examples/Mini/ASTProgram.java - commons-bcel - Git at Google

 /* Generated By:JJTree: Do not edit this line. ASTProgram.java */
 /* JJT: 0.3pre1 */

 package Mini;
 import java.io.PrintWriter;
 import java.util.Vector;
 import org.apache.bcel.classfile.*;
 import org.apache.bcel.generic.*;

 /**
  * Root node of everything, direct children are nodes of type FunDecl
  *
  * @version $Id$
  * @author  <A HREF="http://www.berlin.de/~markus.dahm/">M. Dahm</A>
  */
 public class ASTProgram extends SimpleNode
 implements MiniParserConstants, MiniParserTreeConstants, org.apache.bcel.Constants {
   private ASTFunDecl[] fun_decls; // Children: Function declarations
   private Environment  env;       // Environment contains variables and functions

   ASTProgram(int id) {
     super(id);

     env = new Environment();

     /* Add predefined functions WRITE/READ.
      * WRITE has one arg of type T_INT, both return T_INT.
      */
     ASTIdent   ident  = new ASTIdent("WRITE", T_INT, -1, -1);
     ASTIdent[] args   = { new ASTIdent("", T_INT, -1, -1) };
     Function   fun    = new Function(ident, args, true);
     env.put(fun);

     ident = new ASTIdent("READ", T_INT, -1, -1);
     args  = new ASTIdent[0];
     fun   = new Function(ident, args, true);
     env.put(fun);

     /* Add predefined idents TRUE/FALSE of type T_BOOLEAN
      */
     ident = new ASTIdent("TRUE", T_BOOLEAN, -1, -1);
     Variable var = new Variable(ident, true);
     env.put(var);

     ident = new ASTIdent("FALSE", T_BOOLEAN, -1, -1);
     var   = new Variable(ident, true);
     env.put(var);
   }

   ASTProgram(MiniParser p, int id) {
     super(p, id);
   }

   public static Node jjtCreate(MiniParser p, int id) {
     return new ASTProgram(p, id);
   }

   /**
    * Overrides SimpleNode.closeNode().
    * Cast children to appropiate type.
    */
   public void closeNode() {
     if(children != null) { // Non-empty program ?
       fun_decls = new ASTFunDecl[children.length];
       System.arraycopy(children, 0, fun_decls, 0, children.length);
       children=null; // Throw away old reference
     }
   }

   /**
    * First pass of parse tree.
    *
    * Put everything into the environment, which is copied appropiately to each
    * recursion level, i.e. each FunDecl gets its own copy that it can further
    * manipulate.
    *
    * Checks for name clashes of function declarations.
    */
   public ASTProgram traverse() {
     ASTFunDecl f;
     ASTIdent   name;
     String     fname;
     EnvEntry   fun;
     Function   main=null;

     if(fun_decls != null) {
       // Put function names into hash table aka. environment
       for(int i=0; i < fun_decls.length; i++) {
 	f     = fun_decls[i];
 	name  = f.getName();
 	fname = name.getName();
 	fun   = env.get(fname); // Lookup in env

 	if(fun != null)
 	  MiniC.addError(f.getLine(), f.getColumn(),
 			 "Redeclaration of " + fun + ".");
 	else
 	  env.put(new Function(name, null)); // `args' will be set by FunDecl.traverse()


       }

       // Go for it
       for(int i=0; i < fun_decls.length; i++) {
 	fun_decls[i] = fun_decls[i].traverse((Environment)env.clone());

 	// Look for `main' routine
 	fname = fun_decls[i].getName().getName();
 	if(fname.equals("main"))
 	  main = (Function)env.get(fname);
       }

       if(main == null)
 	 MiniC.addError(0, 0, "You didn't declare a `main' function.");
       else if(main.getNoArgs() != 0)
 	 MiniC.addError(main.getLine(), main.getColumn(),
 			"Main function has too many arguments declared.");
     }

     return this;
   }

   /**
    * Second pass, determine type of each node, if possible.
    * @return type of expression
    */
   public void eval(int pass) {

     for(int i=0; i < fun_decls.length; i++) {
       fun_decls[i].eval(pass);

       if(pass == 3) { // Final check for unresolved types
 	ASTIdent name = fun_decls[i].getName();

 	if(name.getType() == T_UNKNOWN)
 	  MiniC.addError(name.getColumn(), name.getLine(),
 			 "Type of function " + name.getName() +
 			 " can not be determined (infinite recursion?).");
       }
     }
   }

