Editing Abstract Syntax Tree

Jump to: navigation, search

Please note that you are now editing the latest revision of this page, which is not the approved one shown by default.

Warning: You are not logged in.

Your IP address will be recorded in this page's edit history.
The edit can be undone. Please check the comparison below to verify that this is what you want to do, and then save the changes below to finish undoing the edit.
Latest revision Your text
Line 1: Line 1:
olJbLE https://www.genericpharmacydrug.com
+
An abstract syntax tree (AST) is a finite, labeled, directed tree, where the internal nodes are labeled by operators, and the leaf nodes represent the operands of the node operators. Thus, the leaves have nullary operators, i.e., variables or constants. In computing, it is used in a parser as an intermediate between a parse tree and a data structure, the latter which is often used as a compiler or interpreter's internal representation of a computer program while it is being optimized and from which code generation is performed. The range of all possible such structures is described by the abstract syntax.
 +
<br><br>
 +
 
 +
An AST differs from a parse tree by omitting nodes and edges for syntax rules that do not affect the semantics of the program. The classic example of such an omission is grouping parentheses, since in an AST the grouping of operands is explicit in the tree structure. Creating an AST in a parser for a language described by a context free grammar, as nearly all programming languages are, is straightforward. Most rules in the grammar create a new node with the nodes edges being the symbols in the rule. Rules that do not contribute to the AST, such as grouping rules, merely pass through the node for one of their symbols. Alternatively, a parser can create a full parse tree, and a post-pass over the parse tree can convert it to an AST by removing the nodes and edges not used in the abstract syntax.
 +
 
 +
[[Category:Basic Concepts]]

Please note that all contributions to eplmediawiki may be edited, altered, or removed by other contributors. If you do not want your writing to be edited mercilessly, then do not submit it here.
You are also promising us that you wrote this yourself, or copied it from a public domain or similar free resource (see Eplmediawiki:Copyrights for details). Do not submit copyrighted work without permission!

Cancel | Editing help (opens in new window)
Personal tools
Namespaces

Variants
Actions
Navigation
extras
Toolbox