dyaml/doc/html/api/dyaml.constructor.html
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<h1>dyaml.constructor</h1>
<!-- Generated by Ddoc from dyaml/constructor.d -->
<p>Implements a class that processes YAML mappings, sequences and scalars into
nodes. This can be used to implement custom data types. A tutorial can be
found <a href="../tutorials/custom_types.html">here</a>.</p>
<dl><dt class="d_decl"><a name="Constructor"></a>class <a name="Constructor"></a><span class="ddoc_psymbol">Constructor</span>;
</dt>
<dd><p>Constructs YAML values.
</p>
<p>Each YAML scalar, sequence or mapping has a tag specifying its data type.
<a name="Constructor"></a><span class="ddoc_psymbol">Constructor</span> uses user-specifyable functions to create a node of desired
data type from a scalar, sequence or mapping.
<br>
<br>
Each of these functions is associated with a tag, and can process either
a scalar, a sequence, or a mapping. The constructor passes each value to
the function with corresponding tag, which then returns the resulting value
that can be stored in a node.
<br>
If a tag is detected with no known constructor function, it is considered an error.</p>
<dl><dt class="d_decl"><a name="Constructor.this"></a>nothrow @safe this(const Flag!"useDefaultConstructors" <b>defaultConstructors</b> = Yes.useDefaultConstructors);
</dt>
<dd><p>Construct a Constructor.
</p>
<p>If you don't want to support default YAML tags/data types, you can use
<br>
<b>defaultConstructors</b> to disable constructor functions for these.
<br>
<br>
</p>
<b>Parameters:</b><div class="pbr"><table class=parms><tr><td valign=top>Flag!"useDefaultConstructors" <b>defaultConstructors</b></td>
<td valign=top>Use constructors for default YAML tags?</td></tr>
</table></div>
</dd>
<dt class="d_decl"><a name="Constructor.addConstructorScalar"></a>nothrow @safe void <a name="addConstructorScalar"></a><span class="ddoc_psymbol">addConstructorScalar</span>(T)(const string <b>tag</b>, T function(ref Node) <b>ctor</b>);
</dt>
<dd><p>Add a constructor function from scalar.
</p>
<p>The function must take a reference to <span class="d_inlinecode">Node</span> to construct from.
The node contains a string for scalars, <span class="d_inlinecode">Node[]</span> for sequences and
<span class="d_inlinecode">Node.Pair[]</span> for mappings.
<br>
Any exception thrown by this function will be caught by D:YAML and
its message will be added to a <span class="d_inlinecode">YAMLException</span> that will also tell
the user which type failed to construct, and position in the file.
<br>
<br>
The value returned by this function will be stored in the resulting node.
<br>
Only one constructor function can be set for one tag.
<br>
<br>
Structs and classes must implement the <span class="d_inlinecode">opCmp()</span> operator for D:YAML
support. The signature of the operator that must be implemented
is <span class="d_inlinecode">const int opCmp(ref const MyStruct s)</span> for structs where
<i>MyStruct</i> is the struct type, and <span class="d_inlinecode">int opCmp(Object o)</span> for
classes. Note that the class <span class="d_inlinecode">opCmp()</span> should not alter the compared
values - it is not const for compatibility reasons.
</p>
<b>Parameters:</b><div class="pbr"><table class=parms><tr><td valign=top>string tag</td>
<td valign=top>Tag for the function to handle.</td></tr>
<tr><td valign=top>T function(ref Node) ctor</td>
<td valign=top>Constructor function.</td></tr>
</table></div>
<p><b>Example:</b><br>
<pre class="d_code"><span class="d_keyword">import</span> std.string;
<span class="d_keyword">import</span> dyaml.all;
<span class="d_keyword">struct</span> MyStruct
{
<span class="d_keyword">int</span> x, y, z;
<span class="d_comment">//Any D:YAML type must have a custom opCmp operator.
</span> <span class="d_comment">//This is used for ordering in mappings.
</span> <span class="d_keyword">const</span> <span class="d_keyword">int</span> opCmp(<span class="d_keyword">ref</span> <span class="d_keyword">const</span> MyStruct s)
{
<span class="d_keyword">if</span>(x != s.x){<span class="d_keyword">return</span> x - s.x;}
<span class="d_keyword">if</span>(y != s.y){<span class="d_keyword">return</span> y - s.y;}
<span class="d_keyword">if</span>(z != s.z){<span class="d_keyword">return</span> z - s.z;}
<span class="d_keyword">return</span> 0;
}
}
MyStruct constructMyStructScalar(<span class="d_keyword">ref</span> Node node)
{
<span class="d_comment">//Guaranteed to be string as we construct from scalar.
</span> <span class="d_comment">//!mystruct x:y:z
</span> <span class="d_keyword">auto</span> parts = node.as!string().split(<span class="d_string">":"</span>);
<span class="d_comment">// If this throws, the D:YAML will handle it and throw a YAMLException.
