Monday, December 19, 2011

Python-based Web Page to Compute Function with User Input Flexible Function

This is improved from my python-based web based to display function. In this version, users have ability to input a function and then display it with it value for given variable to python-based web page.

The code below will get input from users (if no input, the default value is sin(x)), parsed it to function python understand, and then eval it for given variable (in this code, x=10). After computed, it's inserted to template that resembling html code. Thus, since it's displayed in html style, we could add our customization (background, css, etc)



Here's the code


#!/usr/bin/python
# -*- coding: utf-8 -*-
import BaseHTTPServer, urllib, re
import sys,parser
from math import *

class Handler(BaseHTTPServer.BaseHTTPRequestHandler):
    template = u"""<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN"
        "http://www.w3.org/TR/html4/strict.dtd"><html><head><title>%s</title>
        </head><body><h1>%s</h1><pre>%s</pre>Function<form action="" method="POST"
        class="editor"><div><textarea name="text">%s</textarea><input type="submit"
        value="Compute"></div></form></body></html>"""
    
    def escape_html(self, text):
        """Replace special HTML characters with HTML entities"""
        return text.replace(
                            "&", "&amp;").replace(">", "&gt;").replace("<", "&lt;")
    
    def link_repl(self, match):
        """Return HTML for link"""
        title = match.group(1)
        if title in self.server.pages:
            return u"""<a href="%s">%s</a>""" % (title, title)
        return u"""%s<a href="%s">?</a>""" % (title, title)
    
    def do_HEAD(self):
        """Send response headers"""
        self.send_response(200)
        self.send_header("content-type", "text/html;charset=utf-8")
        self.end_headers()
    
    def do_GET(self):
        """Send page text"""
        self.do_HEAD()
        page = self.escape_html(urllib.unquote(self.path.strip('/')))
        text = self.escape_html(self.server.pages.get(page, "sin(x)"))
        parsed = re.sub(r"\[\[([^]]+)\]\]", self.link_repl, text)
        #hitung fungsi
        fungsi=parser.expr(parsed).compile()
        x = 10
        y = eval(fungsi)
        tout = 'The value of  ',parsed, ' on x = ',x,' is ',y
        tout = str(tout)
        tout = re.sub(r",", "", tout)
        tout = re.sub(r"\'", "", tout)
        tout= tout[1:]
        tout= tout[:-1]
        self.wfile.write(self.template % (page, page, tout, text))
    
    def do_POST(self):
        """Save new page text and display it"""
        length = int(self.headers.getheader('content-length'))
        if length:
            text = self.rfile.read(length)
            page = self.escape_html(urllib.unquote(self.path.strip('/')))
            self.server.pages[page] = urllib.unquote_plus(text[5:])
        self.do_GET()

if __name__ == '__main__':
    server = BaseHTTPServer.HTTPServer(("", 8080), Handler)
    server.pages = {}
    server.serve_forever()

Here's the screenshot
From python