1erl_syntax_lib(3)          Erlang Module Definition          erl_syntax_lib(3)
2
3
4

NAME

6       erl_syntax_lib - Support library for abstract Erlang syntax trees.
7

DESCRIPTION

9       Support library for abstract Erlang syntax trees.
10
11       This  module  contains  utility functions for working with the abstract
12       data type defined in the module erl_syntax.
13

DATA TYPES

15         info_pair() = {key(), term()}:
16
17
18         key() = attributes | errors | exports | functions | imports |  module
19         | records | warnings:
20
21
22         ordset(T) = ordsets:ordset(T):
23
24
25         set(T) = sets:set(T):
26
27
28         syntaxTree() = erl_syntax:syntaxTree():
29
30
31           An abstract syntax tree. See the erl_syntax module for details.
32

EXPORTS

34       analyze_application(Node::syntaxTree()) -> FunctionName | Arity
35
36              Types:
37
38                 FunctionName = {atom(), Arity} | {ModuleName, FunctionName}
39                 Arity = integer()
40                 ModuleName = atom()
41
42              Returns the name of a called function. The result is a represen‐
43              tation of the name of the applied function F/A, if  Node  repre‐
44              sents  a  function  application  "<em>F</em>(<em>X_1</em>,  ...,
45              <em>X_A</em>)". If the function is not explicitly named (i.e., F
46              is given by some expression), only the arity A is returned.
47
48              The  evaluation throws syntax_error if Node does not represent a
49              well-formed application expression.
50
51              See also: analyze_function_name/1.
52
53       analyze_attribute(Node::syntaxTree())  ->   preprocessor   |   {atom(),
54       atom()}
55
56              Analyzes  an  attribute  node. If Node represents a preprocessor
57              directive, the atom preprocessor is returned. Otherwise, if Node
58              represents  a  module  attribute  "-<em>Name</em>...",  a  tuple
59              {Name, Info} is returned, where Info depends on  Name,  as  fol‐
60              lows:
61
62                {module, Info}:
63                  where Info = analyze_module_attribute(Node).
64
65                {export, Info}:
66                  where Info = analyze_export_attribute(Node).
67
68                {import, Info}:
69                  where Info = analyze_import_attribute(Node).
70
71                {file, Info}:
72                  where Info = analyze_file_attribute(Node).
73
74                {record, Info}:
75                  where Info = analyze_record_attribute(Node).
76
77                {Name, Info}:
78                  where {Name, Info} = analyze_wild_attribute(Node).
79
80              The  evaluation throws syntax_error if Node does not represent a
81              well-formed module attribute.
82
83              See also: analyze_export_attribute/1,  analyze_file_attribute/1,
84              analyze_import_attribute/1,   analyze_module_attribute/1,   ana‐
85              lyze_record_attribute/1, analyze_wild_attribute/1.
86
87       analyze_export_attribute(Node::syntaxTree()) -> [FunctionName]
88
89              Types:
90
91                 FunctionName = atom() | {atom(),  integer()}  |  {ModuleName,
92                 FunctionName}
93                 ModuleName = atom()
94
95              Returns  the  list  of  function  names  declared  by  an export
96              attribute. We do not guarantee that each  name  occurs  at  most
97              once in the list. The order of listing is not defined.
98
99              The  evaluation throws syntax_error if Node does not represent a
100              well-formed export attribute.
101
102              See also: analyze_attribute/1.
103
104       analyze_file_attribute(Node::syntaxTree()) -> {string(), integer()}
105
106              Returns the file name and line number of a file  attribute.  The
107              result  is the pair {File, Line} if Node represents "-file(File,
108              Line).".
109
110              The evaluation throws syntax_error if Node does not represent  a
111              well-formed file attribute.
112
113              See also: analyze_attribute/1.
114
115       analyze_form(Node::syntaxTree()) -> {atom(), term()} | atom()
116
117              Analyzes  a  "source  code  form" node. If Node is a "form" type
118              (cf. erl_syntax:is_form/1), the returned value is a tuple {Type,
119              Info}  where  Type is the node type and Info depends on Type, as
120              follows:
121
122                {attribute, Info}:
123                  where Info = analyze_attribute(Node).
