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[](https://crates.io/crates/crabular)
[](https://docs.rs/crabular)
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# Crabular
A high-performance ASCII table library for Rust with zero dependencies.
## Features
- **Multiple table styles** - Classic, Modern (Unicode), Minimal, Compact, Markdown
- **Flexible alignment** - Left, Center, Right per-cell and per-column
- **Vertical alignment** - Top, Middle, Bottom for multi-line cells
- **Width constraints** - Fixed, Min, Max, Proportional, Wrap
- **Multi-line cells** - Automatic word wrapping with configurable widths
- **Cell spanning** - Colspan support for merged cells
- **Sorting** - Sort by column (alphabetic or numeric, ascending or descending)
- **Filtering** - Filter rows by exact match, predicate, or substring
- **Builder API** - Fluent interface for table construction
- **Zero dependencies** - No external crates required (core library)
- **WebAssembly support** - Use in browsers and Node.js via `crabular` npm package
- **Safe Rust** - `#![forbid(unsafe_code)]`
- **High performance** - Zero-allocation Display trait, allocation pooling for repeated renders
## Performance
Crabular v0.2.0+ includes Rust 1.93 optimizations for significant performance improvements:
### Zero-Allocation Display
```rust
use crabular::Table;
let table = Table::new()
.header(["Name", "Age"])
.row(["Kata", "30"]);
// Zero-allocation printing (20-40% faster)
println!("{table}");
// For comparison, this allocates:
println!("{}", table.render());
```
### Allocation Pooling for Repeated Renders
```rust,ignore
use std::io::{stdout, Write};
let mut buffer = Vec::with_capacity(4096);
for item in 0..10 {
buffer.clear();
table.render_into(&mut buffer)?;
stdout().write_all(&buffer)?;
}
```
**Benefits:** 30-50% faster for repeated renders (pagination, filtering UI)
## Installation
Add to your `Cargo.toml`:
```toml
[dependencies]
crabular = "0.7"
```
### WebAssembly (JavaScript/TypeScript)
For browser or Node.js usage, install the WebAssembly package:
```bash
npm install crabular
```
```javascript
import init, { JsTable } from 'crabular';
await init();
const table = new JsTable();
table.style('modern');
table.header(['Name', 'Age']);
table.row(['Alice', '30']);
console.log(table.render());
```
See [crabular-wasm/examples](crabular-wasm/examples/) for more JavaScript examples.
## Quick Start
```rust
use crabular::{Table, TableStyle};
let mut table = Table::new();
table.set_style(TableStyle::Modern);
table.set_headers(["Name", "Age", "City"]);
table.add_row(["Kelana", "30", "Berlin"]);
table.add_row(["Kata", "25", "Yogyakarta"]);
println!("{}", table.render());
```
Output:
```text
┌────────┬─────┬────────────┐
│ Name │ Age │ City │
├────────┼─────┼────────────┤
│ Kelana │ 30 │ Berlin │
│ Kata │ 25 │ Yogyakarta │
└────────┴─────┴────────────┘
```
## Builder API
For a more fluent experience, use `TableBuilder`:
```rust
use crabular::{TableBuilder, TableStyle, Alignment, WidthConstraint};
let output = TableBuilder::new()
.style(TableStyle::Modern)
.header(["ID", "Name", "Score"])
.constrain(0, WidthConstraint::Fixed(5))
.constrain(1, WidthConstraint::Min(15))
.align(2, Alignment::Right)
.rows([
["1", "Kelana", "95.5"],
["2", "Kata", "87.2"],
["3", "Cherry Blossom", "92.0"],
])
.render();
print!("{output}"); // Or use .print() directly with std feature
```
## Truncation
Limit cell content length with truncation:
```rust
use crabular::{TableBuilder, TableStyle};
let output = TableBuilder::new()
.style(TableStyle::Modern)
.header(["ID", "Name", "Description", "Score"])
.truncate(20) // Truncate to 20 characters with "..." suffix
.rows([
["1", "Kata", "A very long description that should be truncated", "95.5"],
["2", "Kelana", "Short desc", "87.2"],
["3", "Squidward", "Another extremely long description text here", "92.0"],
])
.render();
print!("{output}");
```
Output:
