Add BNF support package documentation (#97)

* Initial plan

* Add BNF support package documentation in new Support Packages section

Co-authored-by: hzhangxyz <[email protected]>

---------

Co-authored-by: copilot-swe-agent[bot] <[email protected]>
Co-authored-by: hzhangxyz <[email protected]>

Author: Copilot

docs/support-packages/bnf.md

@@ -0,0 +1,123 @@
+# BNF Support Package
+
+The BNF support package provides bidirectional conversion between DS's two syntax formats:
+
+- **Ds**: The S-expression (lisp-like) syntax used internally by DS
+- **Dsp**: A traditional, human-readable syntax with infix operators
+
+This package enables you to write logical rules in a more natural, mathematical notation and convert them to the DS internal format, or vice versa.
+
+## Installation
+
+### Python
+
+```bash
+pip install apyds-bnf
+```
+
+Requires Python 3.10-3.14.
+
+### JavaScript/TypeScript
+
+```bash
+npm install atsds-bnf
+```
+
+## Usage
+
+### Python Example
+
+```python
+from apyds_bnf import parse, unparse
+
+# Parse: Convert from readable Dsp to DS format
+dsp_input = "a, b -> c"
+ds_output = parse(dsp_input)
+print(ds_output)
+# Output:
+# a
+# b
+# ----
+# c
+
+# Unparse: Convert from DS format to readable Dsp
+ds_input = "a\nb\n----\nc"
+dsp_output = unparse(ds_input)
+print(dsp_output)
+# Output: a, b -> c
+```
+
+### JavaScript/TypeScript Example
+
+```javascript
+import { parse, unparse } from "atsds-bnf";
+
+// Parse: Convert from readable Dsp to DS format
+const dsp_input = "a, b -> c";
+const ds_output = parse(dsp_input);
+console.log(ds_output);
+// Output:
+// a
+// b
+// ----
+// c
+
+// Unparse: Convert from DS format to readable Dsp
+const ds_input = "a\nb\n----\nc";
+const dsp_output = unparse(ds_input);
+console.log(dsp_output);
+// Output: a, b -> c
+```
+
+## Syntax Formats
+
+### Ds Format (Internal)
+
+The Ds format uses S-expressions (lisp-like syntax) for representing logical rules:
+
+```
+premise1
+premise2
+----------
+conclusion
+```
+
+For structured terms:
+
+- Functions: `(function f a b)`
+- Subscripts: `(subscript a i j)`
+- Binary operators: `(binary + a b)`
+- Unary operators: `(unary ~ a)`
+
+### Dsp Format (Human-Readable)
+
+The Dsp format uses traditional mathematical notation:
+
+```
+premise1, premise2 -> conclusion
+```
+
+For structured terms:
+
+- Functions: `f(a, b)`
+- Subscripts: `a[i, j]`
+- Binary operators: `(a + b)` (parenthesized)
+- Unary operators: `(~ a)` (parenthesized)
+
+### Syntax Comparison
+
+| Description | Dsp Format | Ds Format |
+|-------------|------------|-----------|
+| Simple rule | `a, b -> c` | `a\nb\n----\nc` |
+| Axiom | `a` | `----\na` |
+| Function call | `f(a, b) -> c` | `(function f a b)\n----------------\nc` |
+| Subscript | `a[i, j] -> b` | `(subscript a i j)\n-----------------\nb` |
+| Binary operator | `(a + b) -> c` | `(binary + a b)\n--------------\nc` |
+| Unary operator | `~ a -> b` | `(unary ~ a)\n-----------\nb` |
+| Complex expression | `((a + b) * c), d[i] -> f(g, h)` | `(binary * (binary + a b) c)\n(subscript d i)\n---------------------------\n(function f g h)` |
+
+## Package Information
+
+- **Python Package**: [apyds-bnf](https://pypi.org/project/apyds-bnf/)
+- **npm Package**: [atsds-bnf](https://www.npmjs.com/package/atsds-bnf)
+- **Source Code**: [GitHub - bnf directory](https://github.com/USTC-KnowledgeComputingLab/ds/tree/main/bnf)

mkdocs.yml

@@ -59,6 +59,8 @@ nav:
       - TypeScript API: api/typescript.md
       - Python API: api/python.md
       - C++ API: api/cpp.md
+  - Support Packages:
+      - BNF: support-packages/bnf.md
   - Examples:
       - Basis Examples: examples/basic.md
       - Sudoku: examples/sudoku.md