124
125                {error_marker, Info}:
126                  where Info = erl_syntax:error_marker_info(Node).
127
128                {function, Info}:
129                  where Info = analyze_function(Node).
130
131                {warning_marker, Info}:
132                  where Info = erl_syntax:warning_marker_info(Node).
133
134              For other types of forms, only the node type is returned.
135
136              The evaluation throws syntax_error if Node is not well-formed.
137
138              See  also:  analyze_attribute/1,  analyze_function/1,   erl_syn‐
139              tax:error_marker_info/1,  erl_syntax:is_form/1, erl_syntax:warn‐
140              ing_marker_info/1.
141
142       analyze_forms(Forms) -> [{Key, term()}]
143
144              Types:
145
146                 Forms = syntaxTree() | [syntaxTree()]
147                 Key = attributes | errors | exports | functions |  imports  |
148                 module | records | warnings
149
150              Analyzes a sequence of "program forms". The given Forms may be a
151              single syntax tree of type form_list,  or  a  list  of  "program
152              form"  syntax trees. The returned value is a list of pairs {Key,
153              Info}, where each value of Key occurs at most once in the  list;
154              the absence of a particular key indicates that there is no well-
155              defined value for that key.
156
157              Each entry in the resulting list contains the  following  corre‐
158              sponding information about the program forms:
159
160                {attributes, Attributes}:
161
162
163                  * Attributes = [{atom(), term()}]
164
165                  Attributes  is  a  list  of pairs representing the names and
166                  corresponding values of all so-called "wild" attributes  (as
167                  e.g.   "-compile(...)")   occurring   in   Forms  (cf.  ana‐
168                  lyze_wild_attribute/1). We do not guarantee that  each  name
169                  occurs at most once in the list. The order of listing is not
170                  defined.
171
172                {errors, Errors}:
173
174
175                  * Errors = [term()]
176
177                  Errors is the list of error descriptors of all  error_marker
178                  nodes  that  occur  in  Forms.  The  order of listing is not
179                  defined.
180
181                {exports, Exports}:
182
183
184                  * Exports = [FunctionName]
185
186                  * FunctionName = atom() | {atom(), integer()} | {ModuleName,
187                    FunctionName}
188
189                  * ModuleName = atom()
190
191                  Exports is a list of representations of those function names
192                  that are listed by export declaration  attributes  in  Forms
193                  (cf.  analyze_export_attribute/1).  We do not guarantee that
194                  each name occurs at most once in  the  list.  The  order  of
195                  listing is not defined.
196
197                {functions, Functions}:
198
199
200                  * Functions = [{atom(), integer()}]
201
202                  Functions  is  a list of the names of the functions that are
203                  defined in Forms (cf. analyze_function/1). We do not guaran‐
204                  tee  that  each  name  occurs  at most once in the list. The
205                  order of listing is not defined.
206
207                {imports, Imports}:
208
209
210                  * Imports = [{Module, Names}]
211
212                  * Module = atom()
213
214                  * Names = [FunctionName]
215
216                  * FunctionName = atom() | {atom(), integer()} | {ModuleName,
217                    FunctionName}
218
219                  * ModuleName = atom()
220
221                  Imports  is  a list of pairs representing those module names
222                  and corresponding function names that are listed  by  import
223                  declaration     attributes     in     Forms     (cf.    ana‐
224                  lyze_import_attribute/1), where each Module occurs  at  most
225                  once  in  Imports. We do not guarantee that each name occurs
226                  at most once in the lists of function names.  The  order  of
227                  listing is not defined.
228
229                {module, ModuleName}:
230
231
232                  * ModuleName = atom()
233
234                  ModuleName  is  the  name  declared by a module attribute in
235                  Forms. If no module name is defined  in  Forms,  the  result
236                  will contain no entry for the module key. If multiple module
237                  name declarations should occur, all but the  first  will  be
238                  ignored.
