1. Coco/R Compiler Compiler for C#, …
Hanspeter Mössenböck
Albrecht Wöß
Markus Löberbauer
Johannes Kepler University Linz, Austria
SystemSoftWare Group
Coco/R Compiler Compiler for C#, …

2. Coco/R - Compiler Generator
What is Coco/R?
easy-to-use compiler generator
Input: attributed, context-free EBNF grammar (LL(1))
Output: scanner & recursive descent parser
available versions:
C#, Java, Oberon-2:
C/C++, Modula-2, Pascal: cs.ru.ac.za/homes/cspt/cocor.htm
Delphi: parserbuilder.sourgeforge.net,
publications:
Paper and Report:
Pat Terry, Compilers & Compiler Generators - An Introduction with C++, Thomson Computer Press, 1997 (
July 25, 2002
Coco/R - Compiler Generator

3. Coco/R - Compiler Generator
The Architecture
July 25, 2002
Coco/R - Compiler Generator

4. Coco/R - Compiler Generator
An Example
Simple Integer Expression Evaluator:
Task:
read an expression from a text file
evaluate it
write result to console
Grammar in EBNF:
Expr = Term { ("+"|"-") Term }.
Term = Factor { ("*"|"/") Factor }.
Factor = ["-"] ( number | "(" Expr ")" ).
July 25, 2002
Coco/R - Compiler Generator

5. add attributes Expr = Term { ( "+" | "-" ) Term }.
Term = Factor { ( "*" | "/" ) Factor }.
add attributes
Factor = [ "-" ] ( number | "(" Expr ")" ).

6. add semantic actions Expression = Expr<out value>.
<out int val>
Expr = Term { ( "+" | "-" ) Term }.
<out val> <out val1>
<out int val>
Term = Factor { ( "*" | "/" ) Factor }.
<out val> <out val1>
add semantic actions
Factor = [ "-" ] ( number | "(" Expr ")" ).
<out int val>
<out val1>

7. Expression = Expr<out value>.
Expr<out int val> = Term<out val> { ( "+" | "-" ) Term<out val1> }.
(.int val1, sign;.)
(.sign = 1;.)
(.sign = -1;.)
(.val += val1 * sign;.)
Term<out int val> = Factor<out val> { ( "*" | "/" ) Factor<out val1> }.
(.int val1; bool mul;.)
(.mul = true;.)
(.mul = false;.)
(.val = (mul) ? val*val1 : val/val1;.)
Factor<out int val> = [ "-" ] ( number | "(" Expr<out val1> ")" ).
(.int val1; val = 1;.)
(.val = -1;.)
(.val *= Convert.ToInt32(token.val);.)
(.val *= val1;.)

8. Expr<out int val>. (. int val1, sign;
Expr<out int val> (.int val1, sign;.) = Term<out val> { ( "+" (.sign = 1;.) | "-" (.sign = -1;.) ) Term<out val1> (.val += val1 * sign;.) }.
in file " Parser.cs"
static void Expr (out int val) { int val1, sign; Term(out val); while (t.kind==2 || t.kind==3) { if (t.kind==2) { Get(); sign = 1; } else { Get(); sign = -1; } Term(out val1); val += val1 * sign; } } + –

9. Coco/R - Compiler Generator
Structure of Cocol
using System; COMPILER Expression; public static int value; CHARACTERS digit = " ". TOKENS number = digit { digit }. PRODUCTIONS Expression = Expr<out value>. Expr<out int val> (.int val1, sign;.) = Term<out val> { ( "+" (.sign = 1;.) | "-" (.sign = -1;.) ) Term<out val1> (.val += val1 * sign;.) }. Term<out int val> (.int val1; bool mul;.) = Factor<out val> { ( "*" (.mul = true;.) | "/" (.mul = false;.) ) Factor<out val1> (.val = (mul) ? val*val1 : val/val1;.) }. Factor<out int val> (.int val1; val = 1;.) = [ "-" (.val = -1;.) ] ( number (.val *= Convert.ToInt32(token.val);.) | "(" Expr<out val1> ")" (.val *= val1;.) ). END Expression.
arbitrary C# declarations
scanner specification
parser specification
July 25, 2002
Coco/R - Compiler Generator

10. Scanner-Specification
CHARACTERS letter = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz". notZeroDigit = " ". digit = notZeroDigit + "0". hexDigit = digit + "ABCDEFabcdef". noDigit = ANY - digit. tab = CHR(9).
TOKENS ident = letter { letter | digit | "_" }. intNumber = notZeroDigit { digit }. hexNumber = "0x" hexDigit { hexDigit }.
PRAGMAS option = "$" letter. (.switch (t.val[1]) { … }.)
COMMENTS FROM "/*" TO "*/" NESTED
IGNORE tab + CHR(10) + CHR(13).
July 25, 2002
Coco/R - Compiler Generator

11. Coco/R - Compiler Generator
Compiler Main
Compiler.cs:
using System; namespace Expression { public class Compiler { public static void Main (string[] args) { if (args.Length > 0) { Scanner.Init(args[0]); Parser.Parse(); if (Errors.count == 0) Console.WriteLine(Parser.value); } else Console.WriteLine("No source file specified"); } } }
July 25, 2002
Coco/R - Compiler Generator

12. DEMO
Let it run …

13. Coco/R - Compiler Generator
The Project
Extension of Coco/R
use semantic information to resolve LL(1)-conflicts
use Coco/R for non-LL(1)-grammars
ATG template for C#
provides complete parsing facilities for C# programs
just add attributes and semantic actions to create customized applications
Compiler Generation Tools for C#
July 25, 2002
Coco/R - Compiler Generator

14. Coco/R - Compiler Generator
Applications
Instrumenting C# source code
insert, delete or rewrite code fragments
e.g. add profiling, testing or debugging output, …
Analyzing C# source code
extract arbitrary information
e.g. complexity measures, style measures, call graphs, …
Translating C# source code
convert into arbitrary output format
e.g. Java-Bytecode, syntax-highlighted HTML, …
MORE IDEAS WELCOME !
visit dotnet.jku.at/Projects/Rotor
July 25, 2002
Coco/R - Compiler Generator