Initial data commit

Task/Inverted-index/UNIX-Shell/inverted-index-3.sh

@@ -0,0 +1,49 @@
+#!/bin/sh
+# index.sh - create an inverted index
+
+unset IFS
+: ${INDEX:=index}
+
+# Prohibit '\n' in filenames (because '\n' is
+# the record separator for $INDEX/all.tab).
+for file in "$@"; do
+    # Use printf(1), not echo, because "$file" might start with
+    # a hyphen and become an option to echo.
+    test 0 -eq $(printf %s "$file" | wc -l) || {
+        printf '%s\n' "$file: newline in filename" >&2
+        exit 1
+    }
+done
+
+# Make a new directory for the index, or else
+# exit with the error message from mkdir(1).
+mkdir "$INDEX" || exit $?
+
+fi=1
+for file in "$@"; do
+    printf %s "Indexing $file." >&2
+
+    # all.tab maps $fi => $file
+    echo "$fi $file" >> "$INDEX/all.tab"
+
+    # Use punctuation ([:punct:]) and whitespace (IFS)
+    # to split tokens.
+    ti=1
+    tr -s '[:punct:]' ' ' < "$file" | while read line; do
+        for token in $line; do
+            # Index token by position ($fi, $ti). Ignore
+            # error from mkdir(1) if directory exists.
+            mkdir "$INDEX/$token" 2>/dev/null
+            echo $ti >> "$INDEX/$token/$fi"
+            : $((ti += 1))
+
+            # Show progress. Print a dot per 1000 tokens.
+            case "$ti" in
+            *000)   printf .
+            esac
+        done
+    done
+
+    echo >&2
+    : $((fi += 1))
+done