1erl_prettypr(3) Erlang Module Definition erl_prettypr(3)
2
6 erl_prettypr - Pretty printing of abstract Erlang syntax trees.
7
9 Pretty printing of abstract Erlang syntax trees.
10 This module is a front end to the pretty-printing library module pret‐
12 typr, for text formatting of abstract syntax trees defined by the mod‐
13 ule erl_syntax.
14
16 clause_t() = case_expr | fun_expr | if_expr | maybe_expr | re‐
17 ceive_expr | try_expr | {function, prettypr:document()} | spec:
18 context() = #ctxt{prec=integer(), sub_indent=non_neg_integer(),
21 break_indent=non_neg_integer(), clause=clause_t() | undefined,
22 hook=hook(), paper=integer(), ribbon=integer(), user=term(), encod‐
23 ing=epp:source_encoding(), empty_lines=sets:set(integer())}:
24 hook() = none | (erl_syntax:syntaxTree(), term(), term()) -> pret‐
27 typr:document():
28 syntaxTree() = erl_syntax:syntaxTree():
31 An abstract syntax tree. See the erl_syntax module for details.
34
36 best(Node::erl_syntax:syntaxTree()) -> empty | prettypr:document()
37 Equivalent to best(Tree, []).
39 best(Node::erl_syntax:syntaxTree(), Options::[term()]) -> empty | pret‐
41 typr:document()
42 Creates a fixed "best" abstract layout for a syntax tree. This
44 is similar to the layout/2 function, except that here, the final
45 layout has been selected with respect to the given options. The
46 atom empty is returned if no such layout could be produced. For
47 information on the options, see the format/2 function.
48 See also: best/1, format/2, layout/2, prettypr:best/3.
50 format(Node::erl_syntax:syntaxTree()) -> string()
52 Equivalent to format(Tree, []).
54 format(Node::erl_syntax:syntaxTree(), Options::[term()]) -> string()
56 Prettyprint-formats an abstract Erlang syntax tree as text. For
58 example, if you have a .beam file that has been compiled with
59 debug_info, the following should print the source code for the
60 module (as it looks in the debug info representation):
61 {ok,{_,[{abstract_code,{_,AC}}]}} =
63 beam_lib:chunks("myfile.beam",[abstract_code]),
64 io:put_chars(erl_prettypr:format(erl_syntax:form_list(AC)))
65 Available options:
67 {hook, none | hook()}:
69 Unless the value is none, the given function is called for
70 each node whose list of annotations is not empty; see below
71 for details. The default value is none.
72 {paper, integer()}:
74 Specifies the preferred maximum number of characters on any
75 line, including indentation. The default value is 80.
76 {ribbon, integer()}:
78 Specifies the preferred maximum number of characters on any
79 line, not counting indentation. The default value is 65.
80 {user, term()}:
82 User-specific data for use in hook functions. The default
83 value is undefined.
84 {encoding, epp:source_encoding()}:
86 Specifies the encoding of the generated file.
87 A hook function (cf. the hook() type) is passed the current syn‐
89 tax tree node, the context, and a continuation. The context can
90 be examined and manipulated by functions such as get_ctxt_user/1
91 and set_ctxt_user/2. The hook must return a "document" data
92 structure (see layout/2 and best/2); this may be constructed in
93 part or in whole by applying the continuation function. For ex‐
94 ample, the following is a trivial hook:
95 fun (Node, Ctxt, Cont) -> Cont(Node, Ctxt) end
97 which yields the same result as if no hook was given. The fol‐
99 lowing, however:
100 fun (Node, Ctxt, Cont) ->
102 Doc = Cont(Node, Ctxt),
103 prettypr:beside(prettypr:text("<b>"),
104 prettypr:beside(Doc,
105 prettypr:text("</b>")))
106 end
107 will place the text of any annotated node (regardless of the an‐
109 notation data) between HTML "boldface begin" and "boldface end"
110 tags.
111 See also: erl_syntax, best/2, format/1, get_ctxt_user/1, lay‐
113 out/2, set_ctxt_user/2.
114 get_ctxt_hook(Ctxt::context()) -> hook()
116 Returns the hook function field of the prettyprinter context.
118 See also: set_ctxt_hook/2.
120 get_ctxt_linewidth(Ctxt::context()) -> integer()
122 Returns the line widh field of the prettyprinter context.
124 See also: set_ctxt_linewidth/2.
126 get_ctxt_paperwidth(Ctxt::context()) -> integer()
128 Returns the paper widh field of the prettyprinter context.
130 See also: set_ctxt_paperwidth/2.
132 get_ctxt_precedence(Ctxt::context()) -> integer()
134 Returns the operator precedence field of the prettyprinter con‐
136 text.
137 See also: set_ctxt_precedence/2.
139 get_ctxt_user(Ctxt::context()) -> term()
141 Returns the user data field of the prettyprinter context.
143 See also: set_ctxt_user/2.
145 layout(Node::erl_syntax:syntaxTree()) -> prettypr:document()
147 Equivalent to layout(Tree, []).
149 layout(Node::erl_syntax:syntaxTree(), Options::[term()]) -> pret‐
151 typr:document()
152 Creates an abstract document layout for a syntax tree. The re‐
154 sult represents a set of possible layouts (cf. module prettypr).
155 For information on the options, see format/2; note, however,
156 that the paper and ribbon options are ignored by this function.
157 This function provides a low-level interface to the pretty
159 printer, returning a flexible representation of possible lay‐
160 outs, independent of the paper width eventually to be used for
161 formatting. This can be included as part of another document
162 and/or further processed directly by the functions in the pret‐
163 typr module, or used in a hook function (see format/2 for de‐
164 tails).
165 See also: prettypr, format/2, layout/1.
167 set_ctxt_hook(Ctxt::context(), Hook::hook()) -> context()
169 Updates the hook function field of the prettyprinter context.
171 See also: get_ctxt_hook/1.
173 set_ctxt_linewidth(Ctxt::context(), W::integer()) -> context()
175 Updates the line widh field of the prettyprinter context.
177 Note: changing this value (and passing the resulting context to
179 a continuation function) does not affect the normal formatting,
180 but may affect user-defined behaviour in hook functions.
181 See also: get_ctxt_linewidth/1.
183 set_ctxt_paperwidth(Ctxt::context(), W::integer()) -> context()
185 Updates the paper widh field of the prettyprinter context.
187 Note: changing this value (and passing the resulting context to
189 a continuation function) does not affect the normal formatting,
190 but may affect user-defined behaviour in hook functions.
191 See also: get_ctxt_paperwidth/1.
193 set_ctxt_precedence(Ctxt::context(), Prec::integer()) -> context()
195 Updates the operator precedence field of the prettyprinter con‐
197 text. See the erl_parse(3) module for operator precedences.
198 See also: erl_parse(3), get_ctxt_precedence/1.
200 set_ctxt_user(Ctxt::context(), X::term()) -> context()
202 Updates the user data field of the prettyprinter context.
204 See also: get_ctxt_user/1.
206
208 Richard Carlsson <carlsson.richard@gmail.com>
209 syntax_tools 3.0 erl_prettypr(3)