toCommonJS.py

#!/usr/bin/python

import os, sys, re

def usage():
    print "usage: toCommonJS file1 file2 ..."

def readfile(filename):
    ''' read file as a string '''

    fd = None
    try:
        fd = open(filename, 'r')
        s = fd.read()
    except:
        print "file not exist: %s" % filename
        s = ''
    finally:
        if not fd is None:
            fd.close()

    return s

def process(filename, content):
    ''' replace AMD as CommonJS require '''

    regexp = r"define\(\[[^'\]]*(('[^'\]]+',*[^'\]]*)+)\],[ ]*function\((([^,\)]+,*)+)*\)[ ]*\{(.*)return[\s]*([^;]*);.*$"

    matchObj = re.match(regexp, content, re.S)
    if not matchObj or not matchObj.group(1):
        print "regular expression not match: [%s]" % filename
        return content

    requires = matchObj.group(1)
    defines = matchObj.group(3)
    middle = matchObj.group(5)
    variable = matchObj.group(6)

    part_requires = process_requires(requires, defines)
    part_middle = process_middle(middle)
    part_variable = process_variable(variable)

    return "\n\n".join([part_requires, part_middle, part_variable])

def process_requires(requires, defines):
    ''' make requires and defines as CommonJS style '''

    require_list = requires.strip().strip(',').split(',')
    define_list = defines.strip().strip(',').split(',')

    part = ['// require modules']
    pathlen = len(require_list)
    varlen = len(define_list)
    cnt = 0
    while cnt < pathlen:
        path = require_list[cnt].strip()
        if cnt >= varlen:
            break
        var =  define_list[cnt].strip()
        part.append('var %s = require(%s);' % (var, path))
        cnt = cnt + 1

    return "\n".join(part)

def process_middle(middle):
    ''' shift the function part left with tabstop '''

    middle_list = middle.strip().split('\n')

    part = ['// module definition']
    for line in middle_list:
        part.append(re.sub(r'  ', '', line, 1))

    return "\n".join(part)

def process_variable(variable):
    ''' export the variable '''

    return 'module.exports = %s;' % variable

def output(filename, process_content):
    ''' output the new content and replace the file '''

    fd = None
    try:
        fd = open(filename, 'w')
        fd.write(process_content)
    except Exception, e:
        print "write file [%s] error: [%s]" % (filename, e)
    finally:
        if not fd is None:
            fd.close()

def transform(filename):
    ''' transform a file written with AMD style to CommonJS style '''

    content = readfile(filename)
    process_content = process(filename, content)
    output(filename, process_content)

if __name__ == "__main__":

    if len(sys.argv) < 2:
        usage()
        exit(1)

    files = sys.argv[1:]
    for f in files:
        try:
            transform(f)
        except Exception, e:
            print "transform [%s] error: [%s]" % (f, e)
            exit(1)