View Source erl_prettypr (syntax_tools v3.2)
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
.
Summary
Functions
Equivalent to best(Tree, []).
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.
Equivalent to format(Tree, []).
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)
Returns the hook function field of the prettyprinter context.
Returns the line widh field of the prettyprinter context.
Returns the paper widh field of the prettyprinter context.
Returns the operator precedence field of the prettyprinter context.
Returns the user data field of the prettyprinter context.
Equivalent to layout(Tree, []).
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 format/2
; note, however, that the paper
and ribbon
options are ignored
by this function.
Updates the hook function field of the prettyprinter context.
Updates the line widh field of the prettyprinter context.
Updates the paper widh field of the prettyprinter context.
Updates the operator precedence field of the prettyprinter context. See the
//stdlib/erl_parse
module for operator precedences.
Updates the user data field of the prettyprinter context.
Types
-type clause_t() :: case_expr | fun_expr | if_expr | maybe_expr | receive_expr | try_expr | {function, prettypr:document()} | spec.
-type context() :: #ctxt{prec :: integer(), sub_indent :: non_neg_integer(), break_indent :: non_neg_integer(), clause :: clause_t() | undefined, hook :: hook(), paper :: integer(), ribbon :: integer(), user :: term(), encoding :: epp:source_encoding(), empty_lines :: sets:set(integer())}.
-type hook() :: none | fun((syntaxTree(), _, _) -> prettypr:document()).
-type syntaxTree() :: erl_syntax:syntaxTree().
Functions
-spec best(syntaxTree()) -> empty | prettypr:document().
Equivalent to best(Tree, []).
-spec best(syntaxTree(), [term()]) -> empty | prettypr:document().
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 also: best/1
, format/2
, layout/2
, prettypr:best/3
.
-spec format(syntaxTree()) -> string().
Equivalent to format(Tree, []).
-spec format(syntaxTree(), [term()]) -> string().
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:
{hook, none |
hook()
} - Unless the value isnone
, the given function is called for each node whose list of annotations is not empty; see below for details. The default value isnone
.{paper, integer()} - Specifies the preferred maximum number of characters on any line, including indentation. The default value is 80.
{ribbon, integer()} - Specifies the preferred maximum number of characters on any line, not counting indentation. The default value is 65.
{user, term()} - User-specific data for use in hook functions. The default value is
undefined
.{encoding, epp:source_encoding()} - Specifies the encoding of the generated file.
A hook function (cf. the 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 layout/2
and 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 also: erl_syntax
, best/2
, format/1
, get_ctxt_user/1
, layout/2
,
set_ctxt_user/2
.
Returns the hook function field of the prettyprinter context.
See also: set_ctxt_hook/2
.
Returns the line widh field of the prettyprinter context.
See also: set_ctxt_linewidth/2
.
Returns the paper widh field of the prettyprinter context.
See also: set_ctxt_paperwidth/2
.
Returns the operator precedence field of the prettyprinter context.
See also: set_ctxt_precedence/2
.
Returns the user data field of the prettyprinter context.
See also: set_ctxt_user/2
.
-spec layout(syntaxTree()) -> prettypr:document().
Equivalent to layout(Tree, []).
-spec layout(syntaxTree(), [term()]) -> prettypr:document().
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 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).
Updates the hook function field of the prettyprinter context.
See also: get_ctxt_hook/1
.
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 also: get_ctxt_linewidth/1
.
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 also: get_ctxt_paperwidth/1
.
Updates the operator precedence field of the prettyprinter context. See the
//stdlib/erl_parse
module for operator precedences.
See also: //stdlib/erl_parse, get_ctxt_precedence/1
.
Updates the user data field of the prettyprinter context.
See also: get_ctxt_user/1
.