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articles/Contextual completions.md

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+# Contextual completions
+
+xprompt is a prompt for X providing one notable feature over dmenu: contextual
+completions. Contextual completions can be achieved with spmenu as well by
+using the `-r` flag and reading from file.
+
+```Shell
+printf "Type 'git' and it will autocomplete." > /tmp/git-complete-file
+printf "" > /tmp/f
+
+func() {
+    while true; do
+        case "$(tail -n 1 /tmp/f)" in
+            "git ")
+                printf "git clone\ngit pull\ngit fetch\n" > /tmp/git-complete-file
+            ;;
+            "git clone ")
+                printf "git clone https://git.speedie.site/speedie/spmenu\n" > /tmp/git-complete-file
+            ;;
+        esac
+    done
+}
+
+func &
+
+spmenu -lf /tmp/git-complete-file -r >> /tmp/f
+
+tail -n 1 /tmp/f
+```
+
+This is an example of a script which allows you to autocomplete some Git arguments.
+If you type in `git`, git clone, git pull and git fetch will be displayed as matching
+options. If you type in `git clone`, `git clone` will be displayed as a match with
+the spmenu Git repository. Of course, this is a super basic script, which should
+give you an idea of how this works.
+
+Importantly, `-r` is passed to spmenu. This will print the text typed into spmenu
+every single time a key is pressed. We need to output this to a file, so the case
+statement can get the last line. The last line is always the typed/matched
+text. If `-r` is not passed, spmenu will not output anything until enter is pressed,
+and therefore we can't check the input while spmenu is running.
+
+The function `func` is a `while` loop which does the checking and writing of
+`/tmp/git-complete-file`. spmenu reads items from `/tmp/git-complete-file`.