add support for multiline template

2 files changed, 85 insertions, 13 deletions

diff --git a/README.md b/README.md
index 84cf8bc..e01aeae 100644
--- a/README.md
+++ b/README.md
@@ -106,7 +106,7 @@ This will help you to quickly review the results once in a while. Once you are h
 
 ### Templating
 
-Since version `2.0.0`, Gemtexter supports templating. A template file name must have the suffix `gmi.tpl`. A template must be put into the same directory as the Gemtext `.gmi` file to be generated. Gemtexter will generate a Gemtext file `index.gmi` from a given template `index.gmi.tpl`. All lines starting with `<< ` will be evaluated as Bash code and the output will be written into the resulting Gemtext file. 
+Since version `2.0.0`, Gemtexter supports templating. A template file name must have the suffix `gmi.tpl`. A template must be put into the same directory as the Gemtext `.gmi` file to be generated. Gemtexter will generate a Gemtext file `index.gmi` from a given template `index.gmi.tpl`. All lines starting with `<< ` will be evaluated as a single line of Bash code and the output will be written into the resulting Gemtext file. A `<<<` and `>>>` encloses a multiline template.
 
 For example, the template `index.gmi.tpl`:
 
@@ -116,6 +116,12 @@ For example, the template `index.gmi.tpl`:
 << echo "> This site was generated at $(date --iso-8601=seconds) by \`Gemtexter\`"
 
 Welcome to this capsule!
+
+<<<
+  for i in {1..10}; do
+    echo Multiline template line $i
+  done
+>>>
 ```
 
 ... results into the following `index.gmi` after running `./gemtexter --generate` (or `./gemtexter --template`, which instructs to do only template processing and nothing else):
@@ -126,6 +132,17 @@ Welcome to this capsule!
 > This site was generated at 2023-03-15T19:07:59+02:00 by `Gemtexter`
 
 Welcome to this capsule!
+
+Multiline template line 0
+Multiline template line 1
+Multiline template line 2
+Multiline template line 3
+Multiline template line 4
+Multiline template line 5
+Multiline template line 6
+Multiline template line 7
+Multiline template line 8
+Multiline template line 9
 ```
 
 ### Alternative configuration file path
diff --git a/lib/template.source.sh b/lib/template.source.sh
index 26d5acb..f2777e5 100644
--- a/lib/template.source.sh
+++ b/lib/template.source.sh
@@ -7,14 +7,14 @@ template::generate () {
             continue
         fi
         num_tpl_files=$(( num_tpl_files + 1 ))
-        template::_generate "$tpl_path" &
+        template::_generate_file "$tpl_path"
     done < <(find "$CONTENT_BASE_DIR/gemtext" -type f -name \*.gmi.tpl)
 
     wait
     log INFO "Converted $num_tpl_files template files"
 }
 
-template::_generate () {
+template::_generate_file () {
     local -r tpl_path="$1"; shift
     local -r tpl_dir="$(dirname "$tpl_path")"
     local -r tpl="$(basename "$tpl_path")"
@@ -23,28 +23,83 @@ template::_generate () {
     cd "$tpl_dir" || log PANIC "Unable to chdir to $tpl_dir"
     log INFO "$tpl_path -> $dest"
 
+    template::_generate < "$tpl" > "$dest.tmp"
+    mv "$dest.tmp" "$dest"
+    cd -
+}
+
+template::_generate () {
+    local is_block=no
+    local block=''
+
     while IFS='' read -r line; do
+        if [ "$is_block" = yes ]; then
+            if [ "$line" = '>>>' ]; then
+                template::_eval "$block"
+                is_block=no
+            else
+                block="$block
+$line"
+            fi
+            continue
+        fi
         case "$line" in
             '<< '*)
-                template::_line "$line"
+                template::_eval "$line"
+                ;;
+            '<<<')
+                is_block=yes
                 ;;
             *)
                 echo "$line"
                 ;;
         esac
-    done < "$tpl" > "$dest.tmp"
-
-    mv "$dest.tmp" "$dest"
-    cd -
+    done
 }
 
-template::_line () {
+template::_eval () {
     eval "${1/<< /}"
 }
 
 template::test () {
-    assert::equals "$(template::_line '<< echo -n foo')" 'foo'
-    assert::equals "$(template::_line '<< echo foo')" 'foo'
-    assert::equals "$(template::_line '<< $DATE --date @0 +%Y%m%d')" '19700101'
-    assert::equals "$(template::_line '<< echo "$AUTHOR"')" "$AUTHOR"
+    assert::equals "$(template::_eval '<< echo -n foo')" 'foo'
+    assert::equals "$(template::_eval '<< echo foo')" 'foo'
+    assert::equals "$(template::_eval '<< $DATE --date @0 +%Y%m%d')" '19700101'
+    assert::equals "$(template::_eval '<< echo "$AUTHOR"')" "$AUTHOR"
+
+    template::_eval '<< foo=bar'
+    assert::equals "$(template::_eval '<< echo $foo')" bar
+
+    local -r template1='# Hello Mister
+<<<
+    echo -n "Epoch 0 starts at: "
+    $DATE --date @0 +%Y%m%d
+    echo Just so that you know
+>>>'
+    local -r expect1='# Hello Mister
+Epoch 0 starts at: 19700101
+Just so that you know'
+    assert::equals "$(template::_generate <<< "$template1")" "$expect1"
+
+    local -r template2='<<<
+    for i in {1..10}; do
+        echo -n $i
+    done
+>>>'
+    assert::equals "$(template::_generate <<< "$template2")" 12345678910
+
+    local -r template3='<<<
+    foo=baz
+>>>
+<<<
+    echo $foo
+>>>'
+    assert::equals "$(template::_generate <<< "$template3")" baz
+
+    local -r template4='<<<
+>>>
+<<<
+>>>
+<< :'
+    assert::equals "$(template::_generate <<< "$template4")" ''
 }