57 lines
1.2 KiB
Plaintext
57 lines
1.2 KiB
Plaintext
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grammar Errors;
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stat: 'return' INT
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| ID '=' expr ';'
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| ID '(' expr (',' expr)* ')' ';'
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/ ID .* '(' expr (',' expr)* ')' ';'
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/ ID '=' .* ';' // bad assignment
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/ .* ';' // bad stat
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/ .* // match anything else? when to stop?
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/ // match anything else?
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;
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catch[Exception e] { }
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finally { }
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// error to match might be diff than how to resynch? maybe just
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// include resynch pattern on end of error alt.
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/*
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Traps any recog exception in anything called from rule or matched in that rule.
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a : expr ';'
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/ '--' ID ';' // catches any problem in expr or matching ';'
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;
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If no err alt matches, defaults to normal error mechanism at rule level.
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report. resync.
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*/
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atom: '(' expr ')'
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| INT
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/ '(' expr // missing RP; how to resync?
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/ '(' ')'
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;
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// do error alts affect FOLLOW sync sets? nope.
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// foo -> bar says how to make resulting tree for bad alts
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expr: atom ('*' atom)* ;
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atom: INT ;
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ID : 'a'..'z'+ ;
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WS : (' '|'\n')* ;
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/*
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Stop .* when it sees any viable following token, even if it uses FOLLOW. So,
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err alt
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/ .*
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would match until it sees something in FOLLOW (but not context-sensitive follow).
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actually maybe it would be sensitive; just use real outer context when matching
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error alts. who cares about speed.
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*/
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