logicaffeine-base

Foundational infrastructure for the Logicaffeine ecosystem. This crate provides the low-level building blocks—arena allocation, string interning, source spans, and error handling—that all other logicaffeine crates depend on.

Overview

Module	Purpose
`Arena<T>`	Bump allocation for AST nodes with stable references
`Interner`/`Symbol`	String interning with O(1) equality comparison
`Span`	Source location tracking (byte offsets)
`SpannedError`/`Result<T>`	Error handling with source positions

Installation

[dependencies]
logicaffeine-base = "0.6"

Quick Start

use logicaffeine_base::{Arena, Interner, Symbol, Span, SpannedError, Result};

// Arena for bump allocation
let arena: Arena<&str> = Arena::new();
let value = arena.alloc("hello");
assert_eq!(*value, "hello");

// Interner for string deduplication
let mut interner = Interner::new();
let sym1 = interner.intern("hello");
let sym2 = interner.intern("hello");
assert_eq!(sym1, sym2);  // O(1) comparison

// Span for source tracking
let span = Span::new(0, 5);
assert_eq!(span.len(), 5);

// Error with location
let err = SpannedError::new("unexpected token", span);
assert_eq!(err.to_string(), "unexpected token at 0..5");

Module Reference

Arena

Bump allocation for stable AST references. All values live until the arena is dropped or reset.

use logicaffeine_base::Arena;

let arena: Arena<String> = Arena::new();

// Allocate single value
let s = arena.alloc("hello".to_string());

// Allocate slice from iterator
let nums = arena.alloc_slice([1, 2, 3]);

Method	Description
`Arena::new()`	Create empty arena
`arena.alloc(value)`	Allocate value, return stable reference
`arena.alloc_slice(iter)`	Allocate slice from `ExactSizeIterator`
`arena.reset()`	Clear arena, reuse capacity (REPL-friendly)

Interner / Symbol

String interning for O(1) equality. Each unique string is stored once; comparing symbols is just comparing integers.

use logicaffeine_base::{Interner, Symbol, SymbolEq};

let mut interner = Interner::new();

let hello = interner.intern("hello");
let world = interner.intern("world");

// O(1) equality
assert_ne!(hello, world);

// Resolve back to string
assert_eq!(interner.resolve(hello), "hello");

// SymbolEq trait for convenience
assert!(hello.is(&interner, "hello"));

Method	Description
`Interner::new()`	Create interner (empty string pre-interned)
`interner.intern(s)`	Get or create symbol for string
`interner.resolve(sym)`	Get original string from symbol
`interner.lookup(s)`	Non-interning lookup, returns `Option<Symbol>`
`interner.len()`	Count of interned strings
`Symbol::EMPTY`	Pre-interned empty string constant
`symbol.index()`	Internal index for dense storage

Span

Byte-offset range in source text. Matches Rust's string slicing: &source[span.start..span.end].

use logicaffeine_base::Span;

let source = "hello world";
let hello = Span::new(0, 5);
let world = Span::new(6, 11);

assert_eq!(&source[hello.start..hello.end], "hello");

// Merge spans for compound expressions
let full = hello.merge(world);
assert_eq!(full.start, 0);
assert_eq!(full.end, 11);

Method	Description
`Span::new(start, end)`	Create from byte offsets
`span.merge(other)`	Combine two spans (min start, max end)
`span.len()`	Length in bytes
`span.is_empty()`	True if zero-length
`span.start` / `span.end`	Public fields for direct access

SpannedError / Result

Errors annotated with source location. Implements std::error::Error.

use logicaffeine_base::{SpannedError, Span, Result};

fn parse_number(s: &str) -> Result<i32> {
    s.parse().map_err(|_| SpannedError::new(
        format!("invalid number: '{}'", s),
        Span::new(0, s.len()),
    ))
}

let err = parse_number("abc").unwrap_err();
// Display: "invalid number: 'abc' at 0..3"

Type	Description
`SpannedError`	Error with `message: String` and `span: Span`
`Result<T>`	Alias for `std::result::Result<T, SpannedError>`

Design Principles

No vocabulary knowledge: This crate knows nothing about English or natural language
No I/O: Pure data structures only
Minimal dependencies: Only bumpalo for arena allocation
Foundation layer: All other logicaffeine crates build on these types

Dependencies

bumpalo = "3.19"

License

Business Source License 1.1 (BUSL-1.1)

Free for individuals and organizations with <25 employees
Commercial license required for organizations with 25+ employees offering Logic Services
Converts to MIT on December 24, 2029

See LICENSE for full terms.

logicaffeine-base 0.8.4