Examples of org.jnode.shell.syntax.MuSyntax

org.jnode.shell.syntax.MuSyntax
The MuSyntax class and related classes provide an in-memory representation of BNF-like grammars for use in the command line syntax subsystem. The key difference between the Mu and BNF grammar families is that the Mu uses dynamic token recognition and state capture via the MuArgument to Argument binding; e.g. "fred" might be a File or a URI, depending on context. By contrast, BNF assumes a separate context insensitive token recognition mechanism.
It is a given that a MuSyntax tree may represent an ambiguous grammar; i.e. that it may allow multiple parses for a given input token sequence. In reality this is pretty much unavoidable given the way we handle tokenization. @author crawley@jnode.org

    }


    @Test
    public void testStatelessParsing1() throws NoTokensAvailableException, CommandSyntaxException {
        // <start> ::= 'a'
        MuSyntax syntax = new MuSymbol("a");
        MuParser parser = new MuParser();
        CommandLine cl;


        cl = new CommandLine(new String[] {"a"});

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    }


    @Test
    public void testStatelessParsing2() throws NoTokensAvailableException, CommandSyntaxException {
        // <start> ::= 'a' 'b'
        MuSyntax syntax = new MuSequence(new MuSymbol("a"), new MuSymbol("b"));
        MuParser parser = new MuParser();
        CommandLine cl;


        cl = new CommandLine(new String[] {"a", "b"});
        parser.parse(syntax, null, cl.tokenIterator(), null);

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    }


    @Test
    public void testStatelessParsing3() throws NoTokensAvailableException, CommandSyntaxException {
        // <start> :: = 'a' | 'b'
        MuSyntax syntax = new MuAlternation(new MuSymbol("a"), new MuSymbol("b"));
        MuParser parser = new MuParser();
        CommandLine cl;


        cl = new CommandLine(new String[] {"a"});
        parser.parse(syntax, null, cl.tokenIterator(), null);

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    }


    @Test
    public void testStatelessParsing4() throws NoTokensAvailableException, CommandSyntaxException {
        // <root> ::= 'b' | ( 'a' <root> )
        MuSyntax syntax =
                new MuAlternation("root", new MuSymbol("b"), new MuSequence(new MuSymbol("a"),
                        new MuBackReference("root")));
        MuParser parser = new MuParser();
        CommandLine cl;


        cl = new CommandLine(new String[] {"b"});


        parser.parse(syntax, null, cl.tokenIterator(), null);


        try {
            cl = new CommandLine(new String[] {"a", "b"});
            parser.parse(syntax, null, cl.tokenIterator(), null);
            Assert.fail("expected SFE");
        } catch (SyntaxFailureException ex) {
            // expected
        }


        syntax.resolveBackReferences();
        cl = new CommandLine(new String[] {"a", "b"});
        parser.parse(syntax, null, cl.tokenIterator(), null);


        cl = new CommandLine(new String[] {"a", "a", "b"});
        parser.parse(syntax, null, cl.tokenIterator(), null);

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    }


    @Test
    public void testStatelessParsing5() throws NoTokensAvailableException, CommandSyntaxException {
        // <root> ::= ( 'a' <root> ) | 'b'
        MuSyntax syntax =
                new MuAlternation("root", new MuSequence(new MuSymbol("a"), new MuBackReference(
                        "root")), new MuSymbol("b"));
        MuParser parser = new MuParser();
        CommandLine cl;


        syntax.resolveBackReferences();


        cl = new CommandLine(new String[] {"b"});


        parser.parse(syntax, null, cl.tokenIterator(), null);


        syntax.resolveBackReferences();
        cl = new CommandLine(new String[] {"a", "b"});
        parser.parse(syntax, null, cl.tokenIterator(), null);


        cl = new CommandLine(new String[] {"a", "a", "b"});
        parser.parse(syntax, null, cl.tokenIterator(), null);

