af0a0eda44b
parent156aea75186fe9de64b87c2c6919db9abf4a0d60 (diff)
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Generalize bit string comprehensions
The expression in a bit string comprehension is limited to a literal bit string expression. That is, the following code is legal: << <<X>> || X <- List >> but not this code: << foo(X) || X <- List >> The limitation is annoying. For one thing, tools that transform the abstract format must be careful not to produce code such as: << begin %% Some instrumentation code. <<X>> end || X <- List >> One reason for the limitation could be that we'll get reduce/reduce conflicts if we try to allow an arbitrary expression in a bit string comprehension: binary_comprehension -> '<<' expr '||' lc_exprs '>>' : {bc,?anno('$1'),'$2','$4'}. Unfortunately, there does not seem to be an easy way to work around that problem. The best we can do is to allow 'expr_max' expressions (as in the binary syntax): binary_comprehension -> '<<' expr_max '||' lc_exprs '>>' : {bc,?anno('$1'),'$2','$4'}. That will work, but functions calls must be enclosed in parentheses: << (foo(X)) || X <- List >>
-rw-r--r--lib/compiler/src/v3_core.erl40
-rw-r--r--lib/compiler/test/bs_bincomp_SUITE.erl46
-rw-r--r--lib/stdlib/src/erl_parse.yrl2
-rw-r--r--lib/tools/src/cover.erl4
-rw-r--r--lib/tools/test/cover_SUITE.erl29
-rw-r--r--system/doc/reference_manual/expressions.xml8
6 files changed, 106 insertions, 23 deletions
diff --git a/lib/compiler/src/v3_core.erl b/lib/compiler/src/v3_core.erl
index 68c9f964d8..830dd9973a 100644
--- a/lib/compiler/src/v3_core.erl
+++ b/lib/compiler/src/v3_core.erl
@@ -1080,13 +1080,39 @@ bc_tq1(Line, E, [#igen{anno=GAnno,ceps=Ceps,
bc_tq1(Line, E, [#ifilter{}=Filter|Qs], Mc, St) ->
filter_tq(Line, E, Filter, Mc, St, Qs, fun bc_tq1/5);
bc_tq1(_, {bin,Bl,Elements}, [], AccVar, St0) ->
- {E,Pre,St} = expr({bin,Bl,[{bin_element,Bl,
- {var,Bl,AccVar#c_var.name},
- {atom,Bl,all},
- [binary,{unit,1}]}|Elements]}, St0),
+ bc_tq_build(Bl, [], AccVar, Elements, St0);
+bc_tq1(Line, E0, [], AccVar, St0) ->
+ BsFlags = [binary,{unit,1}],
+ BsSize = {atom,Line,all},
+ {E1,Pre0,St1} = safe(E0, St0),
+ case E1 of
+ #c_var{name=VarName} ->
+ Var = {var,Line,VarName},
+ Els = [{bin_element,Line,Var,BsSize,BsFlags}],
+ bc_tq_build(Line, Pre0, AccVar, Els, St1);
+ #c_literal{val=Val} when is_bitstring(Val) ->
+ Bits = bit_size(Val),
+ <<Int0:Bits>> = Val,
+ Int = {integer,Line,Int0},
+ Sz = {integer,Line,Bits},
+ Els = [{bin_element,Line,Int,Sz,[integer,{unit,1},big]}],
+ bc_tq_build(Line, Pre0, AccVar, Els, St1);
+ _ ->
+ %% Any other safe (cons, tuple, literal) is not a
+ %% bitstring. Force the evaluation to fail (and
+ %% generate a warning).
+ Els = [{bin_element,Line,{atom,Line,bad_value},BsSize,BsFlags}],
+ bc_tq_build(Line, Pre0, AccVar, Els, St1)
+ end.
+
+bc_tq_build(Line, Pre0, #c_var{name=AccVar}, Elements0, St0) ->
+ Elements = [{bin_element,Line,{var,Line,AccVar},{atom,Line,all},
+ [binary,{unit,1}]}|Elements0],
+ {E,Pre,St} = expr({bin,Line,Elements}, St0),
#a{anno=A} = Anno0 = get_anno(E),
Anno = Anno0#a{anno=[compiler_generated,single_use|A]},
- {set_anno(E, Anno),Pre,St}.
+ {set_anno(E, Anno),Pre0++Pre,St}.
+
%% filter_tq(Line, Expr, Filter, Mc, State, [Qualifier], TqFun) ->
%% {Case,[PreExpr],State}.
@@ -1307,7 +1333,9 @@ bc_elem_size({bin,_,El}, St0) ->
Vs = [V || {_,#c_var{name=V}} <- Vars0],
{E,Pre,St} = bc_mul_pairs(F, #c_literal{val=Bits}, [], St0),
{E,Pre,Vs,St}
- end.