   /**
    * Fifth pass, produce Java code.
    */
   public void code(PrintWriter out, String name) {
     out.println("import java.io.BufferedReader;");
     out.println("import java.io.InputStreamReader;");
     out.println("import java.io.IOException;\n");

     out.println("public final class " + name + " {");
     out.println("  private static BufferedReader _in = new BufferedReader" +
 		"(new InputStreamReader(System.in));\n");

     out.println("  private static final int _readInt() throws IOException {\n" +
 		"    System.out.print(\"Please enter a number> \");\n" +
 		"    return Integer.parseInt(_in.readLine());\n  }\n");

     out.println("  private static final int _writeInt(int n) {\n" +
 		"    System.out.println(\"Result: \" + n);\n    return 0;\n  }\n");

     for(int i=0; i < fun_decls.length; i++)
       fun_decls[i].code(out);

     out.println("}");
   }

   /**
    * Fifth pass, produce Java byte code.
    */
   public void byte_code(ClassGen class_gen, ConstantPoolGen cp) {
     /* private static BufferedReader _in;
      */
     class_gen.addField(new Field(ACC_PRIVATE | ACC_STATIC,
 				 cp.addUtf8("_in"),
 				 cp.addUtf8("Ljava/io/BufferedReader;"),
 				 null, cp.getConstantPool()));

     MethodGen       method;
     Method          m;
     InstructionList il = new InstructionList();
     byte[]          byte_code;
     String          class_name = class_gen.getClassName();

     /* Often used constant pool entries
      */
     int             _in = cp.addFieldref(class_name, "_in", "Ljava/io/BufferedReader;");

     int             out = cp.addFieldref("java.lang.System", "out",
 					 "Ljava/io/PrintStream;");

     il.append(new GETSTATIC(out));
     il.append(new PUSH(cp, "Please enter a number> "));
     il.append(new INVOKEVIRTUAL(cp.addMethodref("java.io.PrintStream",
 						"print",
 						"(Ljava/lang/String;)V")));
     il.append(new GETSTATIC(_in));
     il.append(new INVOKEVIRTUAL(cp.addMethodref("java.io.BufferedReader",
 						"readLine",
 						"()Ljava/lang/String;")));
     il.append(new INVOKESTATIC(cp.addMethodref("java.lang.Integer",
 						"parseInt",
 						"(Ljava/lang/String;)I")));
     il.append(InstructionConstants.IRETURN);

     /* private static final int _readInt() throws IOException
      */
     method = new MethodGen(ACC_STATIC | ACC_PRIVATE | ACC_FINAL,
 			   Type.INT, Type.NO_ARGS, null,
 			   "_readInt", class_name, il, cp);

     method.addException("java.io.IOException");

     method.setMaxStack(2);
     class_gen.addMethod(method.getMethod());

     /* private static final int _writeInt(int i) throws IOException
      */
     Type[]   args = { Type.INT };
     String[] argv = { "i" } ;
     il = new InstructionList();
     il.append(new GETSTATIC(out));
     il.append(new NEW(cp.addClass("java.lang.StringBuffer")));
     il.append(InstructionConstants.DUP);
     il.append(new PUSH(cp, "Result: "));
     il.append(new INVOKESPECIAL(cp.addMethodref("java.lang.StringBuffer",
 						"<init>",
 						"(Ljava/lang/String;)V")));

     il.append(new ILOAD(0));
     il.append(new INVOKEVIRTUAL(cp.addMethodref("java.lang.StringBuffer",
 						"append",
 						"(I)Ljava/lang/StringBuffer;")));

     il.append(new INVOKEVIRTUAL(cp.addMethodref("java.lang.StringBuffer",
 						"toString",
 						"()Ljava/lang/String;")));

     il.append(new INVOKEVIRTUAL(cp.addMethodref("java.io.PrintStream",
 						"println",
 						"(Ljava/lang/String;)V")));
     il.append(new PUSH(cp, 0));
     il.append(InstructionConstants.IRETURN); // Reuse objects, if possible

     method = new MethodGen(ACC_STATIC | ACC_PRIVATE | ACC_FINAL,
 			   Type.INT, args, argv,
 			   "_writeInt", class_name, il, cp);

     method.setMaxStack(4);
     class_gen.addMethod(method.getMethod());

