summaryrefslogtreecommitdiff
path: root/lib/xmerl/src/xmerl.erl
blob: d27e101fe23d91b105eba128a0536e7701596049 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
%%
%% %CopyrightBegin%
%% 
%% Copyright Ericsson AB 2003-2011. All Rights Reserved.
%% 
%% The contents of this file are subject to the Erlang Public License,
%% Version 1.1, (the "License"); you may not use this file except in
%% compliance with the License. You should have received a copy of the
%% Erlang Public License along with this software. If not, it can be
%% retrieved online at http://www.erlang.org/.
%% 
%% Software distributed under the License is distributed on an "AS IS"
%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
%% the License for the specific language governing rights and limitations
%% under the License.
%% 
%% %CopyrightEnd%
%%

%%
%% Description  : Functions to export simple and complete XML forms
%% 

%% @doc Functions for exporting XML data to an external format.
%%

-module(xmerl).

%-compile(export_all).

-export([export/2, 
	 export/3,
	 export_content/2,
	 export_element/2,
	 export_element/3,
	 export_simple/2,
	 export_simple/3,
	 export_simple_element/2,
	 export_simple_content/2,
	 callbacks/1]).

-include("xmerl.hrl").
-include("xmerl_internal.hrl").


%% @spec export(Content, Callback) -> ExportedFormat
%% @equiv export(Data, Callback, [])

export(Content, Callback) ->
    export(Content, Callback, []).

%% @spec export(Content, Callback, RootAttributes) -> ExportedFormat
%%	Content = [Element]
%%	Callback = atom()
%%      RootAttributes = [XmlAttributes]
%% @doc Exports normal, well-formed XML content, using the specified
%% callback-module.
%% <p><code>Element</code> is any of:</p>
%% <ul>
%% 	<li><code>#xmlText{}</code></li>
%%	<li><code>#xmlElement{}</code></li>
%%	<li><code>#xmlPI{}</code></li>
%%	<li><code>#xmlComment{}</code></li>
%%	<li><code>#xmlDecl{}</code></li>
%% </ul>
%% <p>(See <tt>xmerl.hrl</tt> for the record definitions.)
%% Text in <code>#xmlText{}</code> elements can be deep lists of
%% characters and/or binaries.</p>
%%
%% <p><code>RootAttributes</code> is a list of
%% <code>#xmlAttribute{}</code> attributes for the <code>#root#</code>
%% element, which implicitly becomes the parent of the given
%% <code>Content</code>. The tag-handler function for
%% <code>#root#</code> is thus called with the complete exported data of
%% <code>Content</code>. Root attributes can be used to specify
%% e.g. encoding or other metadata of an XML or HTML document.</p>
%%
%% <p>The <code>Callback</code> module should contain hook functions for
%% all tags present in the data structure. A hook function must have the
%% following format:</p>
%% <pre>    Tag(Data, Attributes, Parents, E)</pre>
%% <p>where <code>E</code> is the corresponding <code>#xmlElement{}</code>,
%% <code>Data</code> is the already-exported contents of <code>E</code>
%% and <code>Attributes</code> is the list of
%% <code>#xmlAttribute{}</code> records of <code>E</code>. Finally,
%% <code>Parents</code> is the list of parent nodes of <code>E</code>,
%% on the form <code>[{ParentTag::atom(),
%% ParentPosition::integer()}]</code>.</p>
%%
%% <p>The hook function should return either the data to be exported, or
%% a tuple <code>{'#xml-alias#', NewTag::atom()}</code>, or a tuple
%% <code>{'#xml-redefine#', Content}</code>, where <code>Content</code>
%% is a content list (which can be on simple-form; see
%% <code>export_simple/2</code> for details).</p>
%%
%% <p>A callback module can inherit definitions from other callback
%% modules, through the required function <code>'#xml-interitance#() ->
%% [ModuleName::atom()]</code>.</p>
%%
%% @see export/2
%% @see export_simple/3

export(Content, Callback, RootAttributes) when is_atom(Callback) ->
    export1(Content, callbacks(Callback), RootAttributes);
export(Content, Callbacks, RootAttrs) when is_list(Callbacks) ->
    export1(Content, Callbacks, RootAttrs).

%% @spec export_simple(Content, Callback) -> ExportedFormat
%% @equiv export_simple(Content, Callback, [])

export_simple(Content, Callback) ->
    export_simple(Content, Callback, []).