+ end;
+bc_elem_size(_, _) ->
+ throw(impossible).
bc_elem_size_1([{bin_element,_,_,{integer,_,N},Flags}|Es], Bits, Vars) ->
{unit,U} = keyfind(unit, 1, Flags),
diff --git a/lib/compiler/test/bs_bincomp_SUITE.erl b/lib/compiler/test/bs_bincomp_SUITE.erl
index 93bce5c1f6..5e5f6e2169 100644
--- a/lib/compiler/test/bs_bincomp_SUITE.erl
+++ b/lib/compiler/test/bs_bincomp_SUITE.erl
@@ -26,7 +26,7 @@
init_per_group/2,end_per_group/2,
byte_aligned/1,bit_aligned/1,extended_byte_aligned/1,
extended_bit_aligned/1,mixed/1,filters/1,trim_coverage/1,
- nomatch/1,sizes/1]).
+ nomatch/1,sizes/1,general_expressions/1]).
-include_lib("common_test/include/ct.hrl").
@@ -36,7 +36,7 @@ all() ->
test_lib:recompile(?MODULE),
[byte_aligned, bit_aligned, extended_byte_aligned,
extended_bit_aligned, mixed, filters, trim_coverage,
- nomatch, sizes].
+ nomatch, sizes, general_expressions].
groups() ->
[].
@@ -295,6 +295,48 @@ sizes(Config) when is_list(Config) ->
cs_end(),
ok.
+-define(BAD(E), {'EXIT',{badarg,_}} = (catch << (E) || _ <- [1,2,3] >>)).
+-define(BAD_V(E), {'EXIT',{badarg,_}} = (catch << (E) || I <- [1,2,3] >>)).
+
+general_expressions(_) ->
+ <<1,2,3>> = << begin <<1,2,3>> end || _ <- [1] >>,
+ <<"abc">> = << begin <<"abc">> end || _ <- [1] >>,
+ <<1,2,3>> = << begin
+ I = <<(I0+1)>>,
+ id(I)
+ end || <<I0>> <= <<0,1,2>> >>,
+ <<1,2,3>> = << I || I <- [<<1,2>>,<<3>>] >>,
+ <<1,2,3>> = << (id(<<I>>)) || I <- [1,2,3] >>,
+ <<2,4>> = << case I rem 2 of
+ 0 -> <<I>>;
+ 1 -> <<>>
+ end || I <- [1,2,3,4,5] >>,
+ <<2,3,4,5,6,7>> = << << (id(<<J>>)) || J <- [2*I,2*I+1] >> ||
+ I <- [1,2,3] >>,
+ <<1,2,2,3,4,4>> = << if
+ I rem 2 =:= 0 -> <<I,I>>;
+ true -> <<I>>
+ end || I <- [1,2,3,4] >>,
+ self() ! <<42>>,
+ <<42>> = << receive B -> B end || _ <- [1] >>,
+ <<10,5,3>> = << try
+ <<(10 div I)>>
+ catch _:_ ->
+ <<>>
+ end || I <- [0,1,2,3] >>,
+
+ %% Failing expressions.
+ ?BAD(bad_atom),
+ ?BAD(42),
+ ?BAD(42.0),
+ ?BAD_V({ok,I}),
+ ?BAD_V([I]),
+ ?BAD_V(fun() -> I end),
+
+ ok.
+
+-undef(BAD).
+
cs_init() ->
erts_debug:set_internal_state(available_internal_state, true),
ok.
diff --git a/lib/stdlib/src/erl_parse.yrl b/lib/stdlib/src/erl_parse.yrl
index b1c574ea60..6f8e5e8449 100644
--- a/lib/stdlib/src/erl_parse.yrl
+++ b/lib/stdlib/src/erl_parse.yrl
@@ -311,7 +311,7 @@ bit_size_expr -> expr_max : '$1'.
list_comprehension -> '[' expr '||' lc_exprs ']' :
{lc,?anno('$1'),'$2','$4'}.
-binary_comprehension -> '<<' binary '||' lc_exprs '>>' :
+binary_comprehension -> '<<' expr_max '||' lc_exprs '>>' :
{bc,?anno('$1'),'$2','$4'}.
lc_exprs -> lc_expr : ['$1'].
lc_exprs -> lc_expr ',' lc_exprs : ['$1'|'$3'].
