%% =====================================================================
%% Licensed under the Apache License, Version 2.0 (the "License"); you may
%% not use this file except in compliance with the License. You may obtain
%% a copy of the License at <http://www.apache.org/licenses/LICENSE-2.0>
%%
%% Unless required by applicable law or agreed to in writing, software
%% distributed under the License is distributed on an "AS IS" BASIS,
%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
%% See the License for the specific language governing permissions and
%% limitations under the License.
%%
%% Alternatively, you may use this file under the terms of the GNU Lesser
%% General Public License (the "LGPL") as published by the Free Software
%% Foundation; either version 2.1, or (at your option) any later version.
%% If you wish to allow use of your version of this file only under the
%% terms of the LGPL, you should delete the provisions above and replace
%% them with the notice and other provisions required by the LGPL; see
%% <http://www.gnu.org/licenses/>. If you do not delete the provisions
%% above, a recipient may use your version of this file under the terms of
%% either the Apache License or the LGPL.
%%
%% @copyright 1997-2006 Richard Carlsson
%% @author Richard Carlsson <[email protected]>
%% @end
%% =====================================================================
%% @doc Pretty printing of abstract Erlang syntax trees.
%%
%% This module is a front end to the pretty-printing library module
%% `prettypr', for text formatting of abstract syntax trees defined by
%% the module `erl_syntax'.
-module(erl_prettypr).
-export([format/1, format/2, best/1, best/2, layout/1, layout/2,
get_ctxt_precedence/1, set_ctxt_precedence/2,
get_ctxt_paperwidth/1, set_ctxt_paperwidth/2,
get_ctxt_linewidth/1, set_ctxt_linewidth/2, get_ctxt_hook/1,
set_ctxt_hook/2, get_ctxt_user/1, set_ctxt_user/2]).
-import(prettypr, [text/1, nest/2, above/2, beside/2, sep/1, par/1,
par/2, floating/3, floating/1, break/1, follow/2,
follow/3, empty/0]).
-import(erl_parse, [preop_prec/1, inop_prec/1, func_prec/0,
max_prec/0, type_inop_prec/1, type_preop_prec/1]).
-define(PADDING, 2).
-define(PAPER, 80).
-define(RIBBON, 56).
-define(NOUSER, undefined).
-define(NOHOOK, none).
-type hook() :: 'none'
| fun((erl_syntax:syntaxTree(), _, _) -> prettypr:document()).
-type clause_t() :: 'case_expr' | 'cond_expr' | 'fun_expr'
| 'if_expr' | 'receive_expr' | 'try_expr'
| {'function', prettypr:document()}
| 'spec'.
-record(ctxt, {prec = 0 :: integer(),
sub_indent = 2 :: non_neg_integer(),
break_indent = 4 :: non_neg_integer(),
clause = undefined :: clause_t() | 'undefined',
hook = ?NOHOOK :: hook(),
paper = ?PAPER :: integer(),
ribbon = ?RIBBON :: integer(),
user = ?NOUSER :: term(),
encoding = epp:default_encoding() :: epp:source_encoding()}).
-type context() :: #ctxt{}.
%% =====================================================================
%% The following functions examine and modify contexts:
%% @spec (context()) -> integer()
%% @doc Returns the operator precedence field of the prettyprinter
%% context.
%%
%% @see set_ctxt_precedence/2
-spec get_ctxt_precedence(context()) -> integer().
get_ctxt_precedence(Ctxt) ->
Ctxt#ctxt.prec.
%% @spec (context(), integer()) -> context()
%%
%% @doc Updates the operator precedence field of the prettyprinter
%% context. See the {@link //stdlib/erl_parse} module for operator precedences.
%%
%% @see //stdlib/erl_parse
%% @see get_ctxt_precedence/1
-spec set_ctxt_precedence(context(), integer()) -> context().
set_ctxt_precedence(Ctxt, Prec) ->
set_prec(Ctxt, Prec).
set_prec(Ctxt, Prec) ->
Ctxt#ctxt{prec = Prec}. % used internally
reset_prec(Ctxt) ->
set_prec(Ctxt, 0). % used internally
%% @spec (context()) -> integer()
%% @doc Returns the paper widh field of the prettyprinter context.
%% @see set_ctxt_paperwidth/2
-spec get_ctxt_paperwidth(context()) -> integer().
get_ctxt_paperwidth(Ctxt) ->
Ctxt#ctxt.paper.
%% @spec (context(), integer()) -> context()
%%
%% @doc Updates the paper widh field of the prettyprinter context.
%%
%% Note: changing this value (and passing the resulting context to a
%% continuation function) does not affect the normal formatting, but may
%% affect user-defined behaviour in hook functions.
%%
%% @see get_ctxt_paperwidth/1
-spec set_ctxt_paperwidth(context(), integer()) -> context().
set_ctxt_paperwidth(Ctxt, W) ->
Ctxt#ctxt{paper = W}.
%% @spec (context()) -> integer()
%% @doc Returns the line widh field of the prettyprinter context.
%% @see set_ctxt_linewidth/2
-spec get_ctxt_linewidth(context()) -> integer().
get_ctxt_linewidth(Ctxt) ->
Ctxt#ctxt.ribbon.
%% @spec (context(), integer()) -> context()
%%
%% @doc Updates the line widh field of the prettyprinter context.
%%
%% Note: changing this value (and passing the resulting context to a
%% continuation function) does not affect the normal formatting, but may
%% affect user-defined behaviour in hook functions.
%%
%% @see get_ctxt_linewidth/1
-spec set_ctxt_linewidth(context(), integer()) -> context().
set_ctxt_linewidth(Ctxt, W) ->
Ctxt#ctxt{ribbon = W}.
%% @spec (context()) -> hook()
%% @doc Returns the hook function field of the prettyprinter context.
%% @see set_ctxt_hook/2
-spec get_ctxt_hook(context()) -> hook().
get_ctxt_hook(Ctxt) ->
Ctxt#ctxt.hook.
%% @spec (context(), hook()) -> context()
%% @doc Updates the hook function field of the prettyprinter context.
%% @see get_ctxt_hook/1
-spec set_ctxt_hook(context(), hook()) -> context().
set_ctxt_hook(Ctxt, Hook) ->
Ctxt#ctxt{hook = Hook}.
%% @spec (context()) -> term()
%% @doc Returns the user data field of the prettyprinter context.
%% @see set_ctxt_user/2
-spec get_ctxt_user(context()) -> term().
get_ctxt_user(Ctxt) ->
Ctxt#ctxt.user.
%% @spec (context(), term()) -> context()
%% @doc Updates the user data field of the prettyprinter context.
