Live Action Search and Replace (LASR)

When performing a global search-and-replace using e.g. sed, it can be difficult to hone in on the exact correct pattern. lasr makes this easier by showing live results as you type.

Installation

Binary artifacts can be downloaded from the releases page.

If you have a rust toolchain, you can install from source:

cargo install lasr

Usage

Simply run lasr to start a search-and-replace in the current directory. You may run lasr <path> [<path>...] to search a specific directories or files. This will open a TUI where you can start typing a search pattern and see live matches below. Once you are happy with the search pattern, press Tab to start editing the replacement pattern. Finally, press Enter to confirm and execute the replacement, or Esc to cancel the replacement. You can press Ctrl+S to toggle case-insensitive searching, or pass the -i flag to enable case-insensitive search on startup.

Syntax

The pattern syntax is based on the rust regex crate. The replacement syntax is based on the replace method in that crate.

Replacements may reference numbered groups as $1 or ${1}, or named groups like $foo or ${foo}. The {} brackets may be necessary to separate the replacement from other text. $0 or ${0} refers to the entire match.

Configuration

The configuration file is located at $XDG_CONFIG_HOME/lasr/lasr.toml (~/.config/lasr/lasr.toml by default). The current configuration can be printed by running lasr --dump-config. This can be used as a starting point to edit your own configuration:

lasr --dump-config > ~/.config/lasr/lasr.toml

Default Config

[theme.base]
fg = "Reset"

[theme.find]
fg = "Red"
add_modifier = "CROSSED_OUT"

[theme.replace]
fg = "Green"
add_modifier = "BOLD"

[keys]
c-b = "cursor_left"
c-s = "toggle_ignore_case"
tab = "toggle_search_replace"
left = "cursor_left"
home = "cursor_home"
c-e = "cursor_end"
c-d = "delete_char"
right = "cursor_right"
c-h = "delete_char_backward"
enter = "confirm"
backspace = "delete_char_backward"
c-k = "delete_to_end_of_line"
c-a = "cursor_home"
end = "cursor_end"
c-f = "cursor_right"
c-c = "exit"
esc = "exit"
c-u = "delete_line"
c-w = "delete_word"

General Config

The following settings may be placed at the top-level of the config, not under any section:

Theme Config

The theme section of the config includes 3 "style" sub-sections:

A "style" has the following attributes

A color can be an ANSI color name like "red", an ANSI 8-bit color index like "7", or a hex string like "#00FF00".

add_modifier and sub_modifier can be one of the following:

• "BOLD"
• "DIM"
• "ITALIC"
• "UNDERLINED"
• "SLOW_BLINK"
• "RAPID_BLINK"
• "REVERSED"
• "HIDDEN"
• "CROSSED_OUT"

Keys Config

The keys section specifies key bindings. Each key is a single character or key name, optionally followed by "c-" and/or "a-" to specify a ctrl or alt modifier. The following are valid key names:

• a-z, 0-9
• f0-f12
• backspace
• enter
• left
• right
• up
• down
• home
• end
• pageup
• pagedown
• tab
• backtab
• delete
• insert
• esc

Each value in the keys section is one of the following actions:

Troubleshooting

Logs are located at $XDG_CACHE_HOME/lasr/log.txt. Log verbosity can be increased by setting the environment variable RUST_LOG to debug or trace. See env_logger for more info.

Other cool search/replace tools

• sad allows you to approve/reject each replacement, but must be re-run each time you change the pattern.
• sd provides a simpler CLI alternative to sed, but is not interactive.
• ast-grep is like sed/grep, but using tree-sitter to match code syntax.