diff --git a/lib/tools/src/cover.erl b/lib/tools/src/cover.erl
index 3732b0fc85..87de31919f 100644
--- a/lib/tools/src/cover.erl
+++ b/lib/tools/src/cover.erl
@@ -2002,9 +2002,7 @@ munge_expr({lc,Line,Expr,Qs}, Vars) ->
{MungedQs, Vars3} = munge_qualifiers(Qs, Vars2),
{{lc,Line,MungedExpr,MungedQs}, Vars3};
munge_expr({bc,Line,Expr,Qs}, Vars) ->
- {bin,BLine,[{bin_element,EL,Val,Sz,TSL}|Es]} = Expr,
- Expr2 = {bin,BLine,[{bin_element,EL,Val,Sz,TSL}|Es]},
- {MungedExpr,Vars2} = munge_expr(Expr2, Vars),
+ {MungedExpr,Vars2} = munge_expr(?BLOCK1(Expr), Vars),
{MungedQs, Vars3} = munge_qualifiers(Qs, Vars2),
{{bc,Line,MungedExpr,MungedQs}, Vars3};
munge_expr({block,Line,Body}, Vars) ->
diff --git a/lib/tools/test/cover_SUITE.erl b/lib/tools/test/cover_SUITE.erl
index b9a9cd5be4..d4b346c407 100644
--- a/lib/tools/test/cover_SUITE.erl
+++ b/lib/tools/test/cover_SUITE.erl
@@ -29,7 +29,7 @@ all() ->
NoStartStop = [eif,otp_5305,otp_5418,otp_7095,otp_8273,
otp_8340,otp_8188,compile_beam_opts,eep37,
analyse_no_beam, line_0, compile_beam_no_file,
- otp_13277],
+ otp_13277, otp_13289],
StartStop = [start, compile, analyse, misc, stop,
distribution, reconnect, die_and_reconnect,
dont_reconnect_after_stop, stop_node_after_disconnect,
@@ -1253,7 +1253,7 @@ otp_8340(doc) ->
["OTP-8340. Bug."];
otp_8340(suite) -> [];
otp_8340(Config) when is_list(Config) ->
- ?line [{{t,1},1},{{t,4},1}] =
+ [{{t,1},1},{{t,2},1},{{t,4},1}] =
analyse_expr(<<"<< \n"
" <<3:2, \n"
" SeqId:62>> \n"
@@ -1547,10 +1547,8 @@ comprehension_8188(Cf) ->
" true]. \n" % 2
" two() -> 2">>, Cf), % 1
- %% The template cannot have a counter since it is not allowed to
- %% be a block.
?line [{{t,1},1},
- %% {{t,2},2},
+ {{t,2},2},
{{t,3},1},
{{t,4},1},
{{t,5},0},
@@ -1560,7 +1558,7 @@ comprehension_8188(Cf) ->
{{t,13},2},
{{t,14},2}] =
analyse_expr(<<"<< \n" % 1
- " << (X*2) >> || \n" % 2 (now: 0)
+ " << (X*2) >> || \n" % 2
" <<X>> <= << (case two() of\n"
" 2 -> 1;\n" % 1
" _ -> 2\n" % 0
@@ -1575,7 +1573,7 @@ comprehension_8188(Cf) ->
"two() -> 2">>, Cf),
?line [{{t,1},1},
- %% {{t,2},4},
+ {{t,2},4},
{{t,4},1},
{{t,6},1},
{{t,7},0},
@@ -1584,7 +1582,7 @@ comprehension_8188(Cf) ->
{{t,12},4},
{{t,13},1}] =
analyse_expr(<<"<< \n" % 1
- " << (2)\n" % 4 (now: 0)
+ " << (2)\n" % 4
" :(8) >> || \n"
" <<X>> <= << 1,\n" % 1
" (case two() of \n"
@@ -1766,6 +1764,21 @@ otp_13277(Config) ->
?line ok = file:delete(File),
ok.
+%% Test general expressions in a binary comprehension.
+otp_13289(Config) ->
+ Test = <<"-module(t).
+ -export([t/0]).
+
+ t() ->
+ << (id(<<I>>)) || I <- [1,2,3] >>.
+
+ id(I) -> I.
+ ">>,
+ File = cc_mod(t, Test, Config),
+ <<1,2,3>> = t:t(),
+ ok = file:delete(File),
+ ok.
+
%%--Auxiliary------------------------------------------------------------
analyse_expr(Expr, Config) ->
diff --git a/system/doc/reference_manual/expressions.xml b/system/doc/reference_manual/expressions.xml
index e98fcbcbb9..75486488e9 100644
--- a/system/doc/reference_manual/expressions.xml
+++ b/system/doc/reference_manual/expressions.xml
@@ -1556,9 +1556,11 @@ end</pre>
<p>Bit string comprehensions are written with
the following syntax:</p>
<pre>
-&lt;&lt; BitString || Qualifier1,...,QualifierN &gt;&gt;</pre>
- <p>Here, <c>BitString</c> is a bit string expression and each
- <c>Qualifier</c> is either a generator, a bit string generator or a filter.</p>
+&lt;&lt; BitStringExpr || Qualifier1,...,QualifierN &gt;&gt;</pre>
+ <p><c>BitStringExpr</c> is an expression that evalutes to a bit
+ string. If <c>BitStringExpr</c> is a function call, it must be
+ enclosed in parentheses. Each <c>Qualifier</c> is either a
+ generator, a bit string generator or a filter.</p>
<list type="bulleted">
<item>A <em>generator</em> is written as: <br></br>
&nbsp;&nbsp;<c><![CDATA[Pattern <- ListExpr]]></c>. <br></br>