%% @see get_ctxt_user/1
-spec set_ctxt_user(context(), term()) -> context().
set_ctxt_user(Ctxt, X) ->
Ctxt#ctxt{user = X}.
%% =====================================================================
%% @spec format(Tree::syntaxTree()) -> string()
%% @equiv format(Tree, [])
-spec format(erl_syntax:syntaxTree()) -> string().
format(Node) ->
format(Node, []).
%% =====================================================================
%% @spec format(Tree::syntaxTree(), Options::[term()]) -> string()
%%
%% @type syntaxTree() = erl_syntax:syntaxTree().
%%
%% An abstract syntax tree. See the {@link erl_syntax} module for
%% details.
%%
%% @type hook() = (syntaxTree(), context(), Continuation) ->
%% prettypr:document()
%% Continuation = (syntaxTree(), context()) ->
%% prettypr:document().
%%
%% A call-back function for user-controlled formatting. See {@link
%% format/2}.
%%
%% @type context(). A representation of the current context of the
%% pretty-printer. Can be accessed in hook functions.
%%
%% @doc Prettyprint-formats an abstract Erlang syntax tree as text. For
%% example, if you have a `.beam' file that has been compiled with
%% `debug_info', the following should print the source code for the
%% module (as it looks in the debug info representation):
%% ```{ok,{_,[{abstract_code,{_,AC}}]}} =
%% beam_lib:chunks("myfile.beam",[abstract_code]),
%% io:put_chars(erl_prettypr:format(erl_syntax:form_list(AC)))
%% '''
%%
%% Available options:
%% <dl>
%% <dt>{hook, none | {@link hook()}}</dt>
%% <dd>Unless the value is `none', the given function is called
%% for each node whose list of annotations is not empty; see below
%% for details. The default value is `none'.</dd>
%%
%% <dt>{paper, integer()}</dt>
%% <dd>Specifies the preferred maximum number of characters on any
%% line, including indentation. The default value is 80.</dd>
%%
%% <dt>{ribbon, integer()}</dt>
%% <dd>Specifies the preferred maximum number of characters on any
%% line, not counting indentation. The default value is 65.</dd>
%%
%% <dt>{user, term()}</dt>
%% <dd>User-specific data for use in hook functions. The default
%% value is `undefined'.</dd>
%% <dt>{encoding, epp:source_encoding()}</dt>
%% <dd>Specifies the encoding of the generated file.</dd>
%% </dl>
%%
%% A hook function (cf. the {@link hook()} type) is passed the current
%% syntax tree node, the context, and a continuation. The context can be
%% examined and manipulated by functions such as `get_ctxt_user/1' and
%% `set_ctxt_user/2'. The hook must return a "document" data structure
%% (see {@link layout/2} and {@link best/2}); this may be constructed in
%% part or in whole by applying the continuation function. For example,
%% the following is a trivial hook:
%% ```
%% fun (Node, Ctxt, Cont) -> Cont(Node, Ctxt) end
%% '''
%% which yields the same result as if no hook was given.
%% The following, however:
%% ```
%% fun (Node, Ctxt, Cont) ->
%% Doc = Cont(Node, Ctxt),
%% prettypr:beside(prettypr:text("<b>"),
%% prettypr:beside(Doc,
%% prettypr:text("</b>")))
%% end
%% '''
%% will place the text of any annotated node (regardless of the
%% annotation data) between HTML "boldface begin" and "boldface end"
%% tags.
%%
%% @see erl_syntax
%% @see format/1
%% @see layout/2
%% @see best/2
%% @see get_ctxt_user/1
%% @see set_ctxt_user/2
-spec format(erl_syntax:syntaxTree(), [term()]) -> string().
format(Node, Options) ->
W = proplists:get_value(paper, Options, ?PAPER),
L = proplists:get_value(ribbon, Options, ?RIBBON),
prettypr:format(layout(Node, Options), W, L).
%% =====================================================================
%% @spec best(Tree::syntaxTree()) -> empty | prettypr:document()
%% @equiv best(Tree, [])
-spec best(erl_syntax:syntaxTree()) -> 'empty' | prettypr:document().
best(Node) ->
best(Node, []).
%% =====================================================================
%% @spec best(Tree::syntaxTree(), Options::[term()]) ->
%% empty | prettypr:document()
%%
%% @doc Creates a fixed "best" abstract layout for a syntax tree. This
%% is similar to the `layout/2' function, except that here, the final
%% layout has been selected with respect to the given options. The atom
%% `empty' is returned if no such layout could be produced. For
%% information on the options, see the `format/2' function.
%%
%% @see best/1
%% @see layout/2
%% @see format/2
%% @see prettypr:best/3
-spec best(erl_syntax:syntaxTree(), [term()]) -> 'empty' | prettypr:document().
best(Node, Options) ->
W = proplists:get_value(paper, Options, ?PAPER),
L = proplists:get_value(ribbon, Options, ?RIBBON),
prettypr:best(layout(Node, Options), W, L).
%% =====================================================================
%% @spec layout(Tree::syntaxTree()) -> prettypr:document()
%% @equiv layout(Tree, [])
-spec layout(erl_syntax:syntaxTree()) -> prettypr:document().
layout(Node) ->
layout(Node, []).
%% =====================================================================
%% @spec layout(Tree::syntaxTree(), Options::[term()]) -> prettypr:document()
%%
%% @doc Creates an abstract document layout for a syntax tree. The
%% result represents a set of possible layouts (cf. module `prettypr').
%% For information on the options, see {@link format/2}; note, however,
%% that the `paper' and `ribbon' options are ignored by this function.
%%
%% This function provides a low-level interface to the pretty printer,
%% returning a flexible representation of possible layouts, independent
%% of the paper width eventually to be used for formatting. This can be
%% included as part of another document and/or further processed
%% directly by the functions in the `prettypr' module, or used in a hook
%% function (see `format/2' for details).
%%
%% @see prettypr
%% @see format/2
%% @see layout/1
-spec layout(erl_syntax:syntaxTree(), [term()]) -> prettypr:document().
layout(Node, Options) ->
lay(Node,
#ctxt{hook = proplists:get_value(hook, Options, ?NOHOOK),
paper = proplists:get_value(paper, Options, ?PAPER),
ribbon = proplists:get_value(ribbon, Options, ?RIBBON),
user = proplists:get_value(user, Options),
encoding = proplists:get_value(encoding, Options,
epp:default_encoding())}).
lay(Node, Ctxt) ->
case erl_syntax:get_ann(Node) of
[] ->
%% Hooks are not called if there are no annotations.
lay_1(Node, Ctxt);
_As ->
case Ctxt#ctxt.hook of
?NOHOOK ->
lay_1(Node, Ctxt);
Hook ->
Hook(Node, Ctxt, fun lay_1/2)
end
end.