     /* public <init> -- constructor
      */
     il.dispose(); // Dispose instruction handles for better memory utilization

     il = new InstructionList();
     il.append(new ALOAD(0)); // Push `this'
     il.append(new INVOKESPECIAL(cp.addMethodref("java.lang.Object",
 						"<init>", "()V")));
     il.append(new RETURN());

     method = new MethodGen(ACC_PUBLIC, Type.VOID, Type.NO_ARGS, null,
 			   "<init>", class_name, il, cp);

     method.setMaxStack(1);
     class_gen.addMethod(method.getMethod());

     /* class initializer
      */
     il.dispose(); // Dispose instruction handles for better memory utilization
     il = new InstructionList();
     il.append(new NEW(cp.addClass("java.io.BufferedReader")));
     il.append(InstructionConstants.DUP);
     il.append(new NEW(cp.addClass("java.io.InputStreamReader")));
     il.append(InstructionConstants.DUP);
     il.append(new GETSTATIC(cp.addFieldref("java.lang.System", "in",
 					   "Ljava/io/InputStream;")));
     il.append(new INVOKESPECIAL(cp.addMethodref("java.io.InputStreamReader",
 						"<init>", "(Ljava/io/InputStream;)V")));
     il.append(new INVOKESPECIAL(cp.addMethodref("java.io.BufferedReader",
 						"<init>", "(Ljava/io/Reader;)V")));
     il.append(new PUTSTATIC(_in));
     il.append(InstructionConstants.RETURN); // Reuse instruction constants

     method = new MethodGen(ACC_STATIC, Type.VOID, Type.NO_ARGS, null,
 			   "<clinit>", class_name, il, cp);

     method.setMaxStack(5);
     class_gen.addMethod(method.getMethod());

     for(int i=0; i < fun_decls.length; i++)
       fun_decls[i].byte_code(class_gen, cp);
   }

   public void dump(String prefix) {
     System.out.println(toString(prefix));

     for(int i = 0; i < fun_decls.length; ++i)
       fun_decls[i].dump(prefix + " ");
   }
 }
	/* Generated By:JJTree: Do not edit this line. ASTProgram.java */
	/* JJT: 0.3pre1 */

	package Mini;
	import java.io.PrintWriter;
	import java.util.Vector;
	import org.apache.bcel.classfile.*;
	import org.apache.bcel.generic.*;

	/**
	* Root node of everything, direct children are nodes of type FunDecl
	*
	* @version $Id$
	* @author <A HREF="http://www.berlin.de/~markus.dahm/">M. Dahm</A>
	*/
	public class ASTProgram extends SimpleNode
	implements MiniParserConstants, MiniParserTreeConstants, org.apache.bcel.Constants {
	private ASTFunDecl[] fun_decls; // Children: Function declarations
	private Environment env; // Environment contains variables and functions

	ASTProgram(int id) {
	super(id);

	env = new Environment();

	/* Add predefined functions WRITE/READ.
	* WRITE has one arg of type T_INT, both return T_INT.
	*/
	ASTIdent ident = new ASTIdent("WRITE", T_INT, -1, -1);
	ASTIdent[] args = { new ASTIdent("", T_INT, -1, -1) };
	Function fun = new Function(ident, args, true);
	env.put(fun);

	ident = new ASTIdent("READ", T_INT, -1, -1);
	args = new ASTIdent[0];
	fun = new Function(ident, args, true);
	env.put(fun);

	/* Add predefined idents TRUE/FALSE of type T_BOOLEAN
	*/
	ident = new ASTIdent("TRUE", T_BOOLEAN, -1, -1);
	Variable var = new Variable(ident, true);
	env.put(var);

	ident = new ASTIdent("FALSE", T_BOOLEAN, -1, -1);
	var = new Variable(ident, true);
	env.put(var);
	}

	ASTProgram(MiniParser p, int id) {
	super(p, id);
	}

	public static Node jjtCreate(MiniParser p, int id) {
	return new ASTProgram(p, id);
	}

