https://github.com/leonardpepa/dragon-book-compiler-frontend
A Simple front end compiler from scratch. The code is from the Dragon Book
https://github.com/leonardpepa/dragon-book-compiler-frontend
Last synced: 7 months ago
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A Simple front end compiler from scratch. The code is from the Dragon Book
- Host: GitHub
- URL: https://github.com/leonardpepa/dragon-book-compiler-frontend
- Owner: Leonardpepa
- Created: 2022-07-29T15:45:25.000Z (about 3 years ago)
- Default Branch: master
- Last Pushed: 2022-08-02T20:37:31.000Z (about 3 years ago)
- Last Synced: 2025-01-17T08:45:46.140Z (9 months ago)
- Language: Java
- Size: 114 KB
- Stars: 1
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
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README
# Dragon Book Compiler Frontend
# Link for Dragon Book from stanford: [Dragon Book](https://suif.stanford.edu/dragonbook/)
## This is a educational project on my journey to learn about programming languages and compiler design.
The code belongs to the owners of the book, i just rewrite it to test it and understand it better.
## Frontend Compiler Components
* main.Lexer (Tokenizer), (if you dont provide a filepath as argument when creating the new instance the input is given from stdin)
* main.Parser (Creates the ast tree with recursice descent)
* main.Inter (Contains classes that generate fake intermediate code)
* main.Symbols (Classes for symbol table and type checking)
## Grammar
* This is the context free grammar of this toy lenguage (this is not LL ready but the modifications are made before the parser is written)
```terminal
program ::= block
block ::= { decls stmts }
decls ::= decls decl | E
decl ::= type id ;
type ::= type [ num ] | basic
stmts ::= stmts stmt | E
stmt ::= loc = bool ;
| if ( bool ) stmt
| if ( bool ) stmt else stmt
| while ( bool ) stmt
| do stmt while ( bool )
| break ;
| block
loc ::= loc [ bool ] | id
bool ::= bool | | join | join
join ::= join && equality | equality
equality ::= equality == rei | equality ! = rei | rei
rei ::= expr < expr | expr <= expr | expr >= expr
expr > expr | expr
expr ::= expr + term | expr - term | term
term ::= term * unary | term / unary | unary
unary ::= ! unary | - unary | factor
factor ::= ( bool ) | loc | num | real | true | false
```
## Test
```terminal
{
int i;
float[200] v;
int[5] array;
int j;
v[0] = 15;
i=0;
if(i > 0){
i=1;
}
j = 0;
while(j <= 5){
array[j] = j;
j = j + 1;
}
while(i <= 100){
v[i] = 0;
i = i + 1;
}
i = 0;
while(true){
i = i + 5;
if(i > 100){
break;
}
}
}
```
## Generated intermediate code from test
```terminal
L1:
t1 = 0 * 8
v [ t1 ] = 15
L3:
i = 0
L4:
iffalse i > 0 goto L5
L6:
i = 1
L5:
j = 0
L7:
iffalse j <= 5 goto L8
L9:
t2 = j * 4
array [ t2 ] = j
L10:
j = j + 1
goto L7
L8:
iffalse i <= 100 goto L11
L12:
t3 = i * 8
v [ t3 ] = 0
L13:
i = i + 1
goto L8
L11:
i = 0
L14:
L15:
i = i + 5
L16:
iffalse i > 100 goto L14
L17:
goto L2
goto L14
L2:
```
## Run Locally
* git clone https://github.com/Leonardpepa/Dragon-Book-Compiler-Frontend.git
* open with intellij
* run main.java
## Tests
the tests are in the /src/main/resources/ folder.
## TODO
create documentation of the implementation so i can myself understand it better