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  """
   File: generator.py
   Authors: Cyrus Harrison, <cyrush@llnl.gov>
           Maysam Moussalem <maysam@tacc.utexas.edu>
  
   Description:
    Takes a list of expressions, parses them and builds a data flow
    network specification.
  
   Usage:
     >>> from generator import *
     >>> print Generator.parse_network("vx = a(2,3) + b^3 + 4 * var")
  
  """
  import sys
  import os
  from parser import *
  
  from ..core import log
  
  def info(msg):
      log.info(msg,"flow.parser")
  
  class Generator(object):
      @classmethod
      def parse_network(cls,txt,ctx=None):
          filters = []
          vmaps   = {}
          stmts = Parser.parse(txt)
          cls.__create_network(stmts,filters,vmaps)
          cls.__vmaps_sub(filters,vmaps)
          filters = cls.__cse_elim(filters)
          if not ctx is None:
              cls.__setup_context(filters,ctx,vmaps)
          return filters
      @classmethod
      def __create_network(cls,stmts,filters,vmaps=None,count=None):
          if vmaps is None: vmaps = {}
          if count is None: count = [0]
          res = []
          for expr in stmts:
              if isinstance(expr,FuncCall):
                  args = cls.__create_network(expr.args,filters,vmaps,count)
                  fname = "f%d" % count[0]
                  msg ="Generator: create_network func_call:"
                  msg += "%s = %s( %s, %s)" % (fname, expr.name,str(args),str(expr.params))
                  info(msg)
                  filters.append([fname, FuncCall(expr.name, args, expr.params)])
                  res.append(Identifier(fname))
                  count[0]+=1
              if isinstance(expr,Assignment):
                  res = cls.__create_network([expr.value],filters,vmaps,count)
                  msg ="Generator: create_network assignment:"
                  msg += "%s := %s"  % (expr.name,res[0])
                  info(msg)
                  vmaps[expr.name] = res[0].name
              if isinstance(expr,Identifier):
                  if expr.name in vmaps.keys():
                      iname =  vmaps[expr.name]
                  else:
                      iname = ":" + expr.name
                  res.append(Identifier(iname))
              if isinstance(expr,list):
                  rvals = cls.__create_network(expr,filters,vmaps,count)
                  res.extend(rvals)
              if isinstance(expr,Constant):
                  fname  = "c%d" % count[0]
                  params = {"value":expr.value}
                  msg ="Generator: create_network constant:"
                  msg += "%s = const([],%s)"  % (fname,str(params))
                  info(msg)
                  filters.append([fname, FuncCall("const", [], params)])
                  res.append(Identifier(fname))
                  count[0]+=1
          return res
      @classmethod
      def __vmaps_sub(cls,filters,vmaps):
          vmaps_inv = dict([[v,k] for k,v in vmaps.items()])
          for f in filters:
              fname = f[0]
              # check for nick name
              if fname in vmaps_inv.keys():
                  fname = vmaps_inv[fname]
                  f[0] = fname
              fcall = f[1]
              for arg in fcall.args:
                  if isinstance(arg,Identifier):
                      if arg.name in vmaps_inv.keys():
                          arg.name = vmaps_inv[arg.name]
      @classmethod
      def __cse_elim(cls,filters):
          rfilters = []
          fmaps    = {}
          rmaps    = {}
          for f in filters:
              fname = f[0]
              fcall = str(f[1])
              if not fcall in fmaps.keys():
                  fmaps[fcall] = fname
                  rfilters.append(f)
              else:
                  rmaps[fname] = fmaps[fcall]
          for f in rfilters:
              fcall = f[1]
              for arg in fcall.args:
                  if arg.name in rmaps.keys():
                      arg.name = rmaps[arg.name]
          return rfilters
      @classmethod
      def __setup_context(cls,filters,ctx,vmaps):
          for f in filters:
              fname = f[0]
              fcall = f[1]
              msg   = "Generator setup_context: "
              msg  += "ctx.add_filter(%s,%s,%s)" % (str(fcall.name),str(fname),str(fcall.params))
              info(msg)
              ctx.add_filter(fcall.name,fname,fcall.params)
              idx = 0
              for arg in fcall.args:
                  if isinstance(arg,Identifier):
                      aname = arg.name
                      msg   = "Generator setup_context: "
                      msg  += "ctx.connect(%s,(%s,%d))\n" % (aname,str(fname),idx)
                      info(msg)
                      ctx.connect(aname,(fname,idx))
                      idx+=1
  