Answer to the line “The tour/Java.g4 grammar only allows annotations for an enumConstant.” of the Original Post. I have used this grammar to extract signatures, with four slight modifications :
compilationUnit
@init {System.out.println("----- grammar Java last update 1359");}
to be sure to work with the latest version.
classDeclaration
: classSignature classBody
;
classSignature
: 'class' Identifier typeParameters? ('extends' type)?
('implements' typeList)?
;
to be able to print only the declaration line, idem for methods and constructors :
methodDeclaration
: methodSignature methodDeclarationRest
;
methodSignature
: type Identifier formalParameters ('[' ']')*
| 'void' Identifier formalParameters
;
constructorDeclaration
: constructorSignature constructorBody
;
constructorSignature
: typeParameters? Identifier formalParameters
('throws' qualifiedNameList)?
;
The listener captures these three events and prints the signatures.
(Note : translated from Ruby. As I don’t know Java, it may look ugly.)
===== file MyJavaListener.java =====
import org.antlr.v4.runtime.CommonTokenStream;
import org.antlr.v4.runtime.ParserRuleContext;
import org.antlr.v4.runtime.Token;
import java.util.List;
public class MyJavaListener extends JavaBaseListener {
String current_indent = "";
String indent;
int logical_level = 0;
ParserRuleContext parent;
String spaces = " ";
CommonTokenStream tokens;
public MyJavaListener(CommonTokenStream p_tokens) {
System.out.println("--- MyJavaListener 1409");
tokens = p_tokens;
}
public void enterClassDeclaration(JavaParser.ClassDeclarationContext ctx) {
logical_level += 1;
}
public void exitClassDeclaration(JavaParser.ClassDeclarationContext ctx) {
logical_level -= 1;
}
public void enterClassSignature(JavaParser.ClassSignatureContext ctx) {
ParserRuleContext cdecl, parent;
Token start, stop;
cdecl = parent = parent(ctx); // classDeclaration
// System.out.println("name=" + JavaParser.ruleNames[parent.getRuleIndex()]);
parent = parent(parent); // typeDeclaration or member
// System.out.println("name=" + JavaParser.ruleNames[parent.getRuleIndex()]);
if (JavaParser.ruleNames[parent.getRuleIndex()] == "typeDeclaration") {
List<JavaParser.ClassOrInterfaceModifierContext> mods =
((JavaParser.TypeDeclarationContext)parent).classOrInterfaceModifier();
if (mods.size() > 0)
start = mods.get(0).getStart();
else
start = cdecl.getStart();
}
else if (JavaParser.ruleNames[parent.getRuleIndex()] == "member") {
parent = parent(parent); // classBodyDeclaration
start = parent.getStart();
}
else
start = ctx.getStart();
stop = ctx.getStop();
System.out.println(current_indent + tokens.getText(start, stop));
current_indent = indent();
}
public void exitConstructorSignature(JavaParser.ConstructorSignatureContext ctx) {
Token start, stop;
parent = parent(ctx); // constructorDeclaration
parent = parent(parent); // member
parent = parent(parent); // classBodyDeclaration
start = parent.getStart();
stop = ctx.getStop();
System.out.println(indent() + tokens.getText(start, stop));
}
public void exitMethodSignature(JavaParser.MethodSignatureContext ctx) {
Token start, stop;
parent = parent(ctx); // methodDeclaration
parent = parent(parent); // member
parent = parent(parent); // classBodyDeclaration
start = parent.getStart();
stop = ctx.getStop();
System.out.println(indent() + tokens.getText(start, stop));
}
public String indent() {
return spaces.substring(0, logical_level * 4);
}
public ParserRuleContext parent(ParserRuleContext p_ctx) {
return p_ctx.getParent();
}
}
Test program :
===== file TestParseJava.java =====
import org.antlr.v4.runtime.*;
import org.antlr.v4.runtime.tree.*;
import java.io.FileInputStream;
import java.io.InputStream;
public class TestParseJava {
public static void main(String[] args) throws Exception {
String input_file = null;
if (args.length > 0)
input_file = args[0];
InputStream input_stream = System.in;
if (input_file != null)
input_stream = new FileInputStream(input_file);
System.out.println("TestParseJava.java 1052, input_file=" + input_file);
ANTLRInputStream input = new ANTLRInputStream(input_stream);
JavaLexer lexer = new JavaLexer(input);
CommonTokenStream tokens = new CommonTokenStream(lexer);
JavaParser parser = new JavaParser(tokens);
ParseTree tree = parser.compilationUnit();
System.out.println("<<< parsing finished");
// Define tha Java Listener
MyJavaListener java_listener = new MyJavaListener(tokens);
// Walk the tree created during the parse, trigger callbacks
ParseTreeWalker walker = new ParseTreeWalker();
walker.walk(java_listener, tree);
}
}
Some test input :
===== file tsig.java =====
public class BisonCParser extends Parser {
public static class Y_parser_ruleContext extends ParserRuleContext {
public TerminalNode ID() { return getToken(BisonCParser.ID, 0); }
public Y_parser_ruleContext(ParserRuleContext parent, int state) {
super(parent, state);
}
@Override public int getRuleIndex() { return RULE_y_parser_rule; }
@Override
public void exitRule(ParseTreeListener listener) {
if ( listener instanceof BisonCListener ) ((BisonCListener)listener).exitY_parser_rule(this);
}
}
public final Y_parser_ruleContext y_parser_rule() throws RecognitionException {
Y_parser_ruleContext _localctx = new Y_parser_ruleContext(_ctx, 18);
enterRule(_localctx, RULE_y_parser_rule);
int _la;
return _localctx;
}
}
Execution :
$ echo $CLASSPATH
.:/usr/local/lib/antlr-4.0b3-complete.jar
$ alias
alias antlr4='java -jar /usr/local/lib/antlr-4.0b3-complete.jar'
$ antlr4 Java.g4
$ javac Java*.java
$ javac TestParseJava.java
$ java TestParseJava tsig.java
TestParseJava.java 1052, input_file=tsig.java
----- grammar Java last update 1359
<<< parsing finished
--- MyJavaListener 1409
public class BisonCParser extends Parser
public static class Y_parser_ruleContext extends ParserRuleContext
public TerminalNode ID()
public Y_parser_ruleContext(ParserRuleContext parent, int state)
@Override public int getRuleIndex()
@Override
public void exitRule(ParseTreeListener listener)
public final Y_parser_ruleContext y_parser_rule()
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