%% This handles attached comments:
lay_1(Node, Ctxt) ->
case erl_syntax:has_comments(Node) of
true ->
D1 = lay_2(Node, Ctxt),
D2 = lay_postcomments(erl_syntax:get_postcomments(Node),
D1),
lay_precomments(erl_syntax:get_precomments(Node), D2);
false ->
lay_2(Node, Ctxt)
end.
%% For pre-comments, all padding is ignored.
lay_precomments([], D) ->
D;
lay_precomments(Cs, D) ->
above(floating(break(stack_comments(Cs, false)), -1, -1), D).
%% For postcomments, individual padding is added.
lay_postcomments([], D) ->
D;
lay_postcomments(Cs, D) ->
beside(D, floating(break(stack_comments(Cs, true)), 1, 0)).
%% Format (including padding, if `Pad' is `true', otherwise not)
%% and stack the listed comments above each other.
stack_comments([C | Cs], Pad) ->
D = stack_comment_lines(erl_syntax:comment_text(C)),
D1 = case Pad of
true ->
P = case erl_syntax:comment_padding(C) of
none ->
?PADDING;
P1 ->
P1
end,
beside(text(spaces(P)), D);
false ->
D
end,
case Cs of
[] ->
D1; % done
_ ->
above(D1, stack_comments(Cs, Pad))
end.
%% Stack lines of text above each other and prefix each string in
%% the list with a single `%' character.
stack_comment_lines([S | Ss]) ->
D = text(add_comment_prefix(S)),
case Ss of
[] ->
D;
_ ->
above(D, stack_comment_lines(Ss))
end;
stack_comment_lines([]) ->
empty().
add_comment_prefix(S) ->
[$% | S].
%% This part ignores annotations and comments:
lay_2(Node, Ctxt) ->
case erl_syntax:type(Node) of
%% We list literals and other common cases first.
variable ->
text(erl_syntax:variable_literal(Node));
atom ->
text(erl_syntax:atom_literal(Node, Ctxt#ctxt.encoding));
integer ->
text(erl_syntax:integer_literal(Node));
float ->
text(tidy_float(erl_syntax:float_literal(Node)));
char ->
text(erl_syntax:char_literal(Node, Ctxt#ctxt.encoding));
string ->
lay_string(erl_syntax:string_literal(Node, Ctxt#ctxt.encoding), Ctxt);
nil ->
text("[]");
tuple ->
Es = seq(erl_syntax:tuple_elements(Node),
floating(text(",")), reset_prec(Ctxt),
fun lay/2),
beside(floating(text("{")),
beside(par(Es),
floating(text("}"))));
list ->
Ctxt1 = reset_prec(Ctxt),
Node1 = erl_syntax:compact_list(Node),
D1 = par(seq(erl_syntax:list_prefix(Node1),
floating(text(",")), Ctxt1,
fun lay/2)),
D = case erl_syntax:list_suffix(Node1) of
none ->
beside(D1, floating(text("]")));
S ->
follow(D1,
beside(
floating(text("| ")),
beside(lay(S, Ctxt1),
floating(text("]")))))
end,
beside(floating(text("[")), D);
operator ->
floating(text(erl_syntax:operator_literal(Node)));
infix_expr ->
Operator = erl_syntax:infix_expr_operator(Node),
{PrecL, Prec, PrecR} =
case erl_syntax:type(Operator) of
operator ->
inop_prec(
erl_syntax:operator_name(Operator));
_ ->
{0, 0, 0}
end,
D1 = lay(erl_syntax:infix_expr_left(Node),
set_prec(Ctxt, PrecL)),
D2 = lay(Operator, reset_prec(Ctxt)),
D3 = lay(erl_syntax:infix_expr_right(Node),
set_prec(Ctxt, PrecR)),
D4 = par([D1, D2, D3], Ctxt#ctxt.sub_indent),
maybe_parentheses(D4, Prec, Ctxt);
prefix_expr ->
Operator = erl_syntax:prefix_expr_operator(Node),
{{Prec, PrecR}, Name} =
case erl_syntax:type(Operator) of
operator ->
N = erl_syntax:operator_name(Operator),
{preop_prec(N), N};
_ ->
{{0, 0}, any}
end,
D1 = lay(Operator, reset_prec(Ctxt)),
D2 = lay(erl_syntax:prefix_expr_argument(Node),
set_prec(Ctxt, PrecR)),
D3 = case Name of
'+' ->
beside(D1, D2);
'-' ->
beside(D1, D2);
_ ->
par([D1, D2], Ctxt#ctxt.sub_indent)
end,
maybe_parentheses(D3, Prec, Ctxt);
application ->
{PrecL, Prec} = func_prec(),
D = lay(erl_syntax:application_operator(Node),
set_prec(Ctxt, PrecL)),
As = seq(erl_syntax:application_arguments(Node),
floating(text(",")), reset_prec(Ctxt),
fun lay/2),
D1 = beside(D, beside(text("("),
beside(par(As),
floating(text(")"))))),
maybe_parentheses(D1, Prec, Ctxt);
match_expr ->
{PrecL, Prec, PrecR} = inop_prec('='),
D1 = lay(erl_syntax:match_expr_pattern(Node),
set_prec(Ctxt, PrecL)),
D2 = lay(erl_syntax:match_expr_body(Node),
set_prec(Ctxt, PrecR)),
D3 = follow(beside(D1, floating(text(" ="))), D2,
Ctxt#ctxt.break_indent),
maybe_parentheses(D3, Prec, Ctxt);
underscore ->
text("_");
clause ->
%% The style used for a clause depends on its context
Ctxt1 = (reset_prec(Ctxt))#ctxt{clause = undefined},
D1 = par(seq(erl_syntax:clause_patterns(Node),
floating(text(",")), Ctxt1,
fun lay/2)),
D2 = case erl_syntax:clause_guard(Node) of
none ->
none;
G ->
lay(G, Ctxt1)
end,
D3 = sep(seq(erl_syntax:clause_body(Node),
floating(text(",")), Ctxt1,
fun lay/2)),
case Ctxt#ctxt.clause of
fun_expr ->
make_fun_clause(D1, D2, D3, Ctxt);
{function, N} ->
make_fun_clause(N, D1, D2, D3, Ctxt);
if_expr ->
make_if_clause(D1, D2, D3, Ctxt);
cond_expr ->
make_if_clause(D1, D2, D3, Ctxt);
case_expr ->
make_case_clause(D1, D2, D3, Ctxt);
receive_expr ->
make_case_clause(D1, D2, D3, Ctxt);
try_expr ->
make_case_clause(D1, D2, D3, Ctxt);
undefined ->
%% If a clause is formatted out of context, we
%% use a "fun-expression" clause style.
make_fun_clause(D1, D2, D3, Ctxt)
end;
function ->
%% Comments on the name itself will be repeated for each
%% clause, but that seems to be the best way to handle it.
