whilestatementnode.java

是有关解释器的.用JAVA编写.可以解释一般的JAVA程序.

class WhileStatementNode extends ExecutableNode
{
	OrClauseNode vOrClauseNode;
	StatementNode vStatementNode;
	Value vOrClauseValue;
	
	static WhileStatementNode parserWhileStatement(Environment env, Scanner s)throws ParserException, ScannerException
	{
		OrClauseNode tmpOrClauseNode;
		StatementNode tmpStatementNode;
		
		matchKeyword(s,"while");
		matchBracket(s,'(');
		tmpOrClauseNode= OrClauseNode.parserOrClause(env,s);
		matchBracket(s,')');
		tmpStatementNode= StatementNode.parserStatement(env,s);
		
		return new WhileStatementNode(tmpOrClauseNode, tmpStatementNode);
	}
	static boolean mIsWhileStatement(Scanner s) throws ScannerException
	{
		return isKeywordToken(s,"while");
	}
	WhileStatementNode()
	{
		vOrClauseNode= null;
		vStatementNode= null;
	}
	WhileStatementNode(OrClauseNode aOrClauseNode, StatementNode aStatementNode)
	{
		vOrClauseNode= aOrClauseNode;
		vStatementNode= aStatementNode;
	}
	String format(int indent)
	{
		return space(indent) + "while(" + vOrClauseNode.format(indent) + ")\n" +
				space(indent)+ vStatementNode.format(indent);
	}
	Environment run(Environment env) throws InterpreterException
	{		
		BooleanValue tmpValue= (BooleanValue)vOrClauseValue;
		while(tmpValue.booleanValue())
		{
			vStatementNode.run(env);
			tmpValue= (BooleanValue)vOrClauseNode.evaluate(env);
		}
		
		return env;
	}
	boolean typeCheck(Environment env) throws InterpreterException
	{
		if(vOrClauseNode.typeCheck(env))
		{
			vOrClauseValue= vOrClauseNode.evaluate(env);		
			if(vOrClauseValue.isBoolean())
				return vStatementNode.typeCheck(env);
			else ProgramNode.mTypeCheckError(this.format(4));
		}else ProgramNode.mTypeCheckError(this.format(4));		
		
		return true;
	}
}