add initial marp implementation with sample content and build configuration

node_modules/@marp-team/marpit/lib/helpers/inline_style.js

@@ -0,0 +1,92 @@
+"use strict";
+
+Object.defineProperty(exports, "__esModule", {
+  value: true
+});
+exports.default = void 0;
+var _postcss = _interopRequireDefault(require("postcss"));
+function _interopRequireDefault(e) { return e && e.__esModule ? e : { default: e }; }
+/**
+ * InlineStyle helper class.
+ *
+ * This is the declarative builder of an inline style using PostCSS. The output
+ * string by `toString()` is sanitized unexpected declarations.
+ *
+ * @module
+ * @alias module:helpers/inline_style
+ */
+class InlineStyle {
+  /**
+   * Create an InlineStyle instance.
+   *
+   * @function constructor
+   * @param {Object|String|InlineStyle} [initialDecls] The initial declarations.
+   */
+  constructor(initialDecls) {
+    this.decls = {};
+    if (initialDecls) {
+      if (initialDecls instanceof InlineStyle || typeof initialDecls === 'string') {
+        const root = _postcss.default.parse(initialDecls.toString(), {
+          from: undefined
+        });
+        root.each(node => {
+          if (node.type === 'decl') this.decls[node.prop] = node.value;
+        });
+      } else {
+        this.decls = {
+          ...initialDecls
+        };
+      }
+    }
+  }
+
+  /**
+   * Delete declaration.
+   *
+   * @param {string} prop A property name of declaration.
+   * @returns {InlineStyle} Returns myself for chaining methods.
+   */
+  delete(prop) {
+    delete this.decls[prop];
+    return this;
+  }
+
+  /**
+   * Set declaration.
+   *
+   * @param {string} prop A property name of declaration.
+   * @param {string} value A value of declaration.
+   * @returns {InlineStyle} Returns myself for chaining methods.
+   */
+  set(prop, value) {
+    this.decls[prop] = value;
+    return this;
+  }
+
+  /**
+   * Build a string of declarations for the inline style.
+   *
+   * The unexpected declarations will strip to prevent a style injection.
+   */
+  toString() {
+    let built = '';
+    for (const prop of Object.keys(this.decls)) {
+      let parsed;
+      try {
+        parsed = _postcss.default.parse(`${prop}:${this.decls[prop]}`, {
+          from: undefined
+        });
+      } catch {
+        // A declaration that have value it cannot parse will ignore.
+      }
+      if (parsed) {
+        parsed.each(node => {
+          if (node.type !== 'decl' || node.prop !== prop) node.remove();
+        });
+        built += `${parsed.toString()};`;
+      }
+    }
+    return built;
+  }
+}
+exports.default = InlineStyle;