Add alias expand to support alias command

[xuanweishan]

Bug fix #424

Description

This pull request fix #424. Make user able to use autocomplete with python alias setting

Changes

1. Add a local variable alias_expanded in /tool/config/config_autocomplete.sh with definition:

   alias_expanded=$(alias -- "${COMP_WORDS[0]}" 2>/dev/null | sed -E "s/^alias ${COMP_WORDS[0]}='([^']+)'/\1/")

2. Add a condition for assigning variable configure_command
   • If alias_expanded is not empty: configure_command=${alias_expanded} ${COMP_WORDS[1]}
   • If alias_expanded is empty: configure_command=${COMP_WORDS[0] ${COMP_WORDS[1]}}

Tests

• ./configure [tab] [tab]
• python configure [tab] [tab] (w/ alias setting: `alias python="python3")
• python3 configure [tab] [tab]

[technic960183]

@xuanweishan Thanks for your contribution and sorry for the late reply.
I have investigated an edge case where the expanded of the alias itself contains spaces or quotes. (e.g. alias python="'/home/ymhsu/undergrad'\''s research/python'", where there is a folder named undergrad's research in the path.)

The solution is to store the command in an array and use eval to parse the string with complex quoting (without starting a new interactive bash).

I have proposed the modifications (7 lines in total).
Besides the 4 lines in the comments, we still need to replace another 3 lines:
all_options=$(${configure_command} --autocomplete_info=all) with all_options=$(eval "${configure_command[@]}" --autocomplete_info=all)
and 2 lines similarly for sub_options=.

Tests done

With alias python="'/home/ymhsu/undergrad'\''s research/python'":

• python configure.py --[tab][tab]
• python configure.py --m[tab][tab] -> print out --machine= --max_patch= --mhd= --model= --mpi=
• python configure.py --mod[tab] -> complete to --model=
• python configure.py --model=[tab][tab] -> print out ELBDM HYDRO PAR_ONLY
• python configure.py --model=H[tab] -> complete to --model=HYDRO
  And the same combination for python3, ./configure.py, and with alias python="'/home/ymhsu/under\"grad'\''s research/python'" for a path with under"grad's research.
  I hope this solution has enough completeness.

[xuanweishan]

@technic960183
Thanks for the great suggestion. I've apply your suggestion in latest commit.

[technic960183]

Looks Good To Me.
Sorry for the late reply.
@xuanweishan Please help me to resolve the conversations. I do not have the permissions to do that.