https://github.com/RohitBhatta/Improved-Interpreter
Advanced Interpreter with Pointers and Structs
https://github.com/RohitBhatta/Improved-Interpreter
Last synced: 5 months ago
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Advanced Interpreter with Pointers and Structs
- Host: GitHub
- URL: https://github.com/RohitBhatta/Improved-Interpreter
- Owner: RohitBhatta
- Created: 2016-09-12T02:42:37.000Z (over 8 years ago)
- Default Branch: master
- Last Pushed: 2016-09-12T02:43:21.000Z (over 8 years ago)
- Last Synced: 2024-04-24T15:34:35.182Z (12 months ago)
- Language: C
- Homepage:
- Size: 12.7 KB
- Stars: 1
- Watchers: 2
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README
Awesome Lists containing this project
- AwesomeInterpreter - Improved-Interpreter
README
Due date: Sunday 1/31/2016 @ 11:59pm
- Please remember to answer the questions in REPORT.txt
Objective:
~~~~~~~~~~
- Improve your C programming skills
- Work with pointers, structs, and the dynamic heap
Assignment:
~~~~~~~~~~~
(1) Answer the questions in REPORT.txt
(2) Finish an interpreter for a more realistic language that the one we defined
in p1.
The interpreter generally has 4 concerns:
- Source character encoding. A string of ASCII characters in our case.
- The lexical rules: how those characters are converted to a sequence of
tokens. Our language has the following tokens.
* keywords: if else while
* special characters: = == ( ) { } + * ;
* identifiers: start with lower case letters followed by a sequence of
lower case letters and numbers.
examples: x hello h123 xy3yt
* immediate values: sequences of digits representing integers. They always
start with a digit but could contain '_' characters that are
ignored
examples: 12 0 12_234
- The syntax: rules for combining tokens into meaningful constructs. Our syntax
looks like familiar syntax for popular languages like C and Java. You're given
most of that code but you need to change it in order to implement the "if" and
"while" statements. Things to keep in mind about our language:
* ';' is optional
* we only have assignment, if, and while statements
* the following operators are supported '*', '+', '=='
- Semantics: assigning meaning to syntactically correct programs
What you need to do:
~~~~~~~~~~~~~~~~~~~~
- Finish the implementation of the lexer. In order to keep the implementation
simple, the code assumes that there is a global variable that represents
the current valid token, starting with the first token in the program.
In order to finish the lexer, you need to implement the following functions:
char *remaining(); // returns the program text starting to the current token
// used for error reporting
void consume(); // consume the current token, move the cursor to the
// next valid token. Must handle end of string.
int isWhile(); // current token is "while"
int isIf(); // current token is "if"
int isElse(); // current token is "else"
int isSemi(); // current token is ';'
int isLeftBlock(); // current token is '{'
int isRightBlock();// current token is '}'
int isEq(); // current token is '='
int isEqEq(); // current token is "=="
int isLeft(); // current token is '('
int isRight(); // current token is ')'
int isEnd(); // current token is end of string (ASCII 0)
int isId(); // current token is identifier
int isInt(); // current token is an immediate value
int isMul(); // current token is '*'
int isPlus(); // current token is '+'
char *getId(); // if current token is an idenifier, return it as a
string
int getInt(); // if current token is an immediate value, return the value
- The language syntax is expressed using recursive functions starting with
the "program()" function. You need to understand what it's doing and you'll
need to make some changes to it in order to implement the "if" and "while"
statements.
- You'll need to implement a symbol table, exposed using those two functions:
int get(char *id); // return the value of the given identifier
void set(char *id, int value); // set the value of the given identifier
// and print it
Examples:
~~~~~~~~~
./p2 "x = 10;"
x:10
./p2 "x = 2_09 ; a = 17;"
x:209
a:17
./p2 "x = 2_09 ; a = 17; x = 3 + 12"
x:209
a:17
x:15
Files you're allowed to change:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
p2.c
Files you're supposed to leave alone:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Everything else
To compile:
~~~~~~~~~~~
make
To run test:
~~~~~~~~~~~~
make clean test
To run one test (e.g. t1):
~~~~~~~~~~~~~~~~~~~~~~~~~~
make clean t1.run
To make the output less noisy:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
make -s clean test
To add your own tests:
~~~~~~~~~~~~~~~~~~~~~~
Let's say you want to create a test called "bob".
- create a file bob.test that contains a program in the first line
- create a file bob.ok that contains the expected output
To debug with gdb
~~~~~~~~~~~~~~~~~
make
gdb ./p2
(gdb) run "x = 100; a = 30;"