feat(core)!: zero-allocation no_std encoding (0.2.0)

.github/workflows/ci.yml

@@ -23,8 +23,17 @@ jobs:
       - name: Format
         run: cargo fmt --all --check
 
-      - name: Clippy
+      - name: Clippy (all features)
         run: cargo clippy --all-targets --all-features -- -D warnings
 
-      - name: Test
+      - name: Clippy (no_std, no alloc)
+        run: cargo clippy --all-targets --no-default-features -- -D warnings
+
+      - name: Build (no_std, no alloc — proves zero heap)
+        run: cargo build --no-default-features
+
+      - name: Test (all features)
         run: cargo test --all-features
+
+      - name: Test (no_std, no alloc)
+        run: cargo test --no-default-features

.gitignore

@@ -6,6 +6,9 @@ target
 # These are backup files generated by rustfmt
 **/*.rs.bk
 
+# Locally generated test barcodes (see examples/gen_all.rs)
+/generated_barcodes/
+
 # MSVC Windows builds of rustc generate these, which store debugging information
 *.pdb
 

CHANGELOG.md

@@ -0,0 +1,120 @@
+# Changelog
+
+All notable changes to this project are documented here. The format is based on
+[Keep a Changelog](https://keepachangelog.com/), and this project adheres to
+[Semantic Versioning](https://semver.org/) (with `0.x` minor bumps signalling
+breaking changes).
+
+## [0.2.0] — Unreleased
+
+### Breaking
+
+- **Zero-allocation core.** The primary API is now
+  [`BarcodeEncoder::encode_into(input, &mut [bool])`](https://docs.rs/barcodes/latest/barcodes/common/traits/trait.BarcodeEncoder.html),
+  which writes a symbol's modules into a caller-provided buffer and returns an
+  `Encoded { Linear | Matrix }` describing the written region. The crate is now
+  pure `no_std` with **no heap allocation** by default.
+- The owned-output convenience methods `encode()` (returning `BarcodeOutput`)
+  and `to_svg_string()` moved behind the new **`alloc`** feature. Code that
+  called `Encoder::encode(...)` on 0.1.x must either enable `features = ["alloc"]`
+  or migrate to `encode_into`. See [Migration](#migration-from-01x) below.
+- `EncodeError` messages are now `&'static str` (no allocated `String`).
+
+### Added
+
+- Feature flags: `alloc` (owned output + SVG string), `std` (implies `alloc`),
+  `image` (implies `std`, raster PNG/GIF/WebP output).
+- Full-spec, scanner-verified rewrites of the larger symbologies:
+  - **PDF417** (ISO/IEC 15438) — byte compaction + Reed–Solomon EC.
+  - **GS1 DataBar Omnidirectional / RSS-14** (ISO/IEC 24724).
+  - **Aztec Code** (ISO/IEC 24778) — Binary Shift, Reed–Solomon over
+    GF(16/64/256/1024).
+  - **USPS Intelligent Mail (IMb)** — verified bit-for-bit against the canonical
+    USPS-B-3200 DAFT reference vector.
+  - **Royal Mail RM4SCC** — 4-state 3-row output.
+- Streaming SVG rendering into any `core::fmt::Write` sink via `common::svg`.
+
+### Fixed
+
+- **Data Matrix** ECC 200 now produces scannable symbols, with 32×32–48×48
+  multi-region support for larger data.
+- **EAN-13/EAN-8 L-code**, **UPC-E parity**, and the **Code 39** pattern table
+  corrected (symbols now scan).
+- **GS1-128** now decodes correctly (Code B path).
+- **UPC-A / UPC-E check digit** for odd-length data (also released as 0.1.3).
+
+### Packaging
+
+- `examples/` and locally generated barcodes are excluded from the published
+  crate.
+
+## [0.1.3] — 2026-07-07
+
+### Fixed
+
+- **UPC-A / UPC-E check digit.** The shared check-digit routine weighted digits
+  from the left, which is only correct for even-length data (EAN-13's 12
+  digits). For UPC-A and UPC-E (11 data digits) the rightmost digit received the
+  wrong weight, producing an invalid check digit — UPC-A symbols failed to scan.
+  It now weights from the right (the length-independent GS1 rule); EAN-13/EAN-8
+  output is unchanged.
+
+## [0.1.2] — 2026
+
+### Fixed
+
+- Critical **EAN-13 / EAN-8 / UPC-E** encoding fixes (L-code digits and UPC-E
+  parity) so retail symbols scan.
+- **GS1-128** decoding correctness.
+
+## [0.1.1] — 2026
+
+### Fixed
+
+- Data Matrix capacity/length handling and scannability improvements.
+
+## [0.1.0] — 2026
+
+- Initial release: QR, EAN-13/8, UPC-A/E, Code 128/39/93, Codabar, ITF, GS1-128,
+  GS1 DataBar, PDF417, Data Matrix, Aztec, USPS IMb, Royal Mail RM4SCC.
+
+## Migration from 0.1.x
+
+**0.1.x (owned output):**
+
+```rust
+use barcodes::common::traits::BarcodeEncoder;
+use barcodes::ean_upc::ean13::Ean13;
+
+let svg = Ean13::encode("5901234123457").unwrap().to_svg_string();
+```
+
+**0.2.0, option A — keep the convenience API** (enable `alloc`):
+
+```toml
+barcodes = { version = "0.2", features = ["alloc"] }
+```
+
+```rust
+// identical code — encode() and to_svg_string() require the `alloc` feature
+let svg = Ean13::encode("5901234123457").unwrap().to_svg_string();
+```
+
+**0.2.0, option B — zero allocation** (default, no features):
+
+```rust
+use barcodes::common::traits::BarcodeEncoder;
+use barcodes::common::types::Encoded;
+use barcodes::ean_upc::ean13::Ean13;
+
+let mut buf = [false; 128]; // one bool per module
+let Encoded::Linear { len, .. } = Ean13::encode_into("5901234123457", &mut buf).unwrap()
+else { unreachable!() };
+let bars = &buf[..len]; // true = dark module
+```
+
+[0.2.0]: https://github.com/ashaffah/barcodes/compare/v0.1.3...HEAD
+[0.1.3]: https://github.com/ashaffah/barcodes/compare/v0.1.2...v0.1.3
+[0.1.2]: https://github.com/ashaffah/barcodes/compare/v0.1.1...v0.1.2
+[0.1.1]: https://github.com/ashaffah/barcodes/compare/v0.1.0...v0.1.1
+[0.1.0]: https://github.com/ashaffah/barcodes/releases/tag/v0.1.0

