What is syntax directed translation?

Syntax Directed Translation is a method of compiler implementation where the source language translation is completely driven by the parser. Here's a step-by-step explanation:

1. Understanding Syntax Directed Translation: Syntax Directed Translation refers to a method of compiler design where the parsing of the source program drives the entire translation process. It's a way of defining the values of certain attributes associated with the programming language's grammar symbols.

2. Role of Syntax Tree: In Syntax Directed Translation, a parse tree (also known as a syntax tree) is generated, which conforms to the grammar of the source language. This tree is then traversed in a specific order (such as depth-first) to generate an output in the target language.

3. Attributes and Semantic Rules: Each node in the syntax tree has a set of attributes. The values of these attributes are computed by the so-called "semantic rules" associated with each grammar rule. The semantic rules are executed when the corresponding grammar rule is used during the construction of the syntax tree.

4. Types of Syntax Directed Translation: There are two types of Syntax Directed Translation - S-attributed and L-attributed. S-attributed definitions have semantic rules that only use attributes of the node's children and itself. L-attributed definitions allow attributes to be passed from left siblings and parents to right siblings.

5. Application: Syntax Directed Translation is used in the implementation of compilers and interpreters, where the source code needs to be translated into a target language, often machine language. It's a powerful tool for defining the translation in a clear and implementable way.