	/**
	* Overrides SimpleNode.closeNode().
	* Cast children to appropiate type.
	*/
	public void closeNode() {
	if(children != null) { // Non-empty program ?
	fun_decls = new ASTFunDecl[children.length];
	System.arraycopy(children, 0, fun_decls, 0, children.length);
	children=null; // Throw away old reference
	}
	}

	/**
	* First pass of parse tree.
	*
	* Put everything into the environment, which is copied appropiately to each
	* recursion level, i.e. each FunDecl gets its own copy that it can further
	* manipulate.
	*
	* Checks for name clashes of function declarations.
	*/
	public ASTProgram traverse() {
	ASTFunDecl f;
	ASTIdent name;
	String fname;
	EnvEntry fun;
	Function main=null;

	if(fun_decls != null) {
	// Put function names into hash table aka. environment
	for(int i=0; i < fun_decls.length; i++) {
	f = fun_decls[i];
	name = f.getName();
	fname = name.getName();
	fun = env.get(fname); // Lookup in env

	if(fun != null)
	MiniC.addError(f.getLine(), f.getColumn(),
	"Redeclaration of " + fun + ".");
	else
	env.put(new Function(name, null)); // `args' will be set by FunDecl.traverse()


	}

	// Go for it
	for(int i=0; i < fun_decls.length; i++) {
	fun_decls[i] = fun_decls[i].traverse((Environment)env.clone());

	// Look for `main' routine
	fname = fun_decls[i].getName().getName();
	if(fname.equals("main"))
	main = (Function)env.get(fname);
	}

	if(main == null)
	MiniC.addError(0, 0, "You didn't declare a `main' function.");
	else if(main.getNoArgs() != 0)
	MiniC.addError(main.getLine(), main.getColumn(),
	"Main function has too many arguments declared.");
	}

	return this;
	}

	/**
	* Second pass, determine type of each node, if possible.
	* @return type of expression
	*/
	public void eval(int pass) {

	for(int i=0; i < fun_decls.length; i++) {
	fun_decls[i].eval(pass);

	if(pass == 3) { // Final check for unresolved types
	ASTIdent name = fun_decls[i].getName();

	if(name.getType() == T_UNKNOWN)
	MiniC.addError(name.getColumn(), name.getLine(),
	"Type of function " + name.getName() +
	" can not be determined (infinite recursion?).");
	}
	}
	}

	/**
	* Fifth pass, produce Java code.
	*/
	public void code(PrintWriter out, String name) {
	out.println("import java.io.BufferedReader;");
	out.println("import java.io.InputStreamReader;");
	out.println("import java.io.IOException;\n");

	out.println("public final class " + name + " {");
	out.println(" private static BufferedReader _in = new BufferedReader" +
	"(new InputStreamReader(System.in));\n");

	out.println(" private static final int _readInt() throws IOException {\n" +
	" System.out.print(\"Please enter a number> \");\n" +
	" return Integer.parseInt(_in.readLine());\n }\n");

	out.println(" private static final int _writeInt(int n) {\n" +
	" System.out.println(\"Result: \" + n);\n return 0;\n }\n");

	for(int i=0; i < fun_decls.length; i++)
	fun_decls[i].code(out);

	out.println("}");
	}

	/**
	* Fifth pass, produce Java byte code.
	*/
	public void byte_code(ClassGen class_gen, ConstantPoolGen cp) {
	/* private static BufferedReader _in;
	*/
	class_gen.addField(new Field(ACC_PRIVATE \| ACC_STATIC,
	cp.addUtf8("_in"),
	cp.addUtf8("Ljava/io/BufferedReader;"),
	null, cp.getConstantPool()));

	MethodGen method;
	Method m;
	InstructionList il = new InstructionList();
	byte[] byte_code;
	String class_name = class_gen.getClassName();

	/* Often used constant pool entries
	*/
	int _in = cp.addFieldref(class_name, "_in", "Ljava/io/BufferedReader;");

	int out = cp.addFieldref("java.lang.System", "out",
	"Ljava/io/PrintStream;");

	il.append(new GETSTATIC(out));
	il.append(new PUSH(cp, "Please enter a number> "));
	il.append(new INVOKEVIRTUAL(cp.addMethodref("java.io.PrintStream",
	"print",
	"(Ljava/lang/String;)V")));
	il.append(new GETSTATIC(_in));
	il.append(new INVOKEVIRTUAL(cp.addMethodref("java.io.BufferedReader",
	"readLine",
	"()Ljava/lang/String;")));
	il.append(new INVOKESTATIC(cp.addMethodref("java.lang.Integer",
	"parseInt",
	"(Ljava/lang/String;)I")));
	il.append(InstructionConstants.IRETURN);

