Salient Features of India constitution especially power and functions
data structure of symbol table.pptx
1. NADAR SARAWATHI COLLEGE OF ARTS
AND SCIENCE,THENI.
DEPARTMENT OF COMPUTER SCIENCE
DATA STRUCTURE OF SYMBOL TABLE
BY:
B.POORANI
I-MSC(CS)
2. Symbol tables
A data structure used by a compiler to keep track of semantic of
names.
•Determine whether the variable is defined already or not.
•Determine the scope
Search : access the information associated with given name.
Insert: add a name into the table.
Delete : remove a name when its scope is closed.
3. Block structured languages
Two basic operation : set and reset
The set operation is invoked when the beginning of a block is recognized
during compilation.
The reset operation ,is applied when the end of a block is encountered.
4. Four structure
a. Unordered symbol table
b. Ordered symbol table
c. Tree structured symbol table
d. Hash symbol table
5. Unordered list:
1. For a very small set of variable.
2. Coding is easy , but performance is bad for large number of variables.
Ordered linear list:
1. Use binary search on arrays,
2. Insertion and deletion are expensive.
3. Coding is relatively easy.
6. Binary search tree:
1. O(log n) time per operation (search ,insert or delete)for n variables.
2. Coding is relatively different.
Hash table:
1. Most commonly used.
2. Very efficient provided the memory space is adequately larger than the
number of variable.
3. Coding is not too difficult.
7.
8. Content in a symbol table
•Possible entries in a symbol table:
Name : a string
Attribute:
Reserved word
Variable name
Type name
Procedure name
Constant name