हम पायथन कोड रूपांतरण लागू करते हैं

एक पेड़ के रूप में प्रोग्राम कोड

BinOp(
  left  = Num(3),
  op    = Add(),
  right = BinOp(
            left  = Num(4),
            op    = Mult(),
            right = Name('x')
          )
)

import ast
my_tree = ast.parse("3 + 4*x")
print(ast.dump(my_tree))

Module(body=[Expr(value=BinOp(left=Num(n=3), op=Add(), right=BinOp(left=Num(n=4), op=Mult(), right=Name(id='x', ctx=Load()))))])

Module(body = [
    Expr(
        value = BinOp(
            left  = Num(n=3),
            op    = Add(),
            right = BinOp(
                left  = Num(n=4),
                op    = Mult(),
                right = Name(id='x', ctx=Load())
            )
        )
    )
])

संकलन प्रक्रिया: शेष

अन्य प्रोग्रामिंग भाषाओं से प्रतिमान

एएसटी के भीतर नोड रूपांतरण

	import ast
 
class MyOptimizer(ast.NodeTransformer):
 
    def visit_Name(self, node: ast.Name):
        if node.id == 'pi':
            return ast.Num(n=3.14159265)
        return node
 
tree = ast.parse("y = 2 * pi")
optimizer = MyOptimizer()
tree = optimizer.visit(tree)
print(ast.dump(tree))

import ast
 
class MyOptimizer(ast.NodeTransformer):
 
    def visit_Name(self, node: ast.Name):
        if node.id == 'pi':
            result = ast.Num(n=3.14159265)
            result.lineno = node.lineno
            result.col_offset = node.col_offset
            return result
        return node
 
tree = ast.parse("print(2 * pi)")
optimizer = MyOptimizer()
tree = optimizer.visit(tree)
code = compile(tree, "<string>", "exec")
exec(code)

def visit_Name(self, node: ast.Name):
        if node.id == 'pi':
            result = ast.Num(n=3.14159265)
            return ast.copy_location(result, node)
        return node

class MyVisitor(ast.NodeTransformer):
 
    def visit_BinOp(self, node: ast.BinOp):
        node.left = self.visit(node.left)
        node.right = self.visit(node.right)
        if isinstance(node.left, ast.Num) and isinstance(node.right, ast.Num):
            if isinstance(node.op, ast.Add):
                result = ast.Num(n = node.left.n + node.right.n)
                return ast.copy_location(result, node)
            elif isinstance(node.op, ast.Mult):
                result = ast.Num(n = node.left.n * node.right.n)
                return ast.copy_location(result, node)
        return node
 
    def visit_Name(self, node: ast.Name):
        if node.id == 'pi':
            result = ast.Num(n=3.14159265)
            return ast.copy_location(result, node)
        return node
 
tree = ast.parse("y = 2 * pi + 1")
optimizer = MyOptimizer()
tree = optimizer.visit(tree)
print(ast.dump(tree))

एएसटी में नोड्स की जाँच

import ast
 
class MyVisitor(ast.NodeVisitor):
 
    def __init__(self):
        self.modify_pi = False
 
    def visit_FunctionDef(self, node: ast.FunctionDef):
        if node.name == 'pi':
            self.modify_pi = True
        self.generic_visit(node)
 
    def visit_Name(self, node: ast.Name):
        if node.id == 'pi' and not isinstance(node.ctx, ast.Load):
            self.modify_pi = True
 
program = """
def pi():
    return 3.1415
print(2 * pi())
"""
tree = ast.parse(program)
my_visitor = MyVisitor()
my_visitor.visit(tree)
print("Pi modified:", my_visitor.modify_pi)

पायथन में स्थानीय मान

x = 1
def print_x():
    print(x)
    if False: x = 0
print_x()

निष्कर्ष