</span> <span class="d_keyword">return</span> MyStruct(to!<span class="d_keyword">int</span>(parts[0]), to!<span class="d_keyword">int</span>(parts[1]), to!<span class="d_keyword">int</span>(parts[2]));
}
<span class="d_keyword">void</span> main()
{
<span class="d_keyword">auto</span> loader = Loader(<span class="d_string">"file.yaml"</span>);
<span class="d_keyword">auto</span> constructor = <span class="d_keyword">new</span> Constructor;
constructor.<span class="d_psymbol">addConstructorScalar</span>(<span class="d_string">"!mystruct"</span>, &amp;constructMyStructScalar);
loader.constructor = constructor;
Node node = loader.load();
}
</pre>
</p>
</dd>
<dt class="d_decl"><a name="Constructor.addConstructorSequence"></a>nothrow @safe void <a name="addConstructorSequence"></a><span class="ddoc_psymbol">addConstructorSequence</span>(T)(const string <b>tag</b>, T function(ref Node) <b>ctor</b>);
</dt>
<dd><p>Add a constructor function from sequence.
</p>
<b>See Also:</b><div class="pbr">addConstructorScalar
</div>
<p><b>Example:</b><br>
<pre class="d_code"><span class="d_keyword">import</span> std.string;
<span class="d_keyword">import</span> dyaml.all;
<span class="d_keyword">struct</span> MyStruct
{
<span class="d_keyword">int</span> x, y, z;
<span class="d_comment">//Any D:YAML type must have a custom opCmp operator.
</span> <span class="d_comment">//This is used for ordering in mappings.
</span> <span class="d_keyword">const</span> <span class="d_keyword">int</span> opCmp(<span class="d_keyword">ref</span> <span class="d_keyword">const</span> MyStruct s)
{
<span class="d_keyword">if</span>(x != s.x){<span class="d_keyword">return</span> x - s.x;}
<span class="d_keyword">if</span>(y != s.y){<span class="d_keyword">return</span> y - s.y;}
<span class="d_keyword">if</span>(z != s.z){<span class="d_keyword">return</span> z - s.z;}
<span class="d_keyword">return</span> 0;
}
}
MyStruct constructMyStructSequence(<span class="d_keyword">ref</span> Node node)
{
<span class="d_comment">//node is guaranteed to be sequence.
</span> <span class="d_comment">//!mystruct [x, y, z]
</span> <span class="d_keyword">return</span> MyStruct(node[0].as!<span class="d_keyword">int</span>, node[1].as!<span class="d_keyword">int</span>, node[2].as!<span class="d_keyword">int</span>);
}
<span class="d_keyword">void</span> main()
{
<span class="d_keyword">auto</span> loader = Loader(<span class="d_string">"file.yaml"</span>);
<span class="d_keyword">auto</span> constructor = <span class="d_keyword">new</span> Constructor;
constructor.<span class="d_psymbol">addConstructorSequence</span>(<span class="d_string">"!mystruct"</span>, &amp;constructMyStructSequence);
loader.constructor = constructor;
Node node = loader.load();
}
</pre>
</p>
</dd>
<dt class="d_decl"><a name="Constructor.addConstructorMapping"></a>nothrow @safe void <a name="addConstructorMapping"></a><span class="ddoc_psymbol">addConstructorMapping</span>(T)(const string <b>tag</b>, T function(ref Node) <b>ctor</b>);
</dt>
<dd><p>Add a constructor function from a mapping.
</p>
<b>See Also:</b><div class="pbr">addConstructorScalar
</div>
<p><b>Example:</b><br>
<pre class="d_code"><span class="d_keyword">import</span> std.string;
<span class="d_keyword">import</span> dyaml.all;
<span class="d_keyword">struct</span> MyStruct
{
<span class="d_keyword">int</span> x, y, z;
<span class="d_comment">//Any D:YAML type must have a custom opCmp operator.
</span> <span class="d_comment">//This is used for ordering in mappings.
</span> <span class="d_keyword">const</span> <span class="d_keyword">int</span> opCmp(<span class="d_keyword">ref</span> <span class="d_keyword">const</span> MyStruct s)
{
<span class="d_keyword">if</span>(x != s.x){<span class="d_keyword">return</span> x - s.x;}
<span class="d_keyword">if</span>(y != s.y){<span class="d_keyword">return</span> y - s.y;}
<span class="d_keyword">if</span>(z != s.z){<span class="d_keyword">return</span> z - s.z;}
<span class="d_keyword">return</span> 0;
}
}
MyStruct constructMyStructMapping(<span class="d_keyword">ref</span> Node node)
{
<span class="d_comment">//node is guaranteed to be mapping.
