https://github.com/siraben/meta-yacc
Self-hosting parser generators in Forth and C.
https://github.com/siraben/meta-yacc
c forth parser-generator
Last synced: 9 months ago
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Self-hosting parser generators in Forth and C.
- Host: GitHub
- URL: https://github.com/siraben/meta-yacc
- Owner: siraben
- License: mit
- Created: 2019-05-22T04:17:53.000Z (about 7 years ago)
- Default Branch: master
- Last Pushed: 2021-02-27T16:41:07.000Z (over 5 years ago)
- Last Synced: 2025-08-24T21:26:15.688Z (9 months ago)
- Topics: c, forth, parser-generator
- Language: Forth
- Homepage:
- Size: 35.2 KB
- Stars: 20
- Watchers: 4
- Forks: 1
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# Self-hosting YACC-like parser generators in Forth and C
## Building
### C
```ShellSession
$ nix build # with Nix
$ make # without Nix
```
### Forth
```ShellSession
$ gforth meta.fs meta-forth.txt meta.fs
```
### Regenerate C/Forth code
```ShellSession
$ make recomp # for C code
$ make forth_recomp # for Forth code
```
## Usage
Suppose one has a grammar file called `my-grammar.txt`:
- Using the Forth parser generator, run `gforth meta.fs my-grammar.txt
my-grammar.fs`
- Using the C parser generator, run `./meta my-grammar.txt
my-grammar.c`
Check the generated file. Syntax errors will be indicated in the
output file.
## Example compilers included
### FlooP language from Gödel, Escher, Bach
The version of FlooP in this repository is differs from the book in
several ways, some of which are (list is subject to change):
- The last statement in a block does not have a semicolon
- Variables must be declared before use
- Comments are allowed only after procedure declarations
- There must be a following block or statement after an `if` statement
(i.e. the `else` clause)
A FlooP → C compiler is given in `floop.txt`. See `floop-test.txt`
for an example FlooP program that prints out the prime numbers
under 1000. Here's another simple Floop program that produces the
output:
```
Hello, world!
Counting up to 10: 1 2 3 4 5 6 7 8 9 10
```
```
def count (n):
'Count up from 1 to n inclusive.'
begin
int out;
out <- 1;
loop at most n times:
begin
print out;
out <- out + 1
end;
println ''
end
main
begin
println 'Hello, world!';
print 'Counting up to 10: ';
do count(10)
end
```
Generated C code:
```c
#include
#include
int count(int n) {
int out = 0;
do {
out = 1;
for(int i = 0, f = 1; i < n && f; i++) {
do {
printf("%d ",out);
out = out + 1;
} while (0);
}
puts("");
} while (0);
}
int main(void) {
do {
puts("Hello, world!");
printf("Counting up to 10: ");
count(10);
} while (0);
}
```
### Convert infix to postfix
Input:
```
29 * 19293 - 129 + (992 * 30 - 10) - (15 * (-15 + 34 * (182 + 3 - 4)) + 382) * 3 + (102 + 239 * 314) - 222
```
Output:
```
29 19293 * 129 - 992 30 * 10 - + 15 -15 34 182 3 + 4 - * + * 382 + 3 * - 102 239 314 * + + 222 -
```