parser.java

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            if (fDef.paramNames.size()!=params.size()) {
                parseError("Expected " +
                fDef.paramNames.size() +
                " parameters, Found " + params.size());
            }
            
            //Create a new parser instance to handle call
            Parser p;
            Hashtable locals=new Hashtable();
            
            //Push the params into the local scope
            for (n=0;n<fDef.paramNames.size();n++) {
                locals.put(fDef.paramNames.elementAt(n),
                params.elementAt(n));
            }
            //watch for recursive calls
            if (gVars==null) {
                p=new Parser(host,locals,vars,funcs);
            } else {
                p=new Parser(host,locals,gVars,funcs);
            }
            //cache the current execution point
            oldLine=code.getCurLine();
            p.setCode(code);
            
            //let it rip
            val=p.parse(fDef.startLine+1,fDef.endLine-1);
            
            //reset execution point
            code.setCurLine(oldLine);
            
            
            
        } else {//calls into super class  code...}
            try {
                val=host.callFunction(name,params);
            } catch (Exception e) {
                parseError(e.getMessage());
            }
        }
        
        return val;
        
    }
    
    //Handle calls to a function
    private Object parseCallFunc(String name) throws FSException {
        
        Vector params=new Vector(4);
        
        //Set up the parameters
        do {
            getNextToken();
            if (tok.ttype==',') {
                getNextToken();
            } else if (tok.ttype==')') {
                break;
            }
            params.addElement(parseExpr());
        } while (tok.ttype==',');
        
        
        
        return callFunction(name,params);
    }
    
    //handles function definitions
    private void parseFunctionDef() throws FSException {
        
        FuncEntry fDef=new FuncEntry();
        Object val;
        String name,fName;
        
        fDef.startLine=code.getCurLine();
        
        getNextToken();
        
        //should be the function name
        if (tok.ttype!=LexAnn.TT_FUNC) {
            parseError("Expected function start identifier");
        }
        fName=(String)tok.value;
        getNextToken();
        
        //should be a '('
        if (tok.ttype!='(') {
            parseError("Expected (");
        }
        
        getNextToken();
        //parse the header...
        while(tok.ttype!=')') {
            if (tok.ttype!=LexAnn.TT_DEFINT&&tok.ttype!=LexAnn.TT_DEFSTRING) {
                parseError("Expected type name");
            }
            
            val=null; //keep the compiler happy..
            
            if (tok.ttype==LexAnn.TT_DEFINT) {
                val=new Integer(0);
            } else if (tok.ttype==LexAnn.TT_DEFSTRING) {
                val=new String("");
            }
            
            getNextToken();
            
            if (tok.ttype!=LexAnn.TT_WORD) {
                parseError("Expected function parameter name identifier");
            }
            
            name=(String)tok.value;
            
            fDef.paramNames.addElement(name);
            fDef.params.put(name,val);
            
            getNextToken();
            if (tok.ttype==',') getNextToken();
        }
        
        //now we just skip to the endfunction
        
        while ((tok.ttype!=LexAnn.TT_EDEFFUNC)&&(tok.ttype!=LexAnn.TT_EOF)) {
            getNextToken();
            if (tok.ttype==LexAnn.TT_DEFFUNC)
                parseError("Nested functions are illegal");
        }
        
        fDef.endLine=code.getCurLine();
        getNextToken();
        
        funcs.put(fName,fDef);
        
    }
    
    //Expression parser
    private Object parseExpr() throws FSException{
        
        ETreeNode curNode=null;
        boolean end=false;
        boolean skipTok=false;
        Object val;
        boolean negate=false; //flag for unary minus
        boolean not=false;//flag for unary not.
        boolean prevOp=true;//flag - true if previous value was an operator
        
        
        
        
        
        while (!end){
            
            switch (tok.ttype) {
                
                //the various possible 'values'
                case LexAnn.TT_INTEGER:
                case LexAnn.TT_DOUBLE:
                case LexAnn.TT_STRING:
                case LexAnn.TT_WORD:
                case LexAnn.TT_FUNC:
                case LexAnn.TT_ARRAY:{
                    
                    if (!prevOp){
                        parseError("Expected Operator");
                    } else {
                        
                        val=null;
                        ETreeNode node=new ETreeNode();
                        node.type=ETreeNode.E_VAL;
                        