Ctxt1 = reset_prec(Ctxt),
D1 = lay(erl_syntax:function_name(Node), Ctxt1),
D2 = lay_clauses(erl_syntax:function_clauses(Node),
{function, D1}, Ctxt1),
beside(D2, floating(text(".")));
case_expr ->
Ctxt1 = reset_prec(Ctxt),
D1 = lay(erl_syntax:case_expr_argument(Node), Ctxt1),
D2 = lay_clauses(erl_syntax:case_expr_clauses(Node),
case_expr, Ctxt1),
sep([par([follow(text("case"), D1, Ctxt1#ctxt.sub_indent),
text("of")],
Ctxt1#ctxt.break_indent),
nest(Ctxt1#ctxt.sub_indent, D2),
text("end")]);
if_expr ->
Ctxt1 = reset_prec(Ctxt),
D = lay_clauses(erl_syntax:if_expr_clauses(Node),
if_expr, Ctxt1),
sep([follow(text("if"), D, Ctxt1#ctxt.sub_indent),
text("end")]);
cond_expr ->
Ctxt1 = reset_prec(Ctxt),
D = lay_clauses(erl_syntax:cond_expr_clauses(Node),
cond_expr, Ctxt1),
sep([text("cond"),
nest(Ctxt1#ctxt.sub_indent, D),
text("end")]);
fun_expr ->
Ctxt1 = reset_prec(Ctxt),
D = lay_clauses(erl_syntax:fun_expr_clauses(Node),
fun_expr, Ctxt1),
sep([follow(text("fun"), D, Ctxt1#ctxt.sub_indent),
text("end")]);
named_fun_expr ->
Ctxt1 = reset_prec(Ctxt),
D1 = lay(erl_syntax:named_fun_expr_name(Node), Ctxt1),
D = lay_clauses(erl_syntax:named_fun_expr_clauses(Node),
{function,D1}, Ctxt1),
sep([follow(text("fun"), D, Ctxt1#ctxt.sub_indent),
text("end")]);
module_qualifier ->
{PrecL, _Prec, PrecR} = inop_prec(':'),
D1 = lay(erl_syntax:module_qualifier_argument(Node),
set_prec(Ctxt, PrecL)),
D2 = lay(erl_syntax:module_qualifier_body(Node),
set_prec(Ctxt, PrecR)),
beside(D1, beside(text(":"), D2));
%%
%% The rest is in alphabetical order (except map and types)
%%
arity_qualifier ->
Ctxt1 = reset_prec(Ctxt),
D1 = lay(erl_syntax:arity_qualifier_body(Node), Ctxt1),
D2 = lay(erl_syntax:arity_qualifier_argument(Node), Ctxt1),
beside(D1, beside(text("/"), D2));
attribute ->
%% The attribute name and arguments are formatted similar to
%% a function call, but prefixed with a "-" and followed by
%% a period. If the arguments is `none', we only output the
%% attribute name, without following parentheses.
Ctxt1 = reset_prec(Ctxt),
Args = erl_syntax:attribute_arguments(Node),
N = erl_syntax:attribute_name(Node),
D = case attribute_type(Node) of
spec ->
[SpecTuple] = Args,
[FuncName, FuncTypes] =
erl_syntax:tuple_elements(SpecTuple),
Name =
case erl_syntax:type(FuncName) of
tuple ->
case erl_syntax:tuple_elements(FuncName) of
[F0, _] ->
F0;
[M0, F0, _] ->
erl_syntax:module_qualifier(M0,
F0);
_ ->
FuncName
end;
_ ->
FuncName
end,
Types = dodge_macros(FuncTypes),
D1 = lay_clauses(erl_syntax:concrete(Types),
spec, Ctxt1),
beside(follow(lay(N, Ctxt1),
lay(Name, Ctxt1),
Ctxt1#ctxt.break_indent),
D1);
type ->
[TypeTuple] = Args,
[Name, Type0, Elements] =
erl_syntax:tuple_elements(TypeTuple),
TypeName = dodge_macros(Name),
Type = dodge_macros(Type0),
As0 = dodge_macros(Elements),
As = erl_syntax:concrete(As0),
D1 = lay_type_application(TypeName, As, Ctxt1),
D2 = lay(erl_syntax:concrete(Type), Ctxt1),
beside(follow(lay(N, Ctxt1),
beside(D1, floating(text(" :: "))),
Ctxt1#ctxt.break_indent),
D2);
Tag when Tag =:= export_type;
Tag =:= optional_callbacks ->
[FuncNs] = Args,
FuncNames = erl_syntax:concrete(dodge_macros(FuncNs)),
As = unfold_function_names(FuncNames),
beside(lay(N, Ctxt1),
beside(text("("),
beside(lay(As, Ctxt1),
floating(text(")")))));
_ when Args =:= none ->
lay(N, Ctxt1);
_ ->
D1 = par(seq(Args, floating(text(",")), Ctxt1,
fun lay/2)),
beside(lay(N, Ctxt1),
beside(text("("),
beside(D1, floating(text(")")))))
end,
beside(floating(text("-")), beside(D, floating(text("."))));
binary ->
Ctxt1 = reset_prec(Ctxt),
Es = seq(erl_syntax:binary_fields(Node),
floating(text(",")), Ctxt1, fun lay/2),
beside(floating(text("<<")),
beside(par(Es), floating(text(">>"))));
binary_field ->
Ctxt1 = set_prec(Ctxt, max_prec()),
D1 = lay(erl_syntax:binary_field_body(Node), Ctxt1),
D2 = case erl_syntax:binary_field_types(Node) of
[] ->
empty();
Ts ->
beside(floating(text("/")),
lay_bit_types(Ts, Ctxt1))
end,
beside(D1, D2);
block_expr ->
Ctxt1 = reset_prec(Ctxt),
Es = seq(erl_syntax:block_expr_body(Node),
floating(text(",")), Ctxt1, fun lay/2),
sep([text("begin"),
nest(Ctxt1#ctxt.sub_indent, sep(Es)),
text("end")]);
catch_expr ->
{Prec, PrecR} = preop_prec('catch'),
D = lay(erl_syntax:catch_expr_body(Node),
set_prec(Ctxt, PrecR)),
D1 = follow(text("catch"), D, Ctxt#ctxt.sub_indent),
maybe_parentheses(D1, Prec, Ctxt);
class_qualifier ->
Ctxt1 = set_prec(Ctxt, max_prec()),
D1 = lay(erl_syntax:class_qualifier_argument(Node), Ctxt1),
D2 = lay(erl_syntax:class_qualifier_body(Node), Ctxt1),
beside(D1, beside(text(":"), D2));
comment ->
D = stack_comment_lines(
erl_syntax:comment_text(Node)),
%% Default padding for standalone comments is empty.
