Transform closure into SQL WHERE statement. TODO: Get Method Values Support Multiline Closures

sql.groovy

import org.codehaus.groovy.ast.CodeVisitorSupport
import org.codehaus.groovy.ast.MethodNode
import org.codehaus.groovy.ast.expr.BinaryExpression
import org.codehaus.groovy.ast.expr.ConstantExpression
import org.codehaus.groovy.ast.expr.Expression
import org.codehaus.groovy.ast.expr.MethodCallExpression
import org.codehaus.groovy.ast.expr.VariableExpression
import org.codehaus.groovy.ast.stmt.BlockStatement
import org.codehaus.groovy.syntax.Token
import org.codehaus.groovy.syntax.Types

class SQLTest {

    String whereStatement;

    public SQLTest(Closure closure){
        MethodNode method = closure.getMetaClass().getClassNode().getDeclaredMethods("doCall").get(0)
        BlockStatement statement = method.getCode()
        WhereVisitor wv = new WhereVisitor()
        statement.visit(wv)
       this.whereStatement = wv.getWhere()
    }

    public static void main(String[] args) {

        SQLTest s = new SQLTest({
            hello == 1.toString()
        })

        println s.whereStatement

    }
}

class WhereVisitor extends CodeVisitorSupport {

    private final StringBuffer buffer = new StringBuffer()
    private final List<Object> parameters = new ArrayList<Object>();

    public void visitBinaryExpression(BinaryExpression exp){
        Expression left = exp.getLeftExpression()
        Expression right = exp.getRightExpression()
        boolean leaf = (right instanceof ConstantExpression || left instanceof ConstantExpression);

        if (!leaf) buffer.append("(")
        left.visit(this)
        buffer.append(" " + tokenAsSQL(exp.getOperation()) + " ")
        right.visit(this)
        if (!leaf) buffer.append(")")
    }

    public void visitMethodCallExpression(MethodCallExpression exp){
        println "METHOD"
        // GET METHOD VALUE
        buffer.append("METHOD VALUE")
    }

    public void visitConstantExpression(ConstantExpression exp){
        parameters.add(exp.getValue())
        buffer.append("?")
    }


    public String getWhere(){
        println parameters
        return buffer.toString()
    }

    public void visitVariableExpression(VariableExpression expression) {
        buffer.append(expression.getName())
    }

    String tokenAsSQL(Token token){
        switch (token.getType()) {
            case Types.COMPARE_EQUAL:
                return "=";
            case Types.LOGICAL_AND:
                return "AND";
            case Types.LOGICAL_OR:
                return "OR";
            default:
                return token.getText();
        }
    }

}