Question

C++ Question

The first phase of compilation is called scanning or lexical analysis. This phase interprets the input program as a sequence of characters and produces a sequence of tokens, which will be used by the parser.

Write a C++ program that implements a simple scanner for a source file given as a command-line argument. The format of the tokens is described below. You may assume that the input is syntactically correct. Optionally, your program can build a symbol table (a hash table is a good choice), which contains an entry for each token that was found in the input. When all the input has been read, your program should produce a summary report that includes a list of all the tokens that appeared in the input, the number of times each token appears in the input and the class of each token. Your program should also list how many times tokens of each category appeared in the input.

Sample token format:

        keyword -> if | then | else | begin | end

        identifier -> character | character identifier

        integer -> digit | digit integer

        real -> integer.integer

        special -> ( | ) | [ | ] | + | - | = | , | ;

        digit -> 0|1|2|3|4|5|6|7|8|9

        character -> a|b|c ... |z|A|B|C ... |Z

Answer 1

ASSUMPTION

Hash function will return an integer from 0 to 19

vector <string> hashTable[20];

int hashTableSize=20;

Implementation of hash tables with separete chaining ( open hashing)

FOR SEARCH

void search(string s)

{

//Compute the index by using the hash function

int index = hashFunc(s);

//Search the linked list at that specific index

for( int i =0; i< hashTable[index].size() ; i++)

{

if(hashTable[index] [i] == s)

{

cout<< s << " is found !"<<endl;

return;

}

}

cout<< s<<" is not found"<<endl;

}

INSERT

void insert(string s)

{

// compute the index using hash function

int index = hashFunc(s);

//Insert the element in the linked list at the particular index

hashTable[index].push_back(s);

}

}