moved the function map to excellib, this should make it easier for pe…

…ople to add new functions

src/pycel/excelcompiler.py

@@ -1,3 +1,4 @@
+from import excellib
 from excellib import *
 from excelutil import *
 from excelwrapper import ExcelComWrapper
@@ -254,22 +255,13 @@ def __init__(self,*args):
         super(FunctionNode,self).__init__(*args)
         self.numargs = 0
 
-        # map excel functions onto their python equivalents, taking care to avoid name clashes
-        self.funmap = {
-                  "ln":"xlog",
-                  "min":"xmin",
-                  "min":"xmin",
-                  "max":"xmax",
-                  "sum":"xsum",
-                  "gammaln":"lgamma"
-                  }
+        # map  excel functions onto their python equivalents
+        self.funmap = excellib.FUNCTION_MAP
 
     def emit(self,ast,context=None):
-        xfun = self.tvalue.lower()
+        fun = self.tvalue.lower()
         str = ''
 
-        fun = self.funmap.get(xfun,xfun)        
-
         # Get the arguments
         args = self.children(ast)
 
@@ -331,7 +323,9 @@ def emit(self,ast,context=None):
         elif fun == "or":
             str = "any([" + ",".join([n.emit(ast,context=context) for n in args]) + "])"
         else:
-            str = fun + "(" + ",".join([n.emit(ast,context=context) for n in args]) + ")"
+            # map to the correct name
+            f = self.funmap.get(fun,fun)
+            str = f + "(" + ",".join([n.emit(ast,context=context) for n in args]) + ")"
 
         return str
 

src/pycel/excellib.py

@@ -5,7 +5,32 @@
 import numpy as np
 from math import log
 from pycel.excelutil import flatten
-
+
+######################################################################################
+# A dictionary that maps excel function names onto python equivalents. You should
+# only add an entry to this map if the python name is different to the excel name
+# (which it may need to be to  prevent conflicts with existing python functions 
+# with that name, e.g., max).
+
+# So if excel defines a function foobar(), all you have to do is add a function
+# called foobar to this module.  You only need to add it to the function map,
+# if you want to use a different name in the python code. 
+
+# Note: some functions (if, pi, atan2, and, or, array, ...) are already taken care of
+# in the FunctionNode code, so adding them here will have no effect.
+FUNCTION_MAP = {
+      "ln":"xlog",
+      "min":"xmin",
+      "min":"xmin",
+      "max":"xmax",
+      "sum":"xsum",
+      "gammaln":"lgamma"
+      }
+
+######################################################################################
+# List of excel equivalent functions
+# TODO: needs unit testing
+
 def value(text):
     # make the distinction for naca numbers
     if text.find('.') > 0: