def makeNode(className, lvl, context):
"""
Given a string className, a tree-depth level, and a context
stack, creates and returns a full AST node generated using
the PCFG. All fields and children of this AST node are
recursively populated as necessary.
Args:
className: string class name of the node that should be
created, e.g. "Module" or "FunctionDef"
lvl: current depth in the AST. The initial call to this
function should have lvl=0. This is mainly used for
help printing out logs of the tree creation, but can
certainly be used in the future to do smarter generation
in a context-sensitive way.
context: a list, representing a stack, of ancestors in
this AST call-chain. Each element of the stack
is of the form (className, fieldName), e.g.
("FunctionDef", "args") meaning that this current
node is a child of FunctionDef under its "args" field.
"""
log("makeNode({})".format(className),lvl)
# copy object since `objects` just stores representative
# object types
node = copy.copy(objects[className])
# Get possible rules and draw a random rule from those given
# the probabilities of each rule in the PCFG
possible_rules = heads[className]
probabilities = [pcfg[rule] for rule in possible_rules]
sRule = util.random_draw(possible_rules, probabilities)
(head, constituent) = util.sRule2tRule(sRule)
log("rule: {}".format(sRule),lvl)
if constituent != "<NULL>":
# For each RHS element in the rule, populate the element
# appropriately and set the attribute.
for attrPair in constituent:
newContext = context + [(className, attrPair[0])]
populatedField = populateField(field=attrPair[1], lvl=lvl+1, context=newContext)
setattr(node, attrPair[0], populatedField)
return node
def make_primitive(primitive_className, context): """ Given the class name of a primitive, as well as the context stack, returns a randomly chosen primitive of the correct type following certain restrictions if applicable. Args: primitive_className: the classname of the primitive. Should be one of the seven class names given in util.PRIMITIVE_CLASSNAMES context: context stack """ # Recall primitives dict is of the form: # primitives[pcn]["normal"|"special"]["vals"|"freqs"] style = "special" if is_namelike(primitive_className, context) else "normal" # Randomly draw one primitive vals = primitives[primitive_className][style]["vals"] frequencies = primitives[primitive_className][style]["freqs"] return util.random_draw(vals, frequencies)