case erl_syntax:comment_padding(Node) of
none ->
floating(break(D));
P ->
floating(break(beside(text(spaces(P)), D)))
end;
conjunction ->
par(seq(erl_syntax:conjunction_body(Node),
floating(text(",")), reset_prec(Ctxt),
fun lay/2));
disjunction ->
%% For clarity, we don't paragraph-format
%% disjunctions; only conjunctions (see above).
sep(seq(erl_syntax:disjunction_body(Node),
floating(text(";")), reset_prec(Ctxt),
fun lay/2));
error_marker ->
E = erl_syntax:error_marker_info(Node),
beside(text("** "),
beside(lay_error_info(E, reset_prec(Ctxt)),
text(" **")));
eof_marker ->
empty();
form_list ->
Es = seq(erl_syntax:form_list_elements(Node), none,
reset_prec(Ctxt), fun lay/2),
vertical_sep(text(""), Es);
generator ->
Ctxt1 = reset_prec(Ctxt),
D1 = lay(erl_syntax:generator_pattern(Node), Ctxt1),
D2 = lay(erl_syntax:generator_body(Node), Ctxt1),
par([D1, beside(text("<- "), D2)], Ctxt1#ctxt.break_indent);
binary_generator ->
Ctxt1 = reset_prec(Ctxt),
D1 = lay(erl_syntax:binary_generator_pattern(Node), Ctxt1),
D2 = lay(erl_syntax:binary_generator_body(Node), Ctxt1),
par([D1, beside(text("<= "), D2)], Ctxt1#ctxt.break_indent);
implicit_fun ->
D = lay(erl_syntax:implicit_fun_name(Node),
reset_prec(Ctxt)),
beside(floating(text("fun ")), D);
list_comp ->
Ctxt1 = reset_prec(Ctxt),
D1 = lay(erl_syntax:list_comp_template(Node), Ctxt1),
D2 = par(seq(erl_syntax:list_comp_body(Node),
floating(text(",")), Ctxt1,
fun lay/2)),
beside(floating(text("[")),
par([D1, beside(floating(text("|| ")),
beside(D2, floating(text("]"))))]));
binary_comp ->
Ctxt1 = reset_prec(Ctxt),
D1 = lay(erl_syntax:binary_comp_template(Node), Ctxt1),
D2 = par(seq(erl_syntax:binary_comp_body(Node),
floating(text(",")), Ctxt1,
fun lay/2)),
beside(floating(text("<< ")),
par([D1, beside(floating(text(" || ")),
beside(D2, floating(text(" >>"))))]));
macro ->
%% This is formatted similar to a normal function call, but
%% prefixed with a "?".
Ctxt1 = reset_prec(Ctxt),
N = erl_syntax:macro_name(Node),
D = case erl_syntax:macro_arguments(Node) of
none->
lay(N, Ctxt1);
Args ->
As = seq(Args, floating(text(",")),
set_prec(Ctxt1, max_prec()), fun lay/2),
beside(lay(N, Ctxt1),
beside(text("("),
beside(par(As),
floating(text(")")))))
end,
D1 = beside(floating(text("?")), D),
maybe_parentheses(D1, 0, Ctxt); % must be conservative!
parentheses ->
D = lay(erl_syntax:parentheses_body(Node),
reset_prec(Ctxt)),
lay_parentheses(D, Ctxt);
receive_expr ->
Ctxt1 = reset_prec(Ctxt),
D1 = lay_clauses(erl_syntax:receive_expr_clauses(Node),
receive_expr, Ctxt1),
D2 = case erl_syntax:receive_expr_timeout(Node) of
none ->
D1;
T ->
D3 = lay(T, Ctxt1),
A = erl_syntax:receive_expr_action(Node),
D4 = sep(seq(A, floating(text(",")),
Ctxt1, fun lay/2)),
sep([D1,
follow(floating(text("after")),
append_clause_body(D4, D3,
Ctxt1),
Ctxt1#ctxt.sub_indent)])
end,
sep([text("receive"),
nest(Ctxt1#ctxt.sub_indent, D2),
text("end")]);
record_access ->
{PrecL, Prec, PrecR} = inop_prec('#'),
D1 = lay(erl_syntax:record_access_argument(Node),
set_prec(Ctxt, PrecL)),
D2 = beside(
floating(text(".")),
lay(erl_syntax:record_access_field(Node),
set_prec(Ctxt, PrecR))),
T = erl_syntax:record_access_type(Node),
D3 = beside(beside(floating(text("#")),
lay(T, reset_prec(Ctxt))),
D2),
maybe_parentheses(beside(D1, D3), Prec, Ctxt);
record_expr ->
{PrecL, Prec, _} = inop_prec('#'),
Ctxt1 = reset_prec(Ctxt),
D1 = lay(erl_syntax:record_expr_type(Node), Ctxt1),
D2 = par(seq(erl_syntax:record_expr_fields(Node),
floating(text(",")), Ctxt1,
fun lay/2)),
D3 = beside(beside(floating(text("#")), D1),
beside(text("{"),
beside(D2, floating(text("}"))))),
D4 = case erl_syntax:record_expr_argument(Node) of
none ->
D3;
A ->
beside(lay(A, set_prec(Ctxt, PrecL)), D3)
end,
maybe_parentheses(D4, Prec, Ctxt);
record_field ->
Ctxt1 = reset_prec(Ctxt),
D1 = lay(erl_syntax:record_field_name(Node), Ctxt1),
case erl_syntax:record_field_value(Node) of
none ->
D1;
V ->
par([D1, floating(text("=")), lay(V, Ctxt1)],
Ctxt1#ctxt.break_indent)
end;
record_index_expr ->
{Prec, PrecR} = preop_prec('#'),
D1 = lay(erl_syntax:record_index_expr_type(Node),
reset_prec(Ctxt)),
D2 = lay(erl_syntax:record_index_expr_field(Node),
set_prec(Ctxt, PrecR)),
D3 = beside(beside(floating(text("#")), D1),
beside(floating(text(".")), D2)),
maybe_parentheses(D3, Prec, Ctxt);
map_expr ->
{PrecL, Prec, _} = inop_prec('#'),
Ctxt1 = reset_prec(Ctxt),
D1 = par(seq(erl_syntax:map_expr_fields(Node),
floating(text(",")), Ctxt1, fun lay/2)),
D2 = beside(text("#{"), beside(D1, floating(text("}")))),
