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https://github.com/rswinkle/c_interpreter

Aims to be interpreted C written in C.
https://github.com/rswinkle/c_interpreter

c interpreted-programming-language interpreter preprocessor recursive-descent-parser

Last synced: 2 months ago
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Aims to be interpreted C written in C.

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README

        

C_Interpreter
=============

[![Build Status](https://travis-ci.org/rswinkle/C_Interpreter.svg?branch=master)](https://travis-ci.org/rswinkle/C_Interpreter)
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[http://www.robertwinkler.com/projects/c_interpreter.html](http://www.robertwinkler.com/projects/c_interpreter.html)

[![Run on Repl.it](https://repl.it/badge/github/rswinkle/C_Interpreter)](https://repl.it/github/rswinkle/C_Interpreter)

This started as C port of an old college assignment
in C++. You can see that in the first commit though I
might have made some minor changes/improvements during
port.

Now my goal is to make something approaching scriptable
C. I'll consider it done when it can run itself ...
so it'll probably never be completely done.

Download
========
Get the source from [Github](https://github.com/rswinkle/C_Interpreter).

Alternatives
============
If you're looking for something more professional there's

* [Cling](http://root.cern.ch/drupal/content/cling)
* [Ch](http://www.softintegration.com/)

* [TCC](http://en.wikipedia.org/wiki/Tiny_C_Compiler), a compiler that's so
fast and self-contained they have a command line switch -run to immediately
run it after compiling so you can use C as a JIT scripting language,

Tests
=====
I've kept the old tests around (updating them so they
keep working) but I've been adding new tests for
new features. They're not comprehensive and they
don't test every edge case but they're growing.

Misc
====
I'm using the 5th edition of C: A Reference Manual for
all the nitty gritty details and the very convenient
complete C grammar/syntax in the appendix.

I've also added a BNF spec for C I found online just
to have something for reference in the repository.

Current Grammar (work in progress)
==================================
### Preprocessor

#include "relative path based on current directory"
#define name
#define name sequence_of_tokens
#define name ( identifier-list ) sequence_of_tokens
#undef name
# (null directive)

It also of course supports actually using the macros.

### C language

translation_unit -> top_level_declaration
translation_unit top_level_declaration

top_level_declaration -> declaration
function_definition

function_definition -> declaration_specifier function_declarator compound_statement

function_declarator -> identifier '(' parameter_list ')'

parameter_list -> parameter_declaration
parameter_list ',' paramater_declaration

parameter_declaration -> declaration_specifier identifier

declaration -> declaration_specifier initialized_declarator_list ';'

initialized_declarator_list -> initialized_declarator
initialized_declarator_list ',' initialized_declarator

initialized_declarator -> identifier
identifier '=' assign_expr

declaration_specifier -> char, signed char
short, short int, signed short, signed short int
int, signed int, signed
long, long int, signed long, signed long int

unsigned char
unsigned short, unsigned short int
unsigned, unsigned int
unsigned long, unsigned long int

float
double

compound_statement -> '{' decl_or_stmt_list '}'

decl_or_stmt_list -> decl_or_stmt
decl_or_stmt_list decl_or_stmt

decl_or_stmt -> declaration
statement

statement -> expr_stmt
while_stmt
for_stmt
do_stmt
if_stmt
print_stmt
compound_statement
return_stmt
goto_stmt
labeled_stmt
break_or_continue_stmt
switch_stmt
case_or_default_stmt
null_stmt

null_stmt -> ';'

switch_stmt -> switch '(' expr ')' statement

case_or_default_stmt -> case constant_expr ':'
default ':'

constant_expr -> cond_expr //nothing but integer literals allowed
//see tests/switch.c

break_or_continue_stmt -> break ';'
continue ';'

labeled_stmt -> identifier ':' statement

do_stmt -> do statement while '(' expr ')' ';'