239
240                {records, Records}:
241
242
243                  * Records = [{atom(), Fields}]
244
245                  * Fields = [{atom(), {Default, Type}}]
246
247                  * Default = none | syntaxTree()
248
249                  * Type = none | syntaxTree()
250
251                  Records is a list of pairs representing the names and corre‐
252                  sponding  field  declarations  of  all  record   declaration
253                  attributes occurring in Forms. For fields declared without a
254                  default value, the corresponding value for  Default  is  the
255                  atom  none.  Similarly,  for fields declared without a type,
256                  the corresponding value for Type is the atom none (cf.  ana‐
257                  lyze_record_attribute/1).  We  do  not  guarantee  that each
258                  record name occurs at most once in the list.  The  order  of
259                  listing is not defined.
260
261                {warnings, Warnings}:
262
263
264                  * Warnings = [term()]
265
266                  Warnings  is  the  list  of  error  descriptors of all warn‐
267                  ing_marker nodes that occur in Forms. The order  of  listing
268                  is not defined.
269
270              The  evaluation throws syntax_error if an ill-formed Erlang con‐
271              struct is encountered.
272
273              See also: analyze_export_attribute/1,  analyze_function/1,  ana‐
274              lyze_import_attribute/1,     analyze_record_attribute/1,    ana‐
275              lyze_wild_attribute/1, erl_syntax:error_marker_info/1,  erl_syn‐
276              tax:warning_marker_info/1.
277
278       analyze_function(Node::syntaxTree()) -> {atom(), integer()}
279
280              Returns  the name and arity of a function definition. The result
281              is a pair {Name, A} if Node  represents  a  function  definition
282              "Name(<em>P_1</em>, ..., <em>P_A</em>) -> ...".
283
284              The  evaluation throws syntax_error if Node does not represent a
285              well-formed function definition.
286
287       analyze_function_name(Node::syntaxTree()) -> FunctionName
288
289              Types:
290
291                 FunctionName = atom() | {atom(),  integer()}  |  {ModuleName,
292                 FunctionName}
293                 ModuleName = atom()
294
295              Returns  the function name represented by a syntax tree. If Node
296              represents a function name, such as "foo/1" or  "bloggs:fred/2",
297              a  uniform  representation  of  that name is returned. Different
298              nestings of arity and module name qualifiers in the syntax  tree
299              does not affect the result.
300
301              The  evaluation throws syntax_error if Node does not represent a
302              well-formed function name.
303
304       analyze_implicit_fun(Node::syntaxTree()) -> FunctionName
305
306              Types:
307
308                 FunctionName = atom() | {atom(),  integer()}  |  {ModuleName,
309                 FunctionName}
310                 ModuleName = atom()
311
312              Returns the name of an implicit fun expression "fun <em>F</em>".
313              The result is a representation of the function name F. (Cf. ana‐
314              lyze_function_name/1.)
315
316              The  evaluation throws syntax_error if Node does not represent a
317              well-formed implicit fun.
318
319              See also: analyze_function_name/1.
320
321       analyze_import_attribute(Node::syntaxTree())  ->  {atom(),   [Function‐
322       Name]} | atom()
323
324              Types:
325
326                 FunctionName  =  atom()  | {atom(), integer()} | {ModuleName,
327                 FunctionName}
328                 ModuleName = atom()
329
330              Returns the module name and (if present) list of function  names
331              declared  by  an import attribute. The returned value is an atom
332              Module or a pair {Module, Names}, where Names is a list of func‐
333              tion names declared as imported from the module named by Module.
334              We do not guarantee that each name occurs at most once in Names.
335              The order of listing is not defined.
336
337              The  evaluation throws syntax_error if Node does not represent a
338              well-formed import attribute.
339
340              See also: analyze_attribute/1.
341
342       analyze_module_attribute(Node::syntaxTree())    ->    Name::atom()    |
343       {Name::atom(), Variables::[atom()]}
344
345              Returns  the  module  name and possible parameters declared by a
346              module attribute. If the attribute is a plain module declaration
347              such  as  -module(name),  the  result is the module name. If the
348              attribute is a parameterized module declaration, the result is a
349              tuple  containing  the  module  name and a list of the parameter
350              variable names.