D3 = case erl_syntax:map_expr_argument(Node) of
none ->
D2;
A ->
beside(lay(A, set_prec(Ctxt, PrecL)), D2)
end,
maybe_parentheses(D3, Prec, Ctxt);
map_field_assoc ->
Ctxt1 = reset_prec(Ctxt),
D1 = lay(erl_syntax:map_field_assoc_name(Node), Ctxt1),
D2 = lay(erl_syntax:map_field_assoc_value(Node), Ctxt1),
par([D1, floating(text("=>")), D2], Ctxt1#ctxt.break_indent);
map_field_exact ->
Ctxt1 = reset_prec(Ctxt),
D1 = lay(erl_syntax:map_field_exact_name(Node), Ctxt1),
D2 = lay(erl_syntax:map_field_exact_value(Node), Ctxt1),
par([D1, floating(text(":=")), D2], Ctxt1#ctxt.break_indent);
size_qualifier ->
Ctxt1 = set_prec(Ctxt, max_prec()),
D1 = lay(erl_syntax:size_qualifier_body(Node), Ctxt1),
D2 = lay(erl_syntax:size_qualifier_argument(Node), Ctxt1),
beside(D1, beside(text(":"), D2));
text ->
text(erl_syntax:text_string(Node));
typed_record_field ->
{_, Prec, _} = type_inop_prec('::'),
Ctxt1 = reset_prec(Ctxt),
D1 = lay(erl_syntax:typed_record_field_body(Node), Ctxt1),
D2 = lay(erl_syntax:typed_record_field_type(Node),
set_prec(Ctxt, Prec)),
D3 = par([D1, floating(text(" ::")), D2],
Ctxt1#ctxt.break_indent),
maybe_parentheses(D3, Prec, Ctxt);
try_expr ->
Ctxt1 = reset_prec(Ctxt),
D1 = sep(seq(erl_syntax:try_expr_body(Node),
floating(text(",")), Ctxt1, fun lay/2)),
Es0 = [text("end")],
Es1 = case erl_syntax:try_expr_after(Node) of
[] -> Es0;
As ->
D2 = sep(seq(As, floating(text(",")), Ctxt1,
fun lay/2)),
[text("after"),
nest(Ctxt1#ctxt.sub_indent, D2)
| Es0]
end,
Es2 = case erl_syntax:try_expr_handlers(Node) of
[] -> Es1;
Hs ->
D3 = lay_clauses(Hs, try_expr, Ctxt1),
[text("catch"),
nest(Ctxt1#ctxt.sub_indent, D3)
| Es1]
end,
Es3 = case erl_syntax:try_expr_clauses(Node) of
[] -> Es2;
Cs ->
D4 = lay_clauses(Cs, try_expr, Ctxt1),
[text("of"),
nest(Ctxt1#ctxt.sub_indent, D4)
| Es2]
end,
sep([par([follow(text("try"), D1, Ctxt1#ctxt.sub_indent),
hd(Es3)])
| tl(Es3)]);
warning_marker ->
E = erl_syntax:warning_marker_info(Node),
beside(text("%% WARNING: "),
lay_error_info(E, reset_prec(Ctxt)));
%%
%% Types
%%
annotated_type ->
{_, Prec, _} = type_inop_prec('::'),
D1 = lay(erl_syntax:annotated_type_name(Node),
reset_prec(Ctxt)),
D2 = lay(erl_syntax:annotated_type_body(Node),
set_prec(Ctxt, Prec)),
D3 = follow(beside(D1, floating(text(" ::"))), D2,
Ctxt#ctxt.break_indent),
maybe_parentheses(D3, Prec, Ctxt);
type_application ->
Name = erl_syntax:type_application_name(Node),
Arguments = erl_syntax:type_application_arguments(Node),
%% Prefer shorthand notation.
case erl_syntax_lib:analyze_type_application(Node) of
{nil, 0} ->
text("[]");
{list, 1} ->
[A] = Arguments,
D1 = lay(A, reset_prec(Ctxt)),
beside(text("["), beside(D1, text("]")));
{nonempty_list, 1} ->
[A] = Arguments,
D1 = lay(A, reset_prec(Ctxt)),
beside(text("["), beside(D1, text(", ...]")));
_ ->
lay_type_application(Name, Arguments, Ctxt)
end;
bitstring_type ->
Ctxt1 = set_prec(Ctxt, max_prec()),
M = erl_syntax:bitstring_type_m(Node),
N = erl_syntax:bitstring_type_n(Node),
D1 = [beside(text("_:"), lay(M, Ctxt1)) ||
(erl_syntax:type(M) =/= integer orelse
erl_syntax:integer_value(M) =/= 0)],
D2 = [beside(text("_:_*"), lay(N, Ctxt1)) ||
(erl_syntax:type(N) =/= integer orelse
erl_syntax:integer_value(N) =/= 0)],
F = fun(D, _) -> D end,
D = seq(D1 ++ D2, floating(text(",")), Ctxt1, F),
beside(floating(text("<<")),
beside(par(D), floating(text(">>"))));
fun_type ->
text("fun()");
constrained_function_type ->
Ctxt1 = reset_prec(Ctxt),
D1 = lay(erl_syntax:constrained_function_type_body(Node),
Ctxt1),
D2 = lay(erl_syntax:constrained_function_type_argument(Node),
Ctxt1),
beside(D1,
beside(floating(text(" when ")), D2));
function_type ->
{Before, After} = case Ctxt#ctxt.clause of
spec ->
{"", ""};
_ ->
{"fun(", ")"}
end,
Ctxt1 = reset_prec(Ctxt),
D1 = case erl_syntax:function_type_arguments(Node) of
any_arity ->
text("(...)");
Arguments ->
As = seq(Arguments,
floating(text(",")), Ctxt1,
fun lay/2),
beside(text("("),
beside(par(As),
floating(text(")"))))
end,
D2 = lay(erl_syntax:function_type_return(Node), Ctxt1),
beside(floating(text(Before)),
beside(D1,
beside(floating(text(" -> ")),
beside(D2, floating(text(After))))));
constraint ->
Name = erl_syntax:constraint_argument(Node),
Args = erl_syntax:constraint_body(Node),
case is_subtype(Name, Args) of
true ->
[Var, Type] = Args,
{PrecL, Prec, PrecR} = type_inop_prec('::'),
D1 = lay(Var, set_prec(Ctxt, PrecL)),
D2 = lay(Type, set_prec(Ctxt, PrecR)),
D3 = follow(beside(D1, floating(text(" ::"))), D2,
Ctxt#ctxt.break_indent),
maybe_parentheses(D3, Prec, Ctxt);
