API Reference for Enthought Tool Suite 2.7.1

Variables

• logger

  logger = logging.getLogger(__name__)
  
  

Classes

• ConstAssignExtractor
• NameFinder - Find and classify variable names
• Transformer

Function summary

• conditional_local_vars(ast, *args, **kw)
• dependency_graph(asts, to_ast = lambda x: x)
• extract_const_assigns(ast)
• free_vars(ast, *args, **kw)
• is_const(ast)
• local_vars(ast, *args, **kw)
• walk(x, visitor, walker = None, verbose = None)

Functions

• conditional_local_vars(ast, *args, **kw)
• dependency_graph(asts, to_ast = lambda x: x)

  Compute the dependency graph for a set of ASTs.

  'asts' is a sequence of either ASTs or objects 'x' such that 'to_ast(x)' is an AST. The returned value is the dependency graph: a directed (acyclic) graph relating the elements of 'asts' such that a->b iff a's AST uses names created by b's AST. We assume 'to_ast' is injective and elements of 'asts' are hashable. Raises a CyclicGraph exception when the output graph would have been cyclic.

  If a name is created by multiple elements of 'asts', then the dependency graph won't determine a well-defined program. e.g.

  >>> from compiler import parse
  >>> assert dependency_graph(to_ast=parse, asts=[
  ...     'a = 1', 'a = 2'
  ... ]) == {
  ...     'a = 1' : [],
  ...     'a = 2' : [],
  ... }
  

  A topological sort of the above graph could produce either ['a = 1', 'a = 2'] or ['a = 2', 'a = 1'].

  Some examples:

  >>> from compiler import parse
  >>> import enthought.util.graph as graph 
  >>>
  >>> assert graph.eq(dependency_graph(to_ast=parse, asts=[
  ...     'a = b+c', 'c = 3', 'b = f(c)'
  ... ]), {
  ...     'a = b+c'  : ['c = 3', 'b = f(c)'],
  ...     'c = 3'    : [],
  ...     'b = f(c)' : ['c = 3'],
  ... })
  >>> assert graph.eq(dependency_graph(to_ast=parse, asts=[
  ...     'a = 1', 'print a', 'a = 2'
  ... ]), {
  ...     'a = 1'   : [],
  ...     'print a' : ['a = 1', 'a = 2'],
  ...     'a = 2'   : [],
  ... })
  >>> assert graph.eq(dependency_graph(to_ast=parse, asts=[
  ...     'a = 1', 'a = 0; print a', 'a = 2'
  ... ]), {
  ...     'a = 1'          : [],
  ...     'a = 0; print a' : [],
  ...     'a = 2'          : [],
  ... })
  

  Sorting non-linear dependency graphs is useful (but non-deterministic):

  >>> from enthought.util.graph import reverse, topological_sort
  >>>
  >>> assert topological_sort(reverse(
  ...     dependency_graph(to_ast=parse, asts=[
  ...         'c = h(a,b)',
  ...         'a = f(z)',
  ...         'b = g(z,y)',
  ...         'd = k(b,c)',
  ...     ])
  ... )) in [
  ...     [ 'a = f(z)', 'b = g(z,y)', 'c = h(a,b)', 'd = k(b,c)' ],
  ...     [ 'b = g(z,y)', 'a = f(z)', 'c = h(a,b)', 'd = k(b,c)' ],
  ... ]
  

• extract_const_assigns(ast)

  Transform an AST by extracting its constant assignment statements.

  >>> from compiler import parse
  >>> from compiler_.ast.api import similar
  >>> ast, const_for = extract_const_assigns(parse('a = 0'))
  >>> similar(ast, parse('a = __a'))
  True
  >>> const_for
  {'__a': 0}
  

• free_vars(ast, *args, **kw)
• is_const(ast)

  Whether an AST represents a constant expression.

  I'm not sure what "constant" means yet, but here are some examples:

  >>> from compiler import parse
  >>> all(is_const(parse(s, mode='eval')) for s in (
  ...     '0',
  ...     'True',
  ...     'None',
  ...     '"foo"',
  ...     '[1,2]',
  ...     '(False, [])',
  ...     '{"a": 1}',
  ...     '{"a": 0, (True, False): [None, 3, "fish", ()]}',
  ... ))
  True
  

  And some non-examples, some of which maybe should be reclassified:

  >>> any(is_const(parse(s, mode='eval')) for s in (
  ...     '0+1',
  ...     '~8',
  ...     '0 < 1',
  ...     'not True',
  ...     '"fo%s" % "o"',
  ...     'len([1,2])',
  ...     '[1,2][0]',
  ...     '[1,a]',
  ...     '[a for a in [1,2]]',
  ...     '{"a": 0}.keys()',
  ...     'set()',
  ...     'list()',
  ...     'dict()',
  ...     'dict',
  ...     'lambda: 3',
  ...     'lambda a: a',
  ... ))
  False
  

• local_vars(ast, *args, **kw)
• walk(x, visitor, walker = None, verbose = None)

  Wrap compiler.walk to handle 'None' and sequences.

Imported Names

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