Fundamentals of Language Processor Analysis Phase Synthesis Phase Lexical Analysis Syntax Analysis Semantic Analysis Intermediate Code Generation Symbol Table Criteria of Classification of Data Structure of Language Processing Linear Data Structure Non-linear Data Structure Symbol Table Organization Sequential Search Organization Binary Search Organization Hash Table Organization Allocation Data Structure : Stacks and Heaps

1. SYSTEM PROGRAMMING
TOPIC : Overview of Language Processor : Fundamentals of LP , Symbol
Table , Data Structure for LP
SUBMITTED BY :
Bhavin Darji
SUBMITTED TO :
Prof.

2. Fundamentals of Language Processor
Language Processing = Analysis of SP + Synthesis of TP
Source program as a analysis phase
Target program in synthesis phase
There are 3 components
◦ Lexical rule
◦ Syntax rule
◦ Semantic rule

3. Analysis Phase
This specification consists of three components
Lexical rules
Specify the information and formation of valid lexical units in the source language
Syntax Rules
Specify the information and formation of valid statements in the source language
Semantic Rules
Associated with valid statements of language

4. Consider the following example
A = (B* 100) /D;
Lexical units identifies =, * and / operators, 100 as constant, and the remaining strings
as identifiers.
Syntax analysis identifies the statement as an assignment statement with A as the left
hand side and (B * 100) / D as the expression on the right hand side.
Semantic analysis determines the meaning of the statement to be the assignment of
B X 100 / D to A.

5. Synthesis Phase
 It performs two main activities:
 Creation of data structures in the target program (memory allocation)
 Generation of target code (code generation)
 Example
MOVER AREG, PROFIT
MULT AREG, 100
DIV AREG, COST_PRICE MOVEM AREG, PERCENT_PROFIT
…

6. Lexical Analysis
Reads the source code & divide the source code into tokens.
Token is group of characters with meaning.
Lexical analyzer takes a stream of Lexeme as a input and the output is stream of token.

7. Example
int a , b;
int Ans;
ans = a+b;
Symbol Type Address
1. int keyword
2. a Identifier 2000

8. Syntax Analysis
Done in order to verify the grammatical mistake of source code.
Takes a stream of tokens as input and generate a syntax tree.
Example : a=b*c
=
a *
b c

9. Semantic Analysis
It verify the meaning of each and every sentence.
It just verify weather an operator is operating on required number of operand or not.
Example : int a , b, ans ;
ans = a + b;

10. Intermediate code generation
Source code is converted into a intermediate representation known as three address code.
Example :
◦ A = b*c+d;
◦ T1=b*c;
◦ A=t1+d;
After this four analysis we get our target program.

11. The Symbol Table
Advance data structure used by compiler to store complete information of source code at any
phase
If new variable encountered that should be store into the symbol table.
Communicate with each and every phase of compiler.
Lexical
Analyzer
Semantic
Analyzer
Code
Generator
Symbol
Table
Syntax
Analyzer

12. Criteria of Classification of Data Structure
of LP:
Nature of a Data Structure :
◦ Linear or
◦ Non Linear
Purpose of a Data Structure :
◦ Search or
◦ Allocation

13. Linear Data Structure
Consist of a linear arrangement of elements in the memory.
Advantage : Facilities Efficient Search
Disadvantage :
◦ Require a contagious area of memory
◦ Wastage of Memory

14. Non Linear Data Structure
Overcomes the disadvantage of Linear DS.
Elements of Non linear DS are accessed using pointers.
Elements need not occupy contiguous area of memory.

15. Symbol Table Organization

16. Sequential Search Organization
#1
#2
#f
#n
Occupied Entries
Free Entries
n: Number of entries in the table f: Number of occupied entries

17. (2)Binary Search Organization
All entries in a table are assumed to satisfy an ordering relation.
‘<‘ relation implies that the symbol occupying an entry is ‘smaller or larger than’ the symbol.
If the new symbol is smaller then it will be put at left side otherwise put at right side.
Every new symbol the existing symbol may have to be shifted to ensure ordering
relation.
Hence , this is not good for the symbol table.
It is suitable for table which has fixed set of symbol.
Ex. Table of reserve word in a programming language.

18. (3)Hash Table Organization
There are three possibilities when eth entry will be arrived :
- Entry may be occupied by symbol S.
- Entry may be occupied by some other symbol.
- Entry may not occupied.
 Collision: when eth entry will be occupied by some other entry then that is collision.
A simple solution to avoid collision is to enter a distinct entry in symbol table. This technique is
known as direct entry organization.

19. Allocation Data Structures
1)Stacks
A linear data structure which satisfies following properties:
- Allocation and de-allocation are performed in a LIFO manner.
- Only last element is accessible at any time.
It has a limited size

20. 2)Heaps
Non Linear Data Structure
It is used for dynamic memory
Permits allocation and de-allocation of entities in random order
We are responsible to de-allocate the memory
It has no size restriction
We use pointer to access it , so it is slightly slower.

21. THANK YOU