1erl_parse(3) Erlang Module Definition erl_parse(3)
2
6 erl_parse - The Erlang parser.
7
9 This module is the basic Erlang parser that converts tokens into the
10 abstract form of either forms (that is, top-level constructs), expres‐
11 sions, or terms. The Abstract Format is described in the ERTS User's
12 Guide. Notice that a token list must end with the dot token to be
13 acceptable to the parse functions (see the erl_scan(3)) module.
14
16 abstract_clause()
17 Abstract form of an Erlang clause.
19 abstract_expr()
21 Abstract form of an Erlang expression.
23 abstract_form()
25 Abstract form of an Erlang form.
27 abstract_type()
29 Abstract form of an Erlang type.
31 erl_parse_tree() =
33 abstract_clause() |
34 abstract_expr() |
35 abstract_form() |
36 abstract_type()
37 error_description() = term()
39 error_info() = {erl_anno:line(), module(), error_description()}
41 form_info() =
43 {eof, erl_anno:line()} |
44 {error, erl_scan:error_info() | error_info()} |
45 {warning, erl_scan:error_info() | error_info()}
46 Tuples {error, error_info()} and {warning, error_info()}, denot‐
48 ing syntactically incorrect forms and warnings, and {eof,
49 line()}, denoting an end-of-stream encountered before a complete
50 form had been parsed.
51 token() = erl_scan:token()
53
55 abstract(Data) -> AbsTerm
56 Types:
58 Data = term()
60 AbsTerm = abstract_expr()
61 Converts the Erlang data structure Data into an abstract form of
63 type AbsTerm. This function is the inverse of normalise/1.
64 erl_parse:abstract(T) is equivalent to erl_parse:abstract(T, 0).
66 abstract(Data, Options) -> AbsTerm
68 Types:
70 Data = term()
72 Options = Line | [Option]
73 Option = {line, Line} | {encoding, Encoding}
74 Encoding = latin1 | unicode | utf8 | none | encoding_func()
75 Line = erl_anno:line()
76 AbsTerm = abstract_expr()
77 encoding_func() = fun((integer() >= 0) -> boolean())
78 Converts the Erlang data structure Data into an abstract form of
80 type AbsTerm.
81 Option Line is the line to be assigned to each node of AbsTerm.
83 Option Encoding is used for selecting which integer lists to be
85 considered as strings. The default is to use the encoding
86 returned by function epp:default_encoding/0. Value none means
87 that no integer lists are considered as strings. encoding_func()
88 is called with one integer of a list at a time; if it returns
89 true for every integer, the list is considered a string.
90 anno_from_term(Term) -> erl_parse_tree() | form_info()
92 Types:
94 Term = term()
96 Assumes that Term is a term with the same structure as a
98 erl_parse tree, but with terms, say T, where a erl_parse tree
99 has collections of annotations. Returns a erl_parse tree where
100 each term T is replaced by the value returned by
101 erl_anno:from_term(T). The term Term is traversed in a depth-
102 first, left-to-right fashion.
103 anno_to_term(Abstr) -> term()
105 Types:
107 Abstr = erl_parse_tree() | form_info()
109 Returns a term where each collection of annotations Anno of the
111 nodes of the erl_parse tree Abstr is replaced by the term
112 returned by erl_anno:to_term(Anno). The erl_parse tree is tra‐
113 versed in a depth-first, left-to-right fashion.
114 fold_anno(Fun, Acc0, Abstr) -> Acc1
116 Types:
118 Fun = fun((Anno, AccIn) -> AccOut)
120 Anno = erl_anno:anno()
121 Acc0 = Acc1 = AccIn = AccOut = term()
122 Abstr = erl_parse_tree() | form_info()
123 Updates an accumulator by applying Fun on each collection of
125 annotations of the erl_parse tree Abstr. The first call to Fun
126 has AccIn as argument, the returned accumulator AccOut is passed
127 to the next call, and so on. The final value of the accumulator
128 is returned. The erl_parse tree is traversed in a depth-first,
129 left-to-right fashion.