351
352              The evaluation throws syntax_error if Node does not represent  a
353              well-formed module attribute.
354
355              See also: analyze_attribute/1.
356
357       analyze_record_attribute(Node::syntaxTree()) -> {atom(), Fields}
358
359              Types:
360
361                 Fields = [{atom(), {Default, Type}}]
362                 Default = none | syntaxTree()
363                 Type = none | syntaxTree()
364
365              Returns  the name and the list of fields of a record declaration
366              attribute. The result is a pair {Name, Fields}, if  Node  repre‐
367              sents  "-record(Name,  {...}).", where Fields is a list of pairs
368              {Label, {Default,  Type}}  for  each  field  "Label",  "Label  =
369              <em>Default</em>",   "Label   ::  <em>Type</em>",  or  "Label  =
370              <em>Default</em> :: <em>Type</em>" in the declaration, listed in
371              left-to-right  order. If the field has no default-value declara‐
372              tion, the value for Default will be the atom none. If the  field
373              has  no  type  declaration,  the value for Type will be the atom
374              none. We do not guarantee that each label occurs at most once in
375              the list.
376
377              The  evaluation throws syntax_error if Node does not represent a
378              well-formed record declaration attribute.
379
380              See also: analyze_attribute/1, analyze_record_field/1.
381
382       analyze_record_expr(Node::syntaxTree()) -> {atom(), Info} | atom()
383
384              Types:
385
386                 Info = {atom(),  [{atom(),  Value}]}  |  {atom(),  atom()}  |
387                 atom()
388                 Value = syntaxTree()
389
390              Returns the record name and field name/names of a record expres‐
391              sion.  If  Node  has  type  record_expr,  record_index_expr   or
392              record_access,  a  pair  {Type,  Info} is returned, otherwise an
393              atom Type is returned. Type is the node type of Node,  and  Info
394              depends on Type, as follows:
395
396                record_expr::
397                  {atom(), [{atom(), Value}]}
398
399                record_access::
400                  {atom(), atom()}
401
402                record_index_expr::
403                  {atom(), atom()}
404
405              For  a record_expr node, Info represents the record name and the
406              list of descriptors for the involved fields, listed in the order
407              they  appear.  A  field  descriptor is a pair {Label, Value}, if
408              Node represents "Label = <em>Value</em>".  For  a  record_access
409              node,  Info represents the record name and the field name. For a
410              record_index_expr node, Info represents the record name and  the
411              name field name.
412
413              The  evaluation  throws syntax_error if Node represents a record
414              expression that is not well-formed.
415
416              See also: analyze_record_attribute/1, analyze_record_field/1.
417
418       analyze_record_field(Node::syntaxTree()) -> {atom(), {Default, Type}}
419
420              Types:
421
422                 Default = none | syntaxTree()
423                 Type = none | syntaxTree()
424
425              Returns the label, value-expression, and type of a record  field
426              specifier.  The  result  is  a pair {Label, {Default, Type}}, if
427              Node represents "Label", "Label = <em>Default</em>",  "Label  ::
428              <em>Type</em>",  or "Label = <em>Default</em> :: <em>Type</em>".
429              If the field has no value-expression, the value for Default will
430              be  the  atom none. If the field has no type, the value for Type
431              will be the atom none.
432
433              The evaluation throws syntax_error if Node does not represent  a
434              well-formed record field specifier.
435
436              See also: analyze_record_attribute/1, analyze_record_expr/1.
437
438       analyze_type_application(Node::syntaxTree()) -> TypeName
439
440              Types:
441
442                 TypeName  = {atom(), integer()} | {ModuleName, {atom(), inte‐
443                 ger()}}
444                 ModuleName = atom()
445
446              Returns the name of a used type. The result is a  representation
447              of  the  name of the used pre-defined or local type N/A, if Node
448              represents     a     local     (user)      type      application
449              "<em>N</em>(<em>T_1</em>,  ..., <em>T_A</em>)", or a representa‐
450              tion of the name of the used remote type M:N/A  if  Node  repre‐
451              sents       a       remote       user      type      application
452              "<em>M</em>:<em>N</em>(<em>T_1</em>, ..., <em>T_A</em>)".
