Alex (Lexer)

alex_7

In alex_7 you will find a parser that reconognize the following numbers:

• integer, eventually preceded by sign (+/-). Ex. +3, 3, -3
• rational, composed by 2 integers, one of which can be omitted. Ex. 1.2, .3, 1.
• floating point, Ex. 1e+3, -3e-5

This lexer will output a list of tokens

Happy (Parser)

Both parser also import a lexer, which you will find in the same folders, built with alex.

N.B.: alex_7 isn't the lexer of happy_7, they are separate, happy_7's parser inside happy_7 folder.

happy_2

• reconognize the matematical language of the direct polish notation, with integers and the operations: +,-,*,/. The parser will output a syntattic derivation tree.

happy_7

Reconognize a language composed by the following expressions:

• integers
• mathemantical operations: +,-,*,/
• equality test: =
• "if then else" function

This parser will output the result of the operations (not a syntattic tree this time).

Ex.

• input = "if = 3 3 then * + 3 4 / 6 3 else / 9 3"
• output = "14"