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-rw-r--r--lib/asn1/doc/src/asn1_getting_started.xml77
1 files changed, 68 insertions, 9 deletions
diff --git a/lib/asn1/doc/src/asn1_getting_started.xml b/lib/asn1/doc/src/asn1_getting_started.xml
index d40b294c39..d2b73d63c3 100644
--- a/lib/asn1/doc/src/asn1_getting_started.xml
+++ b/lib/asn1/doc/src/asn1_getting_started.xml
@@ -187,6 +187,14 @@ erlc -o ../asnfiles -I ../asnfiles -I /usr/local/standards/asn1 Person.asn</pre>
<item>
<p>DER encoding rule. Only when using option <c>-ber</c>.</p>
</item>
+ <tag><c>+maps</c></tag>
+ <item>
+ <p>Use maps instead of records to represent the <c>SEQUENCE</c> and
+ <c>SET</c> types. No <c>.hrl</c> files will be generated.
+ See the Section <seealso marker="asn1_getting_started#MAP_SEQ_SET">
+ Map representation for SEQUENCE and SET</seealso>
+ for more information.</p>
+ </item>
<tag><c>+asn1config</c></tag>
<item>
<p>This functionality works together with option
@@ -766,8 +774,11 @@ Pdu ::= SEQUENCE {
b REAL,
c OBJECT IDENTIFIER,
d NULL } </pre>
- <p>This is a 4-component structure called <c>Pdu</c>. The record format
- is the major format for representation of <c>SEQUENCE</c> in Erlang.
+ <p>This is a 4-component structure called <c>Pdu</c>. By default,
+ a <c>SEQUENCE</c> is represented by a record in Erlang.
+ It can also be represented as a map; see
+ <seealso marker="asn1_getting_started#MAP_SEQ_SET">
+ Map representation for SEQUENCE and SET</seealso>.
For each <c>SEQUENCE</c> and <c>SET</c> in an ASN.1 module an Erlang
record declaration is generated. For <c>Pdu</c>, a record
like the following is defined:</p>
@@ -878,6 +889,48 @@ SExt ::= SEQUENCE {
</section>
<section>
+ <marker id="MAP_SEQ_SET"></marker>
+ <title>Map representation for SEQUENCE and SET</title>
+ <p>If the ASN.1 module has been compiled with option <c>maps</c>,
+ the types <c>SEQUENCE</c> and <c>SET</c> are represented as maps.</p>
+ <p>In the following example, this ASN.1 specification is used:</p>
+ <pre>
+File DEFINITIONS AUTOMATIC TAGS ::=
+BEGIN
+Seq1 ::= SEQUENCE {
+ a INTEGER DEFAULT 42,
+ b BOOLEAN OPTIONAL,
+ c IA5String
+}
+END </pre>
+
+ <p>Optional fields are to be omitted from the map if they have
+ no value:</p>
+
+ <pre>
+1> <input>asn1ct:compile('File', [per,maps]).</input>
+ok
+2> <input>{ok,E} = 'File':encode('Seq1', #{a=>0,c=>"string"}).</input>
+{ok,&lt;&lt;128,1,0,6,115,116,114,105,110,103&gt;&gt;} </pre>
+
+ <p>When decoding, optional fields will be omitted from the map:</p>
+
+ <pre>
+3> <input>'File':decode('Seq1', E).</input>
+{ok,#{a => 0,c => "string"}} </pre>
+
+ <p>Default values can be omitted from the map:</p>
+ <pre>
+4> <input>{ok,E2} = 'File':encode('Seq1', #{c=>"string"}).</input>
+{ok,&lt;&lt;0,6,115,116,114,105,110,103&gt;&gt;}
+5> <input>'File':decode('Seq1', E2).</input>
+{ok,#{a => 42,c => "string"}} </pre>
+
+ <note><p>It is not allowed to use the atoms <c>asn1_VALUE</c> and
+ <c>asn1_DEFAULT</c> with maps.</p></note>
+ </section>
+
+ <section>
<marker id="CHOICE"></marker>
<title>CHOICE</title>
<p>The type <c>CHOICE</c> is a space saver and is similar to the
@@ -1004,11 +1057,16 @@ T ::= CHOICE {
<section>
<title>Naming of Records in .hrl Files</title>
+ <p>When the option <c>maps</c> is given, no <c>.hrl</c> files
+ will be generated. The rest of this section describes the behavior
+ of the compiler when <c>maps</c> is not used.</p>
+
<p>When an ASN.1 specification is compiled, all defined types of type
- <c>SET</c> or <c>SEQUENCE</c> result in a corresponding record in the
- generated <c>.hrl</c> file. This is because the values for
- <c>SET</c> and <c>SEQUENCE</c> are represented as records as
- mentioned earlier.</p>
+ <c>SET</c> or <c>SEQUENCE</c> result in a corresponding record in the
+ generated <c>.hrl</c> file. This is because the values for
+ <c>SET</c> and <c>SEQUENCE</c> are represented as records
+ by default.</p>
+
<p>Some special cases of this functionality are presented in the
next section.</p>
@@ -1144,9 +1202,10 @@ SS ::= SET {
<p>This example shows that a function is generated by the compiler
that returns a valid Erlang representation of the value, although
the value is of a complex type.</p>
- <p>Furthermore, a macro is generated for each value in the <c>.hrl</c>
- file. So, the defined value <c>tt</c> can also be extracted by
- <c>?tt</c> in application code.</p>
+ <p>Furthermore, if the option <c>maps</c> is not used,
+ a macro is generated for each value in the <c>.hrl</c>
+ file. So, the defined value <c>tt</c> can also be extracted by
+ <c>?tt</c> in application code.</p>
</section>
<section>