Source Code for Module gavo.stc.stcsdefaults

  1  """ 
  2  Functions for adding defaults to STC-S concrete syntax trees. 
  3   
  4  Default addition is governed by the two dicts at the bottom of 
  5  the module: 
  6   
  7          - pathFunctions -- maps path tuples to handling functions.  If there 
  8                  is a match here, no name-based defaulting is done 
  9          - nodeNameFunctions -- maps the last element of a path tuple to 
 10                  handling functions. 
 11  """ 
 12   
 13  #c Copyright 2008-2019, the GAVO project 
 14  #c 
 15  #c This program is free software, covered by the GNU GPL.  See the 
 16  #c COPYING file in the source distribution. 
 17   
 18   
 19 -def getSpaceFlavor(node): 
 20          if node["type"]=="Convex": 
 21                  return "UNITSPHER" 
 22          else: 
 23                  return "SPHER2" 
 24   
 25   
 26 -def getSpaceUnit(node): 
 27          if node["frame"] and node["frame"].startswith("GEO"): 
 28                  return "deg deg m" 
 29          elif node["flavor"].startswith("CART"): 
 30                  return "m" 
 31          elif node["flavor"]=="UNITSPHER": 
 32                  return "" 
 33          else: 
 34                  return "deg" 
 35   
 36   
 37 -def getEquinox(node): 
 38          if node["frame"]=="FK4": 
 39                  return "B1950.0" 
 40          elif node["frame"]=="FK5": 
 41                  return "J2000.0" 
 42          else: 
 43                  return None 
 44   
 45   
 46 -def getRedshiftUnit(node): 
 47          if node["redshiftType"]=="VELOCITY": 
 48                  return "km/s" 
 49          else: 
 50                  return "nil" 
 51   
 52   
 53 -def _addDefaultsToNode(node, defaults): 
 54          """adds defaults to node. 
 55   
 56          defaults is a sequence of (key, default) pairs, where default is either 
 57          a string (which gets added in a list node), a list (which gets added 
 58          directly) or a function(node) -> string or list to obtain the default. 
 59   
 60          Values are only added to a node if the correponding key is not yet 
 61          present. 
 62          """ 
 63          for key, value in defaults: 
 64                  if key not in node: 
 65                          if not isinstance(value, (basestring, list)): 
 66                                  value = value(node) 
 67                                  if value is None: 
 68                                          continue 
 69                          node[key] = value 
 70   
 71   
 72 -def _removeDefaultsFromNode(node, defaults): 
 73          """removes defaults from node. 
 74   
 75          See _addDefaultsToNode for details. 
 76          """ 
 77          defaultedKeys = [] 
 78          for key, value in node.iteritems(): 
 79                  if key in defaults: 
 80                          default = defaults[key] 
 81                          if not isinstance(default, (basestring, list)): 
 82                                  default = default(node) 
 83                          if value==default: 
 84                                  defaultedKeys.append(key) 
 85          for key in defaultedKeys: 
 86                  del node[key] 
 87   
 88   
 89 -def _makeDefaulter(defaults): 
 90          """returns a defaulting function filling in what is defined in 
 91          defaults. 
 92          """ 
 93          def func(node): 
 94                  return _addDefaultsToNode(node, defaults) 
 95          return func 
 96   
 97   
 98 -def _makeUndefaulter(defaults): 
 99          """returns a function removing values in nodes that have their default 
100          values. 
101          """ 
102          def func(node): 
103                  return _removeDefaultsFromNode(node, dict(defaults)) 
104          return func 
105   
106   
107  defaults = { 
108          "space": [ 
109                  ("flavor", getSpaceFlavor), 
110                  ("equinox", getEquinox), 
111                  ("unit", getSpaceUnit)], 
112          "time": [ 
113                  # For time, the default is the unit of errors and such. 
114                  # The values are either in days or they're MJD. 
115                  ("unit", "s")], 
116          "spectral": [ 
117                  ("unit", "Hz")], 
118          "redshift": [ 
119                  ("redshiftType", "REDSHIFT"), 
120                  ("unit", getRedshiftUnit), 
121                  ("dopplerdef", "OPTICAL")], 
122          "velocity": [ 
123                  ("unit", "m/s"),], 
124  } 
125   
126  defaultingFunctions = dict( 
127          (k, _makeDefaulter(v)) for k, v in defaults.iteritems()) 
128   
129  undefaultingFunctions = dict( 
130          (k, _makeUndefaulter(v)) for k, v in defaults.iteritems()) 
131