Abstract Syntax Tree (AST) AST:A tree representation of the abstract syntactic structure of source code (1+2)*(3+4) 2 4 The syntax of a PL is defined by a context-free grammar The grammar expansion forms a tree Can also infer semantics information (e.g.,variable type)on ASTAbstract Syntax Tree (AST) AST: A tree representation of the abstract syntactic structure of source code (1+2)*(3+4) * + + 1 2 3 4 The syntax of a PL is defined by a context-free grammar The grammar expansion forms a tree Can also infer semantics information (e.g., variable type) on AST