130 format_error(ErrorDescriptor) -> Chars
132 Types:
134 ErrorDescriptor = error_description()
136 Chars = [char() | Chars]
137 Uses an ErrorDescriptor and returns a string that describes the
139 error. This function is usually called implicitly when an Error‐
140 Info structure is processed (see section Error Information).
141 map_anno(Fun, Abstr) -> NewAbstr
143 Types:
145 Fun = fun((Anno) -> NewAnno)
147 Anno = NewAnno = erl_anno:anno()
148 Abstr = NewAbstr = erl_parse_tree() | form_info()
149 Modifies the erl_parse tree Abstr by applying Fun on each col‐
151 lection of annotations of the nodes of the erl_parse tree. The
152 erl_parse tree is traversed in a depth-first, left-to-right
153 fashion.
154 mapfold_anno(Fun, Acc0, Abstr) -> {NewAbstr, Acc1}
156 Types:
158 Fun = fun((Anno, AccIn) -> {NewAnno, AccOut})
160 Anno = NewAnno = erl_anno:anno()
161 Acc0 = Acc1 = AccIn = AccOut = term()
162 Abstr = NewAbstr = erl_parse_tree() | form_info()
163 Modifies the erl_parse tree Abstr by applying Fun on each col‐
165 lection of annotations of the nodes of the erl_parse tree, while
166 at the same time updating an accumulator. The first call to Fun
167 has AccIn as second argument, the returned accumulator AccOut is
168 passed to the next call, and so on. The modified erl_parse tree
169 and the final value of the accumulator are returned. The
170 erl_parse tree is traversed in a depth-first, left-to-right
171 fashion.
172 new_anno(Term) -> Abstr
174 Types:
176 Term = term()
178 Abstr = erl_parse_tree() | form_info()
179 Assumes that Term is a term with the same structure as a
181 erl_parse tree, but with locations where a erl_parse tree has
182 collections of annotations. Returns a erl_parse tree where each
183 location L is replaced by the value returned by erl_anno:new(L).
184 The term Term is traversed in a depth-first, left-to-right fash‐
185 ion.
186 normalise(AbsTerm) -> Data
188 Types:
190 AbsTerm = abstract_expr()
192 Data = term()
193 Converts the abstract form AbsTerm of a term into a conventional
195 Erlang data structure (that is, the term itself). This function
196 is the inverse of abstract/1.
197 parse_exprs(Tokens) -> {ok, ExprList} | {error, ErrorInfo}
199 Types:
201 Tokens = [token()]
203 ExprList = [abstract_expr()]
204 ErrorInfo = error_info()
205 Parses Tokens as if it was a list of expressions. Returns one of
207 the following:
208 {ok, ExprList}:
210 The parsing was successful. ExprList is a list of the
211 abstract forms of the parsed expressions.
212 {error, ErrorInfo}:
214 An error occurred.
215 parse_form(Tokens) -> {ok, AbsForm} | {error, ErrorInfo}
217 Types:
219 Tokens = [token()]
221 AbsForm = abstract_form()
222 ErrorInfo = error_info()
223 Parses Tokens as if it was a form. Returns one of the following:
225 {ok, AbsForm}:
227 The parsing was successful. AbsForm is the abstract form of
228 the parsed form.
229 {error, ErrorInfo}:
231 An error occurred.
232 parse_term(Tokens) -> {ok, Term} | {error, ErrorInfo}
234 Types:
236 Tokens = [token()]
238 Term = term()
239 ErrorInfo = error_info()
240 Parses Tokens as if it was a term. Returns one of the following:
242 {ok, Term}:
244 The parsing was successful. Term is the Erlang term corre‐
245 sponding to the token list.
246 {error, ErrorInfo}:
248 An error occurred.
249 tokens(AbsTerm) -> Tokens
251 tokens(AbsTerm, MoreTokens) -> Tokens
253 Types:
255 AbsTerm = abstract_expr()
257 MoreTokens = Tokens = [token()]
258 Generates a list of tokens representing the abstract form
260 AbsTerm of an expression. Optionally, MoreTokens is appended.
261
263 ErrorInfo is the standard ErrorInfo structure that is returned from all
264 I/O modules. The format is as follows:
265 {ErrorLine, Module, ErrorDescriptor}
267 A string describing the error is obtained with the following call:
269 Module:format_error(ErrorDescriptor)
271
273 erl_anno(3), erl_scan(3), io(3), section The Abstract Format in the
274 ERTS User's Guide
275Ericsson AB stdlib 3.4.5.1 erl_parse(3)