</span> <span class="d_comment">//!mystruct {"x": x, "y": y, "z": z}
</span> <span class="d_keyword">return</span> MyStruct(node[<span class="d_string">"x"</span>].as!<span class="d_keyword">int</span>, node[<span class="d_string">"y"</span>].as!<span class="d_keyword">int</span>, node[<span class="d_string">"z"</span>].as!<span class="d_keyword">int</span>);
}
<span class="d_keyword">void</span> main()
{
<span class="d_keyword">auto</span> loader = Loader(<span class="d_string">"file.yaml"</span>);
<span class="d_keyword">auto</span> constructor = <span class="d_keyword">new</span> Constructor;
constructor.<span class="d_psymbol">addConstructorMapping</span>(<span class="d_string">"!mystruct"</span>, &amp;constructMyStructMapping);
loader.constructor = constructor;
Node node = loader.load();
}
</pre>
</p>
</dd>
</dl>
</dd>
<dt class="d_decl"><a name="constructNull"></a>YAMLNull <a name="constructNull"></a><span class="ddoc_psymbol">constructNull</span>(ref Node <b>node</b>);
</dt>
<dd><p>Construct a null node.</p>
</dd>
<dt class="d_decl"><a name="constructMerge"></a>YAMLMerge <a name="constructMerge"></a><span class="ddoc_psymbol">constructMerge</span>(ref Node <b>node</b>);
</dt>
<dd><p>Construct a merge node - a node that merges another node into a mapping.</p>
</dd>
<dt class="d_decl"><a name="constructBool"></a>bool <a name="constructBool"></a><span class="ddoc_psymbol">constructBool</span>(ref Node <b>node</b>);
</dt>
<dd><p>Construct a boolean node.</p>
</dd>
<dt class="d_decl"><a name="constructLong"></a>long <a name="constructLong"></a><span class="ddoc_psymbol">constructLong</span>(ref Node <b>node</b>);
</dt>
<dd><p>Construct an integer (long) node.</p>
</dd>
<dt class="d_decl"><a name="constructReal"></a>real <a name="constructReal"></a><span class="ddoc_psymbol">constructReal</span>(ref Node <b>node</b>);
</dt>
<dd><p>Construct a floating point (real) node.</p>
</dd>
<dt class="d_decl"><a name="constructBinary"></a>ubyte[] <a name="constructBinary"></a><span class="ddoc_psymbol">constructBinary</span>(ref Node <b>node</b>);
</dt>
<dd><p>Construct a binary (base64) node.</p>
</dd>
<dt class="d_decl"><a name="constructTimestamp"></a>SysTime <a name="constructTimestamp"></a><span class="ddoc_psymbol">constructTimestamp</span>(ref Node <b>node</b>);
</dt>
<dd><p>Construct a timestamp (SysTime) node.</p>
</dd>
<dt class="d_decl"><a name="constructString"></a>string <a name="constructString"></a><span class="ddoc_psymbol">constructString</span>(ref Node <b>node</b>);
</dt>
<dd><p>Construct a string node.</p>
</dd>
<dt class="d_decl"><a name="getPairs"></a>Node.Pair[] <a name="getPairs"></a><span class="ddoc_psymbol">getPairs</span>(string <b>type</b>, Node[] <b>nodes</b>);
</dt>
<dd><p>Convert a sequence of single-element mappings into a sequence of pairs.</p>
</dd>
<dt class="d_decl"><a name="constructOrderedMap"></a>Node.Pair[] <a name="constructOrderedMap"></a><span class="ddoc_psymbol">constructOrderedMap</span>(ref Node <b>node</b>);
</dt>
<dd><p>Construct an ordered map (ordered sequence of key:value pairs without duplicates) node.</p>
</dd>
<dt class="d_decl"><a name="constructPairs"></a>Node.Pair[] <a name="constructPairs"></a><span class="ddoc_psymbol">constructPairs</span>(ref Node <b>node</b>);
</dt>
<dd><p>Construct a pairs (ordered sequence of key: value pairs allowing duplicates) node.</p>
</dd>
<dt class="d_decl"><a name="constructSet"></a>Node[] <a name="constructSet"></a><span class="ddoc_psymbol">constructSet</span>(ref Node <b>node</b>);
</dt>
<dd><p>Construct a set node.</p>
</dd>
<dt class="d_decl"><a name="constructSequence"></a>Node[] <a name="constructSequence"></a><span class="ddoc_psymbol">constructSequence</span>(ref Node <b>node</b>);
</dt>
<dd><p>Construct a sequence (array) node.</p>
</dd>
<dt class="d_decl"><a name="constructMap"></a>Node.Pair[] <a name="constructMap"></a><span class="ddoc_psymbol">constructMap</span>(ref Node <b>node</b>);
</dt>
<dd><p>Construct an unordered map (unordered set of key:value pairs without duplicates) node.</p>
</dd>
</dl>
</div>
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Copyright &copy; Ferdinand Majerech 2011-2014. Based on <a href="http://www.pyyaml.org">PyYAML</a> by Kirill Simonov. |
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