jsubbooleannode.java

一个JAVA编写的简单编译器

package ast.booleanExpr;

/**
 * the JSubBooleanNode contains the Basis-Functionality for 
 * Boolean account: && || < <= == != > >=
 */
public abstract class JSubBooleanNode extends ast.JSubNode {
  public JSubBooleanNode (ast.IJSubNode n) {
    super (n);
  }
 /**
 * Codegeneration for OR 
 * @param label Label for branch
 * @param test condition or negatived condition
 */ 
  public void codegenOR (int label, boolean test) {
    int labelTrue = codegen.WriteCode.getLabel ();
    JSubBooleanNode node = null;
    for (int i = 0; i < getNumChildren() - 1; i++) {
      node  = (JSubBooleanNode)getChild (i);
      node.codegen (labelTrue, !test);
    }
    node = (JSubBooleanNode)getChild (getNumChildren() - 1);
    node.codegen (label, test);
    codegen.WriteCode.genLabel (labelTrue);
  }
  
 /**
 * Codegeneration for AND
 * @param label Label for branch
 * @param test condition or negatived condition
 */ 
  public void codegenAND (int label, boolean test) {
    for (int i = 0; i < getNumChildren (); i++ ) {
      JSubBooleanNode node = (JSubBooleanNode)getChild (i);
      node.codegen (label, test);
    }
  }
  
 /**
 * Codegeneration for < <= != == > >= 
 * @param label Label for branch
 * @param test condition or negatived condition
 */ 
  public void codegen (int label, boolean test) {
    ast.IJSubNode node = (ast.IJSubNode)getChild (0);
    node.codegen ();
    node = (ast.IJSubNode)getChild (1);
    node.codegen ();
    codegen.WriteCode.genBranchInstruction ("if_icmp" + 
      getCompareInstruction (test), label);
  }

 
  public void codegen () {}
  
  public int getDepth () {
    int depth = 0;
    for (int i = 0; i < children.size(); i++) {
      ast.IJSubNode node = (ast.IJSubNode)children.elementAt(i);
      int ndepth = node.getDepth();
      if (depth < ndepth)
        depth = ndepth;
    }
    return depth;
  }
  

 /**
 * amount the comparison command for the JVM
 * @param test condition or negatived condition
 */ 
  public String getCompareInstruction (boolean negation) {
    return null;
  }
}