453
454              The evaluation throws syntax_error if Node does not represent  a
455              well-formed (user) type application expression.
456
457              See also: analyze_type_name/1.
458
459       analyze_type_name(Node::syntaxTree()) -> TypeName
460
461              Types:
462
463                 TypeName  =  atom()  |  {atom(),  integer()}  |  {ModuleName,
464                 {atom(), integer()}}
465                 ModuleName = atom()
466
467              Returns the type name represented by a syntax tree. If Node rep‐
468              resents  a type name, such as "foo/1" or "bloggs:fred/2", a uni‐
469              form representation of that name is returned.
470
471              The evaluation throws syntax_error if Node does not represent  a
472              well-formed type name.
473
474       analyze_wild_attribute(Node::syntaxTree()) -> {atom(), term()}
475
476              Returns  the name and value of a "wild" attribute. The result is
477              the pair {Name, Value}, if Node represents "-Name(Value)".
478
479              Note that no  checking  is  done  whether  Name  is  a  reserved
480              attribute  name such as module or export: it is assumed that the
481              attribute is "wild".
482
483              The evaluation throws syntax_error if Node does not represent  a
484              well-formed wild attribute.
485
486              See also: analyze_attribute/1.
487
488       annotate_bindings(Tree::syntaxTree()) -> syntaxTree()
489
490              Adds  or  updates annotations on nodes in a syntax tree. Equiva‐
491              lent to annotate_bindings(Tree, Bindings)  where  the  top-level
492              environment  Bindings  is  taken from the annotation {env, Bind‐
493              ings} on the root node of Tree. An exception  is  thrown  if  no
494              such annotation should exist.
495
496              See also: annotate_bindings/2.
497
498       annotate_bindings(Tree::syntaxTree(), Bindings::ordset(atom())) -> syn‐
499       taxTree()
500
501              Adds or updates annotations on nodes in a syntax tree.  Bindings
502              specifies  the  set of bound variables in the environment of the
503              top level node. The following annotations are affected:
504
505                * {env, Vars}, representing the input environment of the  sub‐
506                  tree.
507
508                * {bound,  Vars}, representing the variables that are bound in
509                  the subtree.
510
511                * {free, Vars}, representing the free variables  in  the  sub‐
512                  tree.
513
514              Bindings  and Vars are ordered-set lists (cf. module ordsets) of
515              atoms representing variable names.
516
517              See also: ordsets(3), annotate_bindings/1.
518
519       fold(F::Function, Start::term(), Tree::syntaxTree()) -> term()
520
521              Types:
522
523                 Function = (syntaxTree(), term()) -> term()
524
525              Folds a function over all nodes of a syntax tree. The result  is
526              the  value  of Function(X1, Function(X2, ... Function(Xn, Start)
527              ... )), where [X1, X2, ..., Xn] are the nodes of Tree in a post-
528              order traversal.
529
530              See also: fold_subtrees/3, foldl_listlist/3.
531
532       fold_subtrees(F::Function, Start::term(), Tree::syntaxTree()) -> term()
533
534              Types:
535
536                 Function = (syntaxTree(), term()) -> term()
537
538              Folds  a  function over the immediate subtrees of a syntax tree.
539              This is similar to fold/3, but only on the immediate subtrees of
540              Tree,  in left-to-right order; it does not include the root node
541              of Tree.
542
543              See also: fold/3.
544
545       foldl_listlist(F::Function, Start::term(), Ls::[[term()]]) -> term()
546
547              Types:
548
549                 Function = (term(), term()) -> term()
550
551              Like lists:foldl/3, but over a list of lists.
552
553              See also: lists:foldl/3, fold/3.
554
555       function_name_expansions(Names::[Name]) -> [{ShortName, Name}]
556
557              Types:
558
559                 Name = ShortName | {atom(), Name}
560                 ShortName = atom() | {atom(), integer()}
561
562              Creates a mapping from corresponding short names to  full  func‐
563              tion  names. Names are represented by nested tuples of atoms and
564              integers (cf. analyze_function_name/1). The  result  is  a  list
565              containing a pair {ShortName, Name} for each element Name in the
566              given list, where the corresponding ShortName is the  rightmost-
567              innermost  part  of Name. The list thus represents a finite map‐
568              ping from  unqualified  names  to  the  corresponding  qualified
569              names.
