Lexer
*This homework is a programming assignment.
*While working on the assignment, read this document THOROUGHLY.
Homework
In this homework, you need to complete lexer.py that we’ve worked on during the class. In our interpreter, a lexer needs to handle seven tokens as shown below.
Token Type
Token Value
NUMBER
0,1,2,3,….,9
PLUS
+
MINUS
-
MULTIPLICATION
*
DIVISION
/
LPAREN
(
RPAREN
)
Currently, our lexer produces NUMBER token and PLUS token. Complete lexer.py so that our lexer also produces other tokens (MINUS, MULTIPLICATION, DIVISION, LPAREN, RPAREN).
Assume that we run main.py with srcCode=“((12+3*5)+5/4)” with the completed lexer.py like the below.
import lexer
srcCode = "((12+3*5)+5/4)" tokSeq = lexer.tokenize(srcCode)
for i in tokSeq:
print(i.type, i.value)
main.py
Then, it should print a sequence of tokens:
LPAREN (
LPAREN (
NUMBER 12
PLUS +
NUMBER 3
MULTIPLICATION *
NUMBER 5
RPAREN )
PLUS +
NUMBER 5
DIVISION /
NUMBER 4
RPAREN )
