代做Parser留学生、programs代写、代写c++、代做c/c++程序语言

日期：2019-12-09 10:22

Project 2: The Parser

General Description:

Implement the Parser for the Compiler as an LL(1) Push Down Automata using the Pascal Grammar 2

posted on the course website (published after Homework 2 is due).

We will implement a “Syntax Driven” compiler, meaning the Parser is the “main”. Use the code provided

on Multilab in pas.cpp as the actual main() to invoke parser p; p.compile(filename);

Given:

- pas.cpp provided main() program

- pas my solution, executable

- prints.h/.cpp print functions for the given grammar and token ids

- all of the files for my project 1.3 (the Scanner). You may use these or your own code.

- *.pas test pascal programs (more will be added by Nov 18)

- grammar.h contains MOST of the productions for our grammar as the 2-D array we worked

on in class. Finish this by adding the productions for TOK_STMT and TOK_N_VAL

as mentioned in the comments.

You may implement your own grammar, and not use this one, of course.

Required:

- use the pas.cpp provided for the test program.

- write a Parser class in parser.h and parser.cpp It will of course need to declare a Scanner object

as one of its data members.

- The Parser must use a Stack of tokens. The token.h from Project 1.3 has been extended to

include Non-Terminals of the given Pascal Grammar, if you wish to use that.

- You may use the C++ standard <stack> class, or write your own. If you write your own, the stack

must hold at least 100 tokens; a dynamic stack is preferable.

- The compile() method, and its sub-methods, MUST implement a PDA as described in the class

notes. Small variations are allowed, but the main loop must (each time through the loop):

o Pop the top off the stack

o Either consume a token or push the RHS of a production (or error)

Test Messages:

- Each time a Terminal is consumed by the PDA, print a message with the Token ID string of the

consumed token. Ex: TEST: tokenId consumed

- Each time a Non-Terminal is popped and a production selected to push, print the production

chosen. Ex: TEST: PROD: 15 TOK_N_TYPE --> INTEGER { INTEGER }

where 15 is the production number (array index) and { INTEGER } is the select set.

You do not have to print the select set, but it may be helpful.

- If you use the given token.h? test print functions have been provided in prints.h/.cpp

Error Messages:

- The compile() method returns any error message, or “” for no error (successful parse).

- If a method of the scanner finds an error, simply return the message from the scanner.

- Messages should include the Token ID (as a printable string) when appropriate. If you use the

given token.h, the TOKENID_STR[] constant array is provided for translating TOKENID to a

printable string.

- Parse errors would include:

o Token expected…

This would occur when a Terminal is popped off the stack that does not match the next

token from the source. Print both Token IDs in the message.

o No Production Found…

This would occur when a Non-Terminal is popped off the stack, and the next token from

the source does not match the select set of any production for that Non-Terminal. This

message will never appear if there is a DEFAULT select set for every Non-Terminal in the

grammar. If this message does occur, it should include the top token from the stack and

the next token from the source. Ex:

No production found for top=tokenId next token=tokenId

o Extra tokens at end of source.

This occurs when the stack goes empty, but there are more tokens in the source file.

o Unexpected end of source.

This occurs when the source returns TOK_EOS (end of source), but the stack is not

empty.

Submit in Canvas:

Submit a .zip file that contains all files needed to compile and execute your program. It should compile

by one of two methods:

1. if you have a make file, then just make

2. if you have no make file, then g++ -o pas *.cpp