570
571              Note: the resulting list can contain more than one tuple {Short‐
572              Name, Name} for the same ShortName, possibly with different val‐
573              ues for Name, depending on the given list.
574
575              See also: analyze_function_name/1.
576
577       is_fail_expr(Tree::syntaxTree()) -> boolean()
578
579              Returns true if Tree represents an expression which never termi‐
580              nates normally. Note that the reverse does not apply. Currently,
581              the  detected cases are calls to exit/1, throw/1, erlang:error/1
582              and erlang:error/2.
583
584              See   also:   erlang:error/1,   erlang:error/2,   erlang:exit/1,
585              erlang:throw/1.
586
587       limit(Tree, Depth) -> syntaxTree()
588
589              Equivalent  to  limit(Tree, Depth, Text) using the text "..." as
590              default replacement.
591
592              See also: limit/3, erl_syntax:text/1.
593
594       limit(Tree::syntaxTree(), Depth::integer(), Node::syntaxTree()) -> syn‐
595       taxTree()
596
597              Limits a syntax tree to a specified depth. Replaces all non-leaf
598              subtrees in Tree at the given Depth by Node. If Depth  is  nega‐
599              tive, the result is always Node, even if Tree has no subtrees.
600
601              When  a  group  of  subtrees  (as  e.g., the argument list of an
602              application node) is at the specified depth, and there  are  two
603              or  more  subtrees  in  the  group,  these  will be collectively
604              replaced by Node even if they are leaf nodes. Groups of subtrees
605              that  are  above the specified depth will be limited in size, as
606              if each subsequent tree in the group were one level deeper  than
607              the  previous.  E.g., if Tree represents a list of integers "[1,
608              2, 3, 4, 5, 6, 7, 8, 9, 10]", the result of limit(Tree, 5)  will
609              represent [1, 2, 3, 4, ...].
610
611              The  resulting  syntax tree is typically only useful for pretty-
612              printing or similar visual formatting.
613
614              See also: limit/2.
615
616       map(F::Function, Tree::syntaxTree()) -> syntaxTree()
617
618              Types:
619
620                 Function = (syntaxTree()) -> syntaxTree()
621
622              Applies a function to each node of a syntax tree. The result  of
623              each  application  replaces the corresponding original node. The
624              order of traversal is bottom-up.
625
626              See also: map_subtrees/2.
627
628       map_subtrees(F::Function, Tree::syntaxTree()) -> syntaxTree()
629
630              Types:
631
632                 Function = (Tree) -> Tree1
633
634              Applies a function to each immediate subtree of a  syntax  tree.
635              The result of each application replaces the corresponding origi‐
636              nal node.
637
638              See also: map/2.
639
640       mapfold(F::Function,  Start::term(),  Tree::syntaxTree())  ->  {syntax‐
641       Tree(), term()}
642
643              Types:
644
645                 Function = (syntaxTree(), term()) -> {syntaxTree(), term()}
646
647              Combines  map and fold in a single operation. This is similar to
648              map/2, but also propagates an extra value from each  application
649              of  the Function to the next, while doing a post-order traversal
650              of the tree like fold/3. The value Start is passed to the  first
651              function  application, and the final result is the result of the
652              last application.
653
654              See also: fold/3, map/2.
655
656       mapfold_subtrees(F::Function,  Start::term(),  Tree::syntaxTree())   ->
657       {syntaxTree(), term()}
658
659              Types:
660
661                 Function = (syntaxTree(), term()) -> {syntaxTree(), term()}
662
663              Does a mapfold operation over the immediate subtrees of a syntax
664              tree. This is similar to mapfold/3, but only  on  the  immediate
665              subtrees  of  Tree,  in left-to-right order; it does not include
666              the root node of Tree.
