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syntax: simplify most literal index expressions within arithmetic #1

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22 changes: 17 additions & 5 deletions syntax/simplify.go
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Original file line number Diff line number Diff line change
Expand Up @@ -162,14 +162,26 @@ func (s *simplifier) inlineSimpleParams(x ArithmExpr) ArithmExpr {
return x
}
if pe.Excl || pe.Length || pe.Width || pe.Slice != nil ||
pe.Repl != nil || pe.Exp != nil || pe.Index != nil {
pe.Repl != nil || pe.Exp != nil {
// A complex parameter expansion can't be simplified.
//
// Note that index expressions can't generally be simplified
// either. It's fine to turn ${a[0]} into a[0], but others like
// a[*] are invalid in many shells including Bash.
return x
}
if pe.Index != nil {
// All index expressions can't be simplified either.
// It's fine to turn ${a[0]} into a[0], but others like
// a[*] or a[@] are invalid in many shells including Bash.
ww, _ := pe.Index.(*Word)
if ww == nil || len(ww.Parts) != 1 {
return x
}
l, _ := ww.Parts[0].(*Lit)
if l == nil || l.Value == "*" || l.Value == "@" {
return x
}
s.modified = true
pe.Short = true
return w
}
s.modified = true
return &Word{Parts: []WordPart{pe.Param}}
}
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3 changes: 2 additions & 1 deletion syntax/simplify_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -27,13 +27,14 @@ var simplifyTests = [...]simplifyTest{
{"${foo:(1):(2)}", "${foo:1:2}"},
{"a[(1)]=2", "a[1]=2"},
{"$(($a + ${b}))", "$((a + b))"},
{"((${a[0]}))", "((a[0]))"},
{"((${a[foo]}))", "((a[foo]))"},
noSimple("$((${!a} + ${#b}))"),
noSimple("a[$b]=2"),
noSimple("${a[$b]}"),
noSimple("${a[@]}"),
noSimple("((${a[@]}))"),
noSimple("((${a[*]}))"),
noSimple("((${a[0]}))"),
noSimple("(($3 == $#))"),

// test exprs
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