Cindex, a csv indexer

Cindex is a easy to use csv indexer with a simple SQL-like query support.

Cindex is not intended for heavy database indexing but for simple in-memory querying. Use other databases interaction layer if you're using big chunks of csv files.

Usage

[dependencies]
cindex = "*" # Use the latest version if possible

# Use "default-features = false" if you don't need rayon iteration enhancement.

use std::fs::File;
use cindex::{Indexer, CsvType, Predicate, Query, OutOption, Operator};

let mut indexer = Indexer::new();

// Add table without types
// Default types for every columns are "Text"
indexer.add_table_fast(
    "table1", 
    File::open("test.csv").expect("Failed to open a file")
).expect("Failed to add table");

// Add table with column types
indexer.add_table(
    "table2", 
    vec![CsvType::Text, CsvType::Text],
    "id,address
10,110-2222".as_bytes()
).expect("Failed to add table");

// Add table from stdin
let stdin = std::io::stdin();
indexer.add_table_fast(
    "table3", 
    stdin.lock()
).expect("Failed to add table");

// Indexing

// Create query object and print output to terminal
let query = Query::from_str("SELECT a,b,c FROM table1 WHERE a = 10");
indexer.index(query, OutOption::Term).expect("Failed to index a table");

// Use raw query and yield output to a file
indexer.index_raw(
    "SELECT * FROM table3 WHERE id = 10", 
    OutOption::File(std::fs::File::create("out.csv")
		.expect("Failed to create a file"))
).expect("Failed to index a table");

// Use builder pattern to construct query and index a table
let query = Query::empty("table2")
    .columns(vec!["id", "address"])
    .predicate(Predicate::new("id", Operator::Equal)
        .args(vec!["10"])
    )
    .predicate(Predicate::build()
        .column("address")
        .operator(Operator::NotEqual)
        .raw_args("111-2222")
    );

let mut acc = String::new();
indexer.index(query, OutOption::Value(&mut acc))
	.expect("Failed to index a table");

// Always use unix newline for formatting
indexer.always_use_unix_newline(true);

Query syntax

Cindex's query syntax is similar to SQL but has some small differences.

/* Select everythig from given table*/
SELECT * FROM table1

/* Select everything from given table and order by column with descending
order*/
SELECT * FROM table1 ORDER BY col1 DESC

/* Same with previous commands but map header result */
SELECT * FROM table1 ORDER BY col1 DESC HMAP new_h,new_h2,new_h3

/* -> Previous query result header with underbar substituted with whitespaces
new h,new h2,new h3
<-- Content goes here -->
 */

/* Select given columns from table where column's value is equal to given
condition and also other column's value matches regex expression */
SELECT col1,col2 FROM table1 WHERE col1 = 10 AND col2 LIKE ^start

/* There is a flag syntax which changes query behaviour*/
SELECT * FROM table_name FLAG PHD SUP

/* In this case each flag does next operation
  - PHD (PRINT-HEADER) : Print header in result output
  - SUP (SUPPLEMENT)   : Enable selection of non-existent column with empty values
 */

Supported WHERE operations are

 >= 
 >
 <=
 <
 =
 !=
 IN
 BETWEEN
 LIKE ( with regeular expression )

TODO

• DateTime csv type
• Multi where caluse support
• Join table