667
668              See also: mapfold/3.
669
670       mapfoldl_listlist(F::Function,     S::State,     Ls::[[term()]])     ->
671       {[[term()]], term()}
672
673              Types:
674
675                 Function = (term(), term()) -> {term(), term()}
676
677              Like  lists:mapfoldl/3,  but  over  a list of lists. The list of
678              lists in the result has the same structure as the given list  of
679              lists.
680
681       new_variable_name(Used::set(atom())) -> atom()
682
683              Returns  an  atom  which is not already in the set Used. This is
684              equivalent to new_variable_name(Function, Used), where  Function
685              maps  a  given  integer N to the atom whose name consists of "V"
686              followed by the numeral for N.
687
688              See also: new_variable_name/2.
689
690       new_variable_name(F::Function, Used::set(atom())) -> atom()
691
692              Types:
693
694                 Function = (integer()) -> atom()
695
696              Returns a user-named atom which is not already in the set  Used.
697              The atom is generated by applying the given Function to a gener‐
698              ated integer. Integers are generated using  an  algorithm  which
699              tries to keep the names randomly distributed within a reasonably
700              small range relative to the number of elements in the set.
701
702              This function uses the module rand to  generate  new  keys.  The
703              seed  it  uses  may  be  initialized  by  calling rand:seed/1 or
704              rand:seed/2 before this function is first called.
705
706              See also: random(3), sets(3), new_variable_name/1.
707
708       new_variable_names(N::integer(), Used::set(atom())) -> [atom()]
709
710              Like new_variable_name/1, but generates a list of N new names.
711
712              See also: new_variable_name/1.
713
714       new_variable_names(N::integer(),  F::Function,  Used::set(atom()))   ->
715       [atom()]
716
717              Types:
718
719                 Function = (integer()) -> atom()
720
721              Like new_variable_name/2, but generates a list of N new names.
722
723              See also: new_variable_name/2.
724
725       strip_comments(Tree::syntaxTree()) -> syntaxTree()
726
727              Removes  all comments from all nodes of a syntax tree. All other
728              attributes (such  as  position  information)  remain  unchanged.
729              Standalone  comments in form lists are removed; any other stand‐
730              alone comments are  changed  into  null-comments  (no  text,  no
731              indentation).
732
733       to_comment(Tree) -> syntaxTree()
734
735              Equivalent to to_comment(Tree, "% ").
736
737       to_comment(Tree::syntaxTree(), Prefix::string()) -> syntaxTree()
738
739              Equivalent  to to_comment(Tree, Prefix, F) for a default format‐
740              ting function F. The default F  simply  calls  erl_prettypr:for‐
741              mat/1.
742
743              See also: to_comment/3, erl_prettypr:format/1.
744
745       to_comment(Tree::syntaxTree(), Prefix::string(), F::Printer) -> syntax‐
746       Tree()
747
748              Types:
749
750                 Printer = (syntaxTree()) -> string()
751
752              Transforms a syntax tree into an abstract comment. The lines  of
753              the  comment contain the text for Node, as produced by the given
754              Printer function. Each line of the comment is  prefixed  by  the
755              string  Prefix  (this does not include the initial "%" character
756              of the comment line).
757
758              For    example,    the     result     of     to_comment(erl_syn‐
759              tax:abstract([a,b,c])) represents
760
761                        %% [a,b,c]
762
763              (cf. to_comment/1).
764
765              Note: the text returned by the formatting function will be split
766              automatically into separate comment lines at each line break. No
767              extra work is needed.
768
769              See also: to_comment/1, to_comment/2.
770
771       variables(Tree::syntaxTree()) -> set(atom())
772
773              Returns  the  names of variables occurring in a syntax tree, The
774              result is a set of variable names represented  by  atoms.  Macro
775              names are not included.
776
777              See also: sets(3).
778

AUTHORS

780       Richard Carlsson <carlsson.richard@gmail.com>
781
782
783
784                              syntax_tools 2.1.7             erl_syntax_lib(3)
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