What is the difference between a Concrete Parse Tree (CST) and an Abstract Syntax Tree (AST)?

A Concrete Syntax Tree retains every literal character from the source text, including parentheses, semicolons, whitespace, and comments. An Abstract Syntax Tree discards superficial syntactic noise, preserving only the semantic structural logic of the program.

Does this tool execute my Python code?

No. The tool performs purely static lexical analysis and syntactic parsing into a grammar graph. The code is never run, interpreted, or sent to a runtime engine, making it safe to inspect arbitrary or untrusted code.

How does Python compile AST into execution bytecode?

Python's compiler pipeline operates in stages: Source Code → Lexical Tokenizer → Parse Tree → Abstract Syntax Tree (AST) → Symbol Table → Bytecode (Code Objects .pyc) → Python Virtual Machine (PVM) runtime execution.

What are common AST nodes in Python?

Common nodes include FunctionDef (function definitions), ClassDef (classes), Assign (variable assignment), BinOp (binary arithmetic like + or *), Compare (boolean expressions), and If/For/While (control flow).

Why do modern linters like Ruff and Flake8 rely on AST?

Regular expressions are fragile when searching code because they cannot understand scope, variable shadowing, or multi-line nesting. AST parsing allows tools to query program structure deterministically (e.g., 'find all calls to eval() inside function definitions').

Business & Finance

Python AST Syntax Tree & Lexical Token Hierarchy Inspector

Name: Python AST Syntax Tree & Lexical Token Hierarchy Inspector
Author: AnshuTechy

Inspect Python Abstract Syntax Trees (AST), lexical grammar tokens, and bytecode operator hierarchies in your browser. Parse module definitions, control flow branches, and expression nodes with interactive tree visualization.Documentation & FAQs ↓

Python AST Syntax Tree & Lexical Token Hierarchy Inspector — Interactive Console

Runs locally in your browser • Instant output

Load Preset:

Python Source Input10 lines · 47 tokens

def calculate_factorial(n: int) -> int:
    """Calculates factorial of n iteratively."""
    if n <= 1:
        return 1
    total = 1
    for i in range(2, n + 1):
        total *= i
    return total

print(calculate_factorial(5))

Lexical tokens balanced and ready for tree compilation.

Hierarchical AST Node Graph

▼ModuleTop-level Python Program ScopeL1

▼FunctionDefcalculate_factorialargs=(n: int) -> intL1

•ConditionalBranchif n <= 1:Boolean branching decisionL3

•Return1Expression return statementL4

•Assigntotal = 1Variable binding / AugAssignL5

•ForLoopfor i in range(2, n + 1):Iterative execution targetL6

•Assigntotal *= iVariable binding / AugAssignL7

•ReturntotalExpression return statementL8

•CallExprprint(calculate_factorial(5))Function or method invocationL10

Lexical Token Stream (47)

Line:Col	Token Type	Lexeme Value
1:1	KEYWORD	def
1:5	IDENTIFIER	calculate_factorial
1:24	DELIMITER	(
1:25	IDENTIFIER	n
1:26	DELIMITER	:
1:28	IDENTIFIER	int
1:31	DELIMITER	)
1:33	OPERATOR	->
1:36	IDENTIFIER	int
1:39	DELIMITER	:
2:5	LITERAL	""
2:7	LITERAL	"Calculates factorial of n iteratively."
2:47	LITERAL	""
3:5	KEYWORD	if
3:8	IDENTIFIER	n
3:10	OPERATOR	<=
3:13	LITERAL	1
3:14	DELIMITER	:
4:9	KEYWORD	return
4:16	LITERAL	1
5:5	IDENTIFIER	total
5:11	OPERATOR	=
5:13	LITERAL	1
6:5	KEYWORD	for
6:9	IDENTIFIER	i
6:11	KEYWORD	in
6:14	IDENTIFIER	range
6:19	DELIMITER	(
6:20	LITERAL	2
6:21	DELIMITER	,
6:23	IDENTIFIER	n
6:25	OPERATOR	+
6:27	LITERAL	1
6:28	DELIMITER	)
6:29	DELIMITER	:
7:9	IDENTIFIER	total
7:15	OPERATOR	*=
7:18	IDENTIFIER	i
8:5	KEYWORD	return
8:12	IDENTIFIER	total
10:1	IDENTIFIER	print
10:6	DELIMITER	(
10:7	IDENTIFIER	calculate_factorial
10:26	DELIMITER	(
10:27	LITERAL	5
10:28	DELIMITER	)
10:29	DELIMITER	)

Step-by-Step Instructions

4 Steps to Completion

1Phase 1

Paste any Python code snippet into the code editor or choose from preloaded algorithmic examples.

2Phase 2

Click 'Parse AST & Tokens' to generate the hierarchical syntax tree and lexical token stream.

3Phase 3

Click on any AST node in the visual tree to highlight its corresponding source code range and view internal attributes.

4Phase 4

Toggle between the interactive tree diagram, indented JSON AST schema, and linear lexical token table.

Practical Use Cases & Real-World Scenarios

Learning Compiler Design & Python Internals

Understand how the Python interpreter transforms plain source text into an Abstract Syntax Tree before compiling it into bytecode instructions.

Developing Static Analysis & Linting Rules

Prototype custom AST linters, code rewrite rules, and security pattern scanners (similar to Flake8, Ruff, and Bandit) by inspecting exact node schemas.

Debugging Complex Macro & Code Generation Scripts

Inspect the syntax tree output of automated code generators and refactoring libraries to ensure proper node nesting and scope boundaries.

Python AST Syntax Tree & Lexical Token Hierarchy Inspector

Hierarchical AST Node Graph

Lexical Token Stream (47)

Step-by-Step Instructions

Practical Use Cases & Real-World Scenarios

Full AST Node Hierarchy Visualizer

Lexical Token Stream Breakdown

Node Attribute & Scope Inspector

100% In-Browser Safe Parsing

Frequently Asked Questions

10 Most Popular Python IDE To Use in 2026

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