false ->
lay_type_application(Name, Args, Ctxt)
end;
map_type ->
case erl_syntax:map_type_fields(Node) of
any_size ->
text("map()");
Fs ->
Ctxt1 = reset_prec(Ctxt),
Es = seq(Fs,
floating(text(",")), Ctxt1,
fun lay/2),
D = beside(floating(text("#{")),
beside(par(Es),
floating(text("}")))),
{Prec, _PrecR} = type_preop_prec('#'),
maybe_parentheses(D, Prec, Ctxt)
end;
map_type_assoc ->
Name = erl_syntax:map_type_assoc_name(Node),
Value = erl_syntax:map_type_assoc_value(Node),
lay_type_assoc(Name, Value, Ctxt);
map_type_exact ->
Ctxt1 = reset_prec(Ctxt),
D1 = lay(erl_syntax:map_type_exact_name(Node), Ctxt1),
D2 = lay(erl_syntax:map_type_exact_value(Node), Ctxt1),
par([D1, floating(text(":=")), D2], Ctxt1#ctxt.break_indent);
integer_range_type ->
{PrecL, Prec, PrecR} = type_inop_prec('..'),
D1 = lay(erl_syntax:integer_range_type_low(Node),
set_prec(Ctxt, PrecL)),
D2 = lay(erl_syntax:integer_range_type_high(Node),
set_prec(Ctxt, PrecR)),
D3 = beside(D1, beside(text(".."), D2)),
maybe_parentheses(D3, Prec, Ctxt);
record_type ->
{Prec, _PrecR} = type_preop_prec('#'),
D1 = beside(text("#"),
lay(erl_syntax:record_type_name(Node),
reset_prec(Ctxt))),
Es = seq(erl_syntax:record_type_fields(Node),
floating(text(",")), reset_prec(Ctxt),
fun lay/2),
D2 = beside(D1,
beside(text("{"),
beside(par(Es),
floating(text("}"))))),
maybe_parentheses(D2, Prec, Ctxt);
record_type_field ->
Ctxt1 = reset_prec(Ctxt),
D1 = lay(erl_syntax:record_type_field_name(Node), Ctxt1),
D2 = lay(erl_syntax:record_type_field_type(Node), Ctxt1),
par([D1, floating(text("::")), D2], Ctxt1#ctxt.break_indent);
tuple_type ->
case erl_syntax:tuple_type_elements(Node) of
any_size ->
text("tuple()");
Elements ->
Es = seq(Elements,
floating(text(",")), reset_prec(Ctxt),
fun lay/2),
beside(floating(text("{")),
beside(par(Es), floating(text("}"))))
end;
type_union ->
{_, Prec, PrecR} = type_inop_prec('|'),
Es = par(seq(erl_syntax:type_union_types(Node),
floating(text(" |")), set_prec(Ctxt, PrecR),
fun lay/2)),
maybe_parentheses(Es, Prec, Ctxt);
user_type_application ->
lay_type_application(erl_syntax:user_type_application_name(Node),
erl_syntax:user_type_application_arguments(Node),
Ctxt)
end.
attribute_type(Node) ->
N = erl_syntax:attribute_name(Node),
case catch erl_syntax:concrete(N) of
opaque ->
type;
spec ->
spec;
callback ->
spec;
type ->
type;
export_type ->
export_type;
optional_callbacks ->
optional_callbacks;
_ ->
N
end.
is_subtype(Name, [Var, _]) ->
(erl_syntax:is_atom(Name, is_subtype) andalso
erl_syntax:type(Var) =:= variable);
is_subtype(_, _) -> false.
unfold_function_names(Ns) ->
F = fun ({Atom, Arity}) ->
erl_syntax:arity_qualifier(erl_syntax:atom(Atom),
erl_syntax:integer(Arity))
end,
erl_syntax:list([F(N) || N <- Ns]).
%% Macros are not handled well.
dodge_macros(Type) ->
F = fun (T) ->
case erl_syntax:type(T) of
macro ->
Var = erl_syntax:macro_name(T),
VarName0 = erl_syntax:variable_name(Var),
VarName = list_to_atom("?"++atom_to_list(VarName0)),
Atom = erl_syntax:atom(VarName),
Atom;
_ -> T
end
end,
erl_syntax_lib:map(F, Type).
lay_parentheses(D, _Ctxt) ->
beside(floating(text("(")), beside(D, floating(text(")")))).
maybe_parentheses(D, Prec, Ctxt) ->
case Ctxt#ctxt.prec of
P when P > Prec ->
lay_parentheses(D, Ctxt);
_ ->
D
end.
lay_string(S, Ctxt) ->
%% S includes leading/trailing double-quote characters. The segment
%% width is 2/3 of the ribbon width - this seems to work well.
W = (Ctxt#ctxt.ribbon * 2) div 3,
lay_string_1(S, length(S), W).
lay_string_1(S, L, W) when L > W, W > 0 ->
%% Note that L is the minimum, not the exact, printed length.
case split_string(S, W - 1, L) of
{_S1, ""} ->
text(S);
{S1, S2} ->
above(text(S1 ++ "\""),
lay_string_1([$" | S2], L - W + 1, W)) %" stupid emacs
end;
lay_string_1(S, _L, _W) ->
text(S).
split_string(Xs, N, L) ->
split_string_1(Xs, N, L, []).
%% We only split strings at whitespace, if possible. We must make sure
%% we do not split an escape sequence.
split_string_1([$\s | Xs], N, L, As) when N =< 0, L >= 5 ->
{lists:reverse([$\s | As]), Xs};
split_string_1([$\t | Xs], N, L, As) when N =< 0, L >= 5 ->
{lists:reverse([$t, $\\ | As]), Xs};
split_string_1([$\n | Xs], N, L, As) when N =< 0, L >= 5 ->
{lists:reverse([$n, $\\ | As]), Xs};
split_string_1([$\\ | Xs], N, L, As) ->
split_string_2(Xs, N - 1, L - 1, [$\\ | As]);
split_string_1(Xs, N, L, As) when N =< -10, L >= 5 ->
{lists:reverse(As), Xs};
split_string_1([X | Xs], N, L, As) ->
split_string_1(Xs, N - 1, L - 1, [X | As]);
split_string_1([], _N, _L, As) ->
{lists:reverse(As), ""}.
