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Viewing changes to external/nrefactory/doc/Pattern Matching.html

  • Committer: Package Import Robot
  • Author(s): Jo Shields
  • Date: 2013-05-12 09:46:03 UTC
  • mto: This revision was merged to the branch mainline in revision 29.
  • Revision ID: package-import@ubuntu.com-20130512094603-mad323bzcxvmcam0
Tags: upstream-4.0.5+dfsg
Import upstream version 4.0.5+dfsg

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external/nrefactory/doc/Pattern Matching.html
 
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<html>
 
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<head><title>NRefactory Pattern Matching</title></head>
 
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<body>
 
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    The pattern matching API for the C# AST is similar to how regular
 
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    expressions work in .NET, except that it's working with AstNodes
 
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    instead of characters.<br>
 
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    First you declare a pattern, for example: "X a = new X(...);".<br>
 
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    <span style="color: #000080; ">var</span>&nbsp;pattern =&nbsp;<span
 
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      style="color: #008b8b; font-weight: bold; ">new</span>&nbsp;VariableDeclarationStatement&nbsp;<span
 
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      style="color: #235100; font-weight: normal; font-style: normal; ">{</span><br>
 
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    &nbsp;&nbsp;&nbsp;&nbsp;Type =&nbsp;<span style="color: #008b8b; font-weight: bold; ">new</span>&nbsp;<span
 
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      style="color: #191970; font-weight: bold; ">AnyNode</span><span
 
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      style="color: #235100; font-weight: normal; font-style: normal; ">(</span><span
 
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      style="color: #0000ff; ">"type"</span><span style="color: #235100;
 
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      font-weight: normal; font-style: normal; ">),</span><br>
 
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    &nbsp;&nbsp;&nbsp;&nbsp;Variables =&nbsp;<span style="color: #235100; font-weight: normal;
 
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      font-style: normal; ">{</span><br>
 
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    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span style="color: #008b8b; font-weight: bold; ">new</span>&nbsp;VariableInitializer&nbsp;<span
 
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      style="color: #235100; font-weight: normal; font-style: normal; ">{</span><br>
 
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    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Name = Pattern<span style="color: #235100; font-weight:
 
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      normal; font-style: normal; ">.</span>AnyString<span style="color:
 
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      #235100; font-weight: normal; font-style: normal; ">,</span><br>
 
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    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Initializer =&nbsp;<span style="color: #008b8b; font-weight:
 
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      bold; ">new</span>&nbsp;ObjectCreateExpression&nbsp;<span style="color:
 
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      #235100; font-weight: normal; font-style: normal; ">{</span><br>
 
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    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Type =&nbsp;<span style="color: #008b8b; font-weight:
 
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      bold; ">new</span>&nbsp;<span style="color: #191970; font-weight: bold;
 
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      ">Backreference</span><span style="color: #235100; font-weight:
 
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      normal; font-style: normal; ">(</span><span style="color: #0000ff;
 
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      ">"type"</span><span style="color: #235100; font-weight: normal;
 
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      font-style: normal; ">),</span><br>
 
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    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Arguments =&nbsp;<span style="color: #235100;
 
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      font-weight: normal; font-style: normal; ">{</span>&nbsp;<span
 
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      style="color: #008b8b; font-weight: bold; ">new</span>&nbsp;<span
 
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      style="color: #191970; font-weight: bold; ">Repeat</span><span
 
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      style="color: #235100; font-weight: normal; font-style: normal; ">(</span><span
 
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      style="color: #008b8b; font-weight: bold; ">new</span>&nbsp;<span
 
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      style="color: #191970; font-weight: bold; ">AnyNode</span><span
 
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      style="color: #235100; font-weight: normal; font-style: normal; ">())</span>&nbsp;<span
 
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      style="color: #235100; font-weight: normal; font-style: normal; ">}</span><br>
 
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    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Initializer =&nbsp;<span style="color: #008b8b;
 
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      font-weight: bold; ">new</span>&nbsp;<span style="color: #191970;
 
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      font-weight: bold; ">OptionalNode</span><span style="color:
 
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      #235100; font-weight: normal; font-style: normal; ">(</span><span
 
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      style="color: #008b8b; font-weight: bold; ">new</span>&nbsp;<span
 
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      style="color: #191970; font-weight: bold; ">AnyNode</span><span
 
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      style="color: #235100; font-weight: normal; font-style: normal; ">())</span><br>
 
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    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span style="color: #235100; font-weight: normal;
 
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      font-style: normal; ">}</span><br>
 
