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
.
abstract datatype: context()
A representation of the current context of the pretty-printer. Can be accessed in hook functions.
hook() = (syntaxTree(), context(), Continuation) -> document()
A call-back function for user-controlled formatting. See format/2
.
best/1 | Equivalent to best(Tree, []). |
best/2 | Creates a fixed "best" abstract layout for a syntax tree. |
format/1 | Equivalent to format(Tree, []). |
format/2 | Prettyprint-formats an abstract Erlang syntax tree as text. |
get_ctxt_hook/1 | Returns the hook function field of the prettyprinter context. |
get_ctxt_linewidth/1 | Returns the line widh field of the prettyprinter context. |
get_ctxt_paperwidth/1 | Returns the paper widh field of the prettyprinter context. |
get_ctxt_precedence/1 | Returns the operator precedence field of the prettyprinter context. |
get_ctxt_user/1 | Returns the user data field of the prettyprinter context. |
layout/1 | Equivalent to layout(Tree, []). |
layout/2 | Creates an abstract document layout for a syntax tree. |
set_ctxt_hook/2 | Updates the hook function field of the prettyprinter context. |
set_ctxt_linewidth/2 | Updates the line widh field of the prettyprinter context. |
set_ctxt_paperwidth/2 | Updates the paper widh field of the prettyprinter context. |
set_ctxt_precedence/2 | Updates the operator precedence field of the prettyprinter context. |
set_ctxt_user/2 | Updates the user data field of the prettyprinter context. |
best(Tree::syntaxTree()) -> empty | document()
Equivalent to best(Tree, []).
best(Tree::syntaxTree(), Options::[term()]) -> empty | 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/2.
format(Tree::syntaxTree()) -> string()
Equivalent to format(Tree, []).
format(Tree::syntaxTree(), Options::[term()]) -> string()
Prettyprint-formats an abstract Erlang syntax tree as text.
Available options:
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
.undefined
.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) endwhich 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>"))) endwill 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.
get_ctxt_hook(Ctxt::context()) -> hook()
Returns the hook function field of the prettyprinter context.
See also: set_ctxt_hook/2.
get_ctxt_linewidth(Ctxt::context()) -> integer()
Returns the line widh field of the prettyprinter context.
See also: set_ctxt_linewidth/2.
get_ctxt_paperwidth(Ctxt::context()) -> integer()
Returns the paper widh field of the prettyprinter context.
See also: set_ctxt_paperwidth/2.
get_ctxt_precedence(Ctxt::context()) -> context()
Returns the operator precedence field of the prettyprinter context.
See also: set_ctxt_precedence/2.
get_ctxt_user(Ctxt::context()) -> term()
Returns the user data field of the prettyprinter context.
See also: set_ctxt_user/2.
layout(Tree::syntaxTree()) -> document()
Equivalent to layout(Tree, []).
layout(Tree::syntaxTree(), Options::[term()]) -> 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).
See also: prettypr, format/2, layout/1.
set_ctxt_hook(Ctxt::context(), Hook::hook()) -> context()
Updates the hook function field of the prettyprinter context.
See also: get_ctxt_hook/1.
set_ctxt_linewidth(Ctxt::context(), W::integer()) -> context()
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.
set_ctxt_paperwidth(Ctxt::context(), W::integer()) -> context()
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.
set_ctxt_precedence(Ctxt::context(), Prec::integer()) -> context()
Updates the operator precedence field of the prettyprinter
context. See the erl_parse
module for operator
precedences.
See also: erl_parse, get_ctxt_precedence/1.
set_ctxt_user(Ctxt::context(), X::term()) -> context()
Updates the user data field of the prettyprinter context.
See also: get_ctxt_user/1.