Cargo.toml

@@ -1,15 +1,19 @@
 [package]
 name = "barcodes"
-version = "0.1.0"
+version = "0.2.0"
 edition = "2024"
 description = "Universal Bar/QR codes library"
 keywords = ["barcode", "qrcode", "ean", "code128", "pdf417"]
 categories = ["encoding", "no-std"]
 license = "MIT"
+repository = "https://github.com/ashaffah/barcodes"
+readme = "README.md"
+exclude = ["/examples", "/generated_barcodes"]
 
 [features]
 default = []
-std = []
+alloc = []
+std = ["alloc"]
 image = ["std", "dep:image"]
 
 [dependencies]
@@ -20,5 +24,9 @@ optional = true
 default-features = false
 features = ["png", "gif", "webp"]
 
+[[example]]
+name = "gen_all"
+required-features = ["image"]
+
 [package.metadata.docs.rs]
 all-features = true

README.md

@@ -6,34 +6,79 @@
 [![Rust](https://img.shields.io/badge/rust-edition_2024-orange.svg)]()
 
 A **universal bar/QR code generation library** for Rust, supporting many symbologies.  
-Zero external dependencies, `no_std` compatible (requires `alloc`).
+Zero external dependencies, pure `no_std`, and **zero heap allocation** by default.
 
 ## Features
 
+- **Zero heap allocation** by default — encoders write into a caller-provided
+  `&mut [bool]` buffer via [`encode_into`](#zero-allocation-core); pure `no_std`,
+  no `alloc` required
 - Zero external dependencies (default)
-- `no_std` compatible (requires `alloc`)
-- SVG output built-in (`to_svg_string()`)
+- Optional `alloc` feature for owned-output convenience (`encode()` +
+  `to_svg_string()`)
 - Optional image output (PNG, GIF, WebP) via `image` feature
 - Supports 16+ barcode symbologies: linear, 2D, and postal
 
 ## Installation
 
 Add `barcodes` to your `Cargo.toml`.
 
