RosettaCodeData/Task/Inverted-index/PowerShell/inverted-index-1.psh

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function Index-File ( [string[]]$FileList )
{
# Create index hashtable, as needed
If ( -not $Script:WordIndex ) { $Script:WordIndex = @{} }
# For each file to be indexed...
ForEach ( $File in $FileList )
{
# Find any previously existing entries for this file
$ExistingEntries = $Script:WordIndex.Keys | Where { $Script:WordIndex[$_] -contains $File }
# For any previously existing entries
# Delete them (prior to reindexing the file)
ForEach ( $Key in $ExistingEntries )
{
$Script:WordIndex[$Key] = @( $Script:WordIndex[$Key] | Where { $_ -ne $File } )
}
# Get the contents of the file, split on non-alphanumeric characters, and remove duplicates
$Words = ( Get-Content $File ) -split '[^a-zA-Z\d]' | Sort -Unique
# For each word in the file...
ForEach ( $Word in $Words )
{
# If the entry for the word already exists...
If ( $Script:WordIndex[$Word] )
{
# Add the file name to the entry
$Script:WordIndex[$Word] += $File
}
Else
{
# Create a new entry
$Script:WordIndex[$Word] = @( $File )
}
}
}
}
function Find-Word ( [string]$Word )
{
return $WordIndex[$Word]
}