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Jython is an implementation of the high-level, dynamic, object-oriented language Python written in 100% Pure Java, and seamlessly integrated with the Java platform. It thus allows you to run Python on any Java platform.

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/*
 * Jython Database Specification API 2.0
 *
 *
 * Copyright (c) 2001 brian zimmer 
 *
 */
package com.ziclix.python.sql.util;

import org.python.core.Py;
import org.python.core.PyObject;

import java.util.HashMap;
import java.util.Map;

/**
 * Parse the args and kws for a method call.
 *
 * @author brian zimmer
 */
public class PyArgParser extends Object {

    /** Field keywords. */
    protected Map keywords;

    /** Field arguments. */
    protected PyObject[] arguments;

    /**
     * Construct a parser with the arguments and keywords.
     */
    public PyArgParser(PyObject[] args, String[] kws) {
        keywords = new HashMap();
        arguments = null;
        parse(args, kws);
    }

    /**
     * Method parse
     *
     * @param args
     * @param kws
     */
    protected void parse(PyObject[] args, String[] kws) {
        // walk backwards through the kws and build the map
        int largs = args.length;

        if (kws != null) {
            for (int i = kws.length - 1; i >= 0; i--) {
                keywords.put(kws[i], args[--largs]);
            }
        }

        arguments = new PyObject[largs];
        System.arraycopy(args, 0, arguments, 0, largs);
    }

    /**
     * How many keywords?
     */
    public int numKw() {
        return keywords.keySet().size();
    }

    /**
     * Does the keyword exist?
     */
    public boolean hasKw(String kw) {
        return keywords.containsKey(kw);
    }

    /**
     * Return the value for the keyword, raise a KeyError if the keyword does
     * not exist.
     */
    public PyObject kw(String kw) {
        if (!hasKw(kw)) {
            throw Py.KeyError(kw);
        }

        return keywords.get(kw);
    }

    /**
     * Return the value for the keyword, return the default if the keyword does
     * not exist.
     */
    public PyObject kw(String kw, PyObject def) {
        if (!hasKw(kw)) {
            return def;
        }

        return keywords.get(kw);
    }

    /**
     * Get the array of keywords.
     */
    public String[] kws() {
        return keywords.keySet().toArray(new String[0]);
    }

    /**
     * Get the number of arguments.
     */
    public int numArg() {
        return arguments.length;
    }

    /**
     * Return the argument at the given index, raise an IndexError if out of range.
     */
    public PyObject arg(int index) {
        if (index >= 0 && index <= arguments.length - 1) {
            return arguments[index];
        }

        throw Py.IndexError("index out of range");
    }

    /**
     * Return the argument at the given index, or the default if the index is out of range.
     */
    public PyObject arg(int index, PyObject def) {
        if (index >= 0 && index <= arguments.length - 1) {
            return arguments[index];
        }

        return def;
    }
}