forked from jasder/antlr
add some tests
[git-p4: depot-paths = "//depot/code/antlr4/main/": change = 9763]
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parrt
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/**
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derived from http://svn.r-project.org/R/trunk/src/main/gram.y
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http://cran.r-project.org/doc/manuals/R-lang.html#Parser
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*/
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grammar R;
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// ambig upon a(i)<- (delayed a bit since ';' could follow--really ambig on "a(i)")
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/** ambig since stacks are exact as it loops around; no way to distinguish
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I tried tracking input index in stack to differentiate the 2 invocations
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of expr_or_assign, but that would mean altering the our context from
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the decision-making in expr_or_assign. Also, later we need to have
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context stacks that are not dependent on input position to reuse them.
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The fact that the recursive version correctly matches the input while the
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looping version does not is a problem. We base the notion of ambiguous
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on the same state, different alternatives, same stack. But, if the
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rule invocation stack does not uniquely indicate context, we are not accurately
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detecting ambiguities. We are detecting ambiguities overzealously.
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We need a way for the context stack or configuration to distinguish between
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iterations of the loop that dive into the same rule such as expr_or_assign*.
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Perhaps the answer is to track iteration number in the configuration:
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(s, alt, ctx, iter#)
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When we reached the state following '<-', say p, in expr then we need
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(p, 1, [expr expr_or_assign prog], 1)
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(p, 2, [expr expr_or_assign prog], 2)
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But, that number would be useful... we might pass through 3 or 4 loops.
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The iteration index really has to be a part of the stack context.
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Perhaps we and an additional stack element as if we were doing the
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recursive version
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prog : expr_or_assign prog | ;
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(p, 1, [expr expr_or_assign prog])
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(p, 2, [expr expr_or_assign prog expr_or_assign prog])
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The "expr expr_or_assign prog" represents the second call back down
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into expr_or_assign like the loop would except that the stack looks different.
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Or, we could mark stack references with the loop iteration index.
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(p, 1, [expr expr_or_assign prog])
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(p, 2, [expr expr_or_assign.2 prog])
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This seems reusable as opposed to the input index. It might be complicated
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to track this. In the general case, we would need a mapping from rule
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invocation of rule r to a count, and within a specific rule context. That
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might add a HashMap for every RuleContext. ick. Also, one about the context
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that I create during ATN simulation? I would have to track that as well
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as the generated code in the parser. Rule invocation states would act
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like triggers that would bump account for that target rule in the current ctx.
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*/
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prog : expr_or_assign* ;
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/** This one is not ambig since 2nd time into expr_or_assign has different
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context where expr_or_assign* shows same context.
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*/
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//prog : expr_or_assign expr_or_assign ;
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// not ambig, context different
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//prog : expr_or_assign prog | ;
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expr_or_assign
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: expr '=' expr_or_assign
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| expr // match ID a, fall out, reenter, match "(i)<-x" via alt 1
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;
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expr : expr_primary ('<-' ID)? ;
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expr_primary
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: '(' ID ')'
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| ID '(' ID ')'
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| ID
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;
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/*
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expr : '(' ID ')' // and this
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| expr '<-'<assoc=right> ID
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| ID '(' ID ')'
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| ID
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;
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*/
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HEX : '0' ('x'|'X') HEXDIGIT+ [Ll]? ;
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INT : DIGIT+ [Ll]? ;
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fragment
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HEXDIGIT : ('0'..'9'|'a'..'f'|'A'..'F') ;
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FLOAT : DIGIT+ '.' DIGIT* EXP? [Ll]?
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| DIGIT+ EXP? [Ll]?
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| '.' DIGIT+ EXP? [Ll]?
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;
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fragment
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DIGIT : '0'..'9' ;
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fragment
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EXP : ('E' | 'e') ('+' | '-')? INT ;
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COMPLEX : INT 'i'
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| FLOAT 'i'
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;
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STRING : '"' ( ESC | ~('\\'|'"') )* '"'
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| '\'' ( ESC | ~('\\'|'\'') )* '\''
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;
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fragment
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ESC
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: '\\' ([abtnfrv]|'"'|'\'')
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| UNICODE_ESCAPE
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| HEX_ESCAPE
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| OCTAL_ESCAPE
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;
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fragment
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UNICODE_ESCAPE
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: '\\' 'u' HEXDIGIT HEXDIGIT HEXDIGIT HEXDIGIT
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| '\\' 'u' '{' HEXDIGIT HEXDIGIT HEXDIGIT HEXDIGIT '}'
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;
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fragment
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OCTAL_ESCAPE
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: '\\' ('0'..'3') ('0'..'7') ('0'..'7')
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| '\\' ('0'..'7') ('0'..'7')
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| '\\' ('0'..'7')
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;
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fragment
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HEX_ESCAPE
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: '\\' HEXDIGIT HEXDIGIT?
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;
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ID : '.'? (LETTER|'_'|'.') (LETTER|DIGIT|'_'|'.')*
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| LETTER (LETTER|DIGIT|'_'|'.')*
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;
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fragment
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LETTER : 'a'..'z'|'A'..'Z'|'\u0080'..'\u00FF' ;
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USER_OP : '%' .* '%' ;
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COMMENT : '#' .* '\n' {skip();} ;
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/** Doesn't handle '\n' correctly. it's context-sensitive */
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WS : (' '|'\t'|'\n'|'\r')+ {skip();} ;
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@ -0,0 +1,48 @@
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/*
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[The "BSD license"]
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Copyright (c) 2011 Terence Parr
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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions
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are met:
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1. Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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2. Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the distribution.
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3. The name of the author may not be used to endorse or promote products
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derived from this software without specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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import org.antlr.v4.runtime.ANTLRFileStream;
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import org.antlr.v4.runtime.CommonTokenStream;
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import org.antlr.v4.runtime.DiagnosticErrorStrategy;
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import org.antlr.v4.runtime.Token;
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public class TestR {
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public static void main(String[] args) throws Exception {
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RLexer t = new RLexer(new ANTLRFileStream(args[0]));
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CommonTokenStream tokens = new CommonTokenStream(t);
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// tokens.fill();
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// for (Object tok : tokens.getTokens()) {
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// System.out.println(tok);
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// }
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RParser p = new RParser(tokens);
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p.setBuildParseTree(true);
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p.setErrorHandler(new DiagnosticErrorStrategy<Token>());
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p.prog();
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}
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}
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