I read in a tutorial that when you do something like that :
SimpleNode Program() #Program : {}
{
(Class_decl())* <EOF>
{ return jjtThis; }
}
it should create a Programm class which inherits from SimpleNode (once you compile with jjtree), but in my case it doesn't create such as class. Do I have to create it myself or am I missing something ?
Thanks
Are you first using jjtree
on your grammar (before javacc
)? It works fine with me:
options {
MULTI=true;
NODE_PREFIX="";
}
PARSER_BEGIN(Test)
public class Test {
public static void main(String[] args) throws Exception {
Test parser = new Test(new java.io.StringReader("class A; class B;"));
SimpleNode root = parser.Program();
root.dump("");
}
}
PARSER_END(Test)
TOKEN :
{
< CLASS : "class" >
| < SCOL : ";" >
| < ID : (["a"-"z","A"-"Z"])+ >
}
SKIP :
{
" " | "\t" | "\r" | "\n"
}
SimpleNode Program() #Program :
{}
{
(Class_decl())* <EOF> {return jjtThis;}
}
void Class_decl() #ClassDecl :
{}
{
<CLASS> <ID> <SCOL>
}
And then the commands:
jjtree Test.jjt
javacc Test.jj
which generates the following Java source files:
ClassDecl.java
JJTTestState.java
Node.java
Program.java
SimpleNode.java
TestTreeConstants.java
And both ClassDecl
and Program
extend SimpleNode
:
/* Generated By:JJTree: Do not edit this line. Program.java Version 4.3 */
/* JavaCCOptions:MULTI=true,NODE_USES_PARSER=false,VISITOR=false,TRACK_TOKENS=false,NODE_PREFIX=,NODE_EXTENDS=,NODE_FACTORY=,SUPPORT_CLASS_VISIBILITY_PUBLIC=true */
public
class Program extends SimpleNode {
...
}
/* Generated By:JJTree: Do not edit this line. ClassDecl.java Version 4.3 */
/* JavaCCOptions:MULTI=true,NODE_USES_PARSER=false,VISITOR=false,TRACK_TOKENS=false,NODE_PREFIX=,NODE_EXTENDS=,NODE_FACTORY=,SUPPORT_CLASS_VISIBILITY_PUBLIC=true */
public
class ClassDecl extends SimpleNode {
...
}
Compiling all source files and running the Test
class:
javac -cp . *.java
java -cp . Test
which will print:
Program
ClassDecl
ClassDecl
(i.e. Program
is the root with two ClassDecl
children)
Tested with Java Compiler Compiler Version 5.0.