```text
┌─────┬────────────┬───────────────────────┬───────┐
│ ID │ Name │ Description │ Score │
├─────┼────────────┼───────────────────────┼───────┤
│ 1 │ Kata │ A very long descr... │ 95.5 │
│ 2 │ Kelana │ Short desc │ 87.2 │
│ 3 │ Squidward │ Another extremely... │ 92.0 │
└─────┴────────────┴───────────────────────┴───────┘
```
**Note:** Truncation is applied lazily during row insertion, so there's zero overhead when not used.
## Table Styles
```rust
use crabular::TableStyle;
// Available styles:
let _ = TableStyle::Classic; // +---+---+ with | and -
let _ = TableStyle::Modern; // Unicode box-drawing characters
let _ = TableStyle::Minimal; // Header separator only
let _ = TableStyle::Compact; // No outer borders
let _ = TableStyle::Markdown; // GitHub-flavored markdown tables
```
### Classic
```text
+-----------------+-----+---------------+
| Kelana | 30 | Berlin |
| Kata | 25 | Yogyakarta |
| Cherry Blossom | 35 | Bikini Bottom |
+-----------------+-----+---------------+
```
### Modern
```text
┌─────────────────┬─────┬───────────────┐
│ Name │ Age │ City │
├─────────────────┼─────┼───────────────┤
│ Kelana │ 30 │ Berlin │
│ Kata │ 25 │ Yogyakarta │
│ Cherry Blossom │ 35 │ Bikini Bottom │
└─────────────────┴─────┴───────────────┘
```
### Minimal
```text
Name Age City
──────────────────────────────────────────
Kelana 30 Berlin
Kata 25 Yogyakarta
Cherry Blossom 35 Bikini Bottom
```
### Compact
```text
│ Name │ Age │ City │
──────────────────┼──────┼────────────────
│ Kelana │ 30 │ Berlin │
│ Kata │ 25 │ Yogyakarta │
│ Cherry Blossom │ 35 │ Bikini Bottom │
```
### Markdown
```text
| Kelana | 30 | Berlin |
| Kata | 25 | Yogyakarta |
| Cherry Blossom | 35 | Bikini Bottom |
```
## Width Constraints
Control column widths with various constraints:
```rust
use crabular::{Table, WidthConstraint};
let mut table = Table::new();
// Fixed width (exactly N characters)
table.constrain(WidthConstraint::Fixed(20));
// Minimum width (at least N characters)
table.constrain(WidthConstraint::Min(10));
// Maximum width (at most N characters, truncates if needed)
table.constrain(WidthConstraint::Max(30));
// Proportional (percentage of available width)
table.constrain(WidthConstraint::Proportional(50));
// Wrap (word wrap at N characters)
table.constrain(WidthConstraint::Wrap(25));
```
## Alignment
```rust
use crabular::{Table, Row, Alignment};
let mut table = Table::new();
// Set column alignment
table.align(0, Alignment::Left);
table.align(1, Alignment::Center);
table.align(2, Alignment::Right);
// Per-row alignment via Row::with_alignment
let row = Row::with_alignment(["text"], Alignment::Center);
table.add_row(row);
```
## Vertical Alignment
For multi-line cells:
```rust
use crabular::{Table, VerticalAlignment};
let mut table = Table::new();
table.valign(VerticalAlignment::Top); // Default
table.valign(VerticalAlignment::Middle);
table.valign(VerticalAlignment::Bottom);
```
## Cell Spanning (Colspan)
Create cells that span multiple columns:
```rust
use crabular::{Table, Cell, Row, Alignment};
let mut table = Table::new();
table.set_headers(["A", "B", "C"]);
let mut row = Row::new();
let mut merged = Cell::new("Spans two columns", Alignment::Center);
merged.set_span(2); // This cell spans 2 columns
row.push(merged);
row.push(Cell::new("Normal", Alignment::Left));
table.add_row(row);
```
> **Note:** Standard Markdown does not support colspan. When using `TableStyle::Markdown`
> with spanned cells, the output will render visually but won't be valid Markdown table syntax.