                        switch (tok.ttype){
                            //numbers - just get them
                            case LexAnn.TT_INTEGER:{
                                val=(Integer)tok.value;
                                break;
                            }
                            //functions - evaluate them
                            case LexAnn.TT_FUNC:{
                                String name=(String)tok.value;
                                getNextToken();
                                val=parseCallFunc(name);
                                break;
                            }
                            //arrays - evaluate them
                            case LexAnn.TT_ARRAY:{
                                String name=(String)tok.value;
                                getNextToken(); //should be a '['
                                getNextToken(); //should be the index
                                Object index=parseExpr();
                                try {
                                    val=host.getVar(name,index);
                                } catch (Exception e) {
                                    parseError(e.getMessage());
                                }
                                break;
                            }
                            //variables - resolve them
                            case LexAnn.TT_WORD:{
                                if (hasVar((String)tok.value)) {
                                    val=getVar((String)tok.value);
                                } else {
                                    try {
                                        val=host.getVar((String)tok.value,null);
                                    } catch (Exception e) {
                                        parseError(e.getMessage());
                                    }
                                }
                                break;
                            }
                            //strings - just get again
                            case LexAnn.TT_STRING:{
                                val=(String)tok.value;
                                break;
                            }
                        }
                        
                        //unary not
                        if (not){
                            if (val instanceof Integer){
                                if (((Integer)val).intValue()!=0){
                                    val=new Integer(0);
                                } else {
                                    val=new Integer(1);
                                }
                                not=false;
                            } else {
                                parseError("Type mismatch for !");
                            }
                        }
                        
                        //unary minus
                        if (negate){
                            if (val instanceof Integer){
                                val=new Integer(-((Integer)val).intValue());
                            } else {
                                parseError("Type mistmatch for unary -");
                            }
                        }
                        
                        node.value=val;
                        
                        if (curNode!=null){
                            if (curNode.left==null){
                                curNode.left=node;
                                node.parent=curNode;
                                curNode=node;
                                
                            } else if (curNode.right==null){
                                curNode.right=node;
                                node.parent=curNode;
                                curNode=node;
                                
                            }
                        } else {
                            curNode=node;
                        }
                        
                        prevOp=false;
                    }
                    break;
                }
                                                                                                /*operators - have to be more carefull with these.
                                                                                                We build an expression tree - inserting the nodes at the right
                                                                                                points to get a reasonable approximation to correct operator
                                                                                                precidence*/
                case LexAnn.TT_LEQ:
                case LexAnn.TT_LNEQ:
                case LexAnn.TT_MULT:
                case LexAnn.TT_DIV:
                case LexAnn.TT_MOD:
                case LexAnn.TT_PLUS:
                case LexAnn.TT_MINUS:
                case LexAnn.TT_LGR:
                case LexAnn.TT_LGRE:
                case LexAnn.TT_LLSE:
                case LexAnn.TT_LLS:
                case LexAnn.TT_NOT:
                case LexAnn.TT_LAND:
                case LexAnn.TT_LOR: {
                    if (prevOp){
                        if (tok.ttype==LexAnn.TT_MINUS){
                            negate=true;
                        } else if (tok.ttype==LexAnn.TT_NOT){
                            not=true;
                        } else {
                            parseError("Expected expression");
                        }
                    } else {
                        
                        ETreeNode node=new ETreeNode();
                        
                        node.type=ETreeNode.E_OP;
                        node.value=new Integer(tok.ttype);
                        
                        if (curNode.parent!=null){
                            
                            int curPrio=getPrio(tok.ttype);
                            int parPrio=
                            getPrio(((Integer)curNode.parent.value).intValue());
                            
                            if (curPrio<=parPrio){
                                //this nodes parent is the current nodes grandparent
                                node.parent=curNode.parent.parent;
                                //our nodes left leg is now linked into the current nodes
                                //parent
                                node.left=curNode.parent;
                                //hook into grandparent
                                if (curNode.parent.parent!=null){
                                    curNode.parent.parent.right=node;
                                }
                                
                                //the current nodes parent is now us (because of above)
                                curNode.parent=node;
                                //set the current node.
                                curNode=node;
                            } else {
                                //current node's parent's right is now us.
                                curNode.parent.right=node;
                                //our nodes left is the current node.
                                node.left=curNode;
                                //our nodes parent is the current node's parent.
                                node.parent=curNode.parent;
                                //curent nodes parent is now us.
                                curNode.parent=node;
                                //set the current node.
                                curNode=node;
                            }
                        } else {
                            //our node's left is the current node
                            node.left=curNode;
                            //current node's parent is us now
                            //we don't have to set our parent, as it is null.
                            curNode.parent=node;
                            //set current node
                            curNode=node;
                        }
                        prevOp=true;
                    }
                    break;
                }
                case '(':
                    //start of an bracketed expression, recursively call ourself
                    //to get a value
                {
                    getNextToken();
                    val=parseExpr();
                    
                    ETreeNode node=new ETreeNode();
                    node.value=val;
                    node.type=ETreeNode.E_VAL;
                    
                    if (curNode!=null){
                        if (curNode.left==null){
                            curNode.left=node;
                            node.parent=curNode;
                            curNode=node;
                            
                        } else if (curNode.right==null){
                            curNode.right=node;
                            node.parent=curNode;
                            curNode=node;