How to pass a many string different parse rule in ANTLR 4?

0
votes

I am trying to develop a tool using ANTLR 4.0. I am very new to ANTLR and Advance Java. I had downloaded the package i.e antlr-4.2.2-complete.jar. ANTLER is working fine. I have few doubts.

I took a very basic grammar , give below:

grammar test;
start : (aa) | (bb);
aa : A C D;
bb : A C B;
A : 'a';
B : 'b';
C : 'c';
D : 'd';
WS : [ \t\r\n] ->skip;

now I am using command prompt to parse string in it.. 

C:\javalib\test>java org.antlr.v4.Tool test.g4
C:\javalib\test>javac test*.java
C:\javalib\test>java org.antlr.v4.runtime.misc.TestRig test start -gui -tree
**acb**
^Z
(start (bb a c b))

string acb was parsed and output obtained was (start (bb a c b)). Now, i want know how can i parse manystrings/ a file in ANTLR. Each line in that file will have different start rule. For Example , file which we have to parse will look like (input file)

start : acb
bb : acb
aa : acd

I can't take the advice of changing the grammar accordingly so that i will get one start rule which can be used for all the strings, because the grammar on which i am working really very vast.

I can change the format of my input string, so that we can parse it easily in ANTLR. I wanted to give the basic idea, that i have many strings , each string have different start rule, how can i parse it in ANTLR.

2
javaantlrantlr4

2 Answers

1
votes

To parse each line with a given rule you could do this.

testcase :
     singletest
     ( Linebreak singletest) *
     ;

singletest:
        'ruleA' ':' ruleA 
      | 'ruleB' ':' ruleB 
      |...
      ;


Whitespace: [ \t] -> skip; // no line break!
Linebreak: '\r\n' | '\r' | '\n';
0
votes

Now, i want know how can i parse manystrings/ a file in ANTLR.

To parse the file input.txt, do:

testLexer lexer = new testLexer(new ANTLRFileStream("input.txt"));
testParser parser = new testParser(new CommonTokenStream(lexer));
ParseTree tree = parser.start();
System.out.println(tree.toStringTree());