The document discusses syntax-directed translation (SDT) which is a method of compiler implementation where source language translation is driven by the parser. SDT uses an augmented context-free grammar called an attribute grammar to control semantic analysis and translation. SDT translates a string into a sequence of actions by attaching actions to each rule of the grammar. The parsing process and parse trees are used to direct semantic analysis and translation of the source program according to the order specified by the semantic rules embedded in the grammar.

1. SYNTAX Directed
Translation
Compiler Construction

3. National College of Business
Administration & Economics

4. Group Members
Wamiq Ali
Programmer
Sarmad Shuja
Programmer
Zain Abid
Programmer

5. Background
Parser uses a CFG(Context-free-Grammar) to validate the input
string and produce output for next phase of the compiler.

6. Introduction
Syntax-directed translation (SDT) refers to a method of compiler implementation
where the source language translation is completely driven by the parser.
The parsing process and parse trees are used to direct semantic analysis and the
translation of the source program. We can augment grammar with information to
control the semantic analysis and translation. Such grammars are called attribute
grammars.

7. Terminology
A common method of syntax-directed translation is translating a string in
to a sequence of actions by attaching one such action to each rule of a
grammar.
Formula
Grammar + semantic rule = SDT (syntax directed translation)

8. Syntax Directed Translation Scheme
1 The Syntax directed translation scheme is a context -free grammar.
2 The syntax directed translation scheme is used to evaluate the
order of semantic rules.
3 In translation scheme, the semantic rules are embedded within the
right side of the productions.
4
The position at which an action is to be executed is shown by
enclosed between braces. It is written within the right side of the
production.

9. Implementation of Syntax directed Translation
Syntax direct translation is implemented by constructing a parse tree and
performing the actions in a left to right depth first order.
SDT is implementing by parse the input and produce a parse tree as a
result.

10. Top Down

11. Bottom Up

12. Limitation
Without using global data to create side effects, some of the semantic
actions cannot be performed.
Example
Checking whether a variable is defined before its usage.
Checking the type and storage address of a variable.
Checking whether a variable is used or not.

13. Common Approach
A program with too many global variables is difficult to understand and
maintain.
Restrict the usage of global variables to essential items and use them
as objects.

14. Thank You