我正在努力在ANTLR4中重新实现现有的DSL。 现有的源代码主体有一些非常大的表达式。 似乎 ALL(*) 逻辑中的递归意味着我可以解析的表达式大小是有限制的。
示例语法:(刚好足以重现此处的错误错误)
grammar A4Test;
fragment DIGIT : [0-9];
fragment ALPHA : [a-zA-Z];
WS : [ trnu000D'] {skip();};
ID : ALPHA (ALPHA|DIGIT)*;
NUMBER : '-'?(DIGIT+|(DIGIT*'.'DIGIT+));
e : expr;
expr : '(' expr ')'
| expr 'OR' expr
| expr 'AND' expr
| ID
| NUMBER
;
示例输入:
V0 AND 0 OR
V1 AND 1 OR
... (MANY rows elided)
V3999 AND 3999 OR
V4000 AND 4000
堆栈跟踪:
Exception in thread "main" java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.antlr.v4.runtime.misc.TestRig.process(TestRig.java:249)
at org.antlr.v4.runtime.misc.TestRig.process(TestRig.java:211)
at org.antlr.v4.runtime.misc.TestRig.main(TestRig.java:143)
Caused by: java.lang.StackOverflowError
at java.util.Arrays.equals(Arrays.java:1869)
at org.antlr.v4.runtime.atn.ArrayPredictionContext.equals(ArrayPredictionContext.java:101)
at java.util.HashMap.getEntry(HashMap.java:471)
at java.util.LinkedHashMap.get(LinkedHashMap.java:301)
at org.antlr.v4.runtime.misc.DoubleKeyMap.get(DoubleKeyMap.java:62)
at org.antlr.v4.runtime.atn.PredictionContext.mergeArrays(PredictionContext.java:418)
at org.antlr.v4.runtime.atn.PredictionContext.merge(PredictionContext.java:199)
at org.antlr.v4.runtime.atn.ATNConfigSet.add(ATNConfigSet.java:175)
at org.antlr.v4.runtime.atn.ParserATNSimulator.closure_(ParserATNSimulator.java:1126)
at org.antlr.v4.runtime.atn.ParserATNSimulator.closureCheckingStopState(ParserATNSimulator.java:1111)
at org.antlr.v4.runtime.atn.ParserATNSimulator.closure_(ParserATNSimulator.java:1164)
at org.antlr.v4.runtime.atn.ParserATNSimulator.closureCheckingStopState(ParserATNSimulator.java:1111)
at org.antlr.v4.runtime.atn.ParserATNSimulator.closure_(ParserATNSimulator.java:1164)
at org.antlr.v4.runtime.atn.ParserATNSimulator.closureCheckingStopState(ParserATNSimulator.java:1111)
at org.antlr.v4.runtime.atn.ParserATNSimulator.closure_(ParserATNSimulator.java:1164)
at org.antlr.v4.runtime.atn.ParserATNSimulator.closureCheckingStopState(ParserATNSimulator.java:1111)
at org.antlr.v4.runtime.atn.ParserATNSimulator.closure_(ParserATNSimulator.java:1164)
at org.antlr.v4.runtime.atn.ParserATNSimulator.closureCheckingStopState(ParserATNSimulator.java:1111)
at org.antlr.v4.runtime.atn.ParserATNSimulator.closure_(ParserATNSimulator.java:1164)
。
限制表达式的大小不是一种选择。 他们使用当前的技术编译得很好,所以我们必须支持它。
我是否必须为此分解左递归以避免极高的堆栈利用率? 或者,有更简单的答案吗?
ANTLR 4.2 将通过合并拉取请求 #401 来改善这种情况。由于它尚未发布,我建议从源代码构建最新版本的 ANTLR 4 并再次尝试输入。