%% @spec export_simple(Content, Callback, RootAttributes) -> ExportedFormat
%%	Content = [Element]
%%	Callback = atom()
%%      RootAttributes = [XmlAttributes]
%% @doc Exports "simple-form" XML content, using the specified
%% callback-module.
%% <p><code>Element</code> is any of:</p>
%% <ul>
%%	<li><code>{Tag, Attributes, Content}</code></li>
%%	<li><code>{Tag, Content}</code></li>
%%	<li><code>Tag</code></li>
%%	<li><code>IOString</code></li>
%% 	<li><code>#xmlText{}</code></li>
%%	<li><code>#xmlElement{}</code></li>
%%	<li><code>#xmlPI{}</code></li>
%%	<li><code>#xmlComment{}</code></li>
%%	<li><code>#xmlDecl{}</code></li>
%% </ul>
%% <p>where</p>
%% <ul>
%%	<li><code>Tag = atom()</code></li>
%%	<li><code>Attributes = [{Name, Value}]</code></li>
%%	<li><code>Name = atom()</code></li>
%%	<li><code>Value = IOString | atom() | integer()</code></li>
%% </ul>
%% <p>Normal-form XML elements can thus be included in the simple-form
%% representation. Note that content lists must be flat. An
%% <code>IOString</code> is a (possibly deep) list of characters and/or
%% binaries.</p>
%%
%% <p><code>RootAttributes</code> is a list of:</p>
%% <ul>
%%	<li><code>XmlAttributes = #xmlAttribute{}</code></li>
%%</ul>
%%
%% <p>See <code>export/3</code> for details on the callback module and
%% the root attributes. The XML-data is always converted to normal form
%% before being passed to the callback module.</p>
%%
%% @see export/3
%% @see export_simple/2

export_simple(Content, Callback, RootAttrs) when is_atom(Callback) ->
    export_simple1(Content, callbacks(Callback), RootAttrs);
export_simple(Content, Callbacks, RootAttrs) when is_list(Callbacks) ->
    export_simple1(Content, Callbacks, RootAttrs).

export_simple1(Content, Callback, RootAttrs) ->
    export1(xmerl_lib:expand_content(Content), Callback, RootAttrs).

%% This exports proper XML content in root context.

export1(Content, Callbacks, RootAttrs) when is_list(Content) ->
    Result = export_content(Content, Callbacks),
    Attrs = xmerl_lib:expand_attributes(RootAttrs, 1, [{'#root#',1}]),
    Root = #xmlElement{name = '#root#',
		       pos = 1,
		       parents = [],
		       attributes = Attrs},
    Args = [Result, Root#xmlElement.attributes, [], Root],
    tagdef('#root#',1,[],Args,Callbacks).

%% @doc Exports simple XML content directly, without further context.

export_simple_content(Content, Callback) when is_atom(Callback) ->
    export_content(xmerl_lib:expand_content(Content),
		   callbacks(Callback));
export_simple_content(Content, Callbacks) when is_list(Callbacks) ->
    export_content(xmerl_lib:expand_content(Content), Callbacks).


%% @spec export_content(Content, Callbacks) -> term()
%%	Content = [Element]
%%	Callback = [atom()]
%% @doc Exports normal XML content directly, without further context.
export_content([#xmlText{value = Text} | Es], Callbacks) ->
    [apply_text_cb(Callbacks, Text) | export_content(Es, Callbacks)];
export_content([#xmlPI{} | Es], Callbacks) ->
    export_content(Es, Callbacks);
export_content([#xmlComment{} | Es], Callbacks) ->
    export_content(Es, Callbacks);
export_content([#xmlDecl{} | Es], Callbacks) ->
    export_content(Es, Callbacks);
export_content([E | Es], Callbacks) ->
    [export_element(E, Callbacks) | export_content(Es, Callbacks)];
export_content([], _Callbacks) ->
    [].

%% @doc Exports a simple XML element directly, without further context.

export_simple_element(Content, Callback) when is_atom(Callback) ->
    export_element(xmerl_lib:expand_element(Content),
		   callbacks(Callback));
export_simple_element(Content, Callbacks) when is_list(Callbacks) ->
    export_element(xmerl_lib:expand_element(Content), Callbacks).

%% @doc Exports a normal XML element directly, without further context.

