cpp.py

"""
This module implements the Cpp class containing the methods for dealing with cpp directives
"""
 
from pyfortool.util import debugDecor, alltext, PYFTError, tag, noParallel
from pyfortool.tree import updateTree
from pyfortool.variables import updateVarList
 
 
class Cpp:
    """
    Methods to deal with cpp directives
    """
    @debugDecor
    @noParallel
    @updateVarList
    @updateTree('signal')
    def applyCPPifdef(self, keys):
        """
        Apply #ifdef / #ifndef only on some keys
        :param keys: list of defined and undefined keys. The latter are preceded by a
                     percentage sign '%'.
                     E.g. if K is in keys, "#ifdef K "will be evaluated to True
                          if %K is in keys, "#ifdef K" will be evaluated to False
 
        Warning: only #ifdef and #ifndef are treated and not "#if defined ..."
 
        If key K is in keys
          #ifdef K
          A
          #else
          B
          #endif
        is reduced to A
        If %K is in keys, code snippet is reduced to B.
        If neither K nor %K are present in keys, code is kept untouched.
        """
 
        # We make the hypothesis that #ifdef, #else and #endif have the same parent
        # Get all nodes containing #ifdef or #ifndef
        parents = set(self.getParent(cppNode) for cppNode in self.findall('.//{*}cpp')
                      if (cppNode.text.startswith('#ifdef ') or
                          cppNode.text.startswith('#ifndef ')))
 
        # Iteration over nodes contained in each parent
        toRemove = []
        for par in parents:
            # we deal with nested #ifdef #ifndef and #if
            # We need to track #if cpp directives to discard #else and #endif related to these #if
            # Each time we enter an #ifdef, #ifndef or #if, we add a value to the keep list
            # True or False to keep or discard it, None not to touch it
            keep = [True]
            for node in par:
                if tag(node) == 'cpp':
                    if node.text.startswith('#ifdef '):
                        k = alltext(node).split(' ')[1].strip()
                        if k in keys:
                            toRemove.append((node, par))
                            keep.append(True)
                        elif '%' + k in keys:
                            toRemove.append((node, par))
                            keep.append(False)
                        else:
                            keep.append(None)
                            if False in keep:
                                toRemove.append((node, par))
                    elif node.text.startswith('#ifndef '):
                        k = alltext(node).split(' ')[1].strip()
                        if k in keys:
                            toRemove.append((node, par))
                            keep.append(False)
                        elif '%' + k in keys:
                            toRemove.append((node, par))
                            keep.append(True)
                        else:
                            keep.append(None)
                            if False in keep:
                                toRemove.append((node, par))
                    elif node.text.startswith('#if '):
                        if False in keep:
                            toRemove.append((node, par))
                        # We are in a #if,following #else / #endif  is associated to this #if
                        keep.append(None)
                    elif node.text.startswith('#else'):
                        if keep[-1] is not None:
                            toRemove.append((node, par))
                            keep[-1] = not keep[-1]
                        elif False in keep:
                            toRemove.append((node, par))
                    elif node.text.startswith('#endif'):
                        if keep[-1] is not None or False in keep:
                            toRemove.append((node, par))
                        keep.pop()
                    elif node.text.startswith('#elifdef') or node.text.startswith('#elifndef'):
                        raise NotImplementedError("#elifdef and #elifndef not (yet?) implemented")
                    else:
                        if False in keep:
                            toRemove.append((node, par))
                else:
                    if False in keep:
                        toRemove.append((node, par))
            if len(keep) != 1:
                # We check the hypothesis done at the beginning
                raise PYFTError("#else or #endif hasn't the same parent as #ifdef " +
                                "or #ifndef in {f}".format(f=self.getFileName()))
        # Suppress node in reverse order to attach tail to previous node
        if len(toRemove) != 0:
            self.tree.signal(self)  # Tree may need to be updated
        for node, par in toRemove[::-1]:
            index = list(par).index(node)
            if index != 0:
                if node.tail is not None:
                    if par[index - 1].tail is None:
                        par[index - 1].tail = ""
                    # We only keep '\n' and spaces at the end (indentation)
                    par[index - 1].tail += (node.tail.count('\n') * '\n' +
                                            (len(node.tail) - len(node.tail.rstrip(' '))) * ' ')
            par.remove(node)