	/* private static final int _readInt() throws IOException
	*/
	method = new MethodGen(ACC_STATIC \| ACC_PRIVATE \| ACC_FINAL,
	Type.INT, Type.NO_ARGS, null,
	"_readInt", class_name, il, cp);

	method.addException("java.io.IOException");

	method.setMaxStack(2);
	class_gen.addMethod(method.getMethod());

	/* private static final int _writeInt(int i) throws IOException
	*/
	Type[] args = { Type.INT };
	String[] argv = { "i" } ;
	il = new InstructionList();
	il.append(new GETSTATIC(out));
	il.append(new NEW(cp.addClass("java.lang.StringBuffer")));
	il.append(InstructionConstants.DUP);
	il.append(new PUSH(cp, "Result: "));
	il.append(new INVOKESPECIAL(cp.addMethodref("java.lang.StringBuffer",
	"<init>",
	"(Ljava/lang/String;)V")));

	il.append(new ILOAD(0));
	il.append(new INVOKEVIRTUAL(cp.addMethodref("java.lang.StringBuffer",
	"append",
	"(I)Ljava/lang/StringBuffer;")));

	il.append(new INVOKEVIRTUAL(cp.addMethodref("java.lang.StringBuffer",
	"toString",
	"()Ljava/lang/String;")));

	il.append(new INVOKEVIRTUAL(cp.addMethodref("java.io.PrintStream",
	"println",
	"(Ljava/lang/String;)V")));
	il.append(new PUSH(cp, 0));
	il.append(InstructionConstants.IRETURN); // Reuse objects, if possible

	method = new MethodGen(ACC_STATIC \| ACC_PRIVATE \| ACC_FINAL,
	Type.INT, args, argv,
	"_writeInt", class_name, il, cp);

	method.setMaxStack(4);
	class_gen.addMethod(method.getMethod());

	/* public <init> -- constructor
	*/
	il.dispose(); // Dispose instruction handles for better memory utilization

	il = new InstructionList();
	il.append(new ALOAD(0)); // Push `this'
	il.append(new INVOKESPECIAL(cp.addMethodref("java.lang.Object",
	"<init>", "()V")));
	il.append(new RETURN());

	method = new MethodGen(ACC_PUBLIC, Type.VOID, Type.NO_ARGS, null,
	"<init>", class_name, il, cp);

	method.setMaxStack(1);
	class_gen.addMethod(method.getMethod());

	/* class initializer
	*/
	il.dispose(); // Dispose instruction handles for better memory utilization
	il = new InstructionList();
	il.append(new NEW(cp.addClass("java.io.BufferedReader")));
	il.append(InstructionConstants.DUP);
	il.append(new NEW(cp.addClass("java.io.InputStreamReader")));
	il.append(InstructionConstants.DUP);
	il.append(new GETSTATIC(cp.addFieldref("java.lang.System", "in",
	"Ljava/io/InputStream;")));
	il.append(new INVOKESPECIAL(cp.addMethodref("java.io.InputStreamReader",
	"<init>", "(Ljava/io/InputStream;)V")));
	il.append(new INVOKESPECIAL(cp.addMethodref("java.io.BufferedReader",
	"<init>", "(Ljava/io/Reader;)V")));
	il.append(new PUTSTATIC(_in));
	il.append(InstructionConstants.RETURN); // Reuse instruction constants

	method = new MethodGen(ACC_STATIC, Type.VOID, Type.NO_ARGS, null,
	"<clinit>", class_name, il, cp);

	method.setMaxStack(5);
	class_gen.addMethod(method.getMethod());

	for(int i=0; i < fun_decls.length; i++)
	fun_decls[i].byte_code(class_gen, cp);
	}

	public void dump(String prefix) {
	System.out.println(toString(prefix));

	for(int i = 0; i < fun_decls.length; ++i)
	fun_decls[i].dump(prefix + " ");
	}
	}