%% This is the usual DOM style parsing.

export_element(E, CB) when is_atom(CB) ->
    export_element(E, callbacks(CB));
export_element(#xmlText{value = Text}, CBs) ->
    apply_text_cb(CBs, Text);
export_element(E = #xmlElement{name = Tag,
			       pos = Pos,
			       attributes = Attributes,
			       parents = Parents,
			       content = Content}, CBs) ->
    Data = export_content(Content, CBs),
    Args = [Data, Attributes, Parents, E],
    tagdef(Tag,Pos,Parents,Args,CBs);
export_element(#xmlPI{}, _CBs) ->
    [];
export_element(#xmlComment{}, _CBs) ->
    [];
export_element(#xmlDecl{}, _CBs) ->
    [].


%% @spec export_element(E,CallbackModule,CallbackState) -> ExportedFormat
%% @doc For on-the-fly exporting during parsing (SAX style) of the XML
%% document. 
export_element(E, CallbackModule, CallbackState) when is_atom(CallbackModule) ->
    export_element(E, callbacks(CallbackModule), CallbackState);
export_element(#xmlText{value = Text},CallbackModule,_CallbackState) ->
%%    apply_cb(CallbackModule, '#text#', '#text#', [Text,CallbackState]);
    apply_text_cb(CallbackModule,Text);
export_element(E=#xmlElement{name = Tag,
			   pos = Pos,
			   parents = Parents,
			   attributes = Attributes,
			   content = Content},Callbacks,CBstate) ->
    Args = [Content, Attributes,CBstate,E],
    tagdef(Tag,Pos,Parents,Args,Callbacks);
export_element(#xmlPI{}, _CallbackModule, CallbackState) ->
    CallbackState;
export_element(#xmlComment{},_CallbackModule, CallbackState) ->
    CallbackState;
export_element(#xmlDecl{},_CallbackModule, CallbackState) ->
    CallbackState.

%% A thing returned with #xml-redefine is assumed to be a content list
%% The data may be on "simple" format.

tagdef(Tag,Pos,Parents,Args,CBs) ->
    case apply_tag_cb(CBs, Tag, Args) of
	{'#xml-alias#', NewTag} ->
	    tagdef(NewTag,Pos,Parents,Args,CBs);
	{'#xml-redefine#', Data} ->
	    export_content(xmerl_lib:expand_content(Data, Pos, Parents),
			   CBs);
	Other ->
	    Other
    end.

%% @spec callbacks(Module) -> Result
%%	Module = atom()
%%	Result = [atom()]
%% @doc Find the list of inherited callback modules for a given module.

callbacks(Module) ->
    Result = check_inheritance(Module, []),
%%%     ?dbg("callbacks = ~p~n", [lists:reverse(Result)]),
    lists:reverse(Result).

callbacks([M|Mods], Visited) ->
    case lists:member(M, Visited) of
	false ->
	    NewVisited = check_inheritance(M, Visited),
	    callbacks(Mods, NewVisited);
	true ->
	    exit({cyclic_inheritance, {M, hd(Visited)}})
    end;
callbacks([], Visited) ->
    Visited.

check_inheritance(M, Visited) ->
%%%     ?dbg("calling ~p:'#xml-inheritance#'()~n", [M]),
    case M:'#xml-inheritance#'() of
	[] ->
	    [M|Visited];
	Mods ->
	    callbacks(Mods, [M|Visited])
    end.

apply_text_cb(Ms, Text) ->
    apply_cb(Ms, '#text#', '#text#', [Text]).

apply_tag_cb(Ms, F, Args) ->
    apply_cb(Ms, F, '#element#', Args).

apply_cb(Ms, F, Df, Args) ->
    apply_cb(Ms, F, Df, Args, length(Args)).

apply_cb(Ms, F, Df, Args, A) ->
    apply_cb(Ms, F, Df, Args, A, Ms).

apply_cb([M|Ms], F, Df, Args, A, Ms0) ->
    case erlang:function_exported(M, F, A) of
        true -> apply(M, F, Args);
        false -> apply_cb(Ms, F, Df, Args, A, Ms0)
    end;
apply_cb([], Df, Df, Args, _A, _Ms0) ->
    exit({unknown_tag, {Df, Args}});
apply_cb([], F, Df, Args, A, Ms0) ->
    apply_cb(Ms0, Df, Df, [F|Args], A+1).