split_string_2([$^, X | Xs], N, L, As) ->
split_string_1(Xs, N - 2, L - 2, [X, $^ | As]);
split_string_2([$x, ${ | Xs], N, L, As) ->
split_string_3(Xs, N - 2, L - 2, [${, $x | As]);
split_string_2([X1, X2, X3 | Xs], N, L, As) when
X1 >= $0, X1 =< $7, X2 >= $0, X2 =< $7, X3 >= $0, X3 =< $7 ->
split_string_1(Xs, N - 3, L - 3, [X3, X2, X1 | As]);
split_string_2([X1, X2 | Xs], N, L, As) when
X1 >= $0, X1 =< $7, X2 >= $0, X2 =< $7 ->
split_string_1(Xs, N - 2, L - 2, [X2, X1 | As]);
split_string_2([X | Xs], N, L, As) ->
split_string_1(Xs, N - 1, L - 1, [X | As]).
split_string_3([$} | Xs], N, L, As) ->
split_string_1(Xs, N - 1, L - 1, [$} | As]);
split_string_3([X | Xs], N, L, As) when
X >= $0, X =< $9; X >= $a, X =< $z; X >= $A, X =< $Z ->
split_string_3(Xs, N - 1, L -1, [X | As]);
split_string_3([X | Xs], N, L, As) when
X >= $0, X =< $9 ->
split_string_1(Xs, N - 1, L -1, [X | As]).
%% Note that there is nothing in `lay_clauses' that actually requires
%% that the elements have type `clause'; it just sets up the proper
%% context and arranges the elements suitably for clauses.
lay_clauses(Cs, Type, Ctxt) ->
vertical(seq(Cs, floating(text(";")),
Ctxt#ctxt{clause = Type},
fun lay/2)).
%% Note that for the clause-making functions, the guard argument
%% can be `none', which has different interpretations in different
%% contexts.
make_fun_clause(P, G, B, Ctxt) ->
make_fun_clause(none, P, G, B, Ctxt).
make_fun_clause(N, P, G, B, Ctxt) ->
D = make_fun_clause_head(N, P, Ctxt),
make_case_clause(D, G, B, Ctxt).
make_fun_clause_head(N, P, Ctxt) ->
D = lay_parentheses(P, Ctxt),
if N =:= none ->
D;
true ->
beside(N, D)
end.
make_case_clause(P, G, B, Ctxt) ->
append_clause_body(B, append_guard(G, P, Ctxt), Ctxt).
make_if_clause(_P, G, B, Ctxt) ->
%% We ignore the patterns; they should be empty anyway.
G1 = if G =:= none ->
text("true");
true ->
G
end,
append_clause_body(B, G1, Ctxt).
append_clause_body(B, D, Ctxt) ->
append_clause_body(B, D, floating(text(" ->")), Ctxt).
append_clause_body(B, D, S, Ctxt) ->
sep([beside(D, S), nest(Ctxt#ctxt.break_indent, B)]).
append_guard(none, D, _) ->
D;
append_guard(G, D, Ctxt) ->
par([D, follow(text("when"), G, Ctxt#ctxt.sub_indent)],
Ctxt#ctxt.break_indent).
lay_bit_types([T], Ctxt) ->
lay(T, Ctxt);
lay_bit_types([T | Ts], Ctxt) ->
beside(lay(T, Ctxt),
beside(floating(text("-")),
lay_bit_types(Ts, Ctxt))).
lay_error_info({L, M, T}=T0, Ctxt) when is_integer(L), is_atom(M) ->
case catch M:format_error(T) of
S when is_list(S) ->
if L > 0 ->
beside(text(io_lib:format("~w: ",[L])), text(S));
true ->
text(S)
end;
_ ->
lay_concrete(T0, Ctxt)
end;
lay_error_info(T, Ctxt) ->
lay_concrete(T, Ctxt).
lay_concrete(T, Ctxt) ->
lay(erl_syntax:abstract(T), Ctxt).
lay_type_assoc(Name, Value, Ctxt) ->
Ctxt1 = reset_prec(Ctxt),
D1 = lay(Name, Ctxt1),
D2 = lay(Value, Ctxt1),
par([D1, floating(text("=>")), D2], Ctxt1#ctxt.break_indent).
lay_type_application(Name, Arguments, Ctxt) ->
{PrecL, Prec} = func_prec(), %
D1 = lay(Name, set_prec(Ctxt, PrecL)),
As = seq(Arguments,
floating(text(",")), reset_prec(Ctxt),
fun lay/2),
D = beside(D1, beside(text("("),
beside(par(As),
floating(text(")"))))),
maybe_parentheses(D, Prec, Ctxt).
seq([H | T], Separator, Ctxt, Fun) ->
case T of
[] ->
[Fun(H, Ctxt)];
_ ->
[maybe_append(Separator, Fun(H, Ctxt))
| seq(T, Separator, Ctxt, Fun)]
end;
seq([], _, _, _) ->
[empty()].
maybe_append(none, D) ->
D;
maybe_append(Suffix, D) ->
beside(D, Suffix).
vertical([D]) ->
D;
vertical([D | Ds]) ->
above(D, vertical(Ds));
vertical([]) ->
[].
vertical_sep(_Sep, [D]) ->
D;
vertical_sep(Sep, [D | Ds]) ->
above(above(D, Sep), vertical_sep(Sep, Ds));
vertical_sep(_Sep, []) ->
[].
spaces(N) when N > 0 ->
[$\040 | spaces(N - 1)];
spaces(_) ->
[].
tidy_float([$., C | Cs]) ->
[$., C | tidy_float_1(Cs)]; % preserve first decimal digit
tidy_float([$e | _] = Cs) ->
tidy_float_2(Cs);
tidy_float([C | Cs]) ->
[C | tidy_float(Cs)];
tidy_float([]) ->
[].
tidy_float_1([$0, $0, $0 | Cs]) ->
tidy_float_2(Cs); % cut mantissa at three consecutive zeros.
tidy_float_1([$e | _] = Cs) ->
tidy_float_2(Cs);
tidy_float_1([C | Cs]) ->
[C | tidy_float_1(Cs)];
tidy_float_1([]) ->
[].
tidy_float_2([$e, $+, $0]) -> [];
tidy_float_2([$e, $+, $0 | Cs]) -> tidy_float_2([$e, $+ | Cs]);
tidy_float_2([$e, $+ | _] = Cs) -> Cs;
tidy_float_2([$e, $-, $0]) -> [];
tidy_float_2([$e, $-, $0 | Cs]) -> tidy_float_2([$e, $- | Cs]);
tidy_float_2([$e, $- | _] = Cs) -> Cs;
tidy_float_2([$e | Cs]) -> tidy_float_2([$e, $+ | Cs]);
tidy_float_2([_C | Cs]) -> tidy_float_2(Cs);
tidy_float_2([]) -> [].
%% =====================================================================
