crys

A Crystal one-liner tool.

It does four things only.

• decide how input is iterated
• decide what each record sees
• decide what to require
• decide how output is emitted

It does not add dependency management or a custom DSL. It is a thin wrapper around plain Crystal code.

Installation

Build:

shards build

Binary:

bin/crys

Move it somewhere on your PATH if needed.

Usage

Basic form:

crys [options] 'CRYSTAL_CODE' [file ...]

Process stdin line by line:

printf 'a\nb\n' | crys -n 'puts line.upcase'

Assign the result back to line and print it:

printf 'a\nb\n' | crys -p 'line.upcase'

Auto-split input:

printf 'a:b\nc:d\n' | crys -a -F: 'puts f[1]'

Slurp all input:

printf '{"a":1}' | crys -r json -g 'puts JSON.parse(input)["a"].as_i'

Run setup and teardown code:

printf '1\n2\n3\n' | crys --init 'sum = 0' -n 'sum += line.to_i' --final 'puts sum'

Edit files in place:

crys -pi.bak 'line.gsub("foo", "bar")' file.txt
crys -i 'line.upcase' file.txt

Inspect generated code:

crys --dump -p 'line.upcase'

Options

• -n: read input line by line. Exposes line and nr
• -p: same as -n, but assigns the body result back to line and prints it
• -a: auto-split line into f
• -F SEP: field separator for -a
• -g, --slurp: read all input into input
• -i[SUFFIX]: edit files in place. -i.bak creates backups
• -r LIB: add require "LIB". Repeatable
• --init CODE: insert code before the main body or loop
• --final CODE: insert code after the main body or loop
• --dump: print the generated Crystal code and exit
• -O LEVEL: build with optimization level (0, 1, 2, 3, s, z)
• --release: build with crystal build --release
• --error-trace: build with crystal build --error-trace
• -h, --help: show help

Implicit variables:

• line: current line, always chomped
• f: split fields, only with -a
• nr: record number
• input: full slurped input, only with -g or --slurp
• path: current file path when reading files or editing in place

Generated programs are cached under CRYS_HOME/cache and reused when the generated code and Crystal flags are unchanged.

Constraints:

• -g / --slurp cannot be combined with -n / -p
• -i requires at least one file

Development

Run unit tests:

crystal spec

Run integration tests:

bash spec/integration_test.sh

Build locally:

crystal build src/main.cr -o bin/crys