Allow vars to reference vars defined earlier

The template variable syntax can be used when defining a variable to
reference the value of a previously defined variable:
foo = bar
baz = {{ foo }}

1 files changed, 11 insertions, 1 deletions

diff --git a/template b/template
index a125255..ef1a72e 100755
--- a/template
+++ b/template
@@ -3,7 +3,17 @@
 BEGIN { FS = "[[:space:]]*=[[:space:]]*" }
 
 FILENAME == ARGV[1] && /^#/ { next }
-FILENAME == ARGV[1] && NF == 2 { vals[$1] = $2 }
+FILENAME == ARGV[1] && NF == 2 {
+	# If the value is a template variable that matches a previously defined
+	# variable, use that variable's value. Otherwise, use the literal
+	# value.
+	if (match($2, /\{\{[[:space:]]*[^\{\}[:space:]]+[[:space:]]\}\}/)) {
+		match($2, /[^\{\}[:space:]]+/)
+		vals[$1] = vals[substr($2, RSTART, RLENGTH)]
+	} else {
+		vals[$1] = $2
+	}
+}
 FILENAME == ARGV[1] { next }
 
 /\{\{[[:space:]]*[^\{\}[:space:]]+[[:space:]]*\}\}/ {