96 lines
3.3 KiB
Markdown
96 lines
3.3 KiB
Markdown
# C♯
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## Which frameworks are supported?
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The C# runtime is CLS compliant, and only requires a corresponding 3.5 .Net framework.
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In practice, the runtime has been extensively tested against:
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* Microsoft .Net 3.5 framework
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* Mono .Net 3.5 framework
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No issue was found, so you should find that the runtime works pretty much against any recent .Net framework.
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## How do I get started?
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You will find full instructions on the [Git repo page for ANTLR C# runtime](https://github.com/antlr/antlr4/tree/master/runtime/CSharp).
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## How do I use the runtime from my project?
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(i.e., How do I run the generated lexer and/or parser?)
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Let's suppose that your grammar is named `MyGrammar`. The tool will generate for you the following files:
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* MyGrammarLexer.cs
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* MyGrammarParser.cs
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* MyGrammarListener.cs (if you have not activated the -no-listener option)
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* MyGrammarBaseListener.cs (if you have not activated the -no-listener option)
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* MyGrammarVisitor.cs (if you have activated the -visitor option)
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* MyGrammarBaseVisitor.cs (if you have activated the -visitor option)
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Now a fully functioning code might look like the following for start rule `StartRule`:
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```csharp
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using Antlr4.Runtime;
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using Antlr4.Runtime.Tree;
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public void MyParseMethod() {
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String input = "your text to parse here";
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ICharStream stream = CharStreams.fromstring(input);
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ITokenSource lexer = new MyGrammarLexer(stream);
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ITokenStream tokens = new CommonTokenStream(lexer);
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MyGrammarParser parser = new MyGrammarParser(tokens);
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parser.BuildParseTree = true;
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IParseTree tree = parser.StartRule();
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}
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```
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This program will work. But it won't be useful unless you do one of the following:
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* you visit the parse tree using a custom listener
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* you visit the parse tree using a custom visitor
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* your grammar comprises production code (like AntLR3)
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(please note that production code is target specific, so you can't have multi target grammars that include production code)
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## How do I create and run a custom listener?
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Let's suppose your MyGrammar grammar comprises 2 rules: "key" and "value".
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The antlr4 tool will have generated the following listener (only partial code shown here):
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```csharp
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interface IMyGrammarParserListener : IParseTreeListener {
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void EnterKey (MyGrammarParser.KeyContext context);
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void ExitKey (MyGrammarParser.KeyContext context);
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void EnterValue (MyGrammarParser.ValueContext context);
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void ExitValue (MyGrammarParser.ValueContext context);
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}
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```
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In order to provide custom behavior, you might want to create the following class:
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```csharp
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class KeyPrinter : MyGrammarBaseListener {
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// override default listener behavior
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void ExitKey (MyGrammarParser.KeyContext context) {
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Console.WriteLine("Oh, a key!");
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}
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}
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```
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In order to execute this listener, you would simply add the following lines to the above code:
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```csharp
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...
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IParseTree tree = parser.StartRule() - only repeated here for reference
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KeyPrinter printer = new KeyPrinter();
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ParseTreeWalker.Default.Walk(printer, tree);
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```
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Further information can be found from The Definitive ANTLR Reference book.
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The C# implementation of ANTLR is as close as possible to the Java one, so you shouldn't find it difficult to adapt the examples for C#. See also [Sam Harwell's alternative C# target](https://github.com/tunnelvisionlabs/antlr4cs)
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