erl_prettypr - Pretty printing of abstract Erlang syntax trees.
Please see following description for synopsis
erl_prettypr(3) Erlang Module Definition erl_prettypr(3)
NAME
erl_prettypr - Pretty printing of abstract Erlang syntax trees.
DESCRIPTION
Pretty printing of abstract Erlang syntax trees.
This module is a front end to the pretty-printing library module pret-
typr, for text formatting of abstract syntax trees defined by the mod-
ule erl_syntax.
DATA TYPES
clause_t() = case_expr | fun_expr | if_expr | receive_expr | try_expr
| {function, prettypr:document()} | spec:
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(), encod-
ing=epp:source_encoding(), empty_lines=sets:set(integer())}:
hook() = none | (erl_syntax:syntaxTree(), term(), term()) -> pret-
typr:document():
syntaxTree() = erl_syntax:syntaxTree():
An abstract syntax tree. See the erl_syntax module for details.
EXPORTS
best(Node::erl_syntax:syntaxTree()) -> empty | prettypr:document()
Equivalent to best(Tree, []).
best(Node::erl_syntax:syntaxTree(), Options::[term()]) -> empty | pret-
typr: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.
format(Node::erl_syntax:syntaxTree()) -> string()
Equivalent to format(Tree, []).
format(Node::erl_syntax:syntaxTree(), Options::[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 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.
{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 syn-
tax 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 fol-
lowing, 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, lay-
out/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()) -> integer()
Returns the operator precedence field of the prettyprinter con-
text.
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(Node::erl_syntax:syntaxTree()) -> prettypr:document()
Equivalent to layout(Tree, []).
layout(Node::erl_syntax:syntaxTree(), Options::[term()]) -> pret-
typr:document()
Creates an abstract document layout for a syntax tree. The
result represents a set of possible layouts (cf. module pret-
typr). For information on the options, see format/2; note, how-
ever, 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 lay-
outs, 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 pret-
typr 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 con-
text. See the erl_parse(3) module for operator precedences.
See also: erl_parse(3), 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.
AUTHORS
Richard Carlsson <carlsson.richard@gmail.com>
syntax_tools 2.6 erl_prettypr(3)