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    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span style="color: #235100; font-weight: normal;
 
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      font-style: normal; ">}</span><br>
 
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    &nbsp;&nbsp;&nbsp;&nbsp;<span style="color: #235100; font-weight: normal; font-style:
 
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      normal; ">}};</span><br>
 
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    <br>
 
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    This is a <b>pattern AST</b> - it is a C# AST using the normal C#
 
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    AST classes, but also contains special <b>pattern nodes</b>
 
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    (AnyNode, Repeat, OptionalNode, Backreference, NamedNode, Choice,
 
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    ...).<br>
 
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    If you call<br>
 
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    &nbsp;Match m = pattern<span style="color: #235100; font-weight: normal;
 
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      font-style: normal; ">.</span><span style="color: #191970;
 
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      font-weight: bold; ">Match</span><span style="color: #235100;
 
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      font-weight: normal; font-style: normal; ">(</span>someNode<span
 
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      style="color: rgb(35, 81, 0); font-weight: normal; font-style:
 
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      normal;">);<br>
 
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    </span>then m.Success will be true if someNode is a
 
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    VariableDeclarationStatement that declares a single variable, which
 
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    is initialized to a new object of the variable type.<br>
 
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    Basically, Match performs a comparison of the pattern AST with
 
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    someNode. If the pattern AST does not contain any pattern nodes, the
 
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    match will be successful if the ASTs are syntactically identical
 
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    (whitespace/comments are not compared).<br>
 
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    &nbsp; AnyNode will match any non-null node, and optionally store the
 
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    node it was matched against in a named <b>capture group</b>.<br>
 
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    &nbsp; Backreference will match any node that is syntactically identical
 
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    to the node that was previously stored in the named capture group.<br>
 
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    &nbsp; Repeat can be used only in AstNodeCollections and will try to
 
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    match its child pattern against any number of nodes - this is
 
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    equivalent to * (Kleene star) in regular expressions.<br>
 
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    &nbsp; OptionalNode will match null nodes, or will try to match its child
 
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    pattern against the node. OptionalNode can also be used in
 
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    AstNodeCollections, where it is equivalent to a Repeat with
 
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    MinCount=0 and MaxCount=1.<br>
 
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    <br>
 
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    The resulting match object can also be used to retrieve the nodes
 
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    stored in the capture groups:<br>
 
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    <span style="color: #0000ff; font-weight: bold; ">if</span>&nbsp;<span
 
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      style="color: #235100; font-weight: normal; font-style: normal; ">(</span>m<span
 
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      style="color: #235100; font-weight: normal; font-style: normal; ">.</span>Success<span
 
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      style="color: #235100; font-weight: normal; font-style: normal; ">)</span>&nbsp;<span
 
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      style="color: #235100; font-weight: normal; font-style: normal; ">{</span><br>
 
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    &nbsp;&nbsp;&nbsp;&nbsp;m<span style="color: #235100; font-weight: normal; font-style:
 
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      normal; ">.</span>Get<span style="color: #235100; font-weight:
 
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      normal; font-style: normal; ">&lt;</span>AstType<span
 
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      style="color: #235100; font-weight: normal; font-style: normal; ">&gt;(</span><span
 
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      style="color: #0000ff; ">"type"</span><span style="color: #235100;
 
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      font-weight: normal; font-style: normal; ">).</span><span
 
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      style="color: #191970; font-weight: bold; ">Single</span><span
 
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      style="color: #235100; font-weight: normal; font-style: normal; ">().</span><span
 
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      style="color: #191970; font-weight: bold; ">ReplaceWith</span><span
 
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      style="color: #235100; font-weight: normal; font-style: normal; ">(</span><span
 
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      style="color: #008b8b; font-weight: bold; ">new</span>&nbsp;<span
 
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      style="color: #191970; font-weight: bold; ">SimpleType</span><span
 
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      style="color: #235100; font-weight: normal; font-style: normal; ">(</span><span
 
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      style="color: #0000ff; ">"var"</span><span style="color: #235100;
 
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      font-weight: normal; font-style: normal; ">));</span><br>
 
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    <span style="color: #235100; font-weight: normal; font-style:
 
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      normal; ">}</span><br>
 
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    <br>
 
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    This feature was originally written for the decompiler in ILSpy, but
 
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    it is also very useful for refactorings. You can also implement
 
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    custom pattern nodes (derive from the Pattern base class) with
 
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    custom match logic - for example if you want to check the semantics
 
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    of a node.<br>
 
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</body></html>
 
 
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