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    @Test
    public void testStatelessParsing6() throws NoTokensAvailableException, CommandSyntaxException {
        // <root> ::= ( ( 'a' <root> ) | ( 'b' 'c' ) ) | ( ( 'a' <root> ) | 'b'
        // ) )
        MuSyntax syntax = new MuAlternation("root", new MuAlternation(new MuSequence(new MuSymbol("a"),
            new MuBackReference("root")), new MuSequence(new MuSymbol("b"), new MuSymbol("c"))),
            new MuAlternation(new MuSequence(new MuSymbol("a"), new MuBackReference("root")), new MuSymbol("b")));
        MuParser parser = new MuParser();
        CommandLine cl;


        syntax.resolveBackReferences();


        cl = new CommandLine(new String[] {"b"});


        parser.parse(syntax, null, cl.tokenIterator(), null);


        syntax.resolveBackReferences();
        cl = new CommandLine(new String[] {"a", "b"});
        parser.parse(syntax, null, cl.tokenIterator(), null);


        cl = new CommandLine(new String[] {"a", "a", "b"});
        parser.parse(syntax, null, cl.tokenIterator(), null);

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    @Test
    public void testPathological() throws NoTokensAvailableException, CommandSyntaxException {
        // Pathological grammar.
        // <root> ::= 'b' | ( <root> <root> )
        MuSyntax syntax =
                new MuAlternation("root", new MuSymbol("b"), new MuSequence(new MuBackReference(
                        "root"), new MuBackReference("root")));
        MuParser parser = new MuParser();
        CommandLine cl;


        syntax.resolveBackReferences();


        // This doesn't hit the infinite loop ...
        cl = new CommandLine(new String[] {"b"});
        parser.parse(syntax, null, cl.tokenIterator(), null);

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        }
    }


    @Test
    public void testResolveBackReferences() {
        MuSyntax syntax = new MuAlternation("root", new MuBackReference("root"), null);
        syntax.resolveBackReferences();
        Assert.assertEquals(((MuAlternation) syntax).getAlternatives()[0], syntax);


        syntax =
                new MuAlternation("root", new MuSequence(new MuBackReference("root"),
                        new MuBackReference("root")), null);
        syntax.resolveBackReferences();
        MuSyntax[] tmp = ((MuAlternation) syntax).getAlternatives();
        Assert.assertEquals(((MuSequence) tmp[0]).getElements()[0], syntax);
        Assert.assertEquals(((MuSequence) tmp[0]).getElements()[1], syntax);


        try {
            syntax = new MuAlternation("root", new MuBackReference("foo"), null);
            syntax.resolveBackReferences();
            Assert.fail("expected SFE");
        } catch (SyntaxFailureException ex) {
            // expected
        }
    }

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                new MuSymbol("l2", "hi"), new MuSymbol("mum")).format());
    }


    @Test
    public void testFormat2() {
        MuSyntax syntax = new MuAlternation("root", new MuBackReference("root"), null);
        Assert.assertEquals("<root> ::= ( <[root]> |  )\n<[root]> ::= <root>", syntax.format());
        syntax.resolveBackReferences();
        Assert.assertEquals("<root> ::= ( <root> |  )", syntax.format());
    }

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    public void testStatefullParsing1() throws NoTokensAvailableException, CommandSyntaxException {
        IntegerArgument intArg = new IntegerArgument("intArg", Argument.MULTIPLE);
        ArgumentBundle bundle = new ArgumentBundle(intArg);


        // <start> ::= <<intArg>>
        MuSyntax syntax = new MuArgument("intArg");
        MuParser parser = new MuParser();
        CommandLine cl;


        cl = new CommandLine(new String[] {"1"});

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Related Classes of org.jnode.shell.syntax.MuSyntax

org.jnode.test.shell.syntax.MuParserTest

org.jnode.test.shell.syntax.MuParserTest2

org.jnode.test.shell.syntax.MuSyntaxTest

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