-**Default (no_std, SVG only):**
+**Default (pure `no_std`, zero allocation):**
 
 ```toml
 [dependencies]
-barcodes = "0.1"
+barcodes = "0.2"
 ```
 
-**With image output (PNG/GIF/WebP):**
+**With owned output + SVG string convenience (`alloc`):**
 
 ```toml
 [dependencies]
-barcodes = { version = "0.1", features = ["image"] }
+barcodes = { version = "0.2", features = ["alloc"] }
 ```
 
+**With image output (PNG/GIF/WebP — implies `std`):**
+
+```toml
+[dependencies]
+barcodes = { version = "0.2", features = ["image"] }
+```
+
+## Zero-allocation core
+
+Every encoder implements
+[`BarcodeEncoder::encode_into`](https://docs.rs/barcodes/latest/barcodes/common/traits/trait.BarcodeEncoder.html),
+which writes the symbol's modules into a caller-provided buffer and returns an
+`Encoded` describing the written region — no heap, no `alloc`:
+
+```rust
+use barcodes::common::traits::BarcodeEncoder;
+use barcodes::common::types::Encoded;
+use barcodes::ean_upc::ean13::Ean13;
+
+let mut buf = [false; 128]; // stack buffer, one bool per module
+let Encoded::Linear { len, height } = Ean13::encode_into("5901234123457", &mut buf).unwrap()
+else { unreachable!() };
+
+let bars = &buf[..len]; // true = dark module, false = light
+assert_eq!(bars.len(), 95);
+let _ = height;
+```
+
+2D symbologies return `Encoded::Matrix { width, height }`; their modules fill
+`buf[..width * height]` in row-major order.
+
+Render to SVG without allocating via [`common::svg`](https://docs.rs/barcodes/latest/barcodes/common/svg/index.html),
+which streams into any `core::fmt::Write` sink.
+
+> The `alloc` feature adds the convenience `Encoder::encode()` (returning an
+> owned `BarcodeOutput`) and `.to_svg_string()`. The examples below use it.
+
+> **Upgrading from 0.1.x?** `encode()` / `to_svg_string()` now live behind the
+> `alloc` feature. Enable `features = ["alloc"]` to keep the old code unchanged,
+> or switch to the zero-allocation `encode_into` shown above. See
+> [CHANGELOG.md](CHANGELOG.md#migration-from-01x).
+
 ## Supported symbologies
 
 | Symbology                   | Module                       | Status |
@@ -198,9 +243,9 @@ println!("{svg}");
 
 ```rust
 use barcodes::common::traits::BarcodeEncoder;
-use barcodes::gs1::databar::GS1DataBar;
+use barcodes::gs1::databar::DataBar;
 
-let output = GS1DataBar::encode("0950110153001").unwrap();
+let output = DataBar::encode("0950110153001").unwrap();
 let svg = output.to_svg_string();
 println!("{svg}");
 ```
@@ -299,11 +344,18 @@ let img = qr.to_image(4); // module_size = 4px
 img.save("qrcode.png").unwrap();
 ```
 
-## `no_std` Support
+## `no_std` and features
+
+This library is pure `no_std` by default and performs **no heap allocation** —
+the default build does not even link `alloc`, so any accidental allocation is a
+compile error.
 
-This library is `no_std` compatible by default and only requires the `alloc` crate.  
-Enable the `std` feature if you need standard library support.  
-Image output (`to_image()`) requires the `image` feature, which implies `std`.
+| Feature     | Adds                                                  | Implies |
+| ----------- | ----------------------------------------------------- | ------- |
+| _(default)_ | zero-alloc `encode_into` + `core::fmt::Write` SVG     | —       |
+| `alloc`     | owned `encode()` → `BarcodeOutput`, `to_svg_string()` | —       |
+| `std`       | `std::error::Error` for `EncodeError`                 | `alloc` |
+| `image`     | raster output `to_image()` (PNG/GIF/WebP)             | `std`   |
 
 ## Modules Overview