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erl_prettypr(3erl) [linux man page]

erl_prettypr(3erl)					     Erlang Module Definition						erl_prettypr(3erl)

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 prettypr , for text formatting of abstract syntax trees defined by the module erl_syntax . DATA TYPES
context() : A representation of the current context of the pretty-printer. Can be accessed in hook functions. hook() = (syntaxTree(), context(), Continuation) -> document() : * Continuation = (syntaxTree(), context()) -> document() A call-back function for user-controlled formatting. See format/2 . EXPORTS
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 lay- out has been selected with respect to the given options. The atom empty is returned if no such layout could be produced. For infor- mation on the options, see the format/2 function. See also: best/1 , format/2 , layout/2 , prettypr:best/3 . format(Tree::syntaxTree()) -> string() Equivalent to format(Tree, []) . format(Tree::syntaxTree(), Options::[term()]) -> string() Types syntaxTree() (see module erl_syntax) 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 . 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 fol- lowing 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 . 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 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() Types document() (see module prettypr) 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, inde- pendent 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(3erl) module for operator precedences. See also: erl_parse(3erl) , 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 <richardc@it.uu.se > syntax_tools 1.6.7 erl_prettypr(3erl)

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