Recursive Descent Parser

[jason8998]

I'm writing a program in C for my programming languages class which must implement a RDP using a certain EBNF grammar for legal C statements. I have never programmed in C, so I have been having a tough time formulating the steps that can do this without being ugly, so I would like some advice on writing the parser if anyone can help.

Here is the EBNF grammar

<statement> ::= ; | <assignment> | <ifStatement> | <whileStatement>

<assignment> ::= <identifier> = <expression> ;

<ifStatement> ::= if ( <expression> ) <statement> [ else <statement> ]

<whileStatment> ::= while ( <expression> ) <statement>

<expression> ::= <conjunction> { | | <conjunction> }*

<conjunction> ::= <relation> { && <relation> }*

<relation> ::= <addition> { (< | <= | > | >= | == | !=) <addition> }*

<addition> ::= <term> { (+ | -) <term> }*

<term> ::= <negation> { (* | /) <negation> }*

<negation> ::= [ ! ] <factor>

<factor> ::= <identifier> | <literal> | ( <expression> )

<identifier> ::= <letter> | <identifier> <letter> | <identifier> <digit>

<letter> ::= a | b | ... | z | A | B | ... | Z

<digit> ::= 0 | 1 | 2 | ... | 9

<literal> ::= <boolean> | <integer>

<boolean> ::= true | false

<integer> ::= <digit> | <integer> <digit>

right now, my program is reading input from a sample text file which contains single lines of sample code. It saves each line in a character array, so that is how I am planning on working with each line of text.

I am thinking of making a statement function, that will parse through the string until it finds either a ";" or "=" or a "(" and then depending on what it finds, passing the string down into the appropriate function for that character, ie. if I find the equal sign, it will be an assignment, so I jump into an assignment function.

Does this seem feasible?

[Salem]

> I have never programmed in C
But are you an experienced programmer in some other language?

If not, this seems a tough first assignment.

A separate function for each BNF production is one way to go.

[jason8998]

yeah I've programmed in Java before, but never C.