## Sorting
Sort table rows by any column:
```rust
use crabular::{Table, Row, Alignment};
let mut table = Table::new();
table.add_row(["Kelana", "30"]);
table.add_row(["Kata", "25"]);
// Alphabetic sorting
table.sort(0); // Ascending by column 0
table.sort_desc(0); // Descending by column 0
// Numeric sorting
table.sort_num(1); // Ascending numeric by column 1
table.sort_num_desc(1); // Descending numeric by column 1
// Custom sorting - compare by first column content
table.sort_by(|a, b| {
let a_content = a.cells().first().map_or("", |c| c.content());
let b_content = b.cells().first().map_or("", |c| c.content());
a_content.cmp(b_content)
});
```
## Filtering
Filter rows based on conditions:
```rust
use crabular::{Table, Row, Alignment};
let mut table = Table::new();
table.add_row(["Kelana", "Active", "100"]);
table.add_row(["Kata", "Inactive", "50"]);
table.add_row(["Cherry Blossom", "Active", "75"]);
// Exact match - keeps rows where column 1 equals "Active"
table.filter_eq(1, "Active");
// Substring match - keeps rows where column 0 contains "Kelana"
// table.filter_has(0, "Kelana");
// Custom predicate on column - keeps rows where column 2 > 50
// table.filter_col(2, |val| val.parse::<i32>().unwrap_or(0) > 50);
// Full row predicate - keeps rows with more than 2 cells
```
## Column Operations
```rust
use crabular::{Table, Row, Alignment};
let mut table = Table::new();
table.set_headers(["A", "B"]);
table.add_row(["1", "2"]);
table.add_row(["3", "4"]);
// Add column at the end (first value is header, rest are row values)
table.add_column(&["C", "5", "6"], Alignment::Left);
// Insert column at position (first value is header, rest are row values)
table.insert_column(1, &["X", "a", "b"], Alignment::Center);
// Remove column
table.remove_column(2);
```
## CLI Tool
A separate CLI tool is available at [crabular-cli](https://github.com/kakilangit/crabular/tree/main/crabular-cli):
```bash
# Install
cargo install crabular-cli
# From CSV file (default: first row is header)
crabular-cli -i data.csv
# Truncate long cell content to 20 characters
crabular-cli -i data.csv --truncate 20
# Treat all rows as data (no header)
crabular-cli -i data.csv --no-header
# Skip first row, treat remaining as data
crabular-cli -i data.csv --skip-header
# From stdin
# From JSON (supports nested objects)
# Different styles
crabular-cli -s modern -i data.csv
crabular-cli -s markdown -i data.csv
```
### CLI Options
| `-i, --input <FILE>` | Input file path (use `-` for stdin) |
| `-o, --output <FILE>` | Output file path |
| `-s, --style <STYLE>` | Table style: classic, modern, minimal, compact, markdown |
| `--format <FORMAT>` | Input format: csv, tsv, ssv, json, jsonl |
| `-S, --separator <CHAR>` | Field separator (default: auto-detect) |
| `--truncate N` | Truncate cell content to N characters with "..." suffix |
| `--no-header` | Treat all rows as data (no header row) |
| `--skip-header` | Skip first row, treat remaining as data |
## API Reference
### Table
| `new()` | Create empty table |
| `set_headers(row)` | Set header row |
| `add_row(row)` | Add data row |
| `truncate(limit)` | Set max cell content length |
| `render()` | Render to string |
| `print()` | Print to stdout |
| `set_style(style)` | Set table style |
| `align(col, alignment)` | Set column alignment |
| `valign(alignment)` | Set vertical alignment |
| `constrain(constraint)` | Add width constraint |
| `sort(col)` | Sort ascending |
| `sort_desc(col)` | Sort descending |
| `sort_num(col)` | Sort numeric ascending |
| `sort_num_desc(col)` | Sort numeric descending |
| `filter_eq(col, value)` | Filter by exact match |
| `filter_has(col, substr)` | Filter by substring |
| `filter_col(col, pred)` | Filter by predicate |
### `TableBuilder`
| `new()` | Create new builder |
| `style(style)` | Set table style |
| `header(cells)` | Set header row |
| `row(cells)` | Add data row |
| `rows(data)` | Add multiple rows |
| `truncate(limit)` | Set max cell content length |
| `align(col, alignment)` | Set column alignment |
| `valign(alignment)` | Set vertical alignment |
| `constrain(col, constraint)` | Set column constraint |
| `padding(padding)` | Set cell padding |
| `build()` | Build table |
| `render()` | Build and render |
| `print()` | Build and print |
## License
MIT License - see [LICENSE](LICENSE) for details.