jivanpal · September 29, 2019 17:55 · Sep 29, 2019
diff --git a/compile-tex.sh b/compile-tex.sh
@@ -0,0 +1,120 @@
+#!/bin/bash
+
+debug=0
+
+# Echo usage of this script to STDERR
+usage() {
+    >&2 echo "Usage: $0 <file to compile> <output file>"
+}
+
+# Get a random MD5 hash with 128 bits of entropy
+get_random_hash() {
+    (dd if=/dev/urandom bs=16 count=1 | md5sum | cut -d' ' -f1) 2> /dev/null
+}
+
+tmp_dir="/tmp/com.jivanpal.compile-tex"
+
+# Get a file path to use as a temporary store of data
+get_tmp_file_path() {
+    echo "${tmp_dir}/$(get_random_hash)"
+}
+
+# Replace given line of given file with the contents of another given file.
+# This action is destructive, permanently replacing the file in place!
+replace_line_with_file() {
+    file_to_modify=$1
+    line_number=$2
+    file_to_insert=$3
+
+    sed -i '' "$line_number {
+        r $file_to_insert
+        d
+    }" $file_to_modify
+}
+
+regex='^%__INSERT ".*"$'
+
+# Read input from STDIN, replace lines of the form `%__INSERT "file.txt"`
+# with the contents of `file.txt`, then output the result to STDOUT.
+evaluate_insert_macros() {
+    file_to_evaluate=$(get_tmp_file_path)
+    cp /dev/stdin $file_to_evaluate
+
+    if [[ debug -eq 1 ]] ; then
+        >&2 echo "Evaluating file at \`$file_to_evaluate\` ..."
+    fi
+
+    OLD_IFS=$IFS
+    IFS=$'\n'
+
+    # For each INSERT line, in reverse order ...
+    for macro_line in $(grep -n $regex $file_to_evaluate | tail -r); do
+        line_number=$(cut -d: -f1 <<< $macro_line)
+        file_to_insert=$(cut -d' ' -f2 <<< $macro_line | sed -e 's/^.//' -e 's/.$//')
+
+        if [[ debug -eq 1 ]] ; then
+            >&2 echo "Inserting file \`$file_to_insert\` at line $line_number ..."
+        fi
+
+        if [[ ! -f $file_to_insert ]] ; then
+            >&2 echo "File \`$file_to_insert\` does not exist!"
+            exit 1
+        fi
+
+        tmp_file=$(get_tmp_file_path)
+        cp $file_to_insert $tmp_file
+
+        if [[ debug -eq 1 ]] ; then
+            >&2 echo "Copied \`$file_to_insert\` to \`$tmp_file\`."
+        fi
+
+        # Execution in a sub-shell is necessary here to avoid overwriting
+        # existing variables in this shell's cope. Also allows us to use
+        # relative paths in INSERT statements that are relative to the file
+        # being inserted.
+        (
+            dir_name=$(dirname $file_to_insert)
+            file_to_insert=$(basename $file_to_insert)
+
+            cd $dir_name
+            evaluate_insert_macros < $file_to_insert > $tmp_file
+        )
+
+        replace_line_with_file $file_to_evaluate $line_number $tmp_file
+        if [[ debug -eq 1 ]] ; then
+            >&2 echo "Performed replacement."
+        fi
+    done
+    IFS=$OLD_IFS
+
+    cat $file_to_evaluate
+}
+
+if [[ $# -ne 2 ]] ; then
+    usage
+    exit 1;
+fi
+
+invocation_dir=$(pwd)
+
+mkdir -p $tmp_dir
+working_file=$(get_tmp_file_path)
+
+input_file=$1
+output_file=$2
+input_file_dir=$(dirname $input_file)
+input_file=$(basename $input_file)
+
+cd $input_file_dir
+cp $input_file $working_file
+
+if [[ debug -eq 1 ]] ; then
+    >&2 echo "Working file is \`$working_file\`."
+fi
+
+cd $invocation_dir
+
+evaluate_insert_macros < $working_file > $output_file
+
+# Cleanup tmpfs
+rm -rf $tmp_dir