"""
One class which visits a syntax tree.
:githublink:`%|py|5`
"""
import ast
[docs]class CodeNodeVisitor(ast.NodeVisitor):
"""
Defines a visitor which walks though the syntax tree of the code.
.. exref::
:title: Get the tree of a simple function
The following code uses Python syntax but follows a SQL logic.
.. runpython::
:showcode:
:process:
import ast
import inspect
import textwrap
from pysqllike.translation.node_visitor_translator import CodeNodeVisitor
def myjob(input):
iter = input.select (input.age, input.nom, age2 = input.age2*input.age2)
wher = iter.where( (iter.age > 60).Or(iter.age < 25))
return wher
code = textwrap.dedent(inspect.getsource(myjob))
node = ast.parse(code)
v = CodeNodeVisitor()
v.visit(node)
for r in v.Rows :
print("{0}{1}: {2}".format(" " * r["indent"], r["type"], r["str"]))
:githublink:`%|py|39`
"""
[docs] def __init__(self):
"""
constructor
:githublink:`%|py|44`
"""
ast.NodeVisitor.__init__(self)
self._rows = []
self._indent = 0
self._stack = []
[docs] def push(self, row):
"""
Pushes an element into a list.
:githublink:`%|py|53`
"""
self._rows.append(row)
[docs] def generic_visit(self, node):
"""
Overrides ``generic_visit`` to check it is not used.
:githublink:`%|py|59`
"""
raise AttributeError("generic_visit_args should be used.")
[docs] def generic_visit_args(self, node, row):
"""
Overrides ``generic_visit`` to keep track of the indentation
and the node parent. The function will add field
``row["children"] = visited`` nodes from here.
:param node: node which needs to be visited
:param row: row (a dictionary)
:return: See ``ast.NodeVisitor.generic_visit``
:githublink:`%|py|71`
"""
self._indent += 1
last = len(self._rows)
res = ast.NodeVisitor.generic_visit(self, node)
row["children"] = [
_ for _ in self._rows[
last:] if _["indent"] == self._indent]
self._indent -= 1
return res
[docs] def visit(self, node):
"""
Visits a node, a method must exist for every object class.
:githublink:`%|py|84`
"""
method = 'visit_' + node.__class__.__name__
visitor = getattr(self, method, None)
if visitor is None:
raise TypeError("unable to find a method: " + method)
res = visitor(node)
# print(method, CodeNodeVisitor.print_node(node))
return res
[docs] @staticmethod
def print_node(node):
"""
Debugging purpose.
:githublink:`%|py|97`
"""
r = []
for att in ["s", "name", "str", "id", "body", "n",
"arg", "targets", "attr", "returns", "ctx"]:
if att in node.__dict__:
r.append("{0}={1}".format(att, str(node.__dict__[att])))
return " ".join(r)
[docs] def print_tree(self):
"""
Displays the tree of instructions.
:return: string
:githublink:`%|py|110`
"""
rows = []
for r in self.Rows:
rows.append(
("{0}{1}: {2}".format(
" " *
r["indent"],
r["type"],
r["str"])))
return "\n".join(rows)
@property
def Rows(self):
"""
returns a list of dictionaries with all the elements of the code
:githublink:`%|py|125`
"""
return [_ for _ in self._rows if not _.get("remove", False)]
def visit_Str(self, node):
cont = {
"indent": self._indent,
"type": "Str",
"str": node.s,
"node": node,
"value": node.s}
self.push(cont)
return self.generic_visit_args(node, cont)
def visit_Name(self, node):
cont = {
"indent": self._indent,
"type": "Name",
"str": node.id,
"node": node,
"id": node.id,
"ctx": node.ctx}
self.push(cont)
return self.generic_visit_args(node, cont)
def visit_Module(self, node):
cont = {
"indent": self._indent,
"type": "Module",
"str": "",
"body": node.body,
"node": node}
self.push(cont)
return self.generic_visit_args(node, cont)
def visit_FunctionDef(self, node):
cont = {"indent": self._indent, "type": "FunctionDef", "str": node.name, "name": node.name, "body": node.body,
"node": node, "returns": node.returns}
self.push(cont)
return self.generic_visit_args(node, cont)
def visit_arguments(self, node):
cont = {"indent": self._indent, "type": "arguments", "str": "",
"node": node, "args": node.args}
self.push(cont)
return self.generic_visit_args(node, cont)
def visit_arg(self, node):
cont = {"indent": self._indent, "type": "arg", "str": node.arg,
"node": node,
"arg": node.arg, "annotation": node.annotation}
self.push(cont)
return self.generic_visit_args(node, cont)
def visit_Assign(self, node):
cont = {"indent": self._indent, "type": "Assign", "str": "", "node": node,
"targets": node.targets, "value": node.value}
self.push(cont)
return self.generic_visit_args(node, cont)
def visit_Store(self, node):
#cont = { "indent":self._indent, "type": "Store", "str": "" }
# self.push(cont)
cont = {}
return self.generic_visit_args(node, cont)
def visit_Call(self, node):
if "attr" in node.func.__dict__:
cont = {"indent": self._indent, "type": "Call", "str": node.func.attr,
"node": node, "func": node.func}
else:
cont = {"indent": self._indent, "type": "Call", "str": node.func.id,
"node": node, "func": node.func}
self.push(cont)
return self.generic_visit_args(node, cont)
def visit_Attribute(self, node):
cont = {"indent": self._indent, "type": "Attribute", "str": node.attr,
"node": node, "value": node.value, "ctx": node.ctx, "attr": node.attr}
self.push(cont)
# last = len(self._rows)
res = self.generic_visit_args(node, cont)
if len(cont["children"]) > 0:
fir = cont["children"][0]
if fir["type"] == "Name":
parent = fir["node"].id
cont["str"] = "{0}.{1}".format(parent, cont["str"])
cont["children"][0]["remove"] = True
return res
def visit_Load(self, node):
#cont = { "indent":self._indent, "type": "Load", "str": "" }
# self.push(cont)
cont = {}
return self.generic_visit_args(node, cont)
def visit_keyword(self, node):
cont = {"indent": self._indent, "type": "keyword", "str": "{0}".format(node.arg),
"node": node, "arg": node.arg, "value": node.value}
self.push(cont)
return self.generic_visit_args(node, cont)
def visit_BinOp(self, node):
cont = {
"indent": self._indent,
"type": "BinOp",
"str": "",
"node": node}
self.push(cont)
return self.generic_visit_args(node, cont)
def visit_Mult(self, node):
cont = {
"indent": self._indent,
"type": "Mult",
"str": "",
"node": node}
self.push(cont)
return self.generic_visit_args(node, cont)
def visit_Compare(self, node):
cont = {
"indent": self._indent,
"type": "Compare",
"str": "",
"node": node}
self.push(cont)
return self.generic_visit_args(node, cont)
def visit_Gt(self, node):
cont = {"indent": self._indent, "type": "Gt", "str": "", "node": node}
self.push(cont)
return self.generic_visit_args(node, cont)
def visit_Lt(self, node):
cont = {"indent": self._indent, "type": "Lt", "str": "", "node": node}
self.push(cont)
return self.generic_visit_args(node, cont)
def visit_Num(self, node):
cont = {
"indent": self._indent,
"type": "Num",
"node": node,
"str": "{0}".format(
node.n),
'n': node.n}
self.push(cont)
return self.generic_visit_args(node, cont)
def visit_Return(self, node):
cont = {"indent": self._indent, "type": "Return", "node": node, "str": "",
'value': node.value}
self.push(cont)
return self.generic_visit_args(node, cont)
def visit_(self, node):
help(node)
assert False
