Add: meta-parser

js/meta-parser.js

@@ -0,0 +1,46 @@
+/* global usercssMeta colorConverter */
+'use strict';
+
+// eslint-disable-next-line no-var
+var metaParser = (() => {
+  const parser = usercssMeta.createParser({
+    validateVar: {
+      select: state => {
+        if (state.value !== null && state.varResult.options.every(o => o.name !== state.value)) {
+          throw new Error('select value mismatch');
+        }
+      },
+      color: state => {
+        if (state.value !== null) {
+          colorConverter.format(colorConverter.parse(state.value), 'rgb');
+        }
+      }
+    }
+  });
+  return {parse, nullifyInvalidVars};
+
+  function parse(text, indexOffset) {
+    try {
+      return parser.parse(text);
+    } catch (err) {
+      if (typeof err.index === 'number') {
+        err.index += indexOffset;
+      }
+      throw err;
+    }
+  }
+
+  function nullifyInvalidVars(vars) {
+    for (const va of Object.values(vars)) {
+      if (va.value === null) {
+        continue;
+      }
+      try {
+        parser.validateVar(va);
+      } catch (err) {
+        va.value = null;
+      }
+    }
+    return vars;
+  }
+})();