Description:

Pallyc is a simplified C compiler that supports nested-function definition.
This is an open-source project. Under the agreement of the license, any one can download the binary executive file as well as its source code.
The whole project is written in pure C++ code with the support of STL, which makes Pallyc compiling and running compatible on almost every platform, particularly Windows and Linux.

Goal:

Currently, those prevailing C compilers, such as GNU gcc, MS cl, etc, have no nested-function definition support.
Sometimes, programmer would find that nested-function definition(as in Pascal) can be very useful in making the code concise and hierarchical.
The ultimate goal of this Pallyc Project is to help those compilers become compatible with nested-function definition, by generalizing recognizable assembly code for each of those C compilers as input, respectively.
At that time, the role of Pallyc can be thought of as a mid-ware which builds a bridge between those popular, well-developed compilers and the concise, convenient, nested, hierarchical coding style.

Latest Features:

Now Pallyc source code could be compiled online. Use the this form or go to this URL have new experience of nested function style!

//program that generate the maximal common divisor for two integers int gcd(int u, int v) { /*definition of inner function*/ void swap(int &m, int &n) { long tmp; //cause a warning tmp = m; m = n; n = tmp; } if( u < v ) swap(u, v); int x, y; x = u; y = v; while(y != 0) { int t; t = y; y = x % y; x = t; } return x; } int main() { int a, b, result; a = 54; b = 33; result = gcd(a, b); return 0; }

  

Here is the top-level organization for Pallyc: It takes 3 input files: the source code input, key words table input and grammar specification input. And there are 5 distinctive stages:

• In initiating stage, Pallyc calculates and constructs SLR(1) parsing table;
• In lexer stage, source code input is converted into a token file, in which symbols are represented by tokens(integers), according to the key word table input;
• In parsing stage, token file from lexer stage is parsed and semantic action sequence is generated;
• In semantic process stage, a semantic handler process each semantic action in term of the sequence that parsing stage generates.
• Finally, intermediate code of 4-element expression is output and converted to assembly code (assembly conversion is in progress).

See the following figure.

Here is the C language feature coverage status:

array	supported
multidemensional array	supported
function	supported
nested-function	supported
arithmetic operation	supported
boolean expression	supported
if...else...	supported
while	supported
break/continue	supported
string	not supported
negative integer	not supported
struct	not supported
float type	not supported
pointer type	not supported
bit operation	not supported

Compile Error Specification

Error ID	Error Description	Error Type
0001	parsing table record null	syntax error
0002	undefined keyword	lexeme error
2040	identifier redefinition	semantic error
2043	illegal break	semantic error
2044	illegal continue	semantic error
2064	illegal function call	semantic error
2065	undeclared identifier	semantic error
2065	illegal array reference	semantic error
2118	negative subscript for array	semantic error
2440	type conversion error	semantic error
2440	array reference doesn’t match array definition	semantic error
2441	illegal reference to array	semantic error
2466	cannot allocate an array of constant size 0	semantic error
2660	function argument number doesn’t match	semantic error

Conundrum for Pallyc:

"p" stands for PASCAL's nested function definition, while "c" for C's grammar base frame; the word "ally" represents the combination of those features. And luckily the last 3 letters “lyc᾿happen to be the abbreviation of my name.

Contact the author:

If you have any questions about Pallyc or just interested in compiler implementation, please feel free to send me information. Email: