How to view Clang AST?
The method with -cc1 invocation will have problem with includes and recognizing C++. For full-featured parsing, use: clang -Xclang -ast-dump file.cpp
abstract-syntax-tree
Malformed String ValueError ast.literal_eval() with String representation of Tuple
ast.literal_eval (located in ast.py) parses the tree with ast.parse first, then it evaluates the code with quite an ugly recursive function, interpreting the parse tree elements and replacing them with their literal equivalents. Unfortunately the code is not at all expandable, so to add Decimal to the code you need to copy all the code … Read more
TypeScript: get syntax tree
The TypeScript parser doesn’t directly produce a tree like that, but you can still use its object model to do all sorts of things. We use it in some tools to do syntax transforms for testing purposes, for example. Here’s a snippet that you can use to print the syntax tree: import ts from “typescript”; … Read more
What’s the difference between parse trees and abstract syntax trees (ASTs)?
This is based on the Expression Evaluator grammar by Terrence Parr. The grammar for this example: grammar Expr002; options { output=AST; ASTLabelType=CommonTree; // type of $stat.tree ref etc… } prog : ( stat )+ ; stat : expr NEWLINE -> expr | ID ‘=’ expr NEWLINE -> ^(‘=’ ID expr) | NEWLINE -> ; expr … Read more
Simple example of how to use ast.NodeVisitor?
ast.visit — unless you override it in a subclass, of course — when called to visit an ast.Node of class foo, calls self.visit_foo if that method exists, otherwise self.generic_visit. The latter, again in its implementation in class ast itself, just calls self.visit on every child node (and performs no other action). So, consider, for example: … Read more
What is JavaScript AST, how to play with it?
1.You can take a look at AST explorer. An online tool to explore the ASTs generated by more than 10 parsers. It is a good tool to learn AST tree of a language. AST explorer source at Github.com. 2.Also you can paste your js code into JavaScript AST visualizer and click “show ast” button, you … Read more
How to construct an abstract syntax tree
Well, first off, the grammar is used to construct a parse tree from an expression. So if you already have a parse tree, you don’t need the grammar. Depending on how much work your parser does, the resulting tree that is formed from parsing an expression could already be an abstract syntax tree. Or it … Read more
How to create AST with ANTLR4?
Ok, let’s build a simple math example. Building an AST is totally overkill for such a task but it’s a nice way to show the principle. I’ll do it in C# but the Java version would be very similar. The grammar First, let’s write a very basic math grammar to work with: grammar Math; compileUnit … Read more
What kinds of patterns could I enforce on the code to make it easier to translate to another programming language? [closed]
I’ve been building tools (DMS Software Reengineering Toolkit) to do general purpose program manipulation (with language translation being a special case) since 1995, supported by a strong team of computer scientists. DMS provides generic parsing, AST building, symbol tables, control and data flow analysis, application of translation rules, regeneration of source text with comments, etc., … Read more
What is the difference between an Abstract Syntax Tree and a Concrete Syntax Tree?
A concrete syntax tree represents the source text exactly in parsed form. In general, it conforms to the context-free grammar defining the source language. However, the concrete grammar and tree have a lot of things that are necessary to make source text unambiguously parseable, but do not contribute to actual meaning. For example, to implement … Read more