Source Code for Module gavo.votable.modelgroups

  1  """ 
  2  Legacy data model related code. 
  3   
  4  This is legacy stuff.  Cool folks would use the stuff from gavo.dm.  When 
  5  there's actually something useful to be done with it. 
  6   
  7  This is intended for STC groups and possibly similarly handled data models. 
  8   
  9  Basically, these come in groups with certain utypes; these in turn contain 
 10  FIELDRefs and INFOs specifying utype-value pairs. 
 11   
 12  The idea here is to have [un]marshal_DMNAME functions in here that expect 
 13  some defined top-level element.  In the case of STC, that top-level 
 14  element is the table, but other elements are conceivable. 
 15   
 16  To keep the library working even without the STC package, the stc import is 
 17  protected by a try...except clause.  You can check the availability of 
 18  STC by inspecting modelgroups.stcAvailable. 
 19  """ 
 20   
 21  #c Copyright 2008-2019, the GAVO project 
 22  #c 
 23  #c This program is free software, covered by the GNU GPL.  See the 
 24  #c COPYING file in the source distribution. 
 25   
 26   
 27  from gavo.votable.model import VOTable as V 
 28   
 29   
 30  try: 
 31          from gavo import stc 
 32          stcAvailable = True 
 33  except ImportError: 
 34          stcAvailable = False 
 35   
 36   
 37  ######################## Helpers 
 38   
 39 -def _getUtypedGroupsFromAny(votObj, utype): 
 40          return [g  
 41                  for g in votObj.iterChildrenOfType(V.GROUP)  
 42                  if g.utype and g.utype.startswith(utype)] 
 43   
 44   
 45 -def _getUtypedGroupsFromResource(votRes, utype): 
 46          """yields groups of utype from below the V.RESOURCE votRes. 
 47   
 48          The function recursively searches child TABLE and RESOURCE 
 49          instances. 
 50          """ 
 51          stcGroups = [] 
 52          stcGroups.extend(_getUtypedGroupsFromAny(votRes, utype)) 
 53          for child in votRes.iterChildren(): 
 54                  if isinstance(child, V.TABLE): 
 55                          stcGroups.extend(_getUtypedGroupsFromAny(child, utype)) 
 56                  elif isinstance(child, V.RESOURCE): 
 57                          stcGroups.extend(_getUtypedGroupsFromResource(child, utype)) 
 58          return stcGroups 
 59   
 60   
 61 -def _getUtypedGroupsFromVOTable(vot, utype): 
 62          """returns a list of all groups of utype from a votable. 
 63   
 64          Make this available in the votable library? 
 65          """ 
 66          allGroups = [] 
 67          for res in vot.iterChildrenOfType(V.RESOURCE): 
 68                  allGroups.extend(_getUtypedGroupsFromResource(res, utype)) 
 69          return allGroups 
 70   
 71   
 72 -def _extractUtypes(group, refClass): 
 73          """yields utype-value pairs extracted from the children of group. 
 74   
 75          refClass is the class to be used for column references.  This will 
 76          usually be a stanxml.Stub derived class. 
 77          """ 
 78          for child in group.iterChildren(): 
 79                  if isinstance(child, V.PARAM): 
 80                          yield child.utype, child.value 
 81                  elif isinstance(child, V.FIELDref): 
 82                          yield child.utype, refClass(child.ref) 
 83                  else: 
 84                          pass # other children are ignored. 
 85   
 86   
 87   
 88  ########################## STC 
 89   
 90 -def unmarshal_STC(tableNode): 
 91          """iterates over pairs of (colInfo, system) pairs of STC information 
 92          on tableNode. 
 93   
 94          system are STC ASTs; colInfo maps column ids to the column utype in 
 95          system. 
 96          """ 
 97          for obsLocGroup in _getUtypedGroupsFromAny(tableNode,  
 98                          "stc:CatalogEntryLocation"): 
 99                  utypes, colInfo = [], {} 
100                  for utype, value in _extractUtypes(obsLocGroup, stc.ColRef): 
101                          if isinstance(value, stc.ColRef): 
102                                  colInfo[value.dest] = utype 
103                          utypes.append((utype, value)) 
104                  yield colInfo, stc.parseFromUtypes(utypes) 
105   
106   
107 -def _makeUtypeContainer(utype, value, getIdFor): 
108          """returns a PARAM or FIELDref element serializing the utype, value pair. 
109   
110          If the value is a ColRef, the result will be a FIELDref. 
111   
112          see marshal_STC for info on getIdFor 
113          """ 
114          if isinstance(value, stc.ColRef): 
115                  destId = getIdFor(value) 
116                  if value.toParam: 
117                          return V.PARAMref(utype=utype, ref=destId) 
118                  else: 
119                          return V.FIELDref(utype=utype, ref=destId) 
120          else: 
121                  return V.PARAM(name=utype.split(".")[-1], utype=utype, value=value, 
122                          datatype="char", arraysize="*") 
123   
124   
125 -def marshal_STC(ast, getIdFor): 
126          """returns an stc:CatalogEntryLocation group for ast. 
127   
128          ast is an AST object from GAVO's STC library. 
129   
130          getIdFor must be a function returning the id for an stc.ColRef object. 
131          The main issue here is that the STC library deals with unqualified column  
132          names.  These may clash when several tables are combined within a VOTable. 
133          Thus, you will have to have some mechanism to generate unique ids for 
134          the FIELDs (e.g. using utils.IdManagerMixin).  getIdFor must resolve 
135          ColRefs (with column names in their dest) to unique ids. 
136          """ 
137          container = V.GROUP(utype="stc:CatalogEntryLocation") 
138          utypeMap = {} 
139          for utype, value in stc.getUtypes(ast, includeDMURI=True): 
140                  try: 
141                          container[_makeUtypeContainer(utype, value, getIdFor)] 
142                          utypeMap[utype.lower()] = value 
143                  except KeyError:  # column referenced is not in result 
144                          pass 
145          return container, utypeMap 
146