https://github.com/smoeding/tree-sitter-pic
Tree-sitter grammar for the PIC language
https://github.com/smoeding/tree-sitter-pic
pic tree-sitter
Last synced: 3 months ago
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Tree-sitter grammar for the PIC language
- Host: GitHub
- URL: https://github.com/smoeding/tree-sitter-pic
- Owner: smoeding
- License: bsd-2-clause
- Created: 2024-07-17T08:51:42.000Z (almost 2 years ago)
- Default Branch: main
- Last Pushed: 2025-01-02T11:29:54.000Z (over 1 year ago)
- Last Synced: 2025-02-12T22:47:45.887Z (over 1 year ago)
- Topics: pic, tree-sitter
- Language: C
- Homepage:
- Size: 3.29 MB
- Stars: 1
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# Tree-sitter grammar for the PIC language
[](https://raw.githubusercontent.com/smoeding/tree-sitter-pic/master/LICENSE)
[](https://github.com/smoeding/tree-sitter-pic/actions/workflows/ci.yaml)
Pic is a domain-specific language by Brian W. Kernighan for specifying diagrams. It is mostly used in combination with the [groff](https://www.gnu.org/software/groff/) typesetting system but is also a valid input format for some programs found in the [plotutils](https://www.gnu.org/software/plotutils/) package.
A typical document preparation workflow using the PIC preprocessor could look like this:
The following input was used to create this picture:
``` pic
.PS
ellipse "document"
arrow
box "PIC"
arrow
box "TBL/EQN" "(optional)" dashed
arrow
box "TROFF"
arrow
ellipse "typesetter"
.PE
```
## Limitations
The following limitations are known.
#### Macros definitions and macro parameters may be parsed incorrectly
Macros are not part of the Pic language. When the scanner finds a macro call, it does a simple text replacement using the macro parameters. Neither the macro definition nor the macro call needs to be a correct Pic statement or expression. This makes is impossible to parse all macros correctly.
See the following example which is perfectly legal code for `pic`:
``` pic
define foo { circle at $1 $2 }
foo((2,2), diam 1)
foo((3,5), rad 1)
```
#### The copy thru statement may be parsed incorrectly
Consider the following piece of code:
``` pic
copy thru X
box "$1"
X
10
```
When GNU pic parses this code, it checks if `X` has been defined as a macro. If it is a macro, then it is called using the following three lines as data. If `X` is not defined as a macro, then it is parsed as a character delimiter and the block between the two `X` characters is used as an inline macro.
The tree-sitter implementation doesn't record the defined macros and may therefore parse this specific piece of code differently. You can use longer macro names and non-alphabetic letters as inline macro delimiters to avoid this ambiguity.
## References
1. Brian W. Kernighan, [PIC - A Graphics Language for Typesetting - User Manual](https://raw.githubusercontent.com/smoeding/tree-sitter-pic/main/doc/PIC_-_A_Graphics_Language_for_Typesetting_-_User_Manual.pdf)
1. Eric S. Raymond, [Making Pictures with GNU PIC](https://raw.githubusercontent.com/smoeding/tree-sitter-pic/main/doc/Making_Pictures_with_GNU_PIC.pdf)
1. W. Richard Stevens, [Examples of pic Macros](https://raw.githubusercontent.com/smoeding/tree-sitter-pic/main/doc/Examples_of_pic_Macros.pdf)