aag: per-file logical AND of multiple ag searches

aag

#!/bin/bash
#
# ag with logical AND of multiple searches
#
# Copyright (C) 2020 Maddison Hellstrom <https://github.com/b0o>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

set -euo pipefail

function usage() {
  mapfile -t usage << "EOF"
aag: per-file logical AND of multiple ag searches

Usage:
  aag [path ..] ----] [opts] <pattern> --- [opts] <pattern> [--- [opts] <pattern> ..]

  Paths can either be passed at the beginning of the command line followed by ----,
  or they can be piped to stdin separated by newlines.

Caveats and bugs:
  - aag is a 'naive' interface to ag in that it doesn't attempt to parse or
    understand any options passed to ag, and makes a few assumptions about your
    usage.

    Because of this, aag does not necessarily play niceley with all ag options.
    Some may cause aag to break, while others may produce unexpected output.

    For example, when using ag's -w option, the final output will highlight any
    non-word matches of the pattern if they exist, although the list of matched
    files will still be correct.

    Generally, options that modify the way output is displayed will not work.

    Options that are known to be unsupported:
      -A, -B -c, --color*, -C, -D, --nofilename, -g, -l, -m, --numbers, -o, --pager,
      --print-ling-lines, --passthrough, --stats*, --version, --vimgrep, -0

  - If there are more than ARG_MAX (see sysconf(3)) candidate files for the first
    search, aag will crash.  To work around this, try making your first search more
    specific and/or limit the number/depth of paths searched.

  - Output will not be displayed until the end of program execution.

EOF
  printf '%s\n' "${usage[@]}" >&2
}

declare -ga matches_old=()
declare -ga matches=()
declare -g compound_pattern=""

function run_search() {
  matches_old=("${matches[@]}")
  matches=()

  local -i needs_dashdash=1
  local e
  for e in "$@"; do
    if [[ "$e" == "--" ]]; then
      needs_dashdash=0
      break
    fi
  done

  local args=("$@")
  if [[ $needs_dashdash -eq 1 ]]; then
    args=("${args[@]:0:$((${#args[@]} - 1))}" -- "${args[-1]}")
  fi

  [[ -z "$compound_pattern" ]] || compound_pattern+="|"
  compound_pattern+="(${args[-1]})"

  local res
  res="$(ag "${args[@]}" "${matches_old[@]}")" || {
    echo "no matches" >&2
    return 1
  }
  mapfile -t matches <<< "$res"
}

function main() {
  [[ $# -ge 0 ]] || {
    usage
    exit 1
  }
  [[ ! $1 =~ ^(-h|--help)$ ]] || {
    usage
    exit 0
  }

  local -a maybe_paths=()
  local -a search=()
  local -i sep_found=0

  if [[ -p /dev/stdin ]]; then
    mapfile -t matches
  else
    local -i i=1
    for e in "$@"; do
      [[ "$e" != "----" ]] || {
        matches=("${maybe_paths[@]}")
        shift $i
        break
      }
      [[ "$e" != "---" ]] || break
      maybe_paths+=("$e")
      i=$((i + 1))
    done
  fi

  for e in "$@"; do
    [[ "$e" != "---" ]] || {
      sep_found=1
      run_search --nocolor --files-with-matches "${search[@]}"
      search=()
      continue
    }
    search+=("$e")
  done

  if [[ $sep_found -eq 0 ]]; then
    echo "error: unnecessary use of aag with a single search query" >&2
    return 1
  fi

  if [[ ${#search[@]} -eq 0 ]]; then
    echo "error: unnecessary extra --- not preceding a search query" >&2
    return 1
  fi

  run_search --nocolor --files-with-matches  "${search[@]}"
  run_search --color --heading "$compound_pattern"
  printf '%s\n' "${matches[@]}"
}

main "$@"