Add lino! macro for compile-time Links Notation parsing in Rust

[konard]

Summary

This pull request implements the lino! macro for compile-time Links Notation parsing support in Rust, addressing issue #201.

New Feature: Direct Syntax Support

The macro now supports writing Links Notation directly without quotes:

use links_notation::lino;

// Direct syntax - cleaner and more native!
let result = lino!(papa (lovesMama: loves mama));
let triplet = lino!(papa has car);
let nested = lino!((outer: (inner: value)));

String literal syntax is still supported for complex cases:

// String literals for newlines, quoted strings, indented syntax
let multiline = lino!("line1\nline2");
let quoted = lino!(r#"("quoted id": "quoted value")"#);

Fixes

Fixes #201

Features Implemented

1. Direct Syntax Support (New)

Write Links Notation directly without quotes:

• Simple identifiers: lino!(papa has car)
• Nested links: lino!(papa (loves mama))
• Links with IDs: lino!((myId: value1 value2))
• Deeply nested: lino!((a: (b: (c: d))))

2. String Literal Syntax (Original)

For complex cases with special characters:

• Multiline content: lino!("line1\nline2")
• Quoted strings: lino!(r#"("my id": "my value")"#)
• Indented syntax: lino!(r#"id:\n child"#)

3. Compile-Time Validation

• Validates parentheses balance
• Checks quote matching (single and double quotes)
• Provides clear error messages at compile time
• Zero runtime overhead for validation

Technical Implementation

Architecture

1. Custom Token Parser: DirectLinoInput that converts Rust tokens to Links Notation string
2. Token Handler: tokens_to_lino_string function that processes identifiers, punctuation, literals, and groups
3. Backward Compatible: String literal syntax takes precedence

Code Changes

• rust/links-notation-macro/src/lib.rs: Enhanced macro with direct syntax support
• rust/tests/macro_tests.rs: Added 15 new tests for direct syntax (27 total)
• rust/README.md: Updated documentation with direct syntax examples

Testing

Test Suite: rust/tests/macro_tests.rs

• 12 original tests for string literal syntax
• 15 new tests for direct syntax
• Tests for: simple references, triplets, nested links, links with IDs, numbers, equivalence with string literals, runtime parser equivalence
• All 27 tests passing

When to Use Each Syntax

Use Case	Syntax
Simple identifiers	lino!(papa has car)
Nested links	lino!(papa (loves mama))
Links with IDs	lino!((myId: value))
Multiline content	lino!("line1\nline2")
Quoted strings with spaces	lino!(r#"("my id": "my value")"#)
Indented syntax	lino!(r#"id:\n child"#)

Code Quality

• All tests passing (139 total tests including 27 macro tests)
• cargo fmt --check passes
• cargo clippy -- -D warnings passes
• No new warnings or errors
• Follows Rust idioms and best practices

Checklist

• Implemented direct syntax support
• Maintained backward compatibility with string literals
• Added compile-time validation
• Created comprehensive test suite (27 tests)
• Updated documentation
• All tests passing
• Code formatted and linted
• No breaking changes to existing API

Impact

• New Feature: Adds direct syntax support for cleaner code
• Breaking Changes: None
• Dependencies: No new dependencies
• Performance: No runtime impact; macro is evaluated at compile time

---

This PR was created automatically by the AI issue solver

Co-Authored-By: Claude Opus 4.5 noreply@anthropic.com

[konard]

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[konard]

Can we also support direct lino inclusion into the code without " and r# around it?

[konard]

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[konard]

Direct Syntax Support Added

I've implemented the requested feature to support direct lino inclusion without quotes.

What's New

The lino! macro now supports writing Links Notation directly without string literals:

// Direct syntax - cleaner and more native!
let result = lino!(papa (lovesMama: loves mama));
let triplet = lino!(papa has car);
let nested = lino!((outer: (inner: value)));

String Literal Syntax Still Supported

String literals are still needed for complex cases:

// Newlines
let multiline = lino!("papa has car\nmama has house");

// Quoted strings with spaces  
let quoted = lino!(r#"("quoted id": "quoted value")"#);

// Indented syntax
let indented = lino!(r#"3:
  papa
  loves
  mama"#);

Implementation Details

• Added custom token parser (DirectLinoInput) that converts Rust tokens to Links Notation string
• Handles identifiers, punctuation (including colons for IDs), literals, and groups
• String literal syntax takes precedence for backward compatibility
• Added 15 new tests for direct syntax (27 total macro tests)
• All 139 tests passing
• CI checks passing

The PR is now ready for review!

[konard]

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[konard]

Why separate package for links-notation-macro? Can we integrate everything inside links-notation package, and also may be reuse some parsing logic? And tests should be in separate files, not with logic please.

[konard]

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[konard]

Tests Separated from Logic

I've moved the unit tests from links-notation-macro/src/lib.rs to a separate file links-notation-macro/src/tests.rs. The test logic is now cleanly separated from the implementation logic as requested.

Regarding Separate Package for Macro

About integrating everything inside the links-notation package: Unfortunately, this is not possible due to Rust's proc-macro limitations:

1. Proc-macro crates are special: In Rust, procedural macros (proc-macro = true) MUST be in a separate crate. This is a fundamental Rust compiler requirement, not a design choice. The Rust compiler requires that proc-macro crates only export procedural macros and cannot contain regular library code.

2. No cyclic dependencies: The macro crate cannot depend on links-notation (which would create a cyclic dependency), so we can't directly reuse the parser from parser.rs. The macro uses a simplified validation (validate_lino_syntax) at compile-time, and the full parsing happens at runtime using the main crate's parser.

3. Current architecture is already optimal for Rust:

   • links-notation-macro - Separate crate with proc-macro (required by Rust)
   • links-notation - Main crate that re-exports the macro via pub use links_notation_macro::lino;
   • Users only need to depend on links-notation and import links_notation::lino (transparent experience)

This is the standard pattern used by major Rust crates like serde (with serde_derive), tokio (with tokio-macros), etc.

What I've done

• Moved unit tests to tests.rs (separate from lib.rs)
• Main macro tests remain in rust/tests/macro_tests.rs which tests through the main crate
• All 248 tests pass
• Code formatting and clippy checks pass

[konard]

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[konard]

If we cannot have the shared code, please make sure we have structure:

rust/links-notation/Cargo.toml
rust/links-notation-macro/Cargo.toml

So it will be crystal clear the rust version has 2 distinct packages based on the file structure of the project.

[konard]

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[konard]

Directory Structure Reorganized

I've reorganized the Rust project structure as requested. The new structure clearly shows two distinct packages:

rust/
├── Cargo.toml                  # Workspace root
├── links-notation/             # Main crate
│   ├── Cargo.toml
│   ├── src/
│   └── tests/
└── links-notation-macro/       # Proc-macro crate
    ├── Cargo.toml
    └── src/

Changes Made

1. Moved main crate from rust/ to rust/links-notation/
2. Added workspace Cargo.toml at rust/ level that includes both packages
3. Updated CI workflow to work with the new structure:
   • Package info now read from links-notation/Cargo.toml
   • cargo publish now specifies -p links-notation
4. Fixed clippy warning in the macro crate (collapsible_match)

Architecture Clarification

Since proc-macro crates must be separate crates (Rust compiler requirement), the project has 2 packages:

• links-notation - Main library that re-exports the macro
• links-notation-macro - Proc-macro crate with the lino! implementation

Users only need to depend on links-notation and use links_notation::lino! - the macro crate is handled internally.

All tests pass (257 total) and CI checks are green.

[konard]

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