feat: output metadata (closes #7 and #20)

docs/output-metadata.md

@@ -0,0 +1,47 @@
+# Output metadata
+The output metadata consists of a JSON file with the structure shown below. It is loosely based on [Google emoji metadata](https://github.com/googlefonts/emoji-metadata).
+
+```json
+[
+    {
+        "group": "group_name",
+        "emojis": [
+            // Emoji objects
+        ]
+    }
+]
+```
+
+## Emoji object
+### Required fields
+- `src` is the path to the emoji image
+- `description` is a string
+
+### Optional fields
+- `shortcodes` can be an array of strings, or an empty array
+- `codepoint` and `root_codepoint` can be an array of numbers, or an empty array
+- `category` can be an array of strings, or an empty array
+
+```json
+{
+    "codepoint": [
+        9996,
+        8205,
+        128994
+    ],
+    "root_codepoint": [
+        9996
+    ],
+    "src": "expressions/skintones/human/victory_hand_g",
+    "shortcodes": [
+        ":victory_hand_g:",
+        ":v_g:"
+    ],
+    "category": [
+        "expressions",
+        "skintones",
+        "human"
+    ],
+    "description": "something"
+},
+```

sample-input/emoji/hands/hands.toml

@@ -47,6 +47,7 @@ description = "something"
 tags = [ "extra" ]
 shortcodes = [ "victory_hand%shortcode", "v%shortcode" ]
 codepoint = [ "U+270C", "$zwj", "%codepoint" ]
+root_codepoint = [ "U+270C" ]
 colormaps = [ "$skintones.extra" ]
 
 [[emoji]]
@@ -55,6 +56,7 @@ name = "Victory hand (human)"
 category = [ "expressions", "skintones", "human" ]
 description = "something"
 tags = [ "unicode" ]
-codepoint = [ "U+270C", "$vs16" ]
+codepoint = [ "U+270C" ]
+root_codepoint = [ "U+270C" ]
 shortcodes = [ "victory_hand", "v" ]
 colormaps = [ "%skintones.default" ]

src/load/manifest.rs

@@ -68,6 +68,7 @@ pub struct Emoji {
     pub description: String,
     pub tags: Vec<String>,
     pub codepoint: Option<Vec<String>>,
+    pub root_codepoint: Option<Vec<String>>,
     pub shortcodes: Vec<String>,
     pub colormaps: Vec<String>,
 }
@@ -380,7 +381,28 @@ impl Pack {
                                 .map(|c| match c.as_str() {
                                     Some(c) => c.to_string(),
                                     None => panic!(
-                                        "Emoji codepoint is not a string in {:?}",
+                                        "Emoji 'codepoint' component is not a string in {:?}",
+                                        manifest_path
+                                    ),
+                                })
+                                .collect(),
+                        ),
+                        None => None,
+                    };
+
+                    let root_codepoint: Option<Vec<String>> = match emoji.get("root_codepoint") {
+                        Some(codepoint) => Some(
+                            codepoint
+                                .as_array()
+                                .expect(&format!(
+                                    "Emoji 'root_codepoint' is not an array in {:?}",
+                                    manifest_path
+                                ))
+                                .iter()
+                                .map(|c| match c.as_str() {
+                                    Some(c) => c.to_string(),
+                                    None => panic!(
+                                        "Emoji 'root_codepoint' component is not a string in {:?}",
                                         manifest_path
                                     ),
                                 })
@@ -400,7 +422,7 @@ impl Pack {
                             .map(|s| match s.as_str() {
                                 Some(s) => s.to_string(),
                                 None => {
-                                    panic!("Emoji contains invalid shortcode (must be a string) in {:?}", manifest_path)
+                                    panic!("Emoji contains invalid 'shortcode' (must be a string) in {:?}", manifest_path)
                                 }
                             })
                             .collect(),
@@ -418,7 +440,7 @@ impl Pack {
                             .map(|c| match c.as_str() {
                                 Some(c) => c.to_string(),
                                 None => {
-                                    panic!("Emoji colormap is not a string in {:?}", manifest_path)
+                                    panic!("Emoji 'colormap' is not a string in {:?}", manifest_path)
                                 }
                             })
                             .collect(),
@@ -433,6 +455,7 @@ impl Pack {
                         category,
                         tags,
                         codepoint,
+                        root_codepoint,
                         shortcodes,
                         colormaps,
                     });

src/process/metadata.rs

@@ -11,7 +11,8 @@ struct Group {
 
 #[derive(Serialize)]
 struct Emoji {
-    base: Option<Vec<usize>>,
+    codepoint: Option<Vec<u64>>,
+    root_codepoint: Option<Vec<u64>>,
     src: Option<String>,
     shortcodes: Vec<String>,
     category: Vec<String>,
@@ -27,13 +28,26 @@ pub fn generate_metadata(emojis: &Vec<EmojiEncoded>) -> String {
             groups.insert(group.clone(), Vec::new());
         }
 
-        let base: Option<Vec<usize>> = match emoji.emoji.codepoint.as_ref() {
+        let codepoint: Option<Vec<u64>> = match emoji.emoji.codepoint.as_ref() {
             Some(codepoint) => Some(
                 codepoint
                     .iter()
                     .map(|codepoint| {
                         let codepoint = codepoint.replace("U+", "");
-                        usize::from_str_radix(&codepoint, 16).unwrap()
+                        u64::from_str_radix(&codepoint, 16).unwrap()
+                    })
+                    .collect(),
+            ),
+            None => None,
+        };
+
+        let root_codepoint: Option<Vec<u64>> = match emoji.emoji.root_codepoint.as_ref() {
+            Some(codepoint) => Some(
+                codepoint
+                    .iter()
+                    .map(|codepoint| {
+                        let codepoint = codepoint.replace("U+", "");
+                        u64::from_str_radix(&codepoint, 16).unwrap()
                     })
                     .collect(),
             ),
@@ -48,7 +62,8 @@ pub fn generate_metadata(emojis: &Vec<EmojiEncoded>) -> String {
             .collect();
 
         let emoji = Emoji {
-            base,
+            codepoint,
+            root_codepoint: root_codepoint,
             src: emoji.filename.clone(),
             category: emoji.emoji.category.clone(),
             shortcodes,