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Preserve escaped dollar literals

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Sami Samhuri 2026-02-02 20:43:43 -08:00
parent 52ef7cb7f5
commit 5172c60910
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1 changed files with 28 additions and 1 deletions
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29
ruby/shell/word_expander.rb
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@ -3,6 +3,7 @@ require "shellwords"
module Shell
class WordExpander
ENV_VAR_REGEX = /\$(?:\{([^}]+)\}|(\w+)\b)/
ESCAPED_DOLLAR = "\u0001"
# Splits the given line into multiple words, performing the following transformations:
#
@ -11,13 +12,15 @@ module Shell
# - Tilde expansion, which means that ~ is expanded to $HOME
# - Glob expansion on files and directories
def expand(line)
shellsplit(line)
protected_line = protect_escaped_dollars(line)
shellsplit(protected_line)
.map do |word|
word
.gsub(ENV_VAR_REGEX) do
name = Regexp.last_match(2) || Regexp.last_match(1)
ENV.fetch(name)
end
.tr(ESCAPED_DOLLAR, "$")
# TODO: expand globs
end
end
@ -94,5 +97,29 @@ module Shell
def expand_globs(word)
Dir.glob(word)
end
def protect_escaped_dollars(line)
output = +""
i = 0
while i < line.length
if line.getbyte(i) == "\\".ord
j = i + 1
j += 1 while j < line.length && line.getbyte(j) == "\\".ord
count = j - i
if j < line.length && line.getbyte(j) == "$".ord && count.odd?
output << ("\\" * (count - 1))
output << ESCAPED_DOLLAR
i = j + 1
else
output << ("\\" * count)
i = j
end
else
output << line[i]
i += 1
end
end
output
end
end
end