while_stmt -> while '(' expr ')' statement

for_stmt -> for for_expressions statement

for_expressions -> '(' initial_clause ';' expr ';' expr ')'

initial_clause -> expr
declaration

if_stmt -> if '(' expr ')' statement
if '(' expr ')' statement else statement

print_stmt -> print expr ';'

goto_stmt -> goto identifier ';'

expr_stmt -> expr ';'

expr -> comma_expr

comma_expr -> assign_expr
assign_expr ',' assign_expr

assign_expr -> cond_expr
identifier assign_op assign_expr

assign_op -> one of '=' '+=' '-=' '*=' '/=' '%='

cond_expr -> logical_or_expr
logica_or_expr '?' expr ':' cond_expr

logical_or_expr -> logical_and_expr
logical_or_expr '||' logical_and_expr

logical_and_expr -> bit_or_expr
logical_and_expr '&&' bit_or_expr

bit_or_expr -> bit_xor_expr
bit_or_expr '|' bit_xor_expr

bit_xor_expr -> bit_and_expr
bit_xor_expr '^' bit_and_expr

bit_and_expr -> equality_expr
bit_and_expr '&' equality_expr

equality_expr -> relational_expr
equality_expr '==' relational_expr
equality_expr '!=' relational_expr

relational_expr -> shift_expr
relational_expr relational_op shift_expr

relational_op -> one of '<' '>' '<=' '>='

shift_expr -> add_expr
shift_expr '<<' add_expr
shift_expr '>>' add_expr

add_expr -> mult_expr
add_expr '+' mult_expr
add_expr '-' mult_expr

mult_expr -> unary_expr
mult_expr mult_op unary_expr

mult_op -> one of '*' '/' '%'

unary_expr -> postfix_expr
sizeof_expr
bit_negation_expr
logical_negation_expr
unary_minus_expr
unary_plus_expr
preincrement_expr
predecrement_expr

preincrement_expr -> '++' unary_expr
predecrement_expr -> '--' unary_expr

unary_plus_expr -> '+' unary_expr
unary_minus_expr -> '-' unary_expr

logical_negation_expr -> '!' unary_expr

bit_negation_expr -> '~' unary_expr

sizeof_expr -> sizeof '(' type-name ')'
-> sizeof unary-expr

postfix_expr -> function_call
primary_expr
postincrement_expr
postdecrement_expr

postincrement_expr -> postfix_expr '++'
postdecrement_expr -> postfix_expr '--'

function_call -> identifier '(' expression_list ')'

expression_list -> assign_expr
expression_list ',' assign_expr

primary_expr -> identifier
constant
'(' expr ')'

Building and Running
====================
I use [premake](http://premake.github.io/) for generating makefiles and have shell scripts for running
all my tests at once.

~ $ git clone https://github.com/rswinkle/C_Interpreter.git
Cloning into 'C_Interpreter'...
remote: Reusing existing pack: 489, done.
remote: Total 489 (delta 0), reused 0 (delta 0)
Receiving objects: 100% (489/489), 168.87 KiB | 301.00 KiB/s, done.
Resolving deltas: 100% (264/264), done.
Checking connectivity... done.
~ $ cd C_Interpreter/
~/C_Interpreter $ premake4 gmake
Building configurations...
Running action 'gmake'...
Generating build/Makefile...
Generating build/cinterpreter.make...
Done.
~/C_Interpreter $ cd build/
~/C_Interpreter/build $ make
==== Building cinterpreter (debug) ====
...
Linking cinterpreter
~/C_Interpreter/build $ ./cinterpreter
Usage: ./cinterpreter [-E] script
~/C_Interpreter/build $ ./cinterpreter ../tests/switch.txt
[ouhput from switch.txt here]
~/C_Interpreter/build $ ../runtests.py
Should be nothing here, only failures produce output
~/C_Interpreter/build $ ../run_valgrind_tests.py
Same here. Note this may take a minute, valgrind makes things slow
~/C_Interpreter/build $