DSV Seeker

A small tool to run basic queries on DSV files.

1. Commands
2. How to add a new command

Commands

"select" ("*" | (name ("," name)*))

The select command keeps only the desired columns.

"where" name (("=" value) | ("like" pattern))

The where command filters rows based on string equality or pattern matching of the value in the named column.

"enum" name

The enum command outputs two columns, respectively the number of appearances of a value and the value itself.
This is similar in a way to running uniq -c in Bash.

"sort" "num"? name ("asc" | "desc")

The sort command sorts rows based on the named column.

"trim" ("*" | (name ("," name)*))

The trim command removes heading and trailing whitespace from desired columns' values.

behead

The behead command removes the first line, that usually being the headers.

How to add a new command

Commands are organized in isolated modules as much as possible.
Steps

1. Add the grammar rule to the grammar.pest file:
   • Create a new rule under the other commands' rules, right above the command rule.
   • Add that rule to the end of the command rule.
2. Add your command to the Command enum in src/ast.rs.
3. Handle matching from the rule to a new Command::[your_rule] in src/ast.rs::build_command.
4. Create your command's file in src/operators/ and add the new module to src/operators/mod.rs.
5. Look at other commands to figure out how to write yours.
6. Add the match case for your rule in src/ast.rs::Ast::run_on.
7. Add